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The Carbon Isotope Fluctuations across the Lower–Middle Jurassic Boundary and the Paleoclimate Changes 预览
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作者 YI Haisheng XIA Guoqing +5 位作者 LI Gaojie YI Fan ZHANG Shuai CAI Zhanhu JIAO Haijing WU Chihua 《地质学报:英文版》 SCIE CAS CSCD 2019年第1期244-245,共2页
The Qiangtang Basin of Tibetan Plateau most widely outcrops marine Jurassic strata in China,even in eastern Asian,and the Jurassic strata and ammonites’occurrence are in favor of researching evolution of paleoceanogr... The Qiangtang Basin of Tibetan Plateau most widely outcrops marine Jurassic strata in China,even in eastern Asian,and the Jurassic strata and ammonites’occurrence are in favor of researching evolution of paleoceanography in the Tethyan region and global stratigraphic comparison.This work focused on the carbon isotope changes across the J I–J 2 boundary in the eastern Tethys region. 展开更多
关键词 CARBON STRATA Plateau marine CARBON most
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柴油机装车实际高原环境应用特征分析及验证用试验循环开发 预览
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作者 冀树德 杨天军 +6 位作者 刘逢春 唐智 孔祥鑫 杨文影 魏鹏程 贾晓亮 康佐明 《车用发动机》 北大核心 2019年第3期46-51,共6页
以三型柴油机为对象,基于跟踪记录的道路载荷数据,分析了柴油机装车在实际高原环境条件行驶呈现的主要特征,并就台架验证不充分的问题设计了高原台架模拟的试验循环。结果表明,柴油机在海拔4300m以上实际高原环境地区的运行主要集中在... 以三型柴油机为对象,基于跟踪记录的道路载荷数据,分析了柴油机装车在实际高原环境条件行驶呈现的主要特征,并就台架验证不充分的问题设计了高原台架模拟的试验循环。结果表明,柴油机在海拔4300m以上实际高原环境地区的运行主要集中在中高转速中高负荷区域,运行转速、排气温度、冷却水温度等参数存在较为严重的超限行为,其中柴油机冷却水温约70%以上时间处于超限状态。此外,柴油机主要工作在大于50%输出功率的区间,高原使用时增压比偏大。设计的高原台架模拟试验循环为600s的瞬态试验循环,可表征柴油机装车后高原使用时的运行行为。 展开更多
关键词 柴油机 高原 运行特征 试验循环
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Anthropogenic Aerosol Pollution over the Eastern Slope of the Tibetan Plateau 预览
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作者 Rui JIA Min LUO +4 位作者 Yuzhi LIU Qingzhe ZHU Shan HUA Chuqiao WU Tianbin SHAO 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第8期847-862,共16页
In this study, a combination of satellite observations and reanalysis datasets is used to analyze the spatiotemporal distribution, classification and source of pollutants over the eastern slope of the Tibetan Plateau(... In this study, a combination of satellite observations and reanalysis datasets is used to analyze the spatiotemporal distribution, classification and source of pollutants over the eastern slope of the Tibetan Plateau(ESTP). The aerosol optical depth(AOD) over the ESTP is extremely large and even larger than some important industrialized regions and deserts. The main aerosol component over the ESTP is sulfate, followed by carbonaceous and dust aerosols. Local emissions related to human activity directly contribute to the accumulation of sulfate and carbonaceous aerosols over the Sichuan Basin. In addition, in spring, abundant carbonaceous aerosols emitted from forest, grassland and savanna fires in Southeast Asia can be transported by the prevailing southwesterly wind to southern China and the ESTP. The dust AOD over the ESTP peaks in spring because of the transport from the Taklimakan and Gobi deserts. Additionally, the high aerosol loading over the ESTP is also directly related to the meteorological background. Due to the special topography, the terrain-driven circulation can trap aerosols in the Sichuan Basin and these aerosols can climb along the ESTP due to the perennial updraft. The aerosol loading is lowest in summer because of effective wet deposition induced by the strong precipitation and better dispersion conditions due to the larger vertical temperature gradients and ascending air movement enhanced by the plateau heat pump effect. In contrast,the aerosol loading is greatest in winter. Abundant anthropogenic aerosols over the ESTP may generate some climatic and environmental risks and consequently greatly influence the downstream regions. 展开更多
关键词 eastern SLOPE of the TIBETAN PLATEAU ANTHROPOGENIC AEROSOLS dust
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Continental drift, plateau uplift, and the evolutions of monsoon and arid regions in Asia, Africa, and Australia during the Cenozoic
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作者 Xiaodong LIU Buwen DONG +2 位作者 Zhi-Yong YIN Robin S. SMITH Qingchun GUO 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第7期1053-1075,共23页
