全文获取类型
收费全文 | 3872篇 |
免费 | 34篇 |
专业分类
公路运输 | 941篇 |
综合类 | 392篇 |
水路运输 | 1150篇 |
铁路运输 | 231篇 |
综合运输 | 1192篇 |
出版年
2023年 | 17篇 |
2022年 | 66篇 |
2021年 | 48篇 |
2020年 | 38篇 |
2019年 | 37篇 |
2018年 | 106篇 |
2017年 | 86篇 |
2016年 | 143篇 |
2015年 | 57篇 |
2014年 | 101篇 |
2013年 | 552篇 |
2012年 | 206篇 |
2011年 | 239篇 |
2010年 | 186篇 |
2009年 | 212篇 |
2008年 | 180篇 |
2007年 | 175篇 |
2006年 | 138篇 |
2005年 | 123篇 |
2004年 | 59篇 |
2003年 | 54篇 |
2002年 | 51篇 |
2001年 | 62篇 |
2000年 | 66篇 |
1999年 | 46篇 |
1998年 | 77篇 |
1997年 | 48篇 |
1996年 | 55篇 |
1995年 | 69篇 |
1994年 | 24篇 |
1993年 | 42篇 |
1992年 | 29篇 |
1991年 | 31篇 |
1990年 | 22篇 |
1989年 | 26篇 |
1988年 | 27篇 |
1987年 | 29篇 |
1986年 | 26篇 |
1985年 | 37篇 |
1984年 | 26篇 |
1983年 | 25篇 |
1982年 | 27篇 |
1981年 | 33篇 |
1980年 | 33篇 |
1979年 | 37篇 |
1978年 | 22篇 |
1977年 | 24篇 |
1976年 | 18篇 |
1975年 | 29篇 |
1974年 | 17篇 |
排序方式: 共有3906条查询结果,搜索用时 15 毫秒
991.
论述了通过一种新型磁阻式传感器测量汽车传动系统齿轮装置润滑油中的磨损颗粒含量的方法,以达到在线监测传动系统齿轮装置磨损程度的目的。 相似文献
992.
993.
J. Son B. Reimer B. Mehler A. E. Pohlmeyer K. M. Godfrey J. Orszulak J. Long M. H. Kim Y. T. Lee J. F. Coughlin 《International Journal of Automotive Technology》2010,11(4):533-539
Driving demands significant psychomotor attention and requires even more when drivers are engaged in secondary tasks that
increase cognitive workload and divert attention. It is well established that age influences driving risk. Less is known about
how culture impacts changes in attention. We conducted parallel driving simulations in the US and Korea to measure the extent
to which age and culture influence dual-task performance. There were 135 participants divided into two groups: a younger group
aged 20∼29, and an older group aged 60∼69. Whereas some differences by culture appeared in absolute control measures, the
younger participants showed similar mean velocity and compensatory patterns associated with increased cognitive load in the
urban setting; however, the results from the older samples were less similar. 相似文献
994.
S. Lee D. H. Lee M. H. Kim K. C. Lee 《International Journal of Automotive Technology》2010,11(4):525-531
The controller area network (CAN) is the dominant protocol for in-vehicle network (IVN) systems because it provides bounded transmission delay among electronic control units (ECUs) at data rates between 100 Kbps and 1 Mbps. Many automotive companies have chosen the CAN protocol for their chassis network system of intelligent vehicles. However, the increasing number of ECUs in intelligent vehicles and the need for more intelligent functions require a network system with more network capacity and real-time capability. As one approach to enhance the network capacity of a CAN system, this paper introduces a CAN system with dual communication channels. This paper also presents a traffic-balancing algorithm that predicts the traffic of each channel and allocates frames to the most appropriate channel. An experimental testbed using commercial off-the-shelf microcontrollers with two CAN controllers was used to demonstrate the feasibility of the traffic-balancing algorithm. 相似文献
995.
996.
997.
余定华 《变流技术与电力牵引》2006,(4):9-10
介绍了用于电力变压器保护的数字继电器的发展及其应用技术和原理,简述了变压器保护的传统方法,重点介绍了人工神经网络(ANN)和模糊逻辑概念等最新技术及其涉及的技术成果. 相似文献
998.
混合电动汽车由于其性能和经济上的优势,比纯电动汽车得到更多的用户认可.现在全球两大汽车公司在世界上大多数地区销售的混合电动汽车累计超过12万辆.尽管纯电动汽车在道路运输和短途交通中可得到适当应用,但与非混合的汽车相比,混合电动汽车非常实用,燃料可节省5%~50%,甚至更多.现在由于交流传动使用寿命长,易于采用电力电子控制,它普遍用于混合动力系.但是,因为汽车推进系统独特的应用要求,目前的交流传动还难以满足整个驱动系统性能要求,且达不装置的体积目标.所以,目前混合动力系仍然使用容量过大的电机或电力电子装置的交流传动.本文基于这样的前提:解决混合电动汽车交流传动的宽恒功速比(CPSR)和整体性能最经济的办法是建立在电力电子装置基础上的.文章主要介绍变速装置方面的现状,以及为了提供与客运汽车更好匹配的交流传动装置正在作哪些努力. 相似文献
999.
M.?Oguma Y.?J.?LeeEmail author S.?Goto 《International Journal of Automotive Technology》2012,13(1):33-41
Recently, biofuels have been actively introduced as transportation fuels in Asian countries. Common drivers to use biofuels
are energy security, fuel diversification, and the reduction of greenhouse gases. In addition, some Southeastern Asian countries
look forward to utilizing the abundant agricultural resources and providing stability for farmers. However, a compromised
quality of biofuels could cause vehicle trouble, which is why the quality standard of the fuels is very important. On the
other hand, the quality standard of biofuels differs from country to country and could cause vehicle trouble in some countries
and not others. These differing standards may become an obstacle to trade. In this situation, the harmonization of the biodiesel
standards in the East Asia Summit (EAS) region has been initiated by the ERIA biodiesel working group, in which members are
the specialists from each country. This review summarizes the introduction of biofuels in this region and the recent activities
regarding the harmonization of the fuel quality standard. Important background for this review is based on the results of
the ERIA biodiesel working group meeting. 相似文献
1000.
In this paper, a new non-linear tracking controller for vehicle active suspension systems is analytically designed using an optimization process. The proposed scheme employs a realistic non-linear quarter-car model, which is composed of a hardening spring and a quadratic damping force. The control input is the external active suspension force and is determined by minimizing a performance index defined as a weighted combination of conflicting objectives, namely ride quality, handling performance and control energy. A linear skyhook model with standard parameters is used as the reference model to be tracked by the controller. The robustness of the proposed controller in the presence of modeling uncertainties is investigated. The performed analysis and the simulation results indicate that both vehicle ride comfort and handling performance can be improved using the minimum external force when the proposed non-linear controller is engaged with the model. Meanwhile, a compromise between different objectives and control energy can easily be made by regulating their respective weighting factors, which are the free parameters of the control law. 相似文献