全文获取类型
收费全文 | 2566篇 |
免费 | 92篇 |
专业分类
公路运输 | 772篇 |
综合类 | 677篇 |
水路运输 | 649篇 |
铁路运输 | 473篇 |
综合运输 | 87篇 |
出版年
2024年 | 8篇 |
2023年 | 14篇 |
2022年 | 68篇 |
2021年 | 124篇 |
2020年 | 89篇 |
2019年 | 32篇 |
2018年 | 32篇 |
2017年 | 32篇 |
2016年 | 45篇 |
2015年 | 89篇 |
2014年 | 105篇 |
2013年 | 144篇 |
2012年 | 196篇 |
2011年 | 203篇 |
2010年 | 181篇 |
2009年 | 184篇 |
2008年 | 191篇 |
2007年 | 242篇 |
2006年 | 218篇 |
2005年 | 139篇 |
2004年 | 44篇 |
2003年 | 49篇 |
2002年 | 44篇 |
2001年 | 53篇 |
2000年 | 40篇 |
1999年 | 19篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有2658条查询结果,搜索用时 31 毫秒
131.
132.
采用有限元分析的方法,对一U型半潜式起重铺管平台进行了总强度分析,为该平台的结构设计提供了重要参考依据。 相似文献
133.
工程中常见淤泥类土与砂类土相混构成的混合土,其中淤泥类土土质极软但在土工试验中却可得出较大内摩擦角.以青岛港前湾港区南区的混合土为例,阐述混合土的成因和分布特征,分析与评价混合土的物理力学性质和采用混合土工程设计特性指标的原则、方法,并提出该地区混合土工程特性指标. 相似文献
134.
135.
边坡失稳的水岩相互作用机理分析 总被引:2,自引:0,他引:2
边坡的变形发展及破坏,影响因素很多,内在因素有岩土体的性质、结构等,变化是缓慢的。外在因素有风化作用、水文地质、水的作用、地震及人为因素等,变化是很快的。坡体的变形破坏,实际上是内在和外在的各种因素综合作用的结果,其中水的作用往往是关键的诱发因素。 相似文献
136.
137.
138.
139.
Y.H. Venus Lun Michael BrowneKee-hung Lai Christina W.Y. WongT.C.E. Cheng 《Research in Transportation Economics》2011,32(1):64-70
Container shipping and its related service sectors help accelerate globalization of the world economy. This industry has been experiencing rapid growth, prompting container terminal operators to increase their handling capacity in response. Providing container terminal services requires substantial capital investment in physical assets such as cargo handling facilities and information systems. On the other hand, operating container terminals is a long-term investment that typically spans several business cycles. Hence prudent asset management using appropriate tools is critical for container terminal operators to sustain their businesses. Generally, due to risk-adverseness, investors are unwilling to take more risk in their investment unless they can reap a higher return. Contrary to this argument, this study finds no direct influence of better firm performance as a proxy of higher return on business risk-taking by container terminal operators. Instead, scale of operations is positively associated with business risk-taking, suggesting that container terminal operators with a larger scale of operations are willing to take more business risk. 相似文献
140.
Taking the MK7-3 of USA hydraulic buffer arresting device as the research subject, the dynamical model for the shipboard aircraft arresting system is established, and the magneto-rheological (MR) damper is applied to pulley shock absorbers for shipboard aircraft block system. Due to the effect of the MR damper has not been known completely and so far MR damper model has not been defined, we use a set of characteristic test of the MR damper, through the process of parameters identification, to establish the dynamical model for the MR damper based on the Bingham plastic model. Then, the fuzzy control rules are designed, the buffer control for the pulley buffer of shipboard aircrafts is completed in touchdown moment based on MR technology. Compared with blocking device of hydraulic pulley buffer in the same condition, the simulations results show that the proposed MR pulley buffer can effectively recognize the impact energy for shipboard block system and reduce the pull peak of arresting cable. It improves significantly safety during landing of the air vehicles and lowers the risk of accidents. 相似文献