全文获取类型
收费全文 | 1986篇 |
免费 | 90篇 |
专业分类
公路运输 | 300篇 |
综合类 | 616篇 |
水路运输 | 392篇 |
铁路运输 | 574篇 |
综合运输 | 194篇 |
出版年
2024年 | 10篇 |
2023年 | 8篇 |
2022年 | 52篇 |
2021年 | 58篇 |
2020年 | 65篇 |
2019年 | 32篇 |
2018年 | 51篇 |
2017年 | 61篇 |
2016年 | 65篇 |
2015年 | 96篇 |
2014年 | 139篇 |
2013年 | 134篇 |
2012年 | 185篇 |
2011年 | 163篇 |
2010年 | 127篇 |
2009年 | 121篇 |
2008年 | 105篇 |
2007年 | 169篇 |
2006年 | 146篇 |
2005年 | 65篇 |
2004年 | 64篇 |
2003年 | 46篇 |
2002年 | 27篇 |
2001年 | 22篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1985年 | 1篇 |
排序方式: 共有2076条查询结果,搜索用时 140 毫秒
541.
以美国工业界武器系统效能咨询委员会提出的ADC模型为基础,构建了指挥信息系统作战效能评估的指标体系和评估模型。将使用人员能力素质和战场环境影响因素引人AIX2模型中,建立了改进ADC法的指挥信息系统作战效能评估模型。以某型指挥信息系统为例,用建立的模型进行量化评估,能充分利用决策者的判断信息,较为准确地反映实际情况。该模型可为部队训练和作战提供系统的战斗效能数据,找出影响系统作战能力的敏感因素,为发展新型装备提供依据。 相似文献
542.
543.
544.
通过渤海大道的国民经济评价案例,阐述了公路建设项目国民经济评价方法。对于评价参数、费用效率、敏感性分析的详细计算方法进行了探讨。 相似文献
545.
方显华 《筑路机械与施工机械化》2012,29(9):80-82
通过对当前公路机械设备管理中存在的设备效率不高、管理人员素质不高、修理维护成本较高等现状进行分析,引入全员生产维修(TPM)管理理念,并在公路机械设备管理中提出相应的TPM管理模式,对公路部门或施工单位的机械设备管理具有一定的参考价值. 相似文献
546.
547.
548.
This study provide a straightforward way of examining the rebound effects of switching to more fuel efficient technologies, as well as determining the distribution of the effects in the household sector, including both the residential and transport sectors. A SP-off-RP survey conducted in Japan in 2012 asked people to state their preference for the reallocation behaviors after informing them of their annual operating cost saving resulting from the vehicle efficiency improvement. Coupled who save money from relocation are more likely to spend this either on housing features or transport; supporting the idea of rebound effects, although not only limited to within the transport sector. Regarding the distribution of rebound effects, domestic appliances are more likely to be affected than vehicles. 相似文献
549.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(3):341-361
In this paper, the collision-induced derailment of freight trains was investigated. The collision between two identical freight trains occurring on a curved path rather than along a straight line was investigated. This is because from the point of view of safety against derailment this collision scenario is thought to be more critical than the scenarios defined in the European standard EN 15227. In this work, one of the trains is stationary and the other moving train collides at 36 km/h. Two kinds of container wagons were simulated. One is the two-axle freight wagon Kls 442. Another is the freight wagon Rmms 662 with two Y25 bogies. Simulation results demonstrate that in terms of safety against derailment the bogie wagon Rmms 662 was found to have better behaviour than the two-axle wagon Kls 442. In addition, this study points out that there are many contributory factors to the responses of freight wagons during a collision, such as curve radius, distance between bogie pivots and loading mass. The derailment phenomenon is less likely to occur, when freight trains collide on the curve with a larger radius. Besides that the characteristics of freight wagons with large axle loads, low centre of gravity of car body and appropriate static strength are favourable for the collided wagons in reducing the risk of derailment. 相似文献
550.