全文获取类型
收费全文 | 8125篇 |
免费 | 558篇 |
专业分类
公路运输 | 2499篇 |
综合类 | 2016篇 |
水路运输 | 2507篇 |
铁路运输 | 1334篇 |
综合运输 | 327篇 |
出版年
2024年 | 43篇 |
2023年 | 73篇 |
2022年 | 228篇 |
2021年 | 297篇 |
2020年 | 342篇 |
2019年 | 257篇 |
2018年 | 205篇 |
2017年 | 271篇 |
2016年 | 277篇 |
2015年 | 390篇 |
2014年 | 612篇 |
2013年 | 450篇 |
2012年 | 755篇 |
2011年 | 807篇 |
2010年 | 547篇 |
2009年 | 522篇 |
2008年 | 485篇 |
2007年 | 570篇 |
2006年 | 494篇 |
2005年 | 312篇 |
2004年 | 189篇 |
2003年 | 134篇 |
2002年 | 106篇 |
2001年 | 74篇 |
2000年 | 65篇 |
1999年 | 38篇 |
1998年 | 26篇 |
1997年 | 28篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1984年 | 2篇 |
排序方式: 共有8683条查询结果,搜索用时 15 毫秒
801.
三角转子发动机一个关键核心技术就是转子的径向密封技术。径向密封片在气缸中的磨损过程,各状态参数随时间而改变。在考虑压力对磨损影响的同时,加入了温度影响因素。利用仿真技术对磨损量进行模拟计算,建立了径向密封片磨损的动态仿真模型,并用UG Grip编写了仿真程序。在此仿真模型基础上进行了数值计算,得到径向密封片磨损量的分布与时间的关系。 相似文献
802.
803.
高强度客流设施的服务水平评价是2010年上海世博会需要解决的核心问题之一.目前在这方面缺乏相应的理论和技术支撑.提出通过动态模拟出入口广场人群流动的方法来评估入口设施的服务水平.利用VISSIM仿真技术具有的直观、准确、灵活、可重复试验的特点,进行集散设施抽象建模、进出闸机的关键参数校核和集散广场访客行为的模拟.以上南路入口广场客流集散为研究背景,对该入口未来高峰时段的客流进行了模拟,取得了较好的仿真效果.VISSIM仿真模型可满足客流集散仿真的需求. 相似文献
804.
This paper establishes the simulation model of a city bus on the basis of the EQ6110 bus prototype and its experimental data.
According to the actual urban driving cycle, the fuel economy and the traction performance of the EQ6110 city bus have been
simulated, and factors such as the driving cycle, the loss of power to engine accessories, the gear-shifting strategy, the
fuel shut-off strategy of the engine, etc., which influence on the bus’s fuel economy, are also quantitatively analyzed. Some
conclusions are drawn as follows: (1) driving cycles have a great influence on the fuel economy of a city bus; (2) under the
typical urban driving cycle of the public bus in China, the engine fuel shut-off strategy can save about 1 to 1.5 percent
of the fuel consumption; and (3) the optimized gear-shifting rules can save 6.7 percent of the fuel consumption. Experimental
results verify that the fuel economy for the EQ6110 public bus is improved by 7.2 pecent over the actual Wuhan urban driving
cycle of the current public bus in China. 相似文献
805.
806.
针对隧道洞口浅埋段双侧壁导坑施工工艺的特点,对某高速公路隧道进行了数值模拟,定性地分析了双侧壁导坑开挖法施工力学行为.研究表明,在开挖初期,临时钢架与核心土共同作用形成一个承载整体,能有效地减少地表沉降变形;上部核心土开挖后,临时钢架与初衬连接处出现应力集中现象,在开挖过程中应引起重视. 相似文献
807.
To predict the attitude of satellite during the whole deployment process and evaluate the lockingimpact, a numerical flexible model of a certain satellite associated with four flexible honeycomb solar panelswas established. The flexible solar panel was modeled by the finite element analysis (FEA), and the motionequations were derived by Lagrangian formulation. The locking process was based on the method of Hertziancontact, which enables one to predict the locking impact on the satellite and the subsequent oscillation of solarpanels. The results reveal that locking operation has great impact on the attitude of the satelhte, and theangular acceleration of satellite reaches 22.03 °/s2 at the locking moment; the flexible solar panels model isfeasible to predict the accurate response of the satelhte during deployment and the oscillation of solar panels;the instantly impulsive force occurred during locking process is about 1.5 kN and the changing time is nearly0.32 s. It provides an effective approach to present the flexible solar panels' deployment process and evaluatethe locking impact. 相似文献
808.
基于MATLAB的电力电子技术实验计算机仿真的研究 总被引:2,自引:0,他引:2
概括了MATLAB/Simulink仿真软件的特点,介绍了如何利用MATLAB/Simulink仿真软件对电力电子技术课程实验进行仿真。应用计算机仿真实验教学加深了学生对课程内容的理解,弥补了模拟实验装置的不足。 相似文献
809.
Chunfu SHAO Yi ZHAO Lei YU Juan XU 《Journal of Transportation Systems Engineering and Information Technology》2008,8(6):52-55
As the main venue of the 2008 Beijing Olympic Games, the National Stadium hosted the opening and closing ceremonies, field and track events, and final football games. This paper intends to study the problems associated with vehicle evacuation from the parking lot, and develop evacuation plans. First, the paper analyzes the particular conditions of the parking lot in the National Stadium, as well as its layout and vehicle evacuation. Then, it simulates and evaluates the evacuation plans with the suitably given parameters, based on the real blueprint of the National Stadium and scenarios. Finally, it conducts a comparative analysis on the accuracy and practicability of the vehicle evacuation plans based on the field data collected at the opening ceremony of the Olympic Games. The simulation result shows that the total vehicle evacuation time was 26 minutes and the real evacuation time was 27 minutes on the day of the opening ceremony, which verifies that the study is accurate and practical. 相似文献
810.
基于Matlab/Simulink汽车驾驶员电动座椅控制系统的仿真设计 总被引:1,自引:0,他引:1
张兰江 《湖北汽车工业学院学报》2008,22(3):9-13
以汽车驾驶员电动座椅的水平调节为例,利用Matlab/Simuulink对具有自动调节功能的直流伺服位置控制系统的动态特性进行计算和仿真,从而确定该系统控制器的最佳控制参数的匹配。 相似文献