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船舶发动机结构设计发展趋势 预览
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作者 汤义虎 尤越 +2 位作者 张延亭 巫立民 梁刚 《柴油机》 2020年第1期12-17,共6页
随着船舶发动机强化指标提升,缸盖、活塞等受热零部件以及活塞环、气阀、轴瓦等关键摩擦副的工作条件更加严劣,如何保证上述零部件的可靠性是发动机设计开发的关键。从受热零部件高可靠性设计、摩擦学设计及柔性可变技术等方面介绍了船... 随着船舶发动机强化指标提升,缸盖、活塞等受热零部件以及活塞环、气阀、轴瓦等关键摩擦副的工作条件更加严劣,如何保证上述零部件的可靠性是发动机设计开发的关键。从受热零部件高可靠性设计、摩擦学设计及柔性可变技术等方面介绍了船舶发动机结构设计的最新研究进展。 展开更多
关键词 船舶发动机 零部件 摩擦学 设计 柔性可变技术
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Effects of Tidal Channels and Roads on Landscape Dynamic Distribution in the Yellow River Delta,China 预览
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作者 YU Xiaojuan ZHANG Zhongsheng +2 位作者 XUE Zhenshan WU Haitao ZHANG Hongri 《中国地理科学:英文版》 SCIE CSCD 2020年第1期170-179,共10页
Landscape characters in estuarine regions generally controlled by tidal regimes and human activities like road construction.In this work,tidal channels and road construction in the Yellow River Delta(YRD)were extracte... Landscape characters in estuarine regions generally controlled by tidal regimes and human activities like road construction.In this work,tidal channels and road construction in the Yellow River Delta(YRD)were extracted by visual interpretation methods so as to decipher impacts of tidal channel development and road construction on landscape patch change during 1989–2016.Spatial distribution history of three wetlands,which covered by Phragmites australis(freshwater marsh,FM),Suaeda salsa(salt marsh,SM),and mudflats(MD)were also established.Results indicated that tidal channel,number,frequency,and fractal dimension were all the maximum in 2003,and the minimum in 1998,respectively.Road length,number,and density showed increasing trend during 1989–2016.MD were the predominant landscape type,followed by FM and SM during 1989-2016.Principal component analysis implied two extracted factors,F1 and F2,which could represent 91.93% of the total variations.F1 mainly proxied tidal channel development,while F2 represented road construction.A multiple linear regression analysis showed positive effects of both F1 and F2 on FM patch numbers and negative impacts on SM patch areaes with R^2 values of 0.416 and 0.599,respectively.Tidal channels were negatively related to MD patch numbers,while roads were positively related to that.In any case,road construction showed larger impacts on landscape type shifting than that of tidal channel development in the YRD. 展开更多
关键词 tidal channel development road construction principal component analysis multiple linear regression analysis the Yellow River Delta
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锦灯笼宿萼与果实的石油醚部位化学成分及抗氧化活性比较 预览
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作者 吴爽 吴莉莉 +1 位作者 赵稷 滕杨 《佳木斯大学学报:自然科学版》 CAS 2020年第1期99-102,共4页
提取锦灯笼宿萼与果实中的化学成分,对比研究锦灯笼宿萼和果实石油醚部位的化学成分及抗氧化活性。利用95%乙醇分别提取锦灯笼宿萼和果实中的化学成分,再用石油醚进行萃取,利用MS/MS分析石油醚部分主要化学成分并检测其对DPPH自由基的... 提取锦灯笼宿萼与果实中的化学成分,对比研究锦灯笼宿萼和果实石油醚部位的化学成分及抗氧化活性。利用95%乙醇分别提取锦灯笼宿萼和果实中的化学成分,再用石油醚进行萃取,利用MS/MS分析石油醚部分主要化学成分并检测其对DPPH自由基的清除率,结果用IC50值表示。从锦灯笼宿萼中检测出8个小分子化合物,清除DPPH自由基的IC50值为3.416 mg·mL-1;从果实中检测出10个小分子化合物,清除DPPH自由基的IC50值为1.711mg·mL-1。锦灯笼宿萼和果实石油醚部位化学成分存在明显差异且果实石油醚部位的抗氧化活性优于宿萼的石油醚部位。 展开更多
关键词 锦灯笼 石油醚部位 化学成分 抗氧化