Monsoon and arid regions in the Asia-Africa-Australia (A-A-A) realm occupy more than 60% of the total area of these continents. Geological evidence showed that significant changes occurred to the A-A-A environments of... Monsoon and arid regions in the Asia-Africa-Australia (A-A-A) realm occupy more than 60% of the total area of these continents. Geological evidence showed that significant changes occurred to the A-A-A environments of the monsoon and arid regions, the land-ocean configuration in the Eastern Hemisphere, and the topography of the Tibetan Plateau (TP) in the Cenozoic. Motivated by this background, numerical experiments for 5 typical geological periods during the Cenozoic were conducted using a coupled ocean-atmosphere general circulation model to systemically explore the formations and evolutionary histories of the Ceno zoic A-A-A monso on and arid regions un der the influences of contine ntal drift and plateau uplift. Results of the nu merical experime nts indicate that the timings and causes of the formations of monsoon and arid regi ons in the A-A-A realm were very different. The northern and southern African monsoons existed during the mid-Paleocene, while the South Asian monsoon appeared in the Eocene after the Indian Subcontinent moved into the tropical Northern Hemisphere. In contrast, the East Asian mon soon and northern Australian monso on were established much later in the Miocene. The establishment of the tropical monsoons in northern and southern Africa, South Asia, and Australia were determined by both the continental drift and seas onal migratio n of the In ter-Tropical Convergence Zone (ITCZ), while the position and height of the TP were the key factor for the establishment of the East Asian monsoon. The presence of the subtropical arid regions in northern and southern Africa, Asia, and Australia depended on the positions of the continents and the control of the planetary scale subtropical high pressure zones, while the arid regions in the Arabian Peninsula and West Asia were closely related to the retreat of the Paratethys Sea. The formation of the mid-latitude arid region in the Asian interior, on the other hand, was the consequence of the uplift of the TP. These results from this study provide insi 展开更多
关键词 CENOZOIC MONSOON REGION ARID REGION Continental drift Tibetan Plateau UPLIFT Climate simulation
Quantitative indicative significance of pollen assemblages on vegetation coverage in deciduous Quercus forest in the central Loess Plateau, China
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作者 Yuanhao SUN Shengrui ZHANG +5 位作者 Qinghai XU Yiwen LI Wei SHEN Tao WANG Zhongze ZHOU Ruchun ZHANG 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第6期992-1001,共10页
We compared the pollen assemblages of surface moss samples and corresponding vegetation inventory data from 34 sites in the Huangling region of the central Loess Plateau. Our aims were to determine the characteristics... We compared the pollen assemblages of surface moss samples and corresponding vegetation inventory data from 34 sites in the Huangling region of the central Loess Plateau. Our aims were to determine the characteristics of the pollen assemblages from the deciduous broadleaved forest climax community and its significance in terms of vegetation type and species composition. The pollen assemblages are dominated by woody plants such as Quercus(42% of total terrestrial pollen),Betula(16%) and Pinus(12%), with minor differences between different plant communities. The pollen assemblages of individual sampling sites differed from the vegetation composition within the 0–100 m scope and were more similar to the vegetation coverage within the 0–1000 m scope. This indicates that the surface pollen assemblages mainly reflect the comprehensive information from the vegetation composition of a large area, rather than the vegetation composition close to the sampling site. The contents of Quercus, Betula and Pinus pollen are high, and close to their vegetation coverage;whereas the contents of deciduous broadleaved arbor taxa(such as Malus and Acer) are lower, but their corresponding regional vegetation cover is higher. This suggests that the vegetation information conveyed by poorly-represented pollen taxa should be considered when interpreting stratigraphic pollen assemblages. Using the observed quantitative relationships between pollen and vegetation of the main taxa, we reconstructed the regional vegetation composition in the Gonghai Lake area of the northeastern Loess Plateau during the middle Holocene(7300–5000 yr BP). The results indicated that Quercus-dominated deciduous broadleaved forest climax community developed in the mountains surrounding the lake. 展开更多
