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The dimension splitting element-free Galerkin method for 3D transient heat conduction problems
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作者 ZhiJuan Meng Heng Cheng +1 位作者 LiDong Ma YuMin Cheng 《中国科学:物理学、力学、天文学英文版》 SCIE EI CAS CSCD 2019年第4期45-56,共12页
By transforming a 3D problem into some related 2D problems, the dimension splitting element-free Galerkin(DSEFG) method is proposed to solve 3D transient heat conduction problems. The improved element-free Galerkin(IE... By transforming a 3D problem into some related 2D problems, the dimension splitting element-free Galerkin(DSEFG) method is proposed to solve 3D transient heat conduction problems. The improved element-free Galerkin(IEFG) method is used for 2D transient heat conduction problems, and the finite difference method is applied in the splitting direction. The discretized system equation is obtained based on the Galerkin weak form of 2D problem;the essential boundary conditions are imposed with the penalty method;and the finite difference method is employed in the time domain. Four exemplary problems are chosen to verify the efficiency of the DSEFG method. The numerical solutions show that the efficiency and precision of the DSEFG method are greater than ones of the IEFG method for 3D problems. 展开更多
关键词 improved element-free GALERKIN (IEFG) METHOD DIMENSION SPLITTING METHOD finite DIFFERENCE METHOD DIMENSION SPLITTING element-free GALERKIN (DSEFG) METHOD TRANSIENT heat conduction problem
浅析散打实战中“时空差”训练 预览
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作者 仝子洋 崔建明 《体育科技文献通报》 2019年第3期68-68,98共2页
全文主要运用观察法、文献资料法、讨论法、逻辑分析法对“时空差”在散打比赛中的重要性进行研究。得出如下结果,散打选手在更好掌握了“时空差”打法之后,其在实战或比赛中获胜的机率更大。本研究旨在为散打选手在训练和比赛中提供理... 全文主要运用观察法、文献资料法、讨论法、逻辑分析法对“时空差”在散打比赛中的重要性进行研究。得出如下结果,散打选手在更好掌握了“时空差”打法之后,其在实战或比赛中获胜的机率更大。本研究旨在为散打选手在训练和比赛中提供理论参考。 展开更多
关键词 散打 距离差 时间差 空间差 训练方法
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可比产品成本连环替代法数学模型的改进 预览
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作者 郑智勇 《福建师大福清分校学报》 2019年第2期33-40,共8页
通过构建可比产品成本替代法的数学模型,分别计算产量、品种构成、单位成本三个因素变动对成本降低任务完成情况的影响,并考虑ABC法与LMDI法的改进思路,以克服连环替代顺序改变造成的混合差异,从而实现可比产品成本降低的最优化.
关键词 可比产品 连环替代法 混合差异 ABC法 LMDI法
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2013年吉林松原M5.8地震震前地磁异常分析 预览
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作者 岳力 贾秀玲 +2 位作者 张彦吉 王海涛 胡澜缤 《防灾减灾学报》 2019年第1期26-29,共4页
应用东北地区地磁观测台站地磁总场强度整点值观测数据,利用每日一值相关法和差值法;应用地磁垂直分量日变幅观测数据,利用加卸载响应比和逐日比方法,分析地磁总场强度F分量、垂直Z分量与吉林省松原M5.8地震应震关系,分析上述方法对提... 应用东北地区地磁观测台站地磁总场强度整点值观测数据,利用每日一值相关法和差值法;应用地磁垂直分量日变幅观测数据,利用加卸载响应比和逐日比方法,分析地磁总场强度F分量、垂直Z分量与吉林省松原M5.8地震应震关系,分析上述方法对提取地磁观测数据震前异常信息的有效性。 展开更多
关键词 相关法 差值法 逐日比 加卸载响应比 震前异常
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曲度法和差分法在抽水试验曲线判定中的应用研究——以月池矿泉水水源地为例 预览
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作者 陈巧红 《地下水》 2019年第2期32-34,共3页