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UPLC法同时测定柴胡疏肝散水煎液冻干物中8个成分的含量 预览
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作者 黄星星 朱黎霞 +1 位作者 韦园诗 张英丰 《中国药房》 CAS 北大核心 2020年第1期42-47,共6页
目的:建立柴胡疏肝散水煎液冻干物中8个成分含量同时测定的方法。方法:采用超高效液相色谱法对6批柴胡疏肝散水煎液冻干物样品中8个成分芍药内酯苷、芍药苷、阿魏酸、柚皮苷、橙皮苷、苯甲酰芍药苷、甘草酸、α-香附酮进行含量测定。色... 目的:建立柴胡疏肝散水煎液冻干物中8个成分含量同时测定的方法。方法:采用超高效液相色谱法对6批柴胡疏肝散水煎液冻干物样品中8个成分芍药内酯苷、芍药苷、阿魏酸、柚皮苷、橙皮苷、苯甲酰芍药苷、甘草酸、α-香附酮进行含量测定。色谱柱为Phenomenex,流动相为0.1%甲酸水-乙腈梯度洗脱,检测波长为250 nm,柱温为30℃,流速为1 mL/min,进样体积为10μL。结果:芍药内酯苷、芍药苷、阿魏酸、柚皮苷、橙皮苷、苯甲酰芍药苷、甘草酸、α-香附酮的检测质量浓度线性范围分别3.606~8.414、23.988~55.972、1.218~2.842、35.964~83.916、12.009~28.021、1.194~2.786、3.609~8.421、5.294~12.352μg/mL(r=0.999 5~0.999 9),定量限分别为0.206、0.178、0.256、0.168、0.196、0.242、0.268、0.157μg/mL;精密度试验、稳定性试验(12 h)、重复性试验中的RSD均<2%(n=5或6),回收率分别为97.93%、98.18%、96.57%、97.61%、98.51%、97.45%、98.14%、96.91%(RSD均<2%);6批样品中芍药内酯苷、芍药苷、阿魏酸、柚皮苷、橙皮苷、苯甲酰芍药苷、甘草酸的平均含量分别为59.258、429.237、23.173、625.847、200.424、15.048、67.620μg/g,α-香附酮因具有挥发性未检测出。结论:建立的含量测定方法简便,结果稳定、可靠、准确,可为柴胡疏肝散水煎液冻干物的质量控制提供参考。 展开更多
关键词 柴胡疏肝散 冻干物 超高效液相色谱法 成分 含量测定
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Unexpected metastasis of intraductal papillary neoplasm of the bile duct without an invasive component to the brain and lungs: A case report 预览
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作者 Nguyen Hai Nam Kojiro Taura +7 位作者 Masashi Kanai Keita Fukuyama Norimitsu Uza Hirona Maeda Yojiro Yutaka Toyofumi F Chen-Yoshikawa Manabu Muto Shinji Uemoto 《世界胃肠病学杂志:英文版》 SCIE CAS 2020年第3期366-374,共9页
BACKGROUND Despite an expanding number of studies on intraductal papillary neoplasm of the bile duct(IPNB),distant metastasis remains unexplained especially in cases of carcinoma in situ.In the present study,we report... BACKGROUND Despite an expanding number of studies on intraductal papillary neoplasm of the bile duct(IPNB),distant metastasis remains unexplained especially in cases of carcinoma in situ.In the present study,we report a rare and interesting case of IPNB without invasive components that later metastasized to lungs and brain.CASE SUMMARY A 69-year-old male was referred to our hospital due to suspected cholangiocarcinoma.Laboratory tests on admission reported a mild elevation of alkaline phosphatase,γ-glutamyl transpeptidase,and total bilirubin in serum.Endoscopic retrograde cholangiography revealed a filling defect in the common bile duct(CBD)extending to the left hepatic duct.Peroral cholangioscopy delineated a tumor in the CBD that had a papillary pattern.Multidetector computed tomography and magnetic resonance cholangiopancreatography detected partial blockage ot interlude in the CBD leading to cholestasis without evidence of metastasis.Therefore,a diagnosis of IPNB cT1N0M0 was established.Left hepatectomy with bile duct reconstruction was performed.Pathological examination confirmed an intraepithelial neoplasia pattern without an invasive component and an R0 resection achievement.The patient was monitored carefully by regular examinations.However,at 32 mo after the operation,a 26 mm tumor in the lungs and a 12 mm lesion in the brain were detected following a suspicious elevated CA 19-9 level.Video-assisted thoracoscopic surgery of left upper lobectomy and stereotactic radiotherapy are indicated.In addition to histopathological results,a genomic profiling analysis using whole exome sequencing subsequently confirmed lung metastasis originating from bile duct cancer.CONCLUSION This case highlights the important role of genomic profiling analysis using whole exome sequencing in identifying the origin of metastasis in patients with IPNB. 展开更多
