全文获取类型
收费全文 | 6984篇 |
免费 | 350篇 |
专业分类
公路运输 | 1917篇 |
综合类 | 2324篇 |
水路运输 | 1837篇 |
铁路运输 | 1045篇 |
综合运输 | 211篇 |
出版年
2024年 | 23篇 |
2023年 | 39篇 |
2022年 | 153篇 |
2021年 | 180篇 |
2020年 | 232篇 |
2019年 | 169篇 |
2018年 | 143篇 |
2017年 | 174篇 |
2016年 | 183篇 |
2015年 | 300篇 |
2014年 | 491篇 |
2013年 | 424篇 |
2012年 | 628篇 |
2011年 | 655篇 |
2010年 | 481篇 |
2009年 | 456篇 |
2008年 | 459篇 |
2007年 | 549篇 |
2006年 | 496篇 |
2005年 | 324篇 |
2004年 | 211篇 |
2003年 | 139篇 |
2002年 | 79篇 |
2001年 | 94篇 |
2000年 | 49篇 |
1999年 | 30篇 |
1998年 | 21篇 |
1997年 | 12篇 |
1996年 | 19篇 |
1995年 | 15篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 16篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 7篇 |
排序方式: 共有7334条查询结果,搜索用时 15 毫秒
531.
李华 《铁路工程造价管理》2012,27(5):41-44
为提高施工企业二次经营水平,对二次经营的概念和范围的界定进行详细阐述,并就和谐管理理论引入到二次经营工作中。在二次经营阶段通过确定项目和谐主题,建立谐则机制和和则机制并进行有效结合,使项目参建人员通过学习相关知识,提高认识,积极开展施工方案优化,有效控制项目成本,优质的完成所承建的工程任务,取得业主和监理单位的认同,为二次经营创造条件。并就开展二次经营组织机构的建立,相关制度、管理办法、管理措施的制定进行阐述。 相似文献
532.
结合工程实例,分析强夯法处理软弱路基机理,总结强夯法形成硬壳层在处理下卧深层软基的新思路,对类似公路的建设具有借鉴作用。 相似文献
533.
In order to improve cooperation between traffic management and travelers, traffic assignment is the key component to achieve the objectives of both traffic management and route choice decisions for travelers. Traffic assignment can be classified into two models based on the behavioral assumptions governing route choices: User Equilibrium (UE) and System Optimum (SO) traffic assignment. According to UE and SO traffic assignment, travelers usually compete to choose the least cost routes to minimize their own travel costs, while SO traffic assignment requires travelers to work cooperatively to minimize overall cost in the road network. Thus, the paradox of benefits between UE and SO indicates that both are not practical. Thus, a solution technique needs to be proposed to balance UE and SO models, which can compromise both sides and give more feasible traffic assignments. In this paper, Stackelberg game theory is introduced to the traffic assignment problem, which can achieve the trade-off process between traffic management and travelers. Since traditional traffic assignments have low convergence rates, the gradient projection algorithm is proposed to improve efficiency. 相似文献
534.
利用线性优化理论和教学建模方法,对学院教职工最优化付酬方案进行了研究了最优化分配教职工报酬的控制模型,为主管部门提供了强有力的参考。 相似文献
535.
强夯法地基加固技术因具有众多优点而在国内外获得了广泛的应用.通过对强夯法在我国应用发展的回顾,分析了强夯法的应用和研究现状,然后根据其目前存在的问题,提出未来的研究重点. 相似文献
536.
Pierre Merlin 《运输规划与技术》2013,36(1):39-52
A decade of increasing Federal attention to urban transportation needs has culminated in the 1970 Urban Mass Transportation Assistance Act. This Act is intended to provide 10 thousand million dollars over the next 12 years in Federal assistance money to urban public transportation systems. This paper examines the needs of selected U.S. cities as a basis for (1) understanding the vast, various and complex transportation needs of urban areas throughout the country, and (2) assessing the sufficiency of these funds. The sample cities have been placed into three broad categories based on the state of development of their transportation systems. In Category I cities, the essential need is to ensure the survival of bus systems for the use of non‐drivers, or to provide some other viable alternative to the automobile; in Category II cities, the primary needs are to relieve auto congestion and to improve public transportation components, while in Category III cities, the primary need is massive investment to improve and to extend public transportation facilities. It is concluded that the presently intended Federal funding level for transportation will not meet the financial requirements of the Category III cities. 相似文献
537.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(11):1061-1082
The dynamic model was developed to evaluate vibration accelerations and ride comforts during the running of the Korean-standardised rubber-tired light rail vehicle. Ride comfort indexes were analysed and tested in accordance with UIC 513R by using the dynamic model and the actual vehicle in the test track. Based on the comparisons between analysis results and test results, the validity of the developed dynamic model was evaluated. It was verified whether or not the developed Korean-standardised rubber-tired light rail vehicle met the specified target specification on ride comfort. In addition, the influence of the wearing of guide wheels on ride comfort was estimated. 相似文献
538.
539.
540.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(12):1902-1917
The sleeper-passing impact has always been considered negligible in normal conditions, while the experimental data obtained from a High-speed train in a cold weather expressed significant sleeper-passing impacts on the axle box, bogie frame and car body. Therefore, in this study, a vertical coupled vehicle/track dynamic model was developed to investigate the sleeper-passing impacts and its effects on the dynamic performance of the high-speed train. In the model, the dynamic model of vehicle is established with 10 degrees of freedom. The track model is formulated with two rails supported on the discrete supports through the finite element method. The contact forces between the wheel and rail are estimated using the non-linear Hertz contact theory. The parametric studies are conducted to analyse effects of both the vehicle speeds and the discrete support stiffness on the sleeper-passing impacts. The results show that the sleeper-passing impacts become extremely significant with the increased support stiffness of track, especially when the frequencies of sleeper-passing impacts approach to the resonance frequencies of wheel/track system. The damping of primary suspension can effectively lower the magnitude of impacts in the resonance speed ranges, but has little effect on other speed ranges. Finally, a more comprehensively coupled vehicle/track dynamic model integrating with a flexible wheel set is developed to discuss the sleeper-passing-induced flexible vibration of wheel set. 相似文献