允许开采量的计算是矿泉水资源量评价的核心问题。采用曲度法和差分法相结合的方法,可以较准确地判定抽水试验曲线的类型,并确定合理的涌水量方程,为允许开采量的计算提供可靠依据。以月池矿泉水井为例,利用枯水期抽水试验资料,将曲度... 允许开采量的计算是矿泉水资源量评价的核心问题。采用曲度法和差分法相结合的方法,可以较准确地判定抽水试验曲线的类型,并确定合理的涌水量方程,为允许开采量的计算提供可靠依据。以月池矿泉水井为例,利用枯水期抽水试验资料,将曲度法和差分法相结合,通过建立Excel数据模板,对曲度法和差分法在抽水试验曲线判定中的应用进行研究,结果可知:抽水试验数据适合于指数方程,判定抽水试验曲线类型为指数型,可最终确定月池矿泉水属承压水,水位最大降深为5.7 m,允许可采量为118.54 m~3/d。研究结果为该水源地评价含水层特性与开发利用保护规划提供了依据。 展开更多
关键词 曲度法 差分法 抽水试验曲线 允许开采量
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Numerical storm surge model with higher order finite difference method of lines for the coast of Bangladesh 预览
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作者 Gour Chandra Paul Md. Emran Ali 《海洋学报:英文版》 SCIE CAS CSCD 2019年第6期100-116,共17页
In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs... In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M2 along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,4) method with regard to the root mean square er 展开更多
关键词 SHALLOW water equations METHOD of lines higher order finite difference approximation METHOD SURGE nested scheme
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Application of random set method in a deep excavation: based on a case study in Tehran cemented alluvium
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作者 Arash SEKHAVATIAN Asskar Janalizadeh CHOOBBASTI 《结构与土木工程前沿:英文版》 EI CSCD 2019年第1期66-80,共15页
The design of high-rise buildings often necessitates ground excavation,where buildings are in close proximity to the construction,thus there is a potential for damage to these structures.This paper studies an efficien... The design of high-rise buildings often necessitates ground excavation,where buildings are in close proximity to the construction,thus there is a potential for damage to these structures.This paper studies an efficient user-friendly framework for dealing with uncertainties in a deep excavation in layers of cemented coarse grained soil located in Tehran,Iran by non-deterministic Random Set (RS)method.In order to enhance the acceptability of the method among engineers,a pertinent code was written in FISH language of FLAC2D software which enables the designers to run all simulations simultaneously,without cumbersome procedure of changing input variables in every individual analysis.This could drastically decrease the computational effort and cost imposed to the project,which is of great importance especially to the owners.The results are presented in terms of probability of occurrence and most likely values of the horizontal displacement at top of the wall at every stage of construction.Moreover,a methodology for assessing the credibility of the uncertainty model is presented using a quality indicator.It was concluded that performing RS analysis before the beginning of every stage could cause great economical savings,while improving the safety of the project. 展开更多
关键词 uncertainty reliability analysis deep EXCAVATIONS random set METHOD finite DIFFERENCE METHOD
一维热传导方程的差分法 预览