关键词 Loess Plateau DECIDUOUS broadleaved FOREST CLIMAX community POLLEN assemblage Absolute vegetation coverage
Outcome of complex tibial plateau fractures with Ilizarov external fixation with or without minimal internal fixation
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作者 Koushik Narayan Subramanyam Madhusudhan Tammanaiah +2 位作者 Abhishek Vasant Mundargi Ritesh Nilakanthrao Bhoskar Patllola Siddharth Reddy 《中华创伤杂志:英文版》 CAS CSCD 2019年第3期166-171,共6页
Purpose: To evaluate the clinico-radiological outcome of complex tibial plateau fractures treated with Ilizarov external fixation with or without minimal internal fixation. Methods: This retrospective review was condu... Purpose: To evaluate the clinico-radiological outcome of complex tibial plateau fractures treated with Ilizarov external fixation with or without minimal internal fixation. Methods: This retrospective review was conducted on all the cases of Schatzker types V and VI tibial plateau fractures treated by Ilizarov external fixation between July 2006 and December 2015 with the minimum follow-up duration of one year. There were 30 patients: 24 males and 6 females, mean age 43.33 years, and mean follow-up 3.6 years. Three of them were open fractures;15 cases were Schatzkertype V fractures and the other 15 type VI. According to AO/OTA classification, there were 11 type C1, 12 C2 and 7 type C3 fractures. Outcome assessment was made with American Knee Society Score (AKSS) and Rasmussen's Radiological Score (RRS) at final follow-up. Results: Out of the 30 cases, mini-open reduction was performed in 7, bone graft in 4, minimal internal fixation in 10 and knee temporary immobilisation in 11 patients. Mean duration of external fixation was 11.8 weeks. All fractures united. Pin tract infections in 7 and common peroneal neuropathy in 2 patients were self-limiting. Two patients had axial misalignment of less than 10°. At final follow-up, the mean knee range of motion was 114.7, mean AKSS 81.5 and mean RRS 16.7. On statistical analysis, Schatzker type of fractures, use of minimal internal fixation and knee-spanning did not influence the final outcome. Conclusion: Ilizarov external fixator with or without minimal internal fixation provides acceptable outcome for complex tibial plateau fractures. Care must be taken to look for minor loss of alignment, especially in Type VI Schatzker fractures after removal of the fixator. However small sample size precludes firm conclusions. 展开更多
关键词 TIBIAL plateau FRACTURES Schatzker's classification ILIZAROV techniques Ring FIXATOR
An Untouched Natural Paradise 预览
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作者 JIAO FENG 《今日中国:英文版》 2019年第6期74-77,共4页
HOH Xil Nature Reserve,“Hoh Xil” meaning ‘beautiful girl’ in Mongolian, is located in the hinterland of the Qinghai-Tibet Plateau. Because of its harsh natural environment, no people live here. Therefore it’s als... HOH Xil Nature Reserve,“Hoh Xil” meaning ‘beautiful girl’ in Mongolian, is located in the hinterland of the Qinghai-Tibet Plateau. Because of its harsh natural environment, no people live here. Therefore it’s also known as the “forbidden zone for humans” or “mysterious land.” It is one of the regions on earth that humans have little knowledge of, thus preserving it as an untouched natural paradise. Located in the northeastern corner of the Qinghai- Tibet Plateau, Hoh Xil Nature Reserve covers a large area of mountains and grassland at an altitude of more than 4,500 meters above sea level. 展开更多
关键词 NATURAL PARADISE Qinghai-Tibet PLATEAU
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What is the mass of loess in the Loess Plateau of China?