关键词 Intraductal papillary neoplasm of the bile duct Distant metastasis Invasive component Whole exome sequencing CA 19-9 Case report
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通用虚拟仪器前面板运行平台设计 预览
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作者 陈昌浩 李晓明 《计算机系统应用》 2020年第2期76-82,共7页
随着科学技术的进步,测量仪器技术逐渐向虚拟仪器技术方向发展,开发简单、通用、可拓展已成为虚拟仪器开发的重要指标.为了解决目前市面上虚拟仪器前面板开发软件不易于拓展、运行效率较低的问题,提出了一种通用虚拟仪器前面板的运行平... 随着科学技术的进步,测量仪器技术逐渐向虚拟仪器技术方向发展,开发简单、通用、可拓展已成为虚拟仪器开发的重要指标.为了解决目前市面上虚拟仪器前面板开发软件不易于拓展、运行效率较低的问题,提出了一种通用虚拟仪器前面板的运行平台的实现方法,其主要原理是:界面组件化,前面板界面由组件组合而成,仪器组件以jar包形式存在,方便拓展,平台加载不同的仪器脚本,即可生成不同的虚拟仪器.提出了一种基于观察者模式的一对多的数据交换机制,方便组件间通讯,也可拓展与外部系统通讯.信号发生显示器的例子证明了该通用仪器前面板运行平台的可行性. 展开更多
关键词 虚拟仪器 运行平台 组件
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在线色谱数据共享在天然气计量中的应用 预览
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作者 曹洪超 《石油化工自动化》 CAS 2020年第1期43-45,共3页
基于长输管线数据采集与监控系统(SCADA)的SDH光纤通信网络,或租赁DDN通信网络,将在线色谱实时数据定点分发共享至未设置色谱分析仪的场站,在调控中心设置具有读写功能的协议转换服务器。该方法在采用超声计量的输气场站应用后,将超声... 基于长输管线数据采集与监控系统(SCADA)的SDH光纤通信网络,或租赁DDN通信网络,将在线色谱实时数据定点分发共享至未设置色谱分析仪的场站,在调控中心设置具有读写功能的协议转换服务器。该方法在采用超声计量的输气场站应用后,将超声波流量计声速核查偏差的波动范围缩小为原来的33%,从而有效地提高了计量的准确度。 展开更多
关键词 气相色谱仪 组分 共享 天然气计量 声速核查
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Text Detection in Natural Scene Images Using Morphological Component Analysis and Laplacian Dictionary 预览
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作者 Shuping Liu Yantuan Xian +1 位作者 Huafeng Li Zhengtao Yu 《自动化学报:英文版》 CSCD 2020年第1期214-222,共9页
Text in natural scene images usually carries abundant semantic information. However, due to variations of text and complexity of background, detecting text in scene images becomes a critical and challenging task. In t... Text in natural scene images usually carries abundant semantic information. However, due to variations of text and complexity of background, detecting text in scene images becomes a critical and challenging task. In this paper, we present a novel method to detect text from scene images. Firstly, we decompose scene images into background and text components using morphological component analysis(MCA), which will reduce the adverse effects of complex backgrounds on the detection results.In order to improve the performance of image decomposition,two discriminative dictionaries of background and text are learned from the training samples. Moreover, Laplacian sparse regularization is introduced into our proposed dictionary learning method which improves discrimination of dictionary. Based on the text dictionary and the sparse-representation coefficients of text, we can construct the text component. After that, the text in the query image can be detected by applying certain heuristic rules. The results of experiments show the effectiveness of the proposed method. 展开更多
关键词 Index Terms—Dictionary learning Laplacian sparse regularization morphological component analysis(MCA) sparse representation text detection.
