全文获取类型
收费全文 | 2576篇 |
免费 | 119篇 |
专业分类
公路运输 | 407篇 |
综合类 | 992篇 |
水路运输 | 424篇 |
铁路运输 | 354篇 |
综合运输 | 518篇 |
出版年
2024年 | 10篇 |
2023年 | 7篇 |
2022年 | 25篇 |
2021年 | 56篇 |
2020年 | 81篇 |
2019年 | 50篇 |
2018年 | 77篇 |
2017年 | 69篇 |
2016年 | 101篇 |
2015年 | 121篇 |
2014年 | 208篇 |
2013年 | 271篇 |
2012年 | 174篇 |
2011年 | 216篇 |
2010年 | 207篇 |
2009年 | 165篇 |
2008年 | 179篇 |
2007年 | 167篇 |
2006年 | 160篇 |
2005年 | 88篇 |
2004年 | 64篇 |
2003年 | 55篇 |
2002年 | 34篇 |
2001年 | 38篇 |
2000年 | 15篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 1篇 |
排序方式: 共有2695条查询结果,搜索用时 984 毫秒
561.
Accessibility is a valuable indicator for assessing the effectiveness of a transport network. Nevertheless, its analysis can lead to very heterogeneous results depending on the method adopted, thus still struggling to be considered by policy makers and in planning processes. This article contributes to the development of an accessibility analysis as a planning tool, by proposing an alternative model to estimate the relative accessibility of a destination by public transport (PT). Indeed, PT is a mobility paradigm that has been supported to reduce the negative externalities produced by private transport, especially in environmentally fragile contexts. The model includes a set of eleven factors affecting public transport operation which refer to four macro topics: connectivity, multimodality, tariff/ticketing, and info-mobility. They are integrated into a Public Transport Accessibility index which analyses a series of nodes along a route and detects the progressive variation of accessibility. Eventual shifts are highlighted, including information about the factors feeding them. The model is tested for the Lana-Zurich (IT-CH) connection, showing how the most relevant issues are caused by difficulties in the transnational and transregional integration of the services. Through this process, the model aims at backing policy makers in the detection and understanding of public transport barriers and related causes. 相似文献
562.
对昆明城域传送网的建网原则、网络结构进行了介绍,对目前存在的问题进行了分析。并针对存在的问题提出了网络优化方向。 相似文献
563.
广西面临着西部大开发、CEPA、GMS、中国-东盟自由贸易区、泛珠三角经济圈、环北部湾经济圈等历史性机遇。如何抓住这一历史性机遇,乘势而上,构建广西面向东盟的国际道路运输业,是摆在我们面前的当务之急。作者从广西国际道路运输业的实际出发,分析了广西具有发展国际道路运输的独特优势和良好机遇,着重阐述了广西新一轮国际道路运输发展的战略布局,提出了加快广西国际道路运输发展的目标、方向和对策。 相似文献
564.
This paper describes an approach to the development of metropolitan transport strategies based on community needs and values. A search conference and other consultation methods were used to raise community awareness of transport issues and to give the transport planners an understanding of community concerns and values. The collective values were used to develop a vision statement of where Melbourne could be in the future. Transport strategies were then developed which helped achieve the vision. By this approach transport strategies can be integrated with the delivery of other services so that they are complementary and achieve consistent ends. The process encouraged community debate and helped strategy development to focus on what was to be achieved, rather than on particular techniques or interest group agendas. Integrated strategies which have wide interest group and community support can be developed by the process. 相似文献
565.
凌昌国 《铁路通信信号工程技术》2005,(3):16-17,40
城域传送网技术突飞猛进,MSTP、RPR、ASON三种技术同时并存,各有优缺点,各个运营商根据各自情况选择相应的技术。 相似文献
566.
The paper reviews the current situation on-board microprocessor applications. It first describes the aspects of vehicle technology and performance that are the focus for on-board computing equipment, from engine management systems through to fully intergrated driver decision support. In the second section a wider perspective is taken by examining the interaction of the vehicle and its environment. The third and final section of the paper considers elements of communication which permit extensive transmission of vehicle and journey data for public and private use. The conclusion identifies factors which will influence the speed with which further applications will be adopted. 相似文献
567.
An investigation of the drift velocity induced by water waves of a contminated surface layer is carried out. The theoretical analysis is based on a thin boundary layer on the free surface. The results of the analysis reveal that the drift velocity of a viscous layer on the water surface is 7/4 times the Stokes prediction ofc(ak)
2 wherec is the wave celerity andak the wave slope. The present experimental investigation confirms the validity of the theoretical prediction for the drift velocity for a lightly contaminated surface layer; however, for a heavily contaminated surface layer, the experimental results exceed the theoretical prediction. An investigation for a heavily contaminated layer is carried out assuming an inextensible surface layer. Thus, in the experiment, vinyl sheets are used to substitute the contaminated layers. By balancing the wave-induced mean thrust force with the mean drag force, the drift velocity is obtained and compared with the experimental results. Based on the theoretical and experimental analyses, formulae for predicting the drift velocities for laminar and turbulent flow conditions are proposed. 相似文献
568.
569.
船模航行试验技术在水运工程研究中的应用 总被引:1,自引:1,他引:0
论述了船模航行试验的基本相似条件、相关技术,指出这项技术适于研究航道及通航工程的水流条件及工程方案的优化布置;研究船舶性能、航道尺度、航道水流条件三者的相互关系及提高通航能力的措施。介绍了这项技术在水运工程研究中的应用及发展前景。 相似文献
570.