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作者 Yuanjun Zhu Xiaoxu Jia +1 位作者 Jiangbo Qiao Ming’an Shao 《科学通报:英文版》 SCIE EI CSCD 2019年第8期534-539,共6页
The Loess Plateau of China(LP) has the largest and thickest loess deposits in the world. Quantifying the amount of loess in the LP is crucial for investigating the accumulation and erosion of loess, and determining th... The Loess Plateau of China(LP) has the largest and thickest loess deposits in the world. Quantifying the amount of loess in the LP is crucial for investigating the accumulation and erosion of loess, and determining the regional soil and water resource capacity. We used loess thickness data, a pedotransfer function for bulk density(BD), and the clay content data observed in 242 sites across the LP to derive the BD of loess and then estimate the loess mass and its distribution across the LP. The results indicated that the average BD of loess between the surface and bedrock is 1.58 g cm-3, varying from 1.18 to 1.87 g cm-3.The total loess mass is approximately 5.45 ? 1013 t, and the average loess mass over an area of 1 m2 is 169 t, ranging from 1.36 to 585 t. The greatest mass of loess is in the south-central of the LP while the lowest mass of loess is in the northwest and river valley areas. Our estimate of loess mass provides key data for calculating water, carbon, and nutrient storages in the LP, which improves our understanding of soil-water processes and ecohydrological systems in this landscape. 展开更多
关键词 The LOESS PLATEAU LOESS MASS Pedotransfer function Soil EROSION BULK density
THE IMPACT OF MOUNTAIN TO BASIN WINDS ON THE DIURNAL VARIATION IN FOG OVER THE SICHUAN BASIN, CHINA
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作者 张福颖 刘海文 +3 位作者 朱玉祥 赵亮 段伯隆 傅宁 《热带气象学报:英文版》 SCIE 2019年第2期257-268,共12页
There is an increased demand for the accurate prediction of fog events in the Sichuan Basin(SCB) using numerical methods. A dense fog event that occurred over the SCB on 22 December 2016 was investigated. The results ... There is an increased demand for the accurate prediction of fog events in the Sichuan Basin(SCB) using numerical methods. A dense fog event that occurred over the SCB on 22 December 2016 was investigated. The results show that this dense fog event was influenced by the southwest of a low pressure with a weak horizontal pressure gradient and high relative humidity. This fog event showed typical diurnal variations. The fog began to form at 1800 UTC on 21 December 2016(0200 local standard time on 22 December 2016) and dissipated at 0600 UTC on 22 December 2016(1400 local standard time on 22 December 2016). The Weather Research and Forecasting model was able to partially reproduce the main features of this fog event and the diurnal variation in the local mountain to basin winds. The simulated horizontal visibility and liquid water content were used to characterize the fog. The mountain to basin winds had an important role in the diurnal variation of the fog event. The positive feedback mechanism between the fog and mountain to basin winds was good for the formation and maintain of the fog during the night. During the day, the mountain to basin wind displayed a transition from downslope flows to upslope flows. Water vapor evaporated easily from the warm, strong upslope winds, which resulted in the dissipation of fog during the day. The topography surrounding the SCB favored the lifting and condensation of air parcels in the lower troposphere as a result of the low height of the lifting condensation level. 展开更多
关键词 MOUNTAIN to BASIN winds FOG EVENTS weather research and forecasting simulations TIBETAN PLATEAU
Geomorphic features of Quaternary glaciation in the Taniantaweng Mountain, on the southeastern Qinghai-Tibet Plateau
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作者 ZHANG Wei CHAI Le +5 位作者 IAN S.Evans LIU Liang LI Ya-peng QIAO Jing-ru TANG Qian-yu SUN Bo 《山地科学学报:英文版》 SCIE CSCD 2019年第2期256-274,共19页