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Cross-Band Spectrum Prediction Based on Deep Transfer Learning 预览
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作者 Fandi Lin Jin Chen +2 位作者 Jiachen Sun Guoru Ding Ling Yu 《中国通信:英文版》 SCIE CSCD 2020年第2期66-80,共15页
Spectrum prediction is a promising technology to infer future spectrum state by exploiting inherent patterns of historical spectrum data.In practice,for a given spectrum band of interest,when facing relatively scarce ... Spectrum prediction is a promising technology to infer future spectrum state by exploiting inherent patterns of historical spectrum data.In practice,for a given spectrum band of interest,when facing relatively scarce historical data,spectrum prediction based on traditional learning methods does not work well.Thus,this paper proposes a cross-band spectrum prediction model based on transfer learning.Firstly,by analysing service activities and computing the distances between various frequency points based on Dynamic Time Warping,the similarity between spectrum bands has been verified.Next,the features,which mainly affect the performance of transfer learning in the crossband spectrum prediction,are explored by leveraging transfer component analysis.Then,the effectiveness of transfer learning for the cross-band spectrum prediction has been demonstrated.Further,experimental results with real-world spectrum data demonstrate that the performance of the proposed model is better than the state-of-theart models when the historical spectrum data is limited. 展开更多
关键词 cross-band spectrum prediction deep transfer learning long short-term memory dynamic time warping transfer component analysis
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Oscillatory-Plus-Transient Signal Decomposition Using TQWT and MCA 预览
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作者 G. Ravi Shankar Reddy Rameshwar Rao 《电子科技学刊:英文版》 CAS CSCD 2019年第2期135-151,共17页
This paper describes a method for decomposing a signal into the sum of an oscillatory component and a transient component. The process uses the tunable Q-factor wavelet transform (TQWT): The oscillatory component is m... This paper describes a method for decomposing a signal into the sum of an oscillatory component and a transient component. The process uses the tunable Q-factor wavelet transform (TQWT): The oscillatory component is modeled as a signal that can be sparsely denoted by high Q-factor TQWT;similarly, the transient component is modeled as a piecewise smooth signal that can be sparsely denoted using low Q-factor TQWT. Since the low and high Q-factor TQWT has low coherence, the morphological component analysis (MCA) can effectively decompose the signal into oscillatory and transient components. The corresponding optimization problem of MCA is resolved by the split augmented Lagrangian shrinkage algorithm (SALSA). The applications of the proposed method to speech, electroencephalo-graph (EEG), and electrocardiograph (ECG) signals are included. 展开更多
关键词 Morphological COMPONENT analysis (MCA) OSCILLATORY COMPONENT split AUGMENTED LAGRANGIAN shrinkage algorithm (SALSA) transient COMPONENT tunable Q-factor wavelet transform (TQWT)
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Oblique extension of pre-existing structures and its control on oil accumulation in eastern Bohai Sea 预览
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作者 REN Jian LYU Dingyou +4 位作者 CHEN Xingpeng LIU Pengbo GUAN Dayong SU Kai ZHANG Hongguo 《石油勘探与开发:英文版》 2019年第3期553-564,共12页
