首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   833篇
  免费   64篇
公路运输   292篇
综合类   294篇
水路运输   86篇
铁路运输   169篇
综合运输   56篇
  2024年   6篇
  2023年   12篇
  2022年   19篇
  2021年   23篇
  2020年   31篇
  2019年   24篇
  2018年   24篇
  2017年   24篇
  2016年   34篇
  2015年   29篇
  2014年   69篇
  2013年   50篇
  2012年   91篇
  2011年   87篇
  2010年   53篇
  2009年   61篇
  2008年   56篇
  2007年   51篇
  2006年   55篇
  2005年   33篇
  2004年   20篇
  2003年   10篇
  2002年   9篇
  2001年   11篇
  2000年   4篇
  1999年   1篇
  1996年   3篇
  1994年   2篇
  1990年   3篇
  1989年   1篇
  1984年   1篇
排序方式: 共有897条查询结果,搜索用时 890 毫秒
261.
针对目前规范中振动标线设置原理的不足,分析了各种轮胎在一定胎压下的接地面积和接地长度,从而分别得到了对于大型车和小型车的合理设置间隔;同时从工程心理学的角度讨论了驾驶员对于振动的接受程度,并得到了标线的最佳重复条数。该研究结论对于减速振动标线的合理设置有很好的借鉴和参考作用。  相似文献   
262.
在HXD1型机车上,采用集成式辅助电源模式,即将辅助逆变器集成于牵引变流器中,电源直接从牵引直流电路获得,再通过隔离变压器加滤波的形式为辅助电路供电。文章重点分析这种新型辅助供电系统的工作模式及特点。  相似文献   
263.
设置公交专用道道路的交通脆弱性分析   总被引:2,自引:0,他引:2  
设置公交专用道将对城市道路交通状态产生重大影响。本文首次将脆弱性的概念引入交通系统,通过对其进行评价和系统扰动下的交通状态分析,构建了交通脆弱性评价指标体系,建立了交通脆弱性评估数学模型,并对模型进行应用,对道路的交通脆弱性进行了分级研究。  相似文献   
264.
传统换道模型中,把前后临界空隙作为参数固定数值,忽视了车辆和车道间的动态交互作用等因素.从分子动力学角度,系统考虑跟驰需求安全特性,从动态的需求安全距离角度研究车辆在“跟驰—换道—跟驰”过程中的行驶状态转换.确保在换道完成时,换道车辆和目标车道后车能以需求安全距离进行跟车行驶,建立了模拟分子动力学的期望安全间距模型,并对模型进行了仿真分析.结果表明,分子动力学特性模型可以把跟驰行为和换道行为很好地结合起来.研究成果为分析车辆运行交互特性,车辆可变限速技术,自适应巡航控制技术等提供理论依据和技术支撑.  相似文献   
265.
运用Matlab/Simulink软件包对船用辅锅炉系统进行动态仿真,以锅炉炉膛为例建立了数学模型,给出了该系统的动态模型,并详细介绍了如何利用SIMULINK对锅炉系统进行仿真。仿真结果表明,SIMULINK也是对锅炉系统进行建模的一种有效方法。  相似文献   
266.
地铁车辆上两种典型GTO驱动电路的对比分析   总被引:1,自引:0,他引:1  
对上海地铁一号线进口车辆的GTO直流传动系统上的两种典型GTO驱动电路作了对比分析,并对辅助逆变器和牵引斩波器的GTO驱动电路分别进行了测试与分析。  相似文献   
267.
Inspired by the rapid development of charging-while-driving (CWD) technology, plans are ongoing in government agencies worldwide for the development of electrified road freight transportation systems through the deployment of dynamic charging lanes. This en route method for the charging of plug-in hybrid electric trucks is expected to supplement the more conventional charging technique, thus enabling significant reduction in fossil fuel consumption and pollutant emission from road freight transportation. In this study, we investigated the optimal deployment of dynamic charging lanes for plug-in hybrid electric trucks. First, we developed a multi-class multi-criteria user equilibrium model of the route choice behaviors of truck and passenger car drivers and the resultant equilibrium flow distributions. Considering that the developed user equilibrium model may have non-unique flow distributions, a robust deployment of dynamic charging lanes that optimizes the system performance under the worst-case flow distributions was targeted. The problem was formulated as a generalized semi-infinite min-max program, and a heuristic algorithm for solving it was proposed. This paper includes numerical examples that were used to demonstrate the application of the developed models and solution algorithms.  相似文献   
268.
对长深高速公路遵化至南小营段高速公路运营适应性、纵坡路段服务水平及行车安全性进行分析,提出此路段应设置爬坡车道,并对路线服务性做全面评价,指出此路段平纵线形组合的优缺点及适应性。  相似文献   
269.
The paper explores what can occur when select street lanes throughout a city are periodically reserved for buses. Simulations of an idealized city were performed to that end. The city’s time-varying travel demand was studied parametrically. In all cases, queues formed throughout the city during a rush, and dissipated during the off-peak period that followed. Bus lanes were activated all at once across the city, and were eventually deactivated in like fashion. Activation and deactivation schedules varied parametrically as well. Schedules that roughly balanced the trip-time savings to bus riders against the added delays to car travelers were thus identified.Findings reveal why activating conversions near the start of a rush can degrade travel, both by car and by bus. Balance was struck by instead activating lane conversions nearer the end of the rush, when vehicle accumulation in the city was at or near its maximum. Most of the time savings to bus riders accrued after the conversions had been left in place for only 30 min. Leaving them for longer durations often brought modest additional savings to bus travelers. Yet, the added delays to cars often grew large as a result.These findings held even when buses garnered high ridership shares. This was the case when lane conversions gradually induced new bus trips among residents who formerly did not travel. It was also true when high ridership was a pre-existing feature of the city. Activating conversions a bit earlier in a rush was found to make sense only if commuters shifted from cars to buses in very large numbers. Findings also unveiled how to fine-tune activation and deactivation schedules to suit a city’s congestion level. Guidelines for scheduling conversions in real settings are furnished. So is discussion on how these schedules might be adapted to daily variations in city-wide traffic states. Roles for technology are discussed as well.  相似文献   
270.
邵建练  何慧彬  贾蓉萍 《船舶》2019,30(4):55-62
阐述了DP-3海洋工程船舶动力辅助系统优化设计典型方案。通过归纳各主要船级社规范要求,在满足规范基本要求的基础上,通过举例说明各辅助系统设计优化建议,对类似船舶动力辅助系统设计提供建议及参考,以提高系统设计的安全性及可靠性。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号