We present geomorphological evidence for multiple glacial fluctuations during the Quaternary in the Taniantaweng Mountain, which is situated at the transition zone of the southeastern Qinghai-Tibet Plateau and the Yun... We present geomorphological evidence for multiple glacial fluctuations during the Quaternary in the Taniantaweng Mountain, which is situated at the transition zone of the southeastern Qinghai-Tibet Plateau and the Yunnan-Guizhou Plateau. To reconstruct the history of glacial evolution during the Quaternary Glaciation, we present a ~13000 km~2 geomorphologic map(1:440,000) for the Quaternary glaciations, as well as three electron spin resonance(ESR) ages and three optically stimulated luminescence(OSL) ages from the landforms. By integrating these with ages from previous studies, four major glacial advances are identified during marine oxygen isotope stages(MIS) 6, 3, 2 and 1. This glacial chronology is in reasonable agreement with existing glacial chronologies from other parts of the Hengduan Mountains and surrounding mountains. Glaciers had extended to the Yuqu River during the glacial maximum advance(MIS 6), but became successively more restricted from MIS 3 to MIS 1. The glacial distribution show that precipitation brought by the south Asian monsoon might play a primary role in driving glacial advances during the last glacial period in the southeastern Qinghai-Tibet Plateau. 展开更多
关键词 Qinghai-Tibet Plateau Taniantaweng MOUNTAIN GLACIAL LANDFORM ESR DATING OSL DATING South Asian monsoon
Spatio-temporal evolution of ecologically-sustainable land use in China’s Loess Plateau and detection of its influencing factors
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作者 QU Lu-lu LIU Yan-sui CHEN Zong-feng 《山地科学学报:英文版》 SCIE CSCD 2019年第5期1065-1074,共10页
Ecological land(Eco-land) is a basic resource for human beings to survive, and eco-land use is a strategy, a way to manage the land resource. So, ecologically-sustainable land use is essential for human beings to surv... Ecological land(Eco-land) is a basic resource for human beings to survive, and eco-land use is a strategy, a way to manage the land resource. So, ecologically-sustainable land use is essential for human beings to survive. This paper investigates the spatiotemporal characteristics and mechanisms of urban-rural eco-land using a new and innovative integration way based on eco-land change data in China’s Loess Plateau(LP) prefecture level cities and explores factors of eco-land change. The spatial difference characteristic of eco-land among different level cities in the LP is that: small cities > big cities > middle cities. From 2009 to 2016, the eco-land in the LP from the perspective of urban-rural areas has changed significantly. Significant differences of urban-rural eco-land were identified among various urban growth types, and all the cities in the LP were further classified into four types based on eco-land change trend, with type A and B cities identified as the vital zone and major zone. Taking the eco-fragile region Loess Plateau(LP) as an example, our results demonstrated that the migrants to cities in LP could relieve ecological pressures and promote restoration of ecological vegetation. We have demonstrated that urbanization and the influence of government policy can be discerned through the quantification of the spatial-temporal change of eco-land and suggest that combining both urban and rural eco-land can support more effective land use decisions and provide theoretical basis for the practical application of urban planning, policy-making and sustainable development. What’s more, governments should strive to population mobility and restore vegetation to sustain this fragile ecological environment. 展开更多
关键词 Ecologically-sustainable land use SPATIO-TEMPORAL EVOLUTION influencing factor Population migration LOESS PLATEAU
Thermal dynamics of the permafrost active layer under increased precipitation at the Qinghai-Tibet Plateau
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作者 LI De-sheng WEN Zhi +3 位作者 CHENG Qian-gong XING Ai-guo ZHANG Ming-li LI An-yuan 《山地科学学报:英文版》 SCIE CSCD 2019年第2期309-322,共14页