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作者 张旭清 黄文竹 《科技视界》 2019年第7期118-120,共3页
利用差分法对一维热传导问题进行分析,给出向后差分格式。同时对2018年全国大学生数学建模竞赛A题建立一维热传导方程,并进行数值计算。
关键词 差分法 一维热传导方程 热防护服
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垂直井中连续管的纵向振动分析 预览
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作者 周志宏 殷卓成 《石油机械》 北大核心 2019年第3期124-128,共5页
直井中连续管运动时的阻尼较小,如果激励频率与固有频率相同,在较小的周期性激励下就有可能产生较大幅度的振动,这种振动有可能导致连续管的表面损伤,或加速连续管的疲劳损伤。鉴于此,建立了直井中连续管的纵向振动微分方程,经过简化,... 直井中连续管运动时的阻尼较小,如果激励频率与固有频率相同,在较小的周期性激励下就有可能产生较大幅度的振动,这种振动有可能导致连续管的表面损伤,或加速连续管的疲劳损伤。鉴于此,建立了直井中连续管的纵向振动微分方程,经过简化,得到了连续管振动频率的特征方程,通过数值计算可以得到不同长度连续管纵向振动的固有频率。应用差分方法,计算了共振条件下振幅的增长趋势。研究结果表明:连续管下入越深,基频的频率越低;越高阶固有频率的共振,井口连续管应力振幅增加越快;激励力的频率与连续管起升或下降速度成正比,速度越大,共振时井口连续管应力振幅越大。研究结果可为连续管振动损伤预防研究奠定理论基础。 展开更多
关键词 直井 连续管 管柱振动 固有频率 共振 差分方法 应力振幅
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3D numerical simulation in acoustic-elastic coupled media with staggered-grid finite-difference method 预览
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作者 PENG Changhua WANG Deli ZHOU Jinju 《世界地质:英文版》 2019年第2期112-120,共9页
Acoustic-elastic coupled media is often encountered in most marine explorations, and accurate simulation of acoustic-elastic coupled media is of great significance. At present, the study of acoustic-elastic coupled me... Acoustic-elastic coupled media is often encountered in most marine explorations, and accurate simulation of acoustic-elastic coupled media is of great significance. At present, the study of acoustic-elastic coupled media still assumes that the solid of the acoustic-elastic coupled media is isotropic, but this assumption is not in accordance with the actual situation. In this paper, we derive the solid media of acoustic-elastic coupled media from isotropic media to anisotropic media, and propose an acoustic-elastic coupled medium based ontransverse isotropic media with vertical symmetric axes (VTI) to improve the accuracy of forward modeling. Based on the relationship between the Thomsen parameter and the coefficient matrix of the anisotropic elastic wave equation, we transform the Thomson parameter into a velocity model with anisotropic properties. We use a staggered grid finite difference method to simulate the propagation of a wavefield in a three-dimensional acoustic-elastic coupled media. We obtain the snapshots of the wave field when the solid of the acoustic-elastic coupled media is an isotropic medium and a VTI media. When the solid of the acoustic-elastic coupled media is considered VTI media, we can observe the qP wave and qS wave that cannot be observed in the isotropic medium from the wave field snapshot. We can also find that the seismic records obtained by the method we use are more realistic. The algorithm proposed in this paper is of great significance for high-precision ocean numerical simulation. 展开更多
关键词 finite difference method staggered grid FORWARD modeling 3D acoustic-elastic COUPLED MEDIA transversely ISOTROPIC medium
