全文获取类型
收费全文 | 6247篇 |
免费 | 463篇 |
专业分类
公路运输 | 1824篇 |
综合类 | 1817篇 |
水路运输 | 1691篇 |
铁路运输 | 1165篇 |
综合运输 | 213篇 |
出版年
2024年 | 20篇 |
2023年 | 56篇 |
2022年 | 243篇 |
2021年 | 366篇 |
2020年 | 235篇 |
2019年 | 139篇 |
2018年 | 114篇 |
2017年 | 136篇 |
2016年 | 139篇 |
2015年 | 228篇 |
2014年 | 339篇 |
2013年 | 428篇 |
2012年 | 484篇 |
2011年 | 592篇 |
2010年 | 505篇 |
2009年 | 509篇 |
2008年 | 447篇 |
2007年 | 504篇 |
2006年 | 453篇 |
2005年 | 327篇 |
2004年 | 117篇 |
2003年 | 86篇 |
2002年 | 42篇 |
2001年 | 74篇 |
2000年 | 45篇 |
1999年 | 25篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 2篇 |
排序方式: 共有6710条查询结果,搜索用时 78 毫秒
151.
文中对南海海区航标遥测系统现状和未来发展进行分析思考,提出建议,以期未来遥测遥控系统成为航标维护管理现代化的重要手段。 相似文献
152.
153.
154.
155.
156.
苑鹏 《辽宁省交通高等专科学校学报》2012,14(2):22-24
汽油发动机尾气中主要成份为HC、CO、CO2、NOX、O2等。本文分析了尾气的形成、特征和超标排放原因,以及尾气检测原理和标准,通过几例本人在工作中的实例,说明尾气检测在维修实践中所起到的重要作用,可供维修单位检测参考。 相似文献
157.
158.
文章就某轨道交通设备生产企业对SAP ERP的需求进行了分析,提出了SAP ERP企业解决方案。 相似文献
159.
Urban arterial performance evaluation has been broadly studied, with the major focus on average travel time estimation. However, in view of the stochastic nature of interrupted flow, the ability to capture the characteristics of travel time variability has become a critical step in determining arterial level of service (LOS). This article first presents a stochastic approach that integrates classic cumulative curves and probability theories in order to investigate delay variability at signalized intersections, as a dominant part of the link travel time variability. This serves as a basis for arterial travel time estimation, which can be obtained through a convolution of individual link travel time distributions. The proposed approach is then applied in the estimation of travel time along one arterial in Shanghai, China, with abundant automatic vehicle identification (AVI) data sources. The travel time variability is evaluated thoroughly at 30-min intervals, with promising results achieved in comparison to the field measurements. In addition, the estimated travel time distributions are utilized to illustrate the probability of multiple LOS ranges, namely, reliability LOS. The results provide insights into how we might achieve a more reliable and informative understanding of arterial performance. 相似文献
160.
Peng Hang Xinbo Chen Shude Fang Fengmei Luo 《International Journal of Automotive Technology》2017,18(5):785-797
A four-wheel-independent-steering (4WIS) electric vehicle (EV) with steer-by-wire (SBW) system is proposed in this paper. The fast terminal sliding mode controller (FTSMC) is designed for the SBW system to suppress external disturbances. Taking unstructured and structured uncertainties into consideration, a robust controller is designed for the 4WIS EV utilizing μ synthesis approach and the controller order reduction is implemented based on Hankel-Norm approximation. Since sideslip angle is the feedback signal of robust controller and it is hard to measure, the extended Kalman filter (EKF) is employed to estimate sideslip angle. To evaluate the vehicle performance with the designed control system, step and sinusoidal steering maneuvers are simulated and analyzed. Simulation results show that the designed control system have good tracking ability, strong robust stability and good robust performance to improve vehicle stability and handing performance. 相似文献