Precipitation has a significant influence on the hydro-thermal state of the active layer in permafrost regions, which disturbs the surface energy balance, carbon flux, ecosystem, hydrological cycles and landscape proc... Precipitation has a significant influence on the hydro-thermal state of the active layer in permafrost regions, which disturbs the surface energy balance, carbon flux, ecosystem, hydrological cycles and landscape processes. To better understand the hydro-thermal dynamics of active layer and the interactions between rainfall and permafrost, we applied the coupled heat and mass transfer model for soil-plant-atmosphere system into high-altitude permafrost regions in this study. Meteorological data, soil temperature, heat flux and moisture content from different depths within the active layer were used to calibrate and validate this model. Thereafter, the precipitation was increased to explore the effect of recent climatic wetting on the thermal state of the active layer. The primary results demonstrate that the variation of active layer thickness under the effect of short-term increased precipitation is not obvious, while soil surface heat flux can show the changing trends of thermal state in active layer, which should not be negligible. An increment in year-round precipitation leads to a cooling effect on active layers in the frozen season, i.e. verifying the insulating effect of 'snow cover'. However, in the thawed season, the increased precipitation created a heating effect on active layers, i.e. facilitating the degradation of permafrost. The soil thermal dynamic in single precipitation event reveals that the precipitation event seems to cool the active layer, while compared with the results under increased precipitation, climatic wetting trend has a different influence on the permafrost evolution. 展开更多
关键词 Active layer PRECIPITATION Qinghai-Tibet PLATEAU Hydro-thermal dynamic
承载力自平衡测试技术在高原高海拔地区的应用 预览
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作者 谢礼飞 丁俊跃 陈怡坛 《工程建设与设计》 2019年第7期63-64,67共3页
拉萨贡嘎机场航站区改扩建工程项目位于西藏自治区山南地区贡嘎县,平均海拔为3 564m,属高原高海拔地区,工程建设条件恶劣。本项目桩基采用桩端后压浆技术提高承载力,但受现场环境条件限制,不具备采用传统堆载法进行大吨位承载力测试的... 拉萨贡嘎机场航站区改扩建工程项目位于西藏自治区山南地区贡嘎县,平均海拔为3 564m,属高原高海拔地区,工程建设条件恶劣。本项目桩基采用桩端后压浆技术提高承载力,但受现场环境条件限制,不具备采用传统堆载法进行大吨位承载力测试的条件。自平衡法是近些年出现的一种新型承载力测试技术,具有不受试验场地、环境条件和加载吨位限制等优点,尤其适合于传统静载试验难以开展的桩基承载力检测。本项目依据JGJ/T 403-2017《建筑基桩自平衡静载实验技术规程》,成功进行了试桩承载力自平衡测试。 展开更多
关键词 自平衡法 桩基检测 承载力 高原 高海拔
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Review on simulation of land-surface processes on the Tibetan Plateau 预览
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作者 Rui Chen MeiXue Yang +1 位作者 XueJia Wang GuoNing Wan 《寒旱区科学:英文版》 CSCD 2019年第2期93-115,共23页
The Tibetan Plateau (TP) has powerful dynamics and thermal effects, which makes the interaction between its land and atmosphere significantly affect climate and environment in the regional or global area. By retrospec... The Tibetan Plateau (TP) has powerful dynamics and thermal effects, which makes the interaction between its land and atmosphere significantly affect climate and environment in the regional or global area. By retrospecting the latest research progress in the simulation of land-surface processes (LSPs) over the past 20 years, this study discusses both the simulation ability of land-surface models (LSMs) and the modification of parameterization schemes from two perspectives, the models' applicability and improved parameterization schemes. Our review suggests that different LSMs can well capture the spatiotemporal variations of the physical quantities of LSPs;but none of them can be fully applied to the plateau, meaning that all need to be revised according to the characteristics specific to the TP. Avoiding the unstable iterative computation and determining the freeze?thaw critical temperature according to the thermodynamic equilibrium equation, the unreasonable freeze?thaw parameterization scheme can be