全文获取类型
收费全文 | 560篇 |
免费 | 6篇 |
专业分类
公路运输 | 191篇 |
综合类 | 35篇 |
水路运输 | 169篇 |
铁路运输 | 15篇 |
综合运输 | 156篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 19篇 |
2017年 | 14篇 |
2016年 | 34篇 |
2015年 | 6篇 |
2014年 | 20篇 |
2013年 | 83篇 |
2012年 | 24篇 |
2011年 | 23篇 |
2010年 | 32篇 |
2009年 | 34篇 |
2008年 | 26篇 |
2007年 | 22篇 |
2006年 | 9篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 13篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 19篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有566条查询结果,搜索用时 0 毫秒
141.
Researchers have produced sophisticated modal split and transit demand models, including forecasts that are sensitive to the level of service. However, little effort has been made to integrate these models into corridor studies and route alignment analyses since (a) re-routing is itself an extremely complex modeling task, and (b) the results of the demand models are presented in tabular form with no facility to visualize spatial patterns and relationships that, if recognized, would aid in the routing tasks. GIS tools can be used, together with the demand models, to identify both clusters of city blocks that house families with certain socioeconomic characteristics and potential trip destinations conducive to transit use. In other words, GIS tools can be used to better measure some of the factors that are needed by transit demand models. The results of these models can be displayed graphically, enabling analysts to target places needing improved service, evaluate route re-alignment alternatives, and operate more efficient and effective bus lines. This paper examines how a particular class of model used by transit agencies for estimating ridership can be integrated with GIS tools in order to facilitate such analyses. It also explores the effects of visualization of routes, demographics, and employment data on the process of designing route alignments with better targeting of high transit ridership areas. This paper is part of a research project sponsored by the Region One University Transportation Center, at MIT. 相似文献
142.
James T. Jenkins 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1982,11(5):325-343
The belted radial passenger car tire is idealized as a prestressed circular ring connected to a hub through a distribution of linear springs modeling the sidewall. A second distribution of such springs exterior to the ring represents the tread rubber. The tire is supposed to be at rest, loaded at its hub, and pressed onto a flat, rigid, frictiontess roadway. In this situation the linear differential equations of the model are solved using a singular perturbation technique. Given the load at the hub, the solutions furnish the length of tread in contact with the road, the radial and circumferential displacement of all points on the ring, and the distribution of pressure over the region of contact. 相似文献
143.
Adrian T. Moore Samuel R. Staley Robert W. Poole 《Transportation Research Part A: Policy and Practice》2010,44(8):565-574
This article evaluates the case for vehicle miles traveled (VMT) reduction as a core policy goal for reducing greenhouse gases (GHGs), concluding the economic impacts and social consequences would be too severe given the modest potential environmental benefits. Attempts to reduce VMT typically rely on very blunt policy instruments, such as increasing urban densities, and run the risk of reducing mobility, reducing access to jobs, and narrowing the range of housing choice. VMT reduction, in fact, is an inherently blunt policy instrument because it relies almost exclusively on changing human behavior and settlement patterns to increase transit use and reduce automobile travel rather than directly target GHGs. It also uses long-term strategies with highly uncertain effects on GHGs based on current research. Not surprisingly, VMT reduction strategies often rank among the most costly and least efficient options. In contrast, less intrusive policy approaches such as improved fuel efficiency and traffic signal optimization are more likely to directly reduce GHGs than behavioral approaches such as increasing urban densities to promote higher public transit usage. As a general principle, policymakers should begin addressing policy concerns using the least intrusive and costly approaches first. Climate change policy should focus on directly targeting greenhouse gas emissions (e.g., through a carbon tax) rather than using the blunt instrument of VMT reduction to preserve the economic and social benefits of mobility in modern, service-based economies. Targeted responses are also more cost effective, implying that the social welfare costs of climate change policy will be smaller than using broad-brushed approaches that directly attempt to influence living patterns and travel behavior. 相似文献
144.
145.
146.
E. T. Laing 《Maritime Policy and Management》1976,3(3):141-151
In Part 1*of this article a background to the economics of conference operation was provided, and conference fleet planning and single voyage costs were discussed. This part of the paper will analyse the economic objectives of conferences and will consider the implications of ending the conference princing structure. Some recommendations are also offered. 相似文献
147.
E. T. Laing 《Maritime Policy and Management》1977,4(3):141-154
This paper examines the question of who gains from reduced freight rates passed on by shipowners who derive benefit from port investment. 相似文献
148.
149.
轮-轴组件的三维弹性接触分析 总被引:1,自引:0,他引:1
本文根据接触问题的参变量最小势能原理,建立了接触问题的有限元参数二次规划解,并以RE_2型车轴为例,按三维接触模型进行了计算分析。 相似文献
150.