全文获取类型
收费全文 | 27614篇 |
免费 | 1567篇 |
专业分类
公路运输 | 8164篇 |
综合类 | 9374篇 |
水路运输 | 6116篇 |
铁路运输 | 4533篇 |
综合运输 | 994篇 |
出版年
2024年 | 125篇 |
2023年 | 190篇 |
2022年 | 399篇 |
2021年 | 711篇 |
2020年 | 848篇 |
2019年 | 541篇 |
2018年 | 464篇 |
2017年 | 565篇 |
2016年 | 495篇 |
2015年 | 908篇 |
2014年 | 1891篇 |
2013年 | 1560篇 |
2012年 | 2300篇 |
2011年 | 2498篇 |
2010年 | 1894篇 |
2009年 | 1870篇 |
2008年 | 2059篇 |
2007年 | 2587篇 |
2006年 | 2374篇 |
2005年 | 1436篇 |
2004年 | 900篇 |
2003年 | 578篇 |
2002年 | 401篇 |
2001年 | 374篇 |
2000年 | 241篇 |
1999年 | 139篇 |
1998年 | 102篇 |
1997年 | 101篇 |
1996年 | 95篇 |
1995年 | 75篇 |
1994年 | 85篇 |
1993年 | 58篇 |
1992年 | 48篇 |
1991年 | 47篇 |
1990年 | 50篇 |
1989年 | 53篇 |
1988年 | 28篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 30篇 |
1984年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
421.
422.
423.
424.
425.
概述了特种弹药铁路运输可调试定位装置的主要功能、技术要求、主要战技术指标,介绍了特种弹药铁路运输采用的从箱体顶部固定方式,并进行了相应的可调式定位装置研究,将装置分为整体固定和单点独立固定两种,用于固定弹箱在敞车内的位置,确保弹体运输安全。 相似文献
426.
������ѩ�ڳ��е�·��ͨ��ͻ���¹�Ԥ�� 总被引:1,自引:0,他引:1
�����£��̹����������ԣ���¶¶ 《交通运输系统工程与信息》2016,16(6):216-221
427.
从船舶环境和光伏逆变器的基本原理和功能出发,分别对太阳能游船EMC干扰源和干扰路径进行分析,通过信号滤波与保护、工艺设计和试验测试,实现高可靠性的太阳能游船光伏逆变器控制系统研究和设计,为太阳能游船的光伏逆变器控制系统研究提供基本EMC设计思路与实现技巧。 相似文献
428.
凝露造成高压电缆卷筒滑环箱绝缘下降、箱体内元器件损坏,必须加以解决。分析凝露形成条件和造成高压电缆卷筒滑环箱故障的原因。提出温度控制法和湿度控制法两种措施。效果良好,可供参考。 相似文献
429.
To ensure the safety of navigating ship, working loads and structural load-carrying capacity are two important aspects. In the present paper, a total simulation system combing load calculation and structural collapse analysis is applied to simulate progressive collapse behaviour of a single-hull Kamsarmax type bulk carrier. A three dimensional singularity distribution method is adopted to calculate pressure distribution with time history. A mixed structural model, collapse part simulated by ISUM elements and remaining part by elastic FEM elements with relative coarse mesh, is proposed for collapse analysis. Progressive collapse behaviour obtained by ISUM is good agreement with that by nonlinear software package, MARC. However, the calculation time of ISUM analysis is about 1/70 of MARC analysis. The applicability to structure system, high accuracy and sufficient efficiency of ISUM had been demonstrated. 相似文献
430.
Systems that enable high levels of vehicle-automation are now beginning to enter the commercial marketplace. Road vehicles capable of operating independently of real-time human control under an increasing set of circumstances will likely become more widely available in the near future. Such vehicles are expected to bring a variety of benefits. Two such anticipated advantages (relative to human-driver vehicle control) are said to be increased road network capacity and the freeing up of the driver-occupant’s time to engage in their choice of leisurely or economically-productive (non-driving) tasks.In this study we investigate the implications for intersection capacity and level-of-service of providing occupants of automated (without real-time human control), autonomously-operating (without vehicle-to-X communication) cars with ride quality that is equivalent (in terms of maximum rates of longitudinal and lateral acceleration) to two types of rail systems: [urban] light rail transit and [inter-urban] high-speed rail. The literature suggests that car passengers start experiencing discomfort at lower rates of acceleration than car drivers; it is therefore plausible that occupants of an autonomously-operating vehicle may wish to instruct their vehicle to maneuver in a way that provides them greater ride comfort than if the vehicle-control algorithm simply mimicked human-driving-operation.On the basis of traffic microsimulation analysis, we found that restricting the dynamics of autonomous cars to the acceleration/deceleration characteristics of both rail systems leads to reductions in a signalized intersection’s vehicle-processing capacity and increases in delay. The impacts were found to be larger when constraining the autonomous cars’ dynamics to the more-restrictive acceleration/deceleration profile of high-speed rail. The scenarios we analyzed must be viewed as boundary conditions, because autonomous cars’ dynamics were by definition never allowed to exceed the acceleration/deceleration constraints of the rail systems. Appropriate evidence regarding motorists’ preferences does not exist at present; establishing these preferences is an important item for the future research agenda.This paper concludes with a brief discussion of research needs to advance this line of inquiry. 相似文献