improved. Due to the complex underlying surface of the TP, no parameterization scheme of roughness length can well simulate the various characteristics of the turbulent flux over the TP at different temporal scales. The uniform soil thermodynamic and hydraulic parameterization scheme is unreasonable when it is applied to the plateau, as a result of the strong soil heterogeneity. There is little research on the snow-cover process so far, and the improved scheme has no advantage over the original one due to the lack of some related physical processes. The constant interaction among subprocesses of LSPs makes the improvement of a multiparameterization scheme yield better simulation results. According to the review of existing research, adding high-quality observation stations, developing a parameterization scheme suitable for the special LSPs of the TP, and adjusting the model structures can be helpful to the simulation of LSPs on the TP. 展开更多
关键词 TIBETAN PLATEAU land - ATMOSPHERE interaction LAND-SURFACE models model APPLICABILITY parameterized MODIFICATION
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Analysis of vegetation changes and dominant factors on the Qinghai-Tibet Plateau, China 预览
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作者 HongWei Wang Yuan Qi +3 位作者 ChunLin Huang XiaoYing Li XiaoHong Deng JinLong Zhang 《寒旱区科学:英文版》 CSCD 2019年第2期150-158,共9页
This research was undertaken to clarify the characteristics of vegetation change and its main influencing factors on the Qinghai-Tibet Plateau. Using the greenness rate of change (GRC) and correlation factors, we anal... This research was undertaken to clarify the characteristics of vegetation change and its main influencing factors on the Qinghai-Tibet Plateau. Using the greenness rate of change (GRC) and correlation factors, we analyzed the trend of vegetation change and its dominant factors from 2000 to 2015. The results indicate that the vegetation tended to improve from 2000 to 2015 on the Qinghai-Tibet Plateau, with the improved area accounting for 39.93% of the total;and the degraded area accounting for 19.32%. The areas of degraded vegetation are mainly concentrated in the low-relief and intermediate- relief mountains of the high-altitude and extremely high-altitude areas on the Qinghai-Tibet Plateau, as the vegetation characteristics are impacted by the terrain. Temperature and precipitation have obvious response mechanisms to vegetation growth, but the effects of precipitation and temperature on vegetation degradation are not significant over a short time frame. Overgrazing and population growth are the dominant factors of vegetation degradation on the Qinghai-Tibet Plateau. 展开更多
关键词 Qinghai-Tibet PLATEAU REMOTE SENSING VEGETATION activity degraded DOMINANT factors
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高原核桃采穗圃营建技术试验 预览
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作者 廖东 刘小利 +1 位作者 乔维范 耶芳芳 《青海大学学报:自然科学版》 2019年第3期34-40,共7页
为满足核桃良种推广需求,解决高原地区穗条成熟时间晚于嫁接时间的供需矛盾,以辽宁1号核桃良种建立采穗圃,研究了采穗母株截顶定干、短截促萌和肥水管理对穗条促成的影响。结果表明:采穗母树定植后截顶定干,萌芽率和成枝率分别可达83.45... 为满足核桃良种推广需求,解决高原地区穗条成熟时间晚于嫁接时间的供需矛盾,以辽宁1号核桃良种建立采穗圃,研究了采穗母株截顶定干、短截促萌和肥水管理对穗条促成的影响。结果表明:采穗母树定植后截顶定干,萌芽率和成枝率分别可达83.45%和85.14%。第二年春季萌动时对主枝进行留桩15 cm短截,可作接穗枝的长度和比率分别达54.47 cm和89.43%。采穗前追施复合肥和氮肥2~3次以上,枝条长度可达121.67 cm,粗度达1.21 cm,可作接穗枝的长度达77.40 cm,每公顷产量达12 510条,穗条促成效果明显。对采穗圃中采穗母株产穗能力和穗条质量进行比较,明确了高原核桃采穗圃穗条促成条件。 展开更多
关键词 高原 辽宁1号核桃 采穗圃 营建
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“高原丝绸之路”路网结构的考古学构建与文化内涵 预览
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作者 余小洪 《西藏民族大学学报:哲学社会科学版》 CSSCI 2019年第2期21-27,153共8页
考古发现证明汉晋时期'高原丝绸之路'已正式开通,汉唐时期的'高原丝绸之路'经历了初创、形成、繁荣三个发展阶段。在早期通道基础上,汉晋时期形成了东、南、北三条通道;唐代吐蕃时期形成了东、西、南、北四条通道,'... 考古发现证明汉晋时期'高原丝绸之路'已正式开通,汉唐时期的'高原丝绸之路'经历了初创、形成、繁荣三个发展阶段。在早期通道基础上,汉晋时期形成了东、南、北三条通道;唐代吐蕃时期形成了东、西、南、北四条通道,'高原丝绸之路'的路网结构全面形成,影响至今。在'高原丝绸之路'的初创、形成阶段,西藏高原与周边地区的文化交流,以物质文化交流为主,精神文化交流为辅,文化交流的层次较低;在'高原丝绸之路'的繁荣阶段,西藏高原与周边地区的文化交流是全方位的,文化交流的层次提高。 展开更多
关键词 高原 丝绸之路 路网结构 层次
