全文获取类型
收费全文 | 10742篇 |
免费 | 340篇 |
专业分类
公路运输 | 2667篇 |
综合类 | 3089篇 |
水路运输 | 3006篇 |
铁路运输 | 1632篇 |
综合运输 | 688篇 |
出版年
2024年 | 24篇 |
2023年 | 38篇 |
2022年 | 206篇 |
2021年 | 342篇 |
2020年 | 270篇 |
2019年 | 124篇 |
2018年 | 441篇 |
2017年 | 396篇 |
2016年 | 422篇 |
2015年 | 292篇 |
2014年 | 421篇 |
2013年 | 536篇 |
2012年 | 608篇 |
2011年 | 883篇 |
2010年 | 873篇 |
2009年 | 818篇 |
2008年 | 873篇 |
2007年 | 926篇 |
2006年 | 805篇 |
2005年 | 563篇 |
2004年 | 212篇 |
2003年 | 194篇 |
2002年 | 114篇 |
2001年 | 157篇 |
2000年 | 140篇 |
1999年 | 68篇 |
1998年 | 60篇 |
1997年 | 40篇 |
1996年 | 56篇 |
1995年 | 43篇 |
1994年 | 42篇 |
1993年 | 16篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
PANG Yong-jie YOU Guang-xin 《船舶与海洋工程学报》2005,4(4):1-6
Oceanographic survey, or other similar applications should be the applications of multiple AUVs. In this paper, the skill & simulation based hybrid control architecture (S^2BHCA) as the controller's design reference was proposed. It is a multi-robot cooperation oriented intelligent control architecture based on hybrid ideas. The S^2BHCA attempts to incorporate the virtues of the reactive controller and of the deliberative controller by introducing the concept of the "skill". The additional online task simulation ability for cooperation is supported, too. As an application, a multiple AUV control system was developed with three "skills" for the MCM mission including two different cooperative tasks. The simulation and the sea trials show that simple task expression, fast reaction and better cooperation support can be achieved by realizing the AUV controller based on the S^2BHCA. 相似文献
62.
SUN Tao GUO Jin-cheng SUN Hai-ou 《船舶与海洋工程学报》2005,4(4):7-11
The configuration and aerodynamic performance of the inlet system are important aspects in the process of installing a gas turbine on a naval vessel. Under the requirements, large eddy simulation (LES) is used to simulate the three-dimensional fluid flow in the wave blocker of a marine inlet filter. The Smagorinsky-Lilly sub-grid model was used to model motions of small-scale structures. During numerical simulation, the SIMPLE algorithm was applied. The central-differencing spatial discretization scheme and the second order accuracy finite difference for the temporal discretization were used. Simulation gives satisfactory distribution of the vorticity fields and turbulent kinetic energy. Compared with the k-ε turbulent model, the results of LES are better for the distribution of parameters. The results of experimental study in a small-scale wind tunnel indicate that numerical calculation has higher accuracy. Therefore, the methods used are worthy of reference and introduction for the design of an inlet system. 相似文献
63.
CAI Cheng-tao ZHU Qi-dan YAN Yong-jie 《船舶与海洋工程学报》2005,4(4):43-46
Helicopter blade running elevation measurement is an important measure target in helicopter blade dynamic balance experimentation. The elevation influences the helicopter' s security and other performance capabilities. In testing, however, it has been difficult to measure the elevation when the rotor reaches high speeds. To get a simple, fast and highly accurate measurement system, photo electricity technology was applied to measuring the blade running elevation. Discussed is the measurement principle of blade running elevation, tire design of the measurement system and analysis of the measurement precision. 相似文献
64.
65.
66.
Container line supply chains, based on a near-frictionless international transport belief, have contributed to economic prosperity
and also rendered themselves uniquely vulnerable to various risks. 9/11 terrorists attacks, the lock-out of American West
Ports and the global breakout of SARS disease have gradually shown that a) the safety and reliability in the chains are facing
an unprecedented challenge and b) traditional engineeringbased risk assessment methods are inadequate to deal with the threats
from variational environments, especially in the era of terrorism rampancy. The purpose of this paper is, therefore, to develop
a conceptual risk assessment model for container line supply chains based on a modified Formal Safety Assessment (FSA) methodology
that takes risks from vulnerability rather than only hazards into account. It gives particular emphasis on the analysis of
the threats with a high level of uncertainty from both safety and economic viewpoints. The advantages of the vulnerability-based
risk analysis approach to the hazard-based one are clarified and both engineering-based and managerial risk assessments are
also discussed. 相似文献
67.
68.
AIS系统与船舶保安 总被引:1,自引:0,他引:1
针对AIS系统的特点和所传输的信息,分析了AIS在远洋船舶上全面安装及实施后,在增加航行安全,提高船舶交通管理系统的服务和监控能力的同时,在船舶保安方面可能出现的问题。建议船舶在使用AIS数据信息时应当采取合理的谨慎态度,尤其是在海盗多发地带应适时地暂时关闭系统。 相似文献
69.
70.
近年来城市快速轨道交通在我国各大城市蓬勃兴起,路内外各相关厂家为开发国产城轨车辆进行了大量工作并达到了商业化应用.本文介绍两种典型国产轻轨车辆基本技术参数和牵引性能试验结果,并给出性能评估. 相似文献