全文获取类型
收费全文 | 11733篇 |
免费 | 354篇 |
专业分类
公路运输 | 2806篇 |
综合类 | 1704篇 |
水路运输 | 3579篇 |
铁路运输 | 1444篇 |
综合运输 | 2554篇 |
出版年
2023年 | 66篇 |
2022年 | 263篇 |
2021年 | 273篇 |
2020年 | 166篇 |
2019年 | 141篇 |
2018年 | 279篇 |
2017年 | 171篇 |
2016年 | 234篇 |
2015年 | 241篇 |
2014年 | 441篇 |
2013年 | 1470篇 |
2012年 | 636篇 |
2011年 | 691篇 |
2010年 | 598篇 |
2009年 | 672篇 |
2008年 | 600篇 |
2007年 | 575篇 |
2006年 | 529篇 |
2005年 | 463篇 |
2004年 | 361篇 |
2003年 | 228篇 |
2002年 | 179篇 |
2001年 | 172篇 |
2000年 | 164篇 |
1999年 | 120篇 |
1998年 | 140篇 |
1997年 | 119篇 |
1996年 | 149篇 |
1995年 | 158篇 |
1994年 | 87篇 |
1993年 | 194篇 |
1992年 | 161篇 |
1991年 | 81篇 |
1990年 | 84篇 |
1989年 | 57篇 |
1988年 | 75篇 |
1987年 | 65篇 |
1986年 | 61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 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Yean-Tzong Yang Graduate Research Assistant Benson H. Tongue Associate Professor 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1994,23(1):279-292
This paper presents current research regarding intra-platoon collision dynamics for rapid decelerations. Measures of ride quality and impact severity are introduced to allow comparisons between different collision scenarios. In this study, the disturbance input to the platoon is assumed to be a rapid braking of the lead vehicle. Several deceleration rates are used to assess the overall platoon behavior and the effect of the intra-platoon collisions on the platoon passengers. The role of the desired headway spacing on preventing the occurrence of intra-platoon collisions and improving rider comfort is discussed. 相似文献
93.
94.
柳长茂 《西南交通大学学报》1993,(2):74-80
本文讨论m个变元情形,得到结论:m≥2时,二阶方程为Euler-Lagrange方程的充要条件是它为Monge-Ampere方程,其系数满足某些条件。 相似文献
95.
基于SIMULINK的气垫船垫升推进控制系统仿真 总被引:2,自引:0,他引:2
气垫船垫升推进系统是一个复杂的非线性系统.在气垫船的航行过程中,应严格控制动力涡轮转速,这对它的垫升稳定性非常重要.本文应用SIMULINK仿真平台对该系统进行建模,并对其采用了复合控制.针对螺旋桨螺距角的变化,给出了该系统的动态仿真结果. 相似文献
96.
Ship hulls are built with stiffened steel plates and experience continuous fatigue load cycles when in service. Mechanical properties of the steel are expected to change due to the application of these cyclic loads. Therefore, the mechanical properties of the material at various levels of fatigue damage need to be understood. This paper presents two test series that were conducted to determine the effect of two different strain ranges (2000 and 3000 micro strains) of fatigue cycles on the mechanical properties of high-strength structural steel. The test results indicate that the cycle-dependent behaviours of the material can cause a slight increase or a significant decrease in the yield strength when compared to its virgin state. However, the ductility of the steel does not change much as the strain cycle increases. 相似文献
97.
98.
通过对浙赣线增建二线工程项目后评价,总结了铁路建设项目决策的成功经验,也提出了其中的不足,并对建设项目主要技术标准选择提出了一些有益的建议。 相似文献
99.
This paper aims to gain more insight into the implications of information provision to drivers on the performance of road transport networks with recurrent congestion. For this purpose, a simulation program consisting of three components has been written. The first component is the traffic simulation model, the second component is the information provision mechanism, and the third component monitors the behavioural decision-making process of the drivers, which is modelled using a utility-based satisficing principle. Three types of information provision mechanisms will be considered: information based upon own-experience, after-trip information and real-time en route information. The findings in this paper, obtained in a hypothetical context, underline the important relationship betweenoverreaction, thelevel of market penetration and thequality of the information. High quality information allows a high level of market penetration, while low quality information, even when provided at low levels of market penetration, induces overreaction. Furthermore, real-time en route information is in particular beneficial during the process leading to a steady state; it reduces the variance in travel time considerably. The paper concludes with a discussion on the market potential of motorist information systems when commercially marketed. 相似文献
100.
石冰 《西安交通大学学报(英文版)》1995,(2)
SLENIUMFROMBEEFISHIGHLYBIOAVAILABLEASASSESSEDBYLIVERGLUTATHIONEPEROXIDASE(E.1.1.9)ACTIVITYANDTISSUE SELENIUMShiBing;J.E.Spall... 相似文献