全文获取类型
收费全文 | 4767篇 |
免费 | 218篇 |
专业分类
公路运输 | 1312篇 |
综合类 | 1427篇 |
水路运输 | 1275篇 |
铁路运输 | 824篇 |
综合运输 | 147篇 |
出版年
2024年 | 17篇 |
2023年 | 23篇 |
2022年 | 121篇 |
2021年 | 186篇 |
2020年 | 142篇 |
2019年 | 65篇 |
2018年 | 61篇 |
2017年 | 72篇 |
2016年 | 83篇 |
2015年 | 155篇 |
2014年 | 205篇 |
2013年 | 312篇 |
2012年 | 343篇 |
2011年 | 382篇 |
2010年 | 446篇 |
2009年 | 384篇 |
2008年 | 395篇 |
2007年 | 434篇 |
2006年 | 406篇 |
2005年 | 274篇 |
2004年 | 107篇 |
2003年 | 64篇 |
2002年 | 61篇 |
2001年 | 64篇 |
2000年 | 47篇 |
1999年 | 27篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有4985条查询结果,搜索用时 203 毫秒
831.
832.
833.
834.
提出了基于Hilbert-Huang变换的钢管混凝土脱空检测方法,通过对瞬态冲击下脱空钢管的声振信号进行分析,提取出了瞬时幅值特征样本,采用改进的K均值聚类法对特征样本进行二类模式识别,从而对钢管混凝土的脱空进行判定,试验研究表明本方法的可行性。 相似文献
835.
将城市公共自行车作为一种出行方式,建立了不同交通方式的效用函数,基于多项logit模型,测算得到公共自行车的分担率.以未来年居民出行OD为基础,结合公共自行车分担率,测算得出公共自行车的租借需求,并结合公共自行车和停车桩的周转率最终得到公共自行车以及停车桩的总规模.以西安某新城为案例,采用所提出的方法对公共自行车以及停车桩的总规模进行预测,结果表明方法简单高效,便于应用. 相似文献
836.
采用Magic Formula轮胎模型,运用MATLAB/Simulink软件建立了参考模型和二自由度非线性汽车模型;针对汽车ESP系统的非线性、时变的特点,基于滑模变结构控制理论,设计了以横摆角速度为控制变量的稳定性控制器;在湿滑路面上进行了转向行驶以及移线行驶工况控制效果的仿真分析。研究表明:所设计的控制器能够很好地控制车辆的横摆角速度和质心侧偏角,提高了车辆的稳定性。 相似文献
837.
ABSTRACTDemand for sea space brought about by increasing container-shipping traffic has important implications on how this space is managed and used. This is particularly important given the long-term nature, high-asset specificity, high- opportunity cost of investment, and significant economic impact of container port activity on a locality. The challenge is especially pressing for ports, which are facing constraints in seaside capacity where container traffic also has to co-exist with the needs of other types of ship traffic. This challenge is likely be multiplied for next generation container ports, which are expected to handle even larger traffic volumes. These ports are also likely to face competing sea space demands from other economic and social activities especially when they are concurrently major confluences of trade, logistics, and urban populations. This is the first research to investigate in detail the impact and importance of investigating sea space requirements from the perspective of cargo traffic composition and ship capacity. Results show that transshipment containers can generate much higher demand for sea space due to the higher volume of shipping capacity that accompanies such traffic. Sustainability issues and managerial and policy implications pertaining to the development of next generation container ports are provided. 相似文献
838.
Hui Shan Loh 《Maritime Policy and Management》2013,40(4):436-455
ABSTRACTIn the contemporary port business environment, port resilience is of paramount importance for supply chain continuity. A result of the increased integration of ports into supply chains is ports’ potential to supply chain disruptions. This paper introduces a PSCD management model that incorporates the application of risk management, business continuity management, and quality management theories with the purpose of increasing port resilience such that supply chain continuity is enhanced. To validate this model, primary data were collected from samples of port operators and port authorities and analyzed using structural equation modeling with AMOS 22.0. The results indicate that managing PSCD using the management model contributes positively to the identification of internal and external opportunities and through that to port’s resilience of internal operations. This, in turn, positively influences port’s financial health and market reputation. The management model has several managerial and academic implications as it offers meaningful insights on policy development as well as theory building. 相似文献
839.
840.