Based on 3D seismic data, the evolution mechanism and characteristics of faults were investigated to reveal the structural origin and its control on differential hydrocarbon accumulation through comprehensive analyses... Based on 3D seismic data, the evolution mechanism and characteristics of faults were investigated to reveal the structural origin and its control on differential hydrocarbon accumulation through comprehensive analyses, including structure style analysis, fault activity analysis, analogue modelling and comparison among the wells. The complex fault system with differently trending faults resulted from strike-slip and rifting in Paleogene was partly activated, developed successively and stretched obliquely by the near-NS extensional stress field in Neogene. In the area little affected by pre-existing faults, new faults nearly perpendicular to the extension direction developed. The structural development in the study area was not caused by transpressional strike slip. Under the oblique extension effect of pre-existing faults, if the angle between the strike of pre-existing fault and the extensional direction is different, the strike-slip and extensional stresses are different in ratio. The larger the angle between the two is, the stronger the extensional component, the poorer the sealing ability of the fault, and the stronger the oil and gas migration capacity will be. Conversely, the smaller the angle between the two is, the stronger the strike-slip component, the better the sealing ability of the fault, and the poorer the oil and gas migration capacity will be. The accumulation condition analysis results considering the fault trend are in good agreement with the oil and gas shows in wells drilled in this area. 展开更多
关键词 OBLIQUE EXTENSION pre-existing faults STRIKE-SLIP COMPONENT EXTENSION COMPONENT PALEOGENE NEOGENE Bohai Sea
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Influences of the diameter of the balance hole on the flow characteristics in the hub cavity of the centrifugal pump 预览
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作者 Wei Dong Wu-li Chu Zai-lun Liu 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第5期1060-1068,共9页
The diameter of the impeller balance hole in a centrifugal pump is closely related to axial force.Thus,to select the appropriate diameter of a balance hole is crucial for balancing the axial force of the centrifugal p... The diameter of the impeller balance hole in a centrifugal pump is closely related to axial force.Thus,to select the appropriate diameter of a balance hole is crucial for balancing the axial force of the centrifugal pump.After the validation of the CFD method and the grids independence study,the characteristics of flow in the hub cavity have been analyzed in 4 cases with different diameters of balance holes.The leakage rate of the liquid in the hub cavity of the centrifugal pump is calculated and compared with the test result.According to the research,when no balance hole exists,the distribution of liquid velocity in the core area of the hub cavity exhibits axial symmetry,and the circumferential velocity component is approximately 0.4 times of the impeller's rotational speed.When the balance hole exists,the distribution of liquid velocity in the hub cavity does not exhibit axial symmetry,and the circumferential velocity component is larger than 0.4 times of the impeller's rotational speed.The radial leakage velocity on the turbulent boundary layer of the pump cover will increase with the increasing diameter of the balance hole. 展开更多
关键词 Centrifugal pump balance hole HUB CAVITY CIRCUMFERENTIAL VELOCITY COMPONENT radial VELOCITY COMPONENT
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AED-Net:An Abnormal Event Detection Network 预览
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作者 Tian Wang Zichen Miao +3 位作者 Yuxin Chen Yi Zhou Guangcun Shan Hichem Snoussi 《工程(英文)》 2019年第5期930-939,共10页
