全文获取类型
收费全文 | 2128篇 |
免费 | 50篇 |
专业分类
公路运输 | 375篇 |
综合类 | 286篇 |
水路运输 | 272篇 |
铁路运输 | 1152篇 |
综合运输 | 93篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 23篇 |
2021年 | 32篇 |
2020年 | 44篇 |
2019年 | 25篇 |
2018年 | 23篇 |
2017年 | 34篇 |
2016年 | 31篇 |
2015年 | 41篇 |
2014年 | 162篇 |
2013年 | 107篇 |
2012年 | 173篇 |
2011年 | 150篇 |
2010年 | 139篇 |
2009年 | 135篇 |
2008年 | 154篇 |
2007年 | 176篇 |
2006年 | 164篇 |
2005年 | 159篇 |
2004年 | 129篇 |
2003年 | 55篇 |
2002年 | 41篇 |
2001年 | 44篇 |
2000年 | 22篇 |
1999年 | 21篇 |
1998年 | 18篇 |
1997年 | 20篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1994年 | 13篇 |
1993年 | 2篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1989年 | 1篇 |
排序方式: 共有2178条查询结果,搜索用时 15 毫秒
71.
72.
Developing an enhanced weight-based topological map-matching algorithm for intelligent transport systems 总被引:2,自引:0,他引:2
Nagendra R. Velaga Mohammed A. Quddus Abigail L. Bristow 《Transportation Research Part C: Emerging Technologies》2009,17(6):672-683
Map-matching (MM) algorithms integrate positioning data from a Global Positioning System (or a number of other positioning sensors) with a spatial road map with the aim of identifying the road segment on which a user (or a vehicle) is travelling and the location on that segment. Amongst the family of MM algorithms consisting of geometric, topological, probabilistic and advanced, topological MM (tMM) algorithms are relatively simple, easy and quick, enabling them to be implemented in real-time. Therefore, a tMM algorithm is used in many navigation devices manufactured by industry. However, existing tMM algorithms have a number of limitations which affect their performance relative to advanced MM algorithms. This paper demonstrates that it is possible by addressing these issues to significantly improve the performance of a tMM algorithm. This paper describes the development of an enhanced weight-based tMM algorithm in which the weights are determined from real-world field data using an optimisation technique. Two new weights for turn-restriction at junctions and link connectivity are introduced to improve the performance of matching, especially at junctions. A new procedure is developed for the initial map-matching process. Two consistency checks are introduced to minimise mismatches. The enhanced map-matching algorithm was tested using field data from dense urban areas and suburban areas. The algorithm identified 96.8% and 95.93% of the links correctly for positioning data collected in urban areas of central London and Washington, DC, respectively. In case of suburban area, in the west of London, the algorithm succeeded with 96.71% correct link identification with a horizontal accuracy of 9.81 m (2σ). This is superior to most existing topological MM algorithms and has the potential to support the navigation modules of many Intelligent Transport System (ITS) services. 相似文献
73.
74.
75.
介绍了一种高速铁路CTC中心电源系统冗余方案,并详细阐述了机房稳定电源提供、电源屏及UPS、双电源设备、单电源设备、电源监测系统、电源系统检修的具体方案。 相似文献
76.
我国Ⅲ、Ⅳ级铁路有配备列控系统的需求.ITCS和ERTMS Regional是适合Ⅲ、Ⅳ级铁路的2种列控系统,介绍了它们的结构和功能特点. 相似文献
77.
Rodrigo Mesa-Arango 《智能交通系统杂志
》2014,18(4):327-338
》2014,18(4):327-338
Several transportation problems, such as implementation of truck-only lanes, require understanding the interaction of heterogeneous dynamic traffic flows in order to provide accurate solutions. System-optimal dynamic traffic assignment can be modeled using a network loading procedure based on the cell transmission model, that is, the hydrodynamic wave model, and solved by linear programming. However, this framework cannot handle the asymmetric integration between the flow of trucks and cars. This article presents a novel formulation for network loading in system-optimal dynamic traffic assignment considering car–truck interactions. By using an embedded cell transmission model, this formulation incorporates a set of assumptions related to the kinematic characteristics of the flow of cars, trucks, and their interactions that can be solved using linear programming. We present numerical results supporting our modeling assumptions. Likewise, the observed emergent behavior captures the car–truck interactions accurately and indicates that minimum system-optimal travel time is obtained by encouraging cars to use highways with shorter distances. 相似文献
78.
Y. Q. Sun S. Simson 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(2):113-132
A nonlinear wagon-track model on curved track has been developed to characterize rail corrugation formation due to self-excitation of the wheel-rail stick-slip process. In this model, wagon movements were described using up to 78 degrees of freedom (DOFs) to model a three-piece freight bogie. Innovatively, the wheelset movements are described using nine DOFs, including torsional and bending modes about the longitudinal and vertical directions. The track modelling is considered as a one-layer structure (two rail beams on discrete spring and damper elements). The wheel sliding after creepage saturation is considered in the wheel-rail interface modelling. Simulation of a case study shows that the frequencies of the wheel stick-slip process are composed of the basic frequency, which might come from the combined effect of sleeper-passing frequency and one-third of the combined torsional and bending frequency of the wheelset, and the double and triple basic frequencies, which form the wavelengths of rail corrugation at different situations. 相似文献
79.
键合图理论在汽车系统分析与控制中的应用 总被引:9,自引:0,他引:9
本文分析了键合图理论特点,简介了键合图基本原理及国内外发展概况,重点论述了键合图理论在汽车系统分析与控制的建模和仿真的应用。 相似文献
80.
汽车驾驶室都装设有机油欠压警告等信号装置,以提醒驾驶员警觉,但在实际营运过程中,驾驶员常常疏忽欠压警告信号,或为了完成运输定额,强行运行,结果造成车辆损伤。针对这种情况,城市公共汽车或其它车辆,应该在原有机油欠压信号指示装置的基础上,安装一种在机油欠压时,强制使发动机熄火的装置。 相似文献