全文获取类型
收费全文 | 16934篇 |
免费 | 289篇 |
专业分类
公路运输 | 4943篇 |
综合类 | 3773篇 |
水路运输 | 4308篇 |
铁路运输 | 3119篇 |
综合运输 | 1080篇 |
出版年
2023年 | 50篇 |
2022年 | 272篇 |
2021年 | 427篇 |
2020年 | 364篇 |
2019年 | 128篇 |
2018年 | 164篇 |
2017年 | 206篇 |
2016年 | 305篇 |
2015年 | 381篇 |
2014年 | 703篇 |
2013年 | 1089篇 |
2012年 | 1008篇 |
2011年 | 1245篇 |
2010年 | 1214篇 |
2009年 | 1372篇 |
2008年 | 1265篇 |
2007年 | 1631篇 |
2006年 | 1448篇 |
2005年 | 982篇 |
2004年 | 318篇 |
2003年 | 303篇 |
2002年 | 260篇 |
2001年 | 326篇 |
2000年 | 301篇 |
1999年 | 176篇 |
1998年 | 171篇 |
1997年 | 149篇 |
1996年 | 133篇 |
1995年 | 127篇 |
1994年 | 97篇 |
1993年 | 97篇 |
1992年 | 67篇 |
1991年 | 57篇 |
1990年 | 52篇 |
1989年 | 37篇 |
1988年 | 23篇 |
1987年 | 28篇 |
1986年 | 29篇 |
1985年 | 17篇 |
1984年 | 25篇 |
1983年 | 18篇 |
1982年 | 11篇 |
1981年 | 18篇 |
1980年 | 18篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 16篇 |
1976年 | 13篇 |
1975年 | 21篇 |
1974年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
241.
242.
243.
用碳纤维片修复补强混凝土结构是近年来的一种混凝土结构修复补强新技术,具有轻质高强、施工简便、能适应各种复杂形状结构的补强,且不影响结构尺寸和外观,抗腐蚀、耐久性良好等优异特性。结合山东省枣庄市干线公路S 244省道枣(园)~徐(州)公路台儿庄运河大桥的加固方案,介绍黏贴碳纤维术在桥梁加固中应用。 相似文献
244.
245.
246.
247.
浅谈公路建设项目设计阶段工程造价的控制方法 总被引:1,自引:0,他引:1
工程建设项目投资控制的关键在于设计阶段,对造价的影响高达75%,因此在设计阶段进行造价控制,对公路建设投资具有重要的意义。该文从路线合理选线、推行限额设计、优化设计及加强设计变更等主动控制的方法,达到节约总投资的目的。 相似文献
248.
This paper describes the on-line debugging software developed by our research team. The software has five functions and can be helpful in achieving rapid development for hybrid electric buses. In addition, the software can monitor system states continuously and also modify parametric maps or update control programs using its on-line programming function. Based on the on-line debugging system, the hybrid propulsion control system is designed, and all the working modes of the hybrid electric bus are tested. Finally, experiments are carried out that verify that the debugging system is feasible and reliable. The test results show that the hybrid electric bus can reduce fuel consumption by about 19.1 percent, in comparison with conventional buses. 相似文献
249.
Fault detection method for electric parking brake (EPB) systems with sensorless estimation using current ripples 总被引:1,自引:0,他引:1
C. W. Lee H. B. Chung Y. O. Lee C. C. Chung Y. S. Son P. Yoon 《International Journal of Automotive Technology》2010,11(3):387-394
A fault detection method with parity equations is proposed in this paper. Due to its low cost implementation, the velocity
of the motor is not measurable in electric parking brake (EPB) systems. Therefore, residuals are not reliable when estimating
the motor velocity with a low-resolution encoder. In this paper, we propose a fault detection method with sensorless estimation
using current ripples that estimates the position and velocity of the motor by detecting periodical oscillations of the armature
current caused by rotor slots. In addition, this method can estimate the position and velocity of the motor with less computational
effort than a state observer. Moreover, the method is less sensitive to motor parameters than model-based estimation methods.
The effectiveness of this method is validated with experimental data, and the simulation results show that various faults
have their own residual patterns. Therefore, we can detect the presence of faults by monitoring the residual signals. 相似文献
250.
The importance of vehicle safety cannot be exaggerated in today’s mobile societies. Many manufacturers, associates related
to vehicles and universities make an effort to improve vehicle safety by developing new technologies, applying high strength
steel to the body structure etc. However, the majority of these efforts are focused on decreasing injury. It is absolutely
important to minimize injury, but a more important aspect is coping with vehicle accidents. That is, As undeniably important
as it is to minimize potential injuries, it is critical that experts focus on developing ways to keep drivers out of situations
likely to lead to crashes in the first place. The purpose of this paper is to determine what the most critical factor is when
coping with an unfamiliar driving situation. The answer is to provide a wide-open field of vision, especially for the driver.
The driver’s field of vision is obstructed by the vehicle’s A-pillar. To solve this, the A-pillar obstruction angle, which
is the angle between the driver’s eyes and the A-pillar should be decreased. This paper purposes three-methods for decreasing
this angle structurally and applying a slim A-pillar which is as the best solution to decrease the A-pillar obstruction angle
and ensure the drivers field of vision at the same time 相似文献