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Baossi-Warack monogenetic volcanoes,Adamawa Plateau,Cameroon:petrography,mineralogy and geochemistry
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作者 Anicet Feudjio Tiabou Robert Temdjim +5 位作者 Pierre Wandji Jacques-Marie Bardintzeff Vivian Bih Che Edith Ekatah Bate Tibang Caroline Neh Ngwa Francois Xavier Onana Mebara 《中国地球化学学报:英文版》 EI CAS CSCD 2019年第1期40-67,共28页
Three monogenetic cones in the Baossi-Warack area,Ngaoundere,Adamawa Plateau forming part of the Cameroon Volcanic Line (CVL)are documented in this study.Basaltic lavas (<1 km^3)scattered around these vents and res... Three monogenetic cones in the Baossi-Warack area,Ngaoundere,Adamawa Plateau forming part of the Cameroon Volcanic Line (CVL)are documented in this study.Basaltic lavas (<1 km^3)scattered around these vents and restricted volcaniclastic deposits were emplaced by Hawaiian and mild strombolian style eruptions.The lavas are porphyritic,mainly composed of olivine (chrysolite)and clinopyroxene (diopside and augite)phenocrysts and plagioclase (andesine)microphenocrysts.Accessory minerals include titano-magnetite and titano-hematite,nepheline,apatite and amphibole xenocrysts.Sanidine occurs in some samples and sodi-potassic albite in others.Some olivines and clinopyroxenes exhibit resorbed margins and thin reaction rims while plagioclase displays oscillatory zoning,and sieved textures as a result of magma mixing.Whole-rock geochemistry data indicates that the lavas are silica-under-saturated,composed of basanites and basalts,showing little compositional variations (SiO2:39.20 wt.%-48.01 wt.%,MgO:5.29 wt.%-9.70 wt.%).Trace elements patterns of these lavas suggest they are enriched in LILE including Pb,probably due to crustal contamination.REE patterns suggest cogenetic magmas below Baossi 1 and Baossi 2 volcanoes,and distinct sources below Warack volcano and nearby lavas.The lavas studied show affinity to high-μ (HIMU),enriched typeⅠ(EM1)and Oceanic Island Basalt (OIB)-like mantle signatures and thus indicate a heterogeneous mantle source underneath the vents as noted at other monogenetic and polygenetic volcanoes along the CVL.Primary melts derived from low degrees of partial melting (0.5%-2%)and encountered low rates of fractionation,and crustal contamination coupled with magma mixing.These melts evolved independently through structural weaknesses in the basement. 展开更多
关键词 Cameroon VOLCANIC line Adamawa PLATEAU VOLCANIC field Monogenetic VOLCANO Magma mixing PETROGENESIS
高原高海拔山区三角高程替代水准测量的应用 预览
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作者 吕韶超 王彩云 《价值工程》 2019年第4期182-184,共3页
由于高原高海拔地区相比平原地区气压低,日照时间长,不同时段温差较大,以及地势高,因此在高原高海拔地区进行水准测量具有大气折射变化大、大地水准面间隙变化大等特点,根据相关规范要求针对高原高海拔山区长距离三角高程替代水准测量... 由于高原高海拔地区相比平原地区气压低,日照时间长,不同时段温差较大,以及地势高,因此在高原高海拔地区进行水准测量具有大气折射变化大、大地水准面间隙变化大等特点,根据相关规范要求针对高原高海拔山区长距离三角高程替代水准测量进行了实践作业,可以有效提高作业效率,通过检核隧道进出口端高程控制点成果,消除施工安全隐患,保证测绘成果安全可靠性。 展开更多
关键词 高原 高海拔 山区 水准测量 三角高程
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常驻高原官兵心理应激及其影响因素分析 预览
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作者 杨国帅 安花花 +2 位作者 王天任 金钊 贾玉琪 《西北国防医学杂志》 CAS 2019年第5期276-280,共5页
目的:探讨高原官兵心理应激发生情况及其影响因素。方法:采用整群抽样法抽取高原驻训官兵100例,采用军人心理应激自评问卷(psychological stress self-evaluation tset,PSET)、一般自我效能感量表(general self-efficacy scale,GSES)和... 目的:探讨高原官兵心理应激发生情况及其影响因素。方法:采用整群抽样法抽取高原驻训官兵100例,采用军人心理应激自评问卷(psychological stress self-evaluation tset,PSET)、一般自我效能感量表(general self-efficacy scale,GSES)和积极情绪-消极情绪量表(positive and negative affect scale,PANAS)对其心理应激进行评估,并分析其影响因素。结果:常驻高原官兵心理应激平均得分为(16.11±3.78)分,标准分数(T)≥70分的仅有4人,占总数的4%。心理应激测评中发生频次较多的条目依次为条目4、1、7、2,经常发生的频次分别为48、22、17、15次;其他条目经常发生频次均≤5%。南方部队军人护士条目4与条目1经常发生频次较高,其他条目经常发生频次均<5%。常驻高原官兵心理应激所有条目分值均高于维和集训期官兵,条目5、6、8、9、10分值低于急进高原1周官兵(P<0.05);条目4分值高于急进高原1周官兵(P<0.05)。年龄较大、军龄较长及已婚官兵心理应激得分高于年龄较小、军龄较短及未婚官兵(均P<0.05)。自我感觉压力大及不适应环境的官兵心理应激较大。心理应激条目1、2、3、6、7与自我效能呈明显负相关;除条目4以外的其他条目与积极情绪呈明显负相关,与消极情绪呈明显正相关;心理应激总分与自我效能、积极情绪呈负相关,与消极情绪呈正相关。结论:常驻高原官兵的心理应激水平较高,与他们的年龄、军龄、压力觉察和婚姻情况等因素有关。 展开更多
关键词 心理应激 高原 长期驻训 积极情绪 消极情绪 自我效能
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