It has long been a challenging task to detect an anomaly in a crowded scene.In this paper,a selfsupervised framework called the abnormal event detection network(AED-Net),which is composed of a principal component anal... It has long been a challenging task to detect an anomaly in a crowded scene.In this paper,a selfsupervised framework called the abnormal event detection network(AED-Net),which is composed of a principal component analysis network(PCAnet)and kernel principal component analysis(kPCA),is proposed to address this problem.Using surveillance video sequences of different scenes as raw data,the PCAnet is trained to extract high-level semantics of the crowd’s situation.Next,kPCA,a one-class classifier,is trained to identify anomalies within the scene.In contrast to some prevailing deep learning methods,this framework is completely self-supervised because it utilizes only video sequences of a normal situation.Experiments in global and local abnormal event detection are carried out on Monitoring Human Activity dataset from University of Minnesota(UMN dataset)and Anomaly Detection dataset from University of California,San Diego(UCSD dataset),and competitive results that yield a better equal error rate(EER)and area under curve(AUC)than other state-of-the-art methods are observed.Furthermore,by adding a local response normalization(LRN)layer,we propose an improvement to the original AED-Net.The results demonstrate that this proposed version performs better by promoting the framework’s generalization capacity. 展开更多
关键词 Abnormal events detection Abnormal event detection network Principal component analysis network Kernel principal component analysis
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大型航空复合材料承力构件制造关键技术
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作者 贾振元 肖军 +6 位作者 湛利华 陈磊 张宇民 李刚 王福吉 高航 林莉 《中国基础科学》 2019年第2期20-27,共8页
大型飞机制造水平是国家综合实力的重要体现。大型飞机的研制作为我国建设创新型国家的标志性工程和重大战略决策,对经济、社会和国家安全意义极其重大。在我国发展大型飞机制造水平的大背景下,提高核心部件制造关键技术,为研制大型飞... 大型飞机制造水平是国家综合实力的重要体现。大型飞机的研制作为我国建设创新型国家的标志性工程和重大战略决策,对经济、社会和国家安全意义极其重大。在我国发展大型飞机制造水平的大背景下,提高核心部件制造关键技术,为研制大型飞机提供技术储备至关重要。国家973计划项目"大型航空复合材料承力构件制造基础"围绕大型碳纤维树脂基复合材料航空承力构件制造过程中,预制件自动铺放与固化成型、高质量加工与低损伤装配、缺陷检测与承载评估等3个方面的基础科学理论与具体实施方案展开系统研究,取得了一系列重要研究成果,推动了我国大型航空复合材料承力构件制造水平的发展。本文从项目研究概况、关键研究进展、总结与展望3个方面进行论述。 展开更多
关键词 复合材料 承力构件 制造
Synthesis of Reduced Graphene Oxide-Titanium (rGO-TiO<sub>2</sub>) Composite Using a Solvothermal and Hydrothermal Methods and Characterized via XRD and UV-Vis 预览
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作者 Huzaikha Awang Nurul Infaza Talalah 《自然资源(英文)》 2019年第2期17-28,共12页
Nowadays, Carbon Capture and Conversion (CCC) method?is?one of the alternative solutions in carbon management. The reduced graphene oxide-Titanium?(rGO-TiO2) composites?are?the CCC material that will capture the carbo... Nowadays, Carbon Capture and Conversion (CCC) method?is?one of the alternative solutions in carbon management. The reduced graphene oxide-Titanium?(rGO-TiO2) composites?are?the CCC material that will capture the carbon dioxide (CO2) and convert it into hydrocarbon fuels?such as methane. The effect of synthesizing?method into crystallinity growth and the band gap will be studied?in this research work.Therefore, the rGO-TiO2?will be synthesized?via solvothermal and hydrothermal methods and then will be characterized?via XRD and UV-Vis. The temperature and treatment time were fixed in both synthesis methods. The characterization results via XRD and UV-Vis conclude that, the different synthesis methods?affected?the crystallinity growth and its band gap. The rGO-TiO2?synthesized via modified hydrothermal method shows the lowest crystallite size and band gap compared to other samples. It will indirectly affect the photogenerated electrons on TiO2?to rGO better compared to rGO-TiO2?synthesized via solvothermal. The green synthesis method which requires?a low equipment cost and simple experimental steps?is?the contribution of this research finding. 展开更多
关键词 Component Formatting Style STYLING
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Nanobiotechnology in Agricultural Sector: Overview and Novel Applications 预览
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作者 Katherine Alvarado Mónica Bola?os +2 位作者 Carmen Camacho Elías Quesada José Vega-Baudrit 《生物材料与纳米技术(英文)》 2019年第2期120-141,共22页
