首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   283篇
  免费   8篇
公路运输   79篇
综合类   66篇
水路运输   76篇
铁路运输   67篇
综合运输   3篇
  2023年   1篇
  2022年   5篇
  2021年   11篇
  2020年   6篇
  2019年   5篇
  2018年   4篇
  2017年   2篇
  2016年   3篇
  2015年   9篇
  2014年   12篇
  2013年   13篇
  2012年   13篇
  2011年   31篇
  2010年   24篇
  2009年   16篇
  2008年   22篇
  2007年   28篇
  2006年   29篇
  2005年   17篇
  2004年   7篇
  2003年   3篇
  2002年   3篇
  2001年   3篇
  2000年   5篇
  1999年   1篇
  1998年   6篇
  1997年   2篇
  1996年   2篇
  1994年   3篇
  1993年   2篇
  1992年   2篇
  1991年   1篇
排序方式: 共有291条查询结果,搜索用时 140 毫秒
81.
太行山隧道膏溶角砾岩地段合理断面型式研究   总被引:1,自引:0,他引:1  
石太客运专线太行山隧道膏溶角砾岩地层,围岩松动压力和膨胀压力大。对圆形、马蹄形、椭圆形三种断面型式进行计算、分析对比,提出膏溶角砾岩地层区段隧道的合理断面型式。  相似文献   
82.
介绍Bootstrap方法的原理并将Bootstrap方法应用于检测车辆中存在的故障,通过计算不同故障下的车辆样本之间均匀Kullback-Lcible距离的均值以及在给定置信度下的置信区间等特征值来反映被测车辆的故障种类。给出一种新的随机数产生器用在Bcotstrap法重采样中产生新的随机序列。以车辆卜的驱动桥为检测对象对该算法进行了验证,结果表明该算法能准确检测出驱动桥所存在的故障。  相似文献   
83.
针对某型水雷的水中弹道问题,分析了某型潜布沉底水雷的水下无动力运动过程中的受力情况,在分析海流对其作用力的基础上,建立了研究其水下散布的水下无动力运动的六自由度空间弹道数学模型和海流影响分析模型,并用Matlab软件编写了潜射水雷水下散布仿真程序,并对不同流速条件下的水雷散布进行了研究,给出了仿真结果和分析结论。  相似文献   
84.
水下潜器改进S面控制及控制系统仿真(英文)   总被引:1,自引:0,他引:1  
S surface controllers have been proven to provide effective motion control for an autonomous underwater vehicle (AUV). However, it is difficult to adjust their control parameters manually. Choosing the optimum parameters for the controller of a particular AUV is a significant challenge. To automate the process, a modified particle swarm optimization (MPSO) algorithm was proposed. It was based on immune theory, and used a nonlinear regression strategy for inertia weight to optimize AUV control parameters. A semi-physical simulation system for the AUV was developed as a platform to verify the proposed control method, and its structure was considered. The simulation results indicated that the semi-physical simulation platform was helpful, the optimization algorithm has good local and global searching abilities, and the method can be reliably used for an AUV.  相似文献   
85.
水面无人船的发展与使命(英文)   总被引:5,自引:0,他引:5  
  相似文献   
86.
<正>公元2500年前的一天,中国大陆东南沿海一隅,一支由楼船、戈船、扁舟、轻舟等混编而成的船队正待启航,或者是一次征服,或者是一次移民,或者仅仅是一次巡游。风和日丽,波澜不兴,但船员们知道看似平静的水域蕴藏着怎样的凶险,不过从他们脸上看不到畏惧,更不会退缩,无数次惊涛骇浪中的体验早已化为一种从容。  相似文献   
87.
公交企业的保修厂作为一个独立的工作系统,承担着运营车辆的维修、保养任务,工作头绪多且涉及面宽.保修厂厂长如何做好管理工作,本人结合自己的认识和经验总结工作要点如下,供参考.  相似文献   
88.
本文针对海洋环境中的温度、酸碱度、盐度及溶解氧多个参数对象,以STM32F 103 ARM为核心控制器设计了多参数水质监测系统,可以实时的检测四个参数的数值,并通过蓝牙无线传输将数值显示在上位机的L C D上。实验结果证实该设计可以对海洋环境的多参数进行准确、实时、便携的监测。  相似文献   
89.
The ‘Silk Road Economic Belt and the 21st-Century Maritime Silk Road’ (One Belt One Road, OBOR) strategy initiated by the Chinese government has a significant impact on the business and logistics modes which involves Asia, Europe, Africa, and their adjacent seas. Many countries and ports are developing new strategies that are suitable for this economic environment. Compared with many ports in the world, the ports in Zhejiang province of China have a novel property. In addition to Ningbo-Zhoushan port, there are several other sea ports and river ports in that province. In this paper, we propose a concept of port service network that consists of a huge hub and multiple ports. Ports of small and medium sizes can share their capacities of different types of port service with the hub when the service capacities are integrated into the network. We develop a mixed integer nonlinear programming model to determine the optimal decisions in such a network with constraints on the budget to conduct integration. An optimization algorithm incorporated with a genetic algorithm is developed to solve large size problems. We provide managerial insights on the policies of government, including expanding port capacity, reducing fixed integration cost, and providing better financial condition.  相似文献   
90.
The Austin MetroRail line in Texas, U.S.A. began operations in 2010 and since then transit-oriented development projects have been fuelled around train stations. Traditional location theory holds that proximity to a transit station should be capitalized into land prices, and numerous empirical studies have demonstrated the effects with mixed results. However, to date no empirical study has investigated this relationship between the newly built rail line and land prices in Austin. This study fills the research gap and suggests a positive effect associated with transit proximity by employing spatial hedonic models. This study also contributes to the existing literature especially in the context of Texas cities where there is a lack of relevant research on transit-capitalization-related topics, and provides insights for decision-makers with different perspectives regarding further rail investment or transportation financing strategies such as value capture programs.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号