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一种基于压缩感知的运动目标检测技术 预览
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作者 戴晓芳 《电脑与电信》 2019年第5期64-67,共4页
运动目标检测是计算机视觉、图像处理等相关领域的研究热点,其核心就是对视频图像中的每一帧图像进行相应的研究和处理。本文主要研究思路是从压缩感知技术采样信号的角度出发,将每一帧的二维图像压缩采样成具有少量信息的一维信号,再... 运动目标检测是计算机视觉、图像处理等相关领域的研究热点,其核心就是对视频图像中的每一帧图像进行相应的研究和处理。本文主要研究思路是从压缩感知技术采样信号的角度出发,将每一帧的二维图像压缩采样成具有少量信息的一维信号,再通过信号重构用少量数据量将图像重构出来,最后通过目标检测技术对每一帧的图像进行运动目标提取。仿真实验表明该方法是可行和有效的,同时可以大大减少目标检测中所记录的数据量,解决海量数据的存储与传输问题。 展开更多
关键词 目标检测 压缩感知 差分法 测量矩阵
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Propagation characteristics of oblique incidence terahertz wave through non-uniform plasma
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作者 陈安涛 孙浩宇 +2 位作者 韩一平 汪加洁 崔志伟 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第1期372-378,共7页
The propagation characteristics of oblique incidence terahertz(THz) waves through non-uniform plasma are investigated by the shift-operator finite-difference time-domain(SO-FDTD) method combined with the phase matchin... The propagation characteristics of oblique incidence terahertz(THz) waves through non-uniform plasma are investigated by the shift-operator finite-difference time-domain(SO-FDTD) method combined with the phase matching condition.The electron density distribution of the non-uniform plasma is assumed to be in a Gaussian profile. Validation of the present method is performed by comparing the results with those obtained by an analytical method for a homogeneous plasma slab.Then the effects of parameters of THz wave and plasma layer on the propagation properties are analyzed. It is found that the transmission coefficients greatly depend on the incident angle as well as on the thickness of the plasma, while the polarization of the incident wave has little influence on the propagation process in the range of frequency considered in this paper. The results confirm that the THz wave can pass through the plasma sheath effectively under certain conditions,which makes it a potential candidate to overcome the ionization blackout problem. 展开更多
关键词 TERAHERTZ wave transmission OBLIQUE INCIDENCE plasma SHEATH FINITE-DIFFERENCE TIME-DOMAIN method
Compatibility Evaluation between Direct Coal Liquefaction Residue and Bitumen 预览
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作者 Ji Jie Wu Hao +5 位作者 Xu Ying Suo Zhi Wei Jianming Dai Qingli Zhang Ran Diab Aboelkasim 《中国炼油与石油化工:英文版》 SCIE CAS 2019年第1期90-100,共11页
The compatibility between direct coal liquefaction residue(DCLR) and five kinds of pure bitumen(Shell-90,SK-90, ZSY-70, DM-70 and KLMY-50) was evaluated in this study. The rheological characteristics, glass transition... The compatibility between direct coal liquefaction residue(DCLR) and five kinds of pure bitumen(Shell-90,SK-90, ZSY-70, DM-70 and KLMY-50) was evaluated in this study. The rheological characteristics, glass transition temperatures(T_g), solubility parameters(SP) and SARA(saturates, aromatics, resins, and