The agricultural sector has many problems achieving the desired yield in products because of pathogens, viruses, pesticides, herbicides, temperature, soil moisture, among others. Nanotechnology, along with other scien... The agricultural sector has many problems achieving the desired yield in products because of pathogens, viruses, pesticides, herbicides, temperature, soil moisture, among others. Nanotechnology, along with other sciences, has emerged in industry and society due to the interest in solving problems such as those mentioned above, in order to serve the needs of the world population. The present review discusses the principal topics about Nanobiotechnology, such as generalities, applications, aspects that can be improved and perspectives, beside its influence in the agriculture industry. 展开更多
关键词 COMPONENT NANOTECHNOLOGY BIOTECHNOLOGY AGRICULTURE NANOBIOTECHNOLOGY
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Modified Independent Component Regression Method Without Prewhitening 预览
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作者 Rong Guo Jimin Ye 《哈尔滨工业大学学报:英文版》 EI CAS 2019年第4期50-57,共8页
Independent component analysis(ICA) can reveal the essential underlying structure of data, and independent component regression(ICR) methods usually obtain better performance than other regression methods such as prin... Independent component analysis(ICA) can reveal the essential underlying structure of data, and independent component regression(ICR) methods usually obtain better performance than other regression methods such as principal component regression. However, when existing ICR methods separate or extract independent components using prewhitened data, the backward propagation of inevitable prewhitened errors deteriorates the final linear prediction accuracy. To overcome this weakness, first, we proposed using weighted orthogonal constraint condition to replace the prewhitening of the data in ICA. Next, the statistical independence of ICs and the close relationship between ICs and quality variables are considered at the same time. Then, by combining the merits of improved ICR and ensemble ICR algorithm which solved the problem of selecting an appropriate nonquadratic function in ICA iteration procedure, a modified independent component regression(MICR) method that directly used the measured process data was proposed. Finally, three experimental results were used to validate excellent performance of modified algorithm. 展开更多
关键词 INDEPENDENT COMPONENT analysis WEIGHTED ORTHOGONAL CONSTRAINT INDEPENDENT COMPONENT regression prewhitened data
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中华羊茅内生真菌Epichloe sp.挥发性物质的抑菌活性及成分分析 预览
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作者 周连玉 钟松 +1 位作者 朵红梅 乔枫 《天然产物研究与开发》 CAS CSCD 北大核心 2019年第9期1543-1551,共9页
为测定中华羊茅内生真菌Epichloe sp.挥发性物质的抑菌活性和成分,依次采用挥发油提取器和乙酸乙酯萃取Epichloe sp.菌株的发酵产物,再采用琼脂扩散法、悬滴法和滤纸片扩散法测定其抑菌活性;基于顶空固相微萃取和气相质谱联用法分析挥... 为测定中华羊茅内生真菌Epichloe sp.挥发性物质的抑菌活性和成分,依次采用挥发油提取器和乙酸乙酯萃取Epichloe sp.菌株的发酵产物,再采用琼脂扩散法、悬滴法和滤纸片扩散法测定其抑菌活性;基于顶空固相微萃取和气相质谱联用法分析挥发性物质成分。结果表明:挥发性物质、乙酸乙酯提取物、水相部分和发酵液可以抑制小麦根腐离蠕孢(Bipolaris sorokiniana)、新月弯孢(Curvularia lunata)和黑曲霉(Aspergillus niger)菌丝生长。高浓度的挥发性物质对四种真菌孢子萌发和芽管长度抑制效果显著高于低浓度(P<0.05)。结果表明,随着挥发性物质浓度的增加对金黄色葡萄球菌(Staphylococcus aureus)和大肠杆菌(Escherichia coli)的抑菌作用增强,同一挥发性物质浓度对金黄色葡萄球菌的抑制作用强于大肠杆菌。此外,从挥发性物质中鉴定出32种具有较高质谱匹配度的化合物,其中主要成分包括异山梨醇(16.26%)、甲基叔丁基醚(8.18%)、二氢甘露醇(3.75%)、羟基丙酮(2.99%)、乙酸(1.22%)、己醇(1.20%)、3-糠醛(0.92%)、5-羟甲基二氢呋喃-2-酮(0.86%)、5-羟基戊酸-2,4-二叔丁基苯酯(0.86%)和棕榈酸甲酯(0.85%)。总之,中华羊茅内生真菌Epichlosp.挥发性物质具有拮抗细菌和真菌的作用。 展开更多
关键词 中华羊茅 内生真菌Epichloe sp. 挥发性物质 抑菌活性 组成成分
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Persistence of Cry1Ac Protein from Transgenic Bt Cotton Cultivation and Residue Returning in Fields and Its Effect on Functional Diversity of Soil Microbial Communities
