全文获取类型
收费全文 | 239篇 |
免费 | 4篇 |
专业分类
公路运输 | 34篇 |
综合类 | 80篇 |
水路运输 | 59篇 |
铁路运输 | 20篇 |
综合运输 | 50篇 |
出版年
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 10篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 12篇 |
2016年 | 10篇 |
2015年 | 18篇 |
2014年 | 17篇 |
2013年 | 13篇 |
2012年 | 17篇 |
2011年 | 19篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 18篇 |
2007年 | 20篇 |
2006年 | 11篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 11篇 |
2001年 | 6篇 |
1998年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有243条查询结果,搜索用时 0 毫秒
241.
In transportation studies, variables of interest are often influenced by similar factors and have correlated latent terms
(errors). In such cases, a seemingly unrelated regression (SUR) model is normally used. However, most studies ignore the potential
temporal and spatial autocorrelations across observations, which may lead to inaccurate conclusions. In contrast, the SUR
model proposed in this study also considers these correlations, making the model more behaviorally convincing and applicable
to circumstances where a three-dimensional correlation exists, across time, space, and equations. An example of crash rates
in Chinese cities is used. The results show that incorporation of spatial and temporal effects significantly improves the
model. Moreover, investment in transportation infrastructure is estimated to have statistically significant effects on reducing
severe crash rates, but with an elasticity of only −0.078. It is also observed that, while vehicle ownership is associated
with higher per capita crash rates, elasticities for severe and non-severe crashes are just 0.13 and 0.18, respectively; much
lower than one. The techniques illustrated in this study should contribute to future studies requiring multiple equations
in the presence of temporal and spatial effects.
Ms. Xiaokun Wang is a doctoral student in the Department of Civil, Architectural and Environmental Engineering at the University of Texas at Austin. She received her B.S. and M.S. degrees at Tsinghua University, China. Her research topics range from travel demand modeling and integrated land use-transportation planning, to spatial econometrics, network analysis, and traffic safety analysis. She is a fellow of the International Road Federation. Dr. Kara Kockelman is a Associate Professor of Civil, Architectural & Environmental Engineering and the William J. Murray Jr. Fellow at the University of Texas, Austin. She holds a PhD, MS, and BS in Civil Engineering, a Masters of City Planning, and a minor in Economics from the University of California at Berkeley. She is Chair of the Transportation Research Board’s Committee on Travel Survey Methods. Her primary research interests include the statistical modeling of urban systems (including models of travel behavior, trade, and location choice), economic impacts of transport policy, crash occurrence and consequences, and transport policy-making. 相似文献
Kara M. Kockelman (Corresponding author)Email: |
Ms. Xiaokun Wang is a doctoral student in the Department of Civil, Architectural and Environmental Engineering at the University of Texas at Austin. She received her B.S. and M.S. degrees at Tsinghua University, China. Her research topics range from travel demand modeling and integrated land use-transportation planning, to spatial econometrics, network analysis, and traffic safety analysis. She is a fellow of the International Road Federation. Dr. Kara Kockelman is a Associate Professor of Civil, Architectural & Environmental Engineering and the William J. Murray Jr. Fellow at the University of Texas, Austin. She holds a PhD, MS, and BS in Civil Engineering, a Masters of City Planning, and a minor in Economics from the University of California at Berkeley. She is Chair of the Transportation Research Board’s Committee on Travel Survey Methods. Her primary research interests include the statistical modeling of urban systems (including models of travel behavior, trade, and location choice), economic impacts of transport policy, crash occurrence and consequences, and transport policy-making. 相似文献
242.
以中国11 条物流通道为实证对象,综合测算物流通道技术水平,构造基于地理距 离的空间邻接权重矩阵,检验相关变量的空间自相关性,构建空间杜宾面板数据模型验证了 中国物流通道的空间溢出效应.研究表明:中国物流通道总体上具有显著的正向空间溢出效 应,但从分布于不同空间的物流通道看,长江、沿海、京九、陇海兰新和沪昆物流通道正向空间 溢出效应显著;而京沪、京广和宝昆物流通道研究期内空间溢出效应不显著.我国物流通道的 空间溢出效应具有显著的空间差异,应因地制宜地合理化建设物流通道. 相似文献
243.
Internal solitary waves with a huge amount of energy easily trigger the large dynamic responses of riser-wellhead system and threaten its structural safety. However, previous studies have only focused on the dynamic response of the riser under internal solitary waves. The riser may experience excessive traction from the platform, especially from the mooring platform, in response to the arrival of internal solitary waves. The bottom of the riser connects to the wellhead system, which in turn exerts a reaction force on the riser. To address this problem, a coupled dynamic model of deep-water drilling mooring platform-riser-wellhead system under internal solitary waves is developed in this paper. A dynamic response analysis method based on the fourth-order Runge-Kutta method and finite element method is also proposed for the mooring platform-riser-wellhead system. A dynamical solver for the coupled system is then developed using MATLAB. The dynamic response characteristics of the riser-wellhead system under internal solitary waves are calculated. Results show that the displacement and bending moment of the system initially increases and then decreases along with the propagation of internal solitary waves, and finally reach equilibrium position. The displacement and bending moment reach their peak before the trough of internal solitary waves passes through the riser-wellhead system. The dynamic responses of the riser-wellhead system under the influence of internal solitary wave loads are much larger than those without the effect of internal solitary wave loads. The riser system experiences shearing loads at the interface of internal solitary waves, which trigger a step-like bending moment variation. The bending moment of the conductor under the mudline is greatly increased by the internal solitary waves. 相似文献