asphaltenes) fractions of DCLR,five kinds of pure bitumen and their blends(named as DCLR modified bitumen) were measured using the dynamic shear rheometer(DSR), differential scanning calorimetry(DSC), viscosity, and SARA tests, respectively. And the compatibility between DCLR and pure bitumen was characterized with three approaches, viz. the Cole-Cole plot,T_g, and the solubility parameter difference(SPD) method. Since each method has its own working mechanism, the compatibility ranking for the DCLR and five kinds of pure bitumen is slightly different according to the three approaches. However, the difference is pretty close and sometimes can be ignored. The general compatibility ranking decreases in the following order: Shell-90≈SK-90>DM-70≈ZSY-70>KLMY-50, which is affected by the asphaltenes content and the colloid index(I_c) value in the pure bitumen. Pure bitumen with lower asphaltenes content and colloid index(I_c) value has better compatibility with DCLR. 展开更多
关键词 direct coal LIQUEFACTION RESIDUE (DCLR) PURE BITUMEN compatibility Cole-Cole PLOT glass state temperature (Tg) approach SOLUBILITY parameter difference (SPD) method
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An Optimal Sixth-order Finite Difference Scheme for the Helmholtz Equation in One-dimension 预览
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作者 Liu Xu Wang Hai-na Hu Jing 《数学研究通讯:英文版》 CSCD 2019年第3期264-272,共9页
In this paper, we present an optimal 3-point finite difference scheme for solving the 1D Helmholtz equation. We provide a convergence analysis to show that the scheme is sixth-order in accuracy. Based on minimizing th... In this paper, we present an optimal 3-point finite difference scheme for solving the 1D Helmholtz equation. We provide a convergence analysis to show that the scheme is sixth-order in accuracy. Based on minimizing the numerical dispersion, we propose a refined optimization rule for choosing the scheme’s weight parameters. Numerical results are presented to demonstrate the efficiency and accuracy of the optimal finite difference scheme. 展开更多
关键词 HELMHOLTZ equation finite DIFFERENCE method numerical DISPERSION
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超越论视域下资本主义全球化的本质批判及当代变化 预览
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作者 冉凌宇 《西部论坛》 CSSCI 北大核心 2019年第3期14-25,共12页
一系列黑天鹅事件的发生标志着全球化进入了新阶段。后世很多马克思主义学者在援引《资本论》的政治经济学理论分析全球化问题时,因缺乏超越论视野,总是将研究集中在生产领域而忽视了流通领域,这将直接导致研究停留在表象层面。基于超... 一系列黑天鹅事件的发生标志着全球化进入了新阶段。后世很多马克思主义学者在援引《资本论》的政治经济学理论分析全球化问题时,因缺乏超越论视野,总是将研究集中在生产领域而忽视了流通领域,这将直接导致研究停留在表象层面。基于超越论视野,我们能看到马克思早已从剩余价值在流通领域的实现中揭示出了资本主义全球化的本质,即在共同体的差异中追求剩余价值的实现。通过对近代以来资本主义国家的基本构成元素——资本、民族、国家进行分析,还能发现导致当代全球化发展进入新阶段的根本原因是,资本无法实现对资本、民族、国家三位一体结构的超越而引发的历史的反复。基于上述研究能提供一种全新的视野用以解释民主社会主义、区域经济体、民粹主义和分配正义等现象,进而对基于流通领域社会主义应该如何实现对资本主义的超越有所启示。 展开更多
关键词 超越论 全球化 差异 交换方式 资本论
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初至波剩余静校正技术在南安集海地区的应用 预览
