全文获取类型
收费全文 | 16026篇 |
免费 | 253篇 |
专业分类
公路运输 | 4175篇 |
综合类 | 4145篇 |
水路运输 | 4151篇 |
铁路运输 | 3337篇 |
综合运输 | 471篇 |
出版年
2024年 | 5篇 |
2023年 | 45篇 |
2022年 | 235篇 |
2021年 | 425篇 |
2020年 | 342篇 |
2019年 | 102篇 |
2018年 | 149篇 |
2017年 | 141篇 |
2016年 | 218篇 |
2015年 | 369篇 |
2014年 | 575篇 |
2013年 | 757篇 |
2012年 | 1039篇 |
2011年 | 1264篇 |
2010年 | 1233篇 |
2009年 | 1234篇 |
2008年 | 1267篇 |
2007年 | 1701篇 |
2006年 | 1684篇 |
2005年 | 1085篇 |
2004年 | 331篇 |
2003年 | 248篇 |
2002年 | 221篇 |
2001年 | 291篇 |
2000年 | 302篇 |
1999年 | 182篇 |
1998年 | 136篇 |
1997年 | 107篇 |
1996年 | 122篇 |
1995年 | 89篇 |
1994年 | 85篇 |
1993年 | 64篇 |
1992年 | 51篇 |
1991年 | 49篇 |
1990年 | 50篇 |
1989年 | 27篇 |
1988年 | 18篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 5篇 |
1984年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 946 毫秒
321.
阐述太原市山洪沟河及排退水渠的现状及发展 ,研讨河道及排水渠道的规划和复盖中应遵循的原则和存在的一些问题 相似文献
322.
影响水利工程施工质量的主要因素与控制措施 总被引:4,自引:0,他引:4
在水利工程施工过程中 ,影响其质量的主要因素有“人、材料、机具、方法、环境”等五方面。一个水利工程项目从开工到竣工投入运行的施工过程中 ,只要某一环节上出现问题 ,都会影响工程质量的提高或可能埋下质量事故隐患。因此 ,保证水利工程施工质量 ,努力实现施工合同条件中确定的施工质量要求 ,必须做到事前主动控制 ,事中积极检查 ,事后严肃把关的积极的预防措施。同时 ,必须贯彻“以防为主 ,防检结合”的方针 ,做到纵向全过程、横向全系统、意识全方向、时间全控制的质量管理要求 ,综合运用多种督查手段措施 ,确保结构安全 ,满足使用功能 ,外表美观大方 相似文献
323.
324.
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
325.
近年来,随着摩托车交通事故的不断攀升,摩托车的行驶安全性已成为影响社会安定的一道屏障,传统鼓式制动器已经无法满足现代摩托车安全行驶的需要,唯有采用ABS主动安全系统才能满足要求。国外摩托车自1988年开始应用ABS技术以来,已从最初的大排量豪华摩托车发展到如今的中小排量豪华摩托车上,国产摩托车也已开始应用这一先进技术。 相似文献
326.
327.
328.
329.
Bus Priority Using pre-signals 总被引:2,自引:0,他引:2
The need to provide efficient public transport services in urban areas has led to the implementation of bus priority measures in many congested cities. Much interest has recently centred on priority at signal controlled junctions, including the concept of pre-signals, where traffic signals are installed at or near the end of a with-flow bus lane to provide buses with priority access to the downstream junction. Although a number of pre-signals have now been installed in the U.K., particularly in London, there has been very little published research into their design, operation and optimisation. This paper addresses these points through the development of analytical procedures which allow pre-implementation evaluation of specific categories of pre-signals. The paper initially sets out three categories of pre-signal, which have different operating characteristics, different requirements for signalling and different impacts on capacity and delay. Key issues concerning signalling arrangements for these categories are then discussed, together with a summary of the analytical approach adopted and the assumptions required. Equations are developed to allow appropriate signal timings to be calculated for pre-signalised intersections. Further equations are then developed to enable delays to priority and non-priority traffic, with and without pre-signals, to be estimated with delay being taken here as the key performance criterion. The paper concludes with three application examples illustrating how the equations are applied and the impacts of pre-signals in different situations.The analyses confirm the potential benefits of pre-signals, where these signals apply to non-priority traffic only. Where buses are also subject to a pre-signal, it is shown that disbenefits to buses can often occur, unless bus detectors are used to gain priority signalling. 相似文献
330.
车用柴油机电控开发系统的软,硬件设计及应用 总被引:8,自引:0,他引:8
本文研制了一种新的发动机电 控燃油系统的开发系统的微机测控系统。 相似文献