全文获取类型
收费全文 | 4395篇 |
免费 | 92篇 |
专业分类
公路运输 | 953篇 |
综合类 | 1317篇 |
水路运输 | 1295篇 |
铁路运输 | 473篇 |
综合运输 | 449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 | 362篇 |
2017年 | 321篇 |
2016年 | 287篇 |
2015年 | 91篇 |
2014年 | 106篇 |
2013年 | 146篇 |
2012年 | 252篇 |
2011年 | 405篇 |
2010年 | 387篇 |
2009年 | 228篇 |
2008年 | 361篇 |
2007年 | 363篇 |
2006年 | 218篇 |
2005年 | 190篇 |
2004年 | 85篇 |
2003年 | 104篇 |
2002年 | 60篇 |
2001年 | 53篇 |
2000年 | 41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4487条查询结果,搜索用时 546 毫秒
521.
1辽宁省集装箱运输现状1.1港口集装箱运输辽宁港口集装箱运量增长速度高于货物吞吐量增长速度。全省港口集装箱运输主要集中在大连、营口、丹东、锦州4个海港。据统计 ,2003年全省港口集装箱吞吐量为221.3万TEU ,同比上年增长24.3 % ,其中大连港167万TEU ,营口港40.3万TEU ,丹东港6.8万TEU ,锦州港7.2万TEU。全省港口集装箱吞吐量呈大幅上升趋势。据调查 ,辽宁港口集装箱吞吐量的绝对数逐年增加 ,2000年以后总量的增幅更大 ,但各港所占比例有增有减 ,其中大连港呈下降趋势、营口港增幅较大、锦州港略减、丹东港上升。详见表1-1。1.2铁… 相似文献
522.
HANBing ZHAOGuo-liang 《船舶与海洋工程学报》2004,3(1):24-27
The course-keeping control of underactuated hovercraft with two aft propellers was considered. The control of the heading error and cross-track error was accomplished by the yaw torque merely in this case. The hovercraft dynamic model is nonlinear and underactuated. At first the Controllability of course-keeping control for hovercraft was proved, then a course-keeping control law was derived that keeps hovercraft heading constant as well as minimizes the lateral movement of hovercraft. The proposed law guarantees heading error and sway error all converge to zero exponentially. Simulation tests were carried out to illustrate the effectiveness of the proposed control law. For further research, the disturbance influence would be considered in the dynamic equations. 相似文献
523.
为了尽可能估计出捷联惯导系统中惯性仪表的误差,建立捷联惯导系统误差方程和量测方程,运用传递对准技术,构建了速度匹配方式下的Kalman滤波器模型,研究了线加速和拐弯机动下对惯性仪表误差估计的影响,并对计算机仿真结果进行比较分析,仿真结果表明:线加速情况下可以提高陀螺漂移误差的估计精度,拐弯情况下可以提高加速度计偏置误差的估计精度。 相似文献
524.
525.
Chang Doo Jang Jong Jin Jung Alexander A. Korobkin 《Journal of Marine Science and Technology》2007,12(2):95-101
This article describes an estimation method for the hull girder response of a ship due to springing. The linear and nonlinear
springing effects on the hull girder are evaluated. Previous studies on the springing response focused mainly on the symmetric
response, or vertical response. In this article, however, the springing analysis is extended to asymmetric responses, or horizontal
and torsional responses. The Timoshenko beam model was used to calculate the hull girder response and the quadratic strip
method was employed to calculate hydrodynamic forces and moments on the hull. To remove irregular frequencies, a rigid lid
was adopted on the hull free surface level and hydrodynamic coefficients were interpolated for asymptotic values. Applications
to two ships for the symmetric and asymmetric responses were carried out and the effect of springing responses is also discussed. 相似文献
526.
Sales tax measures passed at the local level and dedicated to transportation projects have become increasingly popular in
the United States. While revenues from fuel taxes stagnate, growth of local transportation sales taxes (LTSTs), most approved
in local elections, has led to a gradual shift of the financial base for transportation projects away from user fees and toward
broader-based taxes. In this study, the relationship between voter support and the social, political, and geographic characteristics
of the voters is explored. Using precinct-level voting data and census demographic data for three local transportation sales
tax elections in Sonoma County, in the San Francisco Metropolitan area of California, regression models were constructed to
analyze this relationship. In addition, the relationship between the outcomes of the three measures was explored to better
understand which transportation projects might have garnered more support for the successful measure. It was found that the
closer voters lived to the transportation projects to be funded, the greater their support. Higher incomes were also positively
related to support, controlling for other variables. Political leanings were found to affect support, with the direction of
the effect dependent upon the project list in each measure’s expenditure plan. Finally, it appears that the latest measure,
which passed successfully, benefited greatly from its multi-modal expenditure plan. 相似文献
527.
洋山港二期正式投入运营,东海二桥也正在规划当中,关于东海二桥的建铁路桥、公路桥还是公路铁路两用桥的争议一直没有停止过,不同的专家给出了不同的答案。本文在分析影响东海二桥建设方案选取的通过能力、投资额、营运安全和环保等四个因素的基础上,通过建立层次分析模型并求解,得出东海二桥最佳建设方案。 相似文献
528.
529.
WAN De-Cheng 《船舶与海洋工程学报》2007,6(2):51-58
In this paper, an efficient multigrid fictitious boundary method (MFBM) coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NACA0012 airfoils. The calculations were carried on a fixed multigrid finite element mesh on which fluid equations were satisfied everywhere, and the airfoils were allowed to move freely through the mesh. The MFBM was employed to treat interactions between the fluid and the airfoils. The motion of the airfoils was modeled by Newton-Euler equations. Numerical results of experiments verify that this method provides an efficient way to simulate incompressible viscous flows around moving airfoils. 相似文献
530.