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作者 潘龙 刘宜文 +2 位作者 郑鸿明 赵勇 郭琪 《石油地球物理勘探》 EI CSCD 北大核心 2019年第2期274-279,I0006共7页
准噶尔盆地南缘山前南安集海探区表层结构复杂,常规的基准面静校正技术难以有效解决严重的基准面静校正问题,导致基于相关的自动反射波剩余静校正方法受地震记录信噪比低和最大1/2波形周期静校正量的限制而不能很好地解决复杂近地表的... 准噶尔盆地南缘山前南安集海探区表层结构复杂,常规的基准面静校正技术难以有效解决严重的基准面静校正问题,导致基于相关的自动反射波剩余静校正方法受地震记录信噪比低和最大1/2波形周期静校正量的限制而不能很好地解决复杂近地表的剩余静校正问题。初至波剩余静校正方法由高信噪比初至时差统计求解炮检点的剩余静校正量,不需依赖表层模型、较高信噪比资料等,对校正量的大小也无限制,侧重补充基准面静校正量的中、高频分量。通过应用和进一步研究,明晰了模型曲线和差分两种初至波剩余静校正技术的应用假设前提及综合应用思路,并在南安集海探区获得了良好的应用效果。 展开更多
关键词 静校正 初至时间 剩余静校正 差分法 模型
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基于偏微分方程的高温作业专用服装设计模型 预览
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作者 高振 房越 许乾宸 《无线互联科技》 2019年第6期65-66,69共3页
长期在高温环境下工作会对工作人员的生理及心理状态产生影响,引发各种意外和危机,如何设计高温作业专业服装,已经成为人们日益关注的焦点。文章建立衣服各层材料的一维无内热源热传导偏微分方程,结合各层交界处热传导平衡且温度相同的... 长期在高温环境下工作会对工作人员的生理及心理状态产生影响,引发各种意外和危机,如何设计高温作业专业服装,已经成为人们日益关注的焦点。文章建立衣服各层材料的一维无内热源热传导偏微分方程,结合各层交界处热传导平衡且温度相同的条件,建立出温度分布模型并进行分析。 展开更多
关键词 热传导偏微分方程 差分法 服装设计
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高合金化GH4065镍基变形高温合金点状偏析研究
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作者 王资兴 黄烁 +2 位作者 张北江 王磊 赵光普 《金属学报》 SCIE EI CAS CSCD 北大核心 2019年第3期417-426,共10页
以真空感应熔炼+电渣重熔+真空自耗重熔三联冶炼GH4065高合金化镍基变形高温合金棒材(直径280 mm)为对象,系统研究了该合金点状偏析的低倍组织、元素分布、第二相及晶粒形貌,分析了典型溶质元素对点状偏析行为的影响,探讨点状偏析的形... 以真空感应熔炼+电渣重熔+真空自耗重熔三联冶炼GH4065高合金化镍基变形高温合金棒材(直径280 mm)为对象,系统研究了该合金点状偏析的低倍组织、元素分布、第二相及晶粒形貌,分析了典型溶质元素对点状偏析行为的影响,探讨点状偏析的形成规律与机制及控制思路。结果表明,GH4065合金点状偏析主要源于枝晶间富Ti、Nb等元素的熔体密度较小冲破枝晶臂流动形成的通道偏析;锻造后生成较多的板条状η相、块状M3B2型硼化物与MC型碳化物。热力学相计算亦证实了点状偏析区较正常组织区域更容易生成η相、M3B2和MC。热处理后,与正常组织区域相比,点状偏析中仍存在板条状η相,一次γ′相的尺寸和数量明显增加,二次γ′相尺寸和形貌基本相同但数量减少。分析发现,由于点状偏析区的成分变化使得γ′相回溶温度升高,导致锻造中粗大γ′相阻碍再结晶长大,点状偏析区晶粒尺寸小于正常组织区域。采取前道次冶炼精细化控制、释放电极残余应力、适度降低真空自耗重熔熔化速率、加强真空自耗重熔冷却等措施,可以有效降低点状偏析的形成倾向。 展开更多
关键词 镍基合金 GH4065合金 点状偏析 密度差 控制方法
基于 Tikhonov正则化的高分辨率群时延测量与计算方法 预览
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作者 骆睿 刘莉 +1 位作者 佟瑞 李凌云 《电子学报》 EI CAS CSCD 北大核心 2019年第5期1044-1048,共5页
在衡量传输网络对信号传输时间延迟和信号失真影响时,群时延是非常重要的一项指标.基于差分法计算群时延是目前测量仪器普遍使用的方法,该方法存在着分辨率和精度之间的矛盾,在提高频率分辨率的同时势必引起测量精度的下降.本文在分析... 在衡量传输网络对信号传输时间延迟和信号失真影响时,群时延是非常重要的一项指标.基于差分法计算群时延是目前测量仪器普遍使用的方法,该方法存在着分辨率和精度之间的矛盾,在提高频率分辨率的同时势必引起测量精度的下降.本文在分析差分法误差来源的基础上,基于 Tikhonov正则化给出了一种新的群时延计算方法.比较分析得出该方法能够在存在测量误差的情况下,精确得到具有较高频率分辨率的群时延.在实际给出的测量验证中,通过与矢量网络分析仪得到的群时延数据对比,验证了该方法的有效性. 展开更多
关键词 群时延 差分法 TIKHONOV正则化
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京津冀地区城市绿色发展水平区域差异分析 预览
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作者 王国力 韩慧慧 《辽宁师范大学学报:自然科学版》 CAS 2019年第1期106-111,共6页
《关于加快推进生态文明建设的意见》首次提出'绿色化'概念,并将'新四化'拓展整合为'新五化'.京津冀地区作为'首都经济圈',位于中国的心脏地带.首先构建京津冀地区城市绿色发展评价综合指标体系,运用... 《关于加快推进生态文明建设的意见》首次提出'绿色化'概念,并将'新四化'拓展整合为'新五化'.京津冀地区作为'首都经济圈',位于中国的心脏地带.首先构建京津冀地区城市绿色发展评价综合指标体系,运用熵值法对2016年京津冀地区各市城市绿色发展水平的各项指标进行综合分析,得出各市绿色发展水平指数,并分析各地区之间的水平差异及影响因素.结果表明:京津冀地区绿色发展水平极不均衡,北京城市绿色发展水平最高,廊坊、秦皇岛、沧州较高,唐山城市绿色发展水平最低;城市经济绿色发展水平对城市绿色发展的影响最大,经济的增长并不等同于经济发展的'绿色化'. 展开更多
关键词 京津冀地区 绿色发展 区域差异 熵值法
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