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   3262篇
  免费   67篇
公路运输   1106篇
综合类   565篇
水路运输   796篇
铁路运输   419篇
综合运输   443篇
  2023年   12篇
  2022年   47篇
  2021年   84篇
  2020年   64篇
  2019年   27篇
  2018年   79篇
  2017年   93篇
  2016年   189篇
  2015年   65篇
  2014年   86篇
  2013年   210篇
  2012年   205篇
  2011年   279篇
  2010年   282篇
  2009年   207篇
  2008年   262篇
  2007年   251篇
  2006年   191篇
  2005年   126篇
  2004年   67篇
  2003年   42篇
  2002年   39篇
  2001年   64篇
  2000年   42篇
  1999年   22篇
  1998年   35篇
  1997年   28篇
  1996年   28篇
  1995年   28篇
  1994年   12篇
  1993年   13篇
  1992年   6篇
  1991年   14篇
  1989年   11篇
  1988年   10篇
  1987年   6篇
  1986年   8篇
  1985年   7篇
  1984年   7篇
  1982年   5篇
  1981年   8篇
  1980年   9篇
  1979年   5篇
  1978年   6篇
  1977年   11篇
  1976年   6篇
  1975年   7篇
  1974年   6篇
  1973年   7篇
  1972年   4篇
排序方式: 共有3329条查询结果,搜索用时 109 毫秒
91.
对黄骅港现有取料机在使用过程中回转减速机出现的故障进行了详细的分析,完成了减速机的国产化改造,降低了故障率.  相似文献   
92.
This research seeks to improve the understanding of the full range of determinants for mode choice behavior and to offer practical solutions to practitioners on representing and distinguishing these characteristics in travel demand forecasting models. The principal findings were that the representation of awareness of transit services is significantly different than the underlying assumption of mode choice and forecasting models that there is perfect awareness and consideration of all modes. Furthermore, inclusion of non-traditional transit attributes and attitudes can improve mode choice models and reduce bias constants. Additional methods and analyses are necessary to bring these results into practice. The work is being conducted in two phases. This paper documents the results of Phase I, which included data collection for one case study city (Salt Lake City), research and analysis of non-traditional transit attributes in mode choice models, awareness of transit services, and recommendations for bringing these analyses into practice. Phase II will include data collection for two additional case study cities (Chicago and Charlotte) with minor modifications based on limitations identified in Phase I, additional analyses where Phase I results indicated a need, and a demonstration of the research in practice for at least one case study city.  相似文献   
93.
Container shipping and its related service sectors help accelerate globalization of the world economy. This industry has been experiencing rapid growth, prompting container terminal operators to increase their handling capacity in response. Providing container terminal services requires substantial capital investment in physical assets such as cargo handling facilities and information systems. On the other hand, operating container terminals is a long-term investment that typically spans several business cycles. Hence prudent asset management using appropriate tools is critical for container terminal operators to sustain their businesses. Generally, due to risk-adverseness, investors are unwilling to take more risk in their investment unless they can reap a higher return. Contrary to this argument, this study finds no direct influence of better firm performance as a proxy of higher return on business risk-taking by container terminal operators. Instead, scale of operations is positively associated with business risk-taking, suggesting that container terminal operators with a larger scale of operations are willing to take more business risk.  相似文献   
94.
The aim of this study was to assess proof of concept and usability of a maritime service website prototype in a full-mission ship bridge simulator through Swedish mariners’ experiences and perceptions. This test was part of the European Commission’s EfficienSea2 project for e-navigation. The prototype was intended as an aid to existing standard systems and methodologies for planning, executing and monitoring voyages. The study began with 5 days of simulator trials focused on today’s standard practices. This served as a baseline to compare to subsequent 4 days of simulator trials testing the prototype. For data collection, observations, video footage, interviews, and eye tracking were used. Data analysis included breaking apart the qualitative data to capture the perceptions of the participants, and a preliminary analysis of eye-tracking data as a complement. The results suggested that the prototype could be more suitable for a route planning stage, that the participants were familiar with similar existing solutions from other manufacturers, and that the contents of the tool would be most beneficial if integrated within the Electronic Chart Display and Information Systems (ECDIS). There is a pressing need for the novel solutions to be user needs-driven, integrated with the existing technologies, and standardized across the domain, and these processes must go hand-in-hand with accounting for all involved stakeholders, procedures, regulations, and training, as this will alter the course of shipping.  相似文献   
95.
交叉口协调感应信号控制   总被引:1,自引:0,他引:1  
介绍了传统的感应控制方法,着重对协调感应信号控制的基本原理,控制过程等进行了分析,并提出了解决问题的方法。分析了定时信号控制和感应信号控制的优缺点,对感应信号控制的进一步研究提出了几点看法。  相似文献   
96.
利用太沙基单向固结理论,按照多级加载路堤沉降的叠加原理,建立非线性规划模型。用沉降实测资料确定模型参数,确定最优化模型后预测任意时刻沉降量。最后,用工程实例说明其方法在预测提前量上具有明显优势,是一种有效而实用的沉降早期预测方法。  相似文献   
97.
根据简易瞬态工况污染物排放检测系统(Vmas)的工作原理,开发了测试系统硬件和控制软件,在此基础上进行了系统的标定和响应时间的测定,并完成与定容取样系统(CVS)的实验对比。该实验结果表明所开发的系统具有较高的测试精度,能够满足国家标准的要求。  相似文献   
98.
丰田汽车公司开发的FCHV-4型采用燃料电池和辅助电池作为混合动力系统的能源,极大提高能源转换效率,使汽车具有良好的性能。燃料电池与牵引电机逆变器直接相连,与辅助电池和DC/DC器串联。该燃料电池汽车的效率为传统内燃机汽车的3倍。  相似文献   
99.
预应力锚索腐蚀原理与防腐技术方法初探   总被引:3,自引:0,他引:3  
从腐蚀机理出发,阐述预应力锚索受腐蚀的现状及其防腐蚀的技术方法,提出浅显的建议。  相似文献   
100.
预应力混凝土连续刚构悬臂施工的几点看法   总被引:1,自引:0,他引:1  
引入应力集中的概念,分析挂篮施工的安全问题、受力预埋件焊接情况和结构物混凝土开裂问题,为类似工程的安全、质量控制提供参考.  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