全文获取类型
收费全文 | 1520篇 |
免费 | 91篇 |
专业分类
公路运输 | 448篇 |
综合类 | 469篇 |
水路运输 | 311篇 |
铁路运输 | 340篇 |
综合运输 | 43篇 |
出版年
2024年 | 6篇 |
2023年 | 20篇 |
2022年 | 42篇 |
2021年 | 76篇 |
2020年 | 43篇 |
2019年 | 34篇 |
2018年 | 10篇 |
2017年 | 34篇 |
2016年 | 30篇 |
2015年 | 66篇 |
2014年 | 118篇 |
2013年 | 96篇 |
2012年 | 113篇 |
2011年 | 137篇 |
2010年 | 112篇 |
2009年 | 86篇 |
2008年 | 111篇 |
2007年 | 158篇 |
2006年 | 100篇 |
2005年 | 66篇 |
2004年 | 50篇 |
2003年 | 28篇 |
2002年 | 11篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1986年 | 2篇 |
排序方式: 共有1611条查询结果,搜索用时 390 毫秒
21.
介绍南京地铁新街口换乘站的规划、设计和建设概况.以取得的经济、社会综合效益为实例,说明在城市繁华的中心地区,结合地铁建设进行地下空间开发是必要的,也是可行的. 相似文献
22.
23.
Storage space allocation in container terminals 总被引:7,自引:0,他引:7
Chuqian Zhang Jiyin Liu Yat-wah Wan Katta G. Murty Richard J. Linn 《Transportation Research Part B: Methodological》2003,37(10):883-903
Container terminals are essential intermodal interfaces in the global transportation network. Efficient container handling at terminals is important in reducing transportation costs and keeping shipping schedules. In this paper, we study the storage space allocation problem in the storage yards of terminals. This problem is related to all the resources in terminal operations, including quay cranes, yard cranes, storage space, and internal trucks. We solve the problem using a rolling-horizon approach. For each planning horizon, the problem is decomposed into two levels and each level is formulated as a mathematical programming model. At the first level, the total number of containers to be placed in each storage block in each time period of the planning horizon is set to balance two types of workloads among blocks. The second level determines the number of containers associated with each vessel that constitutes the total number of containers in each block in each period, in order to minimize the total distance to transport the containers between their storage blocks and the vessel berthing locations. Numerical runs show that with short computation time the method significantly reduces the workload imbalance in the yard, avoiding possible bottlenecks in terminal operations. 相似文献
24.
Simon-Cella高空作业车的自动调平机构 总被引:3,自引:0,他引:3
董大为 《筑路机械与施工机械化》2004,21(6):33-34
介绍了意大利Simon公司VTl65型高空作业车的主要技术参数、整体结构以及该车的一些主要特点,分析了电液自动调平机构的液压电子回路,为高性能高空作业车的研究设计提供了参考。 相似文献
25.
介绍如何应用美国SPX公司的OTC3545多功能汽车检测仪对汽车常规电气系统进行检测,以及与其它汽车检测仪相比,它所具有的突出优点。 相似文献
26.
简单介绍了微燃机电、热联供机组工作原理,详细对比分析了工程实例与普通柴油发电机组及锅炉采暖技术与经济性能参数,对以后野外施工及偏远无市电地区能源保障提出了看法。 相似文献
27.
未来平地机模型 总被引:5,自引:1,他引:5
刘清华 《筑路机械与施工机械化》2005,22(1):44-46
通过对液压与电子控制技术发展的研究,并结合机、电、液一体化在工程机械领域的应用,从平地机恒速驱动的变速传动系统与基于CAN总线技术的电子控制两个方面进行详细论述,对未来平地机的发展提供了一种新的思路,并就未来平地机自动调平技术提供了可实施的解决方案. 相似文献
28.
29.
Pedestrians adjust both speed and stride length when they navigate difficult situations such as tight corners or dense crowds. They try to avoid collisions and to preserve their personal space. State-of-the-art pedestrian motion models automatically reduce speed in dense crowds simply because there is no space where the pedestrians could go. The stride length and its correct adaptation, however, are rarely considered. This leads to artefacts that impact macroscopic observation parameters such as densities in front of bottlenecks and, through this, flow. Hence modelling stride adaptation is important to increase the predictive power of pedestrian models. To achieve this we reformulate the problem as an optimisation problem on a disk around the pedestrian. Each pedestrian seeks the position that is most attractive in a sense of balanced goals between the search for targets, the need for individual space and the need to keep a distance from obstacles. The need for space is modelled according to findings from psychology defining zones around a person that, when invaded, cause unease. The result is a fully automatic adjustment that allows calibration through meaningful social parameters and that gives visually natural results with an excellent fit to measured experimental data. 相似文献
30.
The Traffic Alert and Collision Avoidance System (TCAS) is a world-wide accepted last-resort means of reducing the probability and frequency of mid-air collisions between aircraft. Unfortunately, it is widely known that in congested airspace, the use of the TCAS may actually lead to induced collisions. Therefore, further research regarding TCAS logic is required. In this paper, an encounter model is formalised to identify all of the potential collision scenarios that can be induced by a resolution advisory that was generated previously by the TCAS without considering the downstream consequences in the surrounding traffic. The existing encounter models focus on checking and validating the potential collisions between trajectories of a specific scenario. In contrast, the innovative approach described in this paper concentrates on quantitative analysis of the different induced collision scenarios that could be reached for a given initial trajectory and a rough specification of the surrounding traffic. This approach provides valuable information at the operational level. Furthermore, the proposed encounter model can be used as a test-bed to evaluate future TCAS logic changes to mitigate potential induced collisions in hot spot volumes. In addition, the encounter model is described by means of the coloured Petri net (CPN) formalism. The resulting state space provides a deep understanding of the cause-and-effect relationship that each TCAS action proposed to avoid an actual collision with a potential new collision in the surrounding traffic. Quantitative simulation results are conducted to validate the proposed encounter model, and the resulting collision scenarios are summarised as valuable information for future Air Traffic Management (ATM) systems. 相似文献