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作者 ZHANG Meijun FENG Meichen +3 位作者 XIAO Lujie SONG Xiaoyan Guangwei DING YANG Wude 《土壤圈:英文版》 SCIE CAS CSCD 2019年第1期114-122,共9页
The persistence of Cry1 Ac protein in the soil and its effect on soil microbial communities are a core issue in assessing the ecological risk of transgenic Bacillus thuringiensis(Bt) cotton. In this study a field expe... The persistence of Cry1 Ac protein in the soil and its effect on soil microbial communities are a core issue in assessing the ecological risk of transgenic Bacillus thuringiensis(Bt) cotton. In this study a field experiment was conducted on the cultivation of transgenic Bt cotton(Jin 26 and BtJ i 668) with the immediate returning of residues to the fields, in order to quantify the Cry1 Ac protein content in the fields and investigate its effects on the functional diversity of soil microbial communities. Cry1 Ac protein in the residue-soil mixture was gradually degraded in the transgenic Bt cotton fields. After transgenic Bt cotton straw was returned to the fields for 30 d, 63.73%and 58.33% of the initial amounts of Cry1 Ac protein were degraded in the Jin 26 and BtJ i 668 fields, respectively. Before the crops were sown in the following year(180 d after returning the straw), no Cry1 Ac protein was detected in the fields. After returning the cotton straw to the fields for 30 d, the Shannon-Wiener and McIntosh indices of soil microbial communities in the transgenic Bt cotton fields were significantly higher than those in the non-transgenic cotton fields. Meanwhile, the utilization of carbon sources including amino acids, amines, and carbohydrates by the soil microbial communities significantly increased. Both the McIntosh index and the utilization of carbohydrates increased until 180 d. Principal component analysis revealed that amino acids, amides, and carbohydrates were the main carbon sources distinguishing the two principal component factors. These findings indicated that Cry1 Ac protein did not accumulate in the fields after transgenic Bt cotton was planted for one year and the residues were immediately returned to the fields;however, the original functional diversity of soil microbial communities was affected continuously. 展开更多
关键词 BIOLOG GN2 carbon source utilization diversity index principal component analysis STRAW RETURN
Hydrogeochemical Modeling of the Shallow Thermal Water Evolution in Yangbajing Geothermal Field, Tibet
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作者 Xiuhua Zheng Chenyang Duan +2 位作者 Bairu Xia Yong Jiang Jian Wen 《地球科学学刊:英文版》 SCIE CAS CSCD 2019年第4期870-878,共9页
The exploitation of thermal water and the mix of cold water changed the properties of geofluid in shallow reservoir,which altered the concentration of the chemical constitutes and continuously built new water-rock rea... The exploitation of thermal water and the mix of cold water changed the properties of geofluid in shallow reservoir,which altered the concentration of the chemical constitutes and continuously built new water-rock reaction. This paper deduced reservoir pressure and temperature variation tendency from 2004 to 2013,analyzed the change of some components in the shallow reservoir water,and finally obtained the evolution of the shallow geothermal water with hydrogeochemical model. The results show the reservoir pressure decreased significantly compared with the slight decline of reservoir temperature,and much cold groundwater infiltrated into the shallow reservoir,which affected the solubility of SiO2 and led to precipitation,the increased CO2 in shallow reservoir promoted the dissolution of aluminosilicate. Calcite and kaolinite precipitation zone has extended to the north in the field,which influenced the porosity of the reservoir rock. 展开更多
关键词 RESERVOIR pressure and temperature COMPONENT analysis hydrochemical modeling dissolution/precipitation
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