全文获取类型
收费全文 | 8239篇 |
免费 | 111篇 |
专业分类
公路运输 | 1923篇 |
综合类 | 607篇 |
水路运输 | 2589篇 |
铁路运输 | 778篇 |
综合运输 | 2453篇 |
出版年
2022年 | 113篇 |
2021年 | 64篇 |
2020年 | 47篇 |
2019年 | 86篇 |
2018年 | 203篇 |
2017年 | 132篇 |
2016年 | 202篇 |
2015年 | 95篇 |
2014年 | 245篇 |
2013年 | 1233篇 |
2012年 | 350篇 |
2011年 | 446篇 |
2010年 | 291篇 |
2009年 | 370篇 |
2008年 | 348篇 |
2007年 | 276篇 |
2006年 | 231篇 |
2005年 | 273篇 |
2004年 | 297篇 |
2003年 | 185篇 |
2002年 | 151篇 |
2001年 | 135篇 |
2000年 | 139篇 |
1999年 | 106篇 |
1998年 | 129篇 |
1997年 | 112篇 |
1996年 | 138篇 |
1995年 | 149篇 |
1994年 | 84篇 |
1993年 | 189篇 |
1992年 | 160篇 |
1991年 | 77篇 |
1990年 | 83篇 |
1989年 | 58篇 |
1988年 | 74篇 |
1987年 | 65篇 |
1986年 | 59篇 |
1985年 | 77篇 |
1984年 | 73篇 |
1983年 | 73篇 |
1982年 | 73篇 |
1981年 | 95篇 |
1980年 | 68篇 |
1979年 | 91篇 |
1978年 | 56篇 |
1977年 | 69篇 |
1976年 | 53篇 |
1975年 | 65篇 |
1974年 | 50篇 |
1973年 | 45篇 |
排序方式: 共有8350条查询结果,搜索用时 0 毫秒
91.
大广高速公路河北段路线长,地质条件十分复杂,在工程前期设计中通过对路线的优化,很好地解决了地基处理问题和环境保护问题,值得同行借鉴。 相似文献
92.
John C.Humphrey 《汽车与配件》2006,(6):18-19
汽车产品的质量总是会受到巨大的关注。质量较差会导致财务成本的增加,这使得制造商把提升质量作为一项商业必要的手段。过去的数年中有无数方法和流程被用来减少浪费和消除缺陷 (比如6-Sigma法和TQM完全质量管理法)。我们并不缺少这样的衡量工具,来衡量因质量问题和返工而产生的负面经济效益。运用这些衡量工具能够理解质量对每辆车或者公司的盈利能力造成的影响,并且帮助公司取得显著的产品质 相似文献
93.
介绍了车辆动态模拟装置在评价车辆乘坐舒适性方面的应用情况,并阐述了车辆动态模拟装置在车辆部件研发过程中的重要作用. 相似文献
94.
H. M. Abdul Aziz Nicholas N. Nagle April M. Morton Michael R. Hilliard Devin A. White Robert N. Stewart 《Transportation》2018,45(5):1207-1229
This study estimates a random parameter (mixed) logit model for active transportation (walk and bicycle) choices for work trips in the New York City (using 2010–2011 Regional Household Travel Survey Data). We explored the effects of traffic safety, walk–bike network facilities, and land use attributes on walk and bicycle mode choice decision in the New York City for home-to-work commute. Applying the flexible econometric structure of random parameter models, we capture the heterogeneity in the decision making process and simulate scenarios considering improvement in walk–bike infrastructure such as sidewalk width and length of bike lane. Our results indicate that increasing sidewalk width, total length of bike lane, and proportion of protected bike lane will increase the likelihood of more people taking active transportation mode This suggests that the local authorities and planning agencies to invest more on building and maintaining the infrastructure for pedestrians. Further, improvement in traffic safety by reducing traffic crashes involving pedestrians and bicyclists, will increase the likelihood of taking active transportation modes. Our results also show positive correlation between number of non-motorized trips by the other family members and the likelihood to choose active transportation mode. The model would be an essential tool to estimate the impact of improving traffic safety and walk–bike infrastructure which will assist in investment decision making. 相似文献
95.
Fully autonomous vehicles (AVs) have the potential to considerably change urban mobility in the future. This study simulates potential AV operating scenarios in the Greater Toronto Area (GTA), Canada, and assesses transportation system performance on a regional level. For each scenario, the base capacities of certain types of road links are modified to simulate the theoretical increase in throughput enabled by AV driving behavior. Another scenario examines driverless parking operations in downtown Toronto. Simulation results indicate that the increased attractiveness of freeways relative to other routes leads to slightly increased average travel distance as vehicles divert to access higher capacity road links. Average travel time is found to decrease by up to one-fifth at the 90% AV market penetration level. Concurrently, localized increases in congestion suggest that proactive transportation planning will be needed to mitigate negative consequences of AV adoption, especially in relation to induced demand for personal automobile travel. 相似文献
96.
Transportation - Taxi trips have been somewhat neglected in transportation mobility and multimodal connection studies. The socio-demographic characteristics of taxi riders are often not fully... 相似文献
97.
A survey of U.S. and European responses to the energy crises engendered by the Arab boycott of October 1973–April 1974 is presented. U.S. Government policy actions with respect to allocation, rationing, price, and conservation measures are reviewed and contrasted with those of affected European governments. The results of those policies and their effects on transportation energy supply and demand behavior with respect to both commodity and passenger movement are described.Based on short- and long-term impact assessments of the policies considered, the authors identify significant research requirements.The authors were heavily engaged in U.S. responses to the energy emergency, and were asked to undertake study missions to those European nations significantly affected by the crisis to seek out avenues for mutual aid, and joint research, in resolving common energy problems. This paper is one product of those study missions. 相似文献
98.
99.
100.