全文获取类型
收费全文 | 8476篇 |
免费 | 579篇 |
专业分类
公路运输 | 1609篇 |
综合类 | 3089篇 |
水路运输 | 1638篇 |
铁路运输 | 1860篇 |
综合运输 | 859篇 |
出版年
2024年 | 34篇 |
2023年 | 64篇 |
2022年 | 164篇 |
2021年 | 214篇 |
2020年 | 289篇 |
2019年 | 206篇 |
2018年 | 221篇 |
2017年 | 286篇 |
2016年 | 313篇 |
2015年 | 404篇 |
2014年 | 623篇 |
2013年 | 596篇 |
2012年 | 626篇 |
2011年 | 776篇 |
2010年 | 608篇 |
2009年 | 545篇 |
2008年 | 587篇 |
2007年 | 705篇 |
2006年 | 543篇 |
2005年 | 335篇 |
2004年 | 230篇 |
2003年 | 163篇 |
2002年 | 102篇 |
2001年 | 111篇 |
2000年 | 71篇 |
1999年 | 29篇 |
1998年 | 32篇 |
1997年 | 31篇 |
1996年 | 28篇 |
1995年 | 20篇 |
1994年 | 13篇 |
1993年 | 22篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
排序方式: 共有9055条查询结果,搜索用时 9 毫秒
161.
Abstract The number of bus‐based Park and Ride (P&R) schemes in the UK has grown substantially over the past 40 years as a result of its encouragement by the Government as a tool to deal with increasing traffic congestion and traffic‐related pollution. The aim of this article is to analyse the degree to which P&R is effective in the contemporary policy context. The authors identify phases of development of P&R since its emergence as a local solution to transport capacity constraints in historic towns. Policy goals are identified against which a review of literature is used to highlight its effectiveness. It is concluded that P&R may increase the distance travelled by its users due to low load factors on dedicated buses, public transport abstraction and trip generation, although it is highlighted that there are areas in which further research is required to clarify its impacts. 相似文献
162.
Recently connected vehicle (CV) technology has received significant attention thanks to active pilot deployments supported by the US Department of Transportation (USDOT). At signalized intersections, CVs may serve as mobile sensors, providing opportunities of reducing dependencies on conventional vehicle detectors for signal operation. However, most of the existing studies mainly focus on scenarios that penetration rates of CVs reach certain level, e.g., 25%, which may not be feasible in the near future. How to utilize data from a small number of CVs to improve traffic signal operation remains an open question. In this work, we develop an approach to estimate traffic volume, a key input to many signal optimization algorithms, using GPS trajectory data from CV or navigation devices under low market penetration rates. To estimate traffic volumes, we model vehicle arrivals at signalized intersections as a time-dependent Poisson process, which can account for signal coordination. The estimation problem is formulated as a maximum likelihood problem given multiple observed trajectories from CVs approaching to the intersection. An expectation maximization (EM) procedure is derived to solve the estimation problem. Two case studies were conducted to validate our estimation algorithm. One uses the CV data from the Safety Pilot Model Deployment (SPMD) project, in which around 2800 CVs were deployed in the City of Ann Arbor, MI. The other uses vehicle trajectory data from users of a commercial navigation service in China. Mean absolute percentage error (MAPE) of the estimation is found to be 9–12%, based on benchmark data manually collected and data from loop detectors. Considering the existing scale of CV deployments, the proposed approach could be of significant help to traffic management agencies for evaluating and operating traffic signals, paving the way of using CVs for detector-free signal operation in the future. 相似文献
163.
A novel multiclass macroscopic model is proposed in this article. In order to enhance first-in, first-out property (FIFO) and transmission function in the multiclass traffic modeling, a new multiclass cell transmission model with FIFO property (herein called FM-CTM) is extended from its prior multiclass cell transmission model (M-CTM). Also, to enhance its analytical compactness and resultant computational convenience, FM-CTM is formulated in this paper as a set of closed-form matrix equations. The objective is to improve the accuracy of traffic state estimation by enforcing FIFO property when a fast vehicle cannot overtake a slow vehicle due to a limitation of a single-lane road. Moreover, the proposed model takes into account a different priority for vehicles of each class to move forward through congested road conditions, and that makes the flow calculation independent from their free-flow speeds. Some hypothetical and real-world freeway networks with a constant or varying number of lanes are selected to verify FM-CTM by comparing with M-CTM and the conventional CTM. Observed densities of VISSIM and real-world dataset of I-80 are selected to compare with the simulated densities from the three CTMs. The numerical results show that FM-CTM outperforms the other two models by 15% of accuracy measures in most cases. Therefore, the proposed model is expected to be well applicable to the road network with a mixed traffic and varying number of lanes. 相似文献
164.
Public Transport (PT) systems rely more and more on online information extracted from both operator’s intelligent equipment and user’s smartphone applications. This allows for a better fit between supply and demand of the multimodal PT system, especially through the use of PT real-time control actions/tactics. In doing so there is also an opportunity to consider environmental-related issues to approach energy saving and reduced pollution. This study investigates and analyses the benefits of using real-time PT operational tactics in reducing the undesirable environmental impacts. A tactic-based control (TBC) optimization model is used to minimize total passenger travel time and maximize direct transfers (without waiting). The model consists of a control policy built upon a combination of three tactics: holding, skip-stops, and boarding limit. The environmental-related measure is the global warming potential (GWP) using the life cycle assessment technique. The methodology developed is applied to a real life case study in Auckland, New Zealand. Results show that TBC could reduce the GWP by means of reduction of total passenger travel times and vehicle travel cycle time. That is, the TBC model results in a 5.6% reduction in total GWP per day compared with an existing no-tactic scenario. This study supports the use of real-time control actions to maintain a reliable PT service, reducing greenhouse gas emissions and subsequently moving towards greener PT systems. 相似文献
165.
Hartmut H. Topp 《Transportation》1988,15(4):279-295
West Germany is densely populated, averaging 245 inhabitants/km2, but varying widely between urban agglomerations and rural areas. Transport volume has increased by 40% since 1970, with virtually all growth due to private automobiles. Since 1981 public transit has been suffering from decreasing demand.A 1964 Expert's Report to the German federal government was the stimulus for initiating an effective funding mechanism for new public transit construction. In 1965 Germany's first federated transit authority was founded for the region of Hamburg.Principal among the goals of any cooperative agreement among transit companies are improvements for the passengers and improvement of revenues for the companies. To attain these ends, two distinct forms of transit aggrements have been developed in Germany: transit cooperative (Verkehrsgemeinschaft) and transit federation (Verkehrsverbund). The former is more suitable for smaller to medium-sized towns, while the latter is more suitable for larger cities. The two types are described in this article.German transit federations during the 1970s succeeded in significantly increasing ridership, while during the 1980s patronage has either remained steady or has declined. Yet transit federations showed much better perfomance than did public transit in general. In terms of costs and revenues, no public transit organization in Germany is able to break even; deficits vary between 42% and 55%. The author concludes, however, that hidden subsidies for automobile traffic are far higher, because of environmental damage and the high social cost of traffic accidents. 相似文献
166.
低质心混凝土搅拌车的主要结构和特点。针对市场上大容量混凝土搅拌车质心高的结构特点,介绍了一种能改善整车行驶稳定性的 相似文献
167.
168.
169.
立意于对乘客体验的解读,提出"乘客体验观",阐述"人城和谐"型的城市公交体系模式,提出个体空间占有概念及衍生公式理论,诠释以乘客体验要素为出发点的城市公交规划和设计思路。 相似文献
170.