全文获取类型
收费全文 | 383篇 |
免费 | 10篇 |
专业分类
公路运输 | 145篇 |
综合类 | 82篇 |
水路运输 | 94篇 |
铁路运输 | 66篇 |
综合运输 | 6篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 11篇 |
2014年 | 16篇 |
2013年 | 15篇 |
2012年 | 31篇 |
2011年 | 34篇 |
2010年 | 33篇 |
2009年 | 24篇 |
2008年 | 32篇 |
2007年 | 42篇 |
2006年 | 44篇 |
2005年 | 28篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有393条查询结果,搜索用时 15 毫秒
91.
基于液压技术的地铁防淹门系统方案 总被引:1,自引:0,他引:1
倪士浩 《城市轨道交通研究》2008,11(8)
地铁防淹门系统是一种防灾设备。国内使用的防淹门有升降式和平开式两种。通过对两种地铁防淹门系统的功能和现状的分析,提出了采用液压启闭机形式的升降式防淹门系统的新设计思路。介绍了该方案的系统构成和性能特点,并通过对启闭机液压原理、控制特性以及液压技术发展情况的描述论证了方案具备可实施性。 相似文献
92.
Travel time estimation and its variation for urban expressways are vital to both the information provision to road users, and the system evaluation and management for traffic administrators. Fruitful research efforts have been made to develop methodologies of reconstructing spatiotemporal traffic states mainly for freeways based on one or multiple data sources. However, few studies specifically focused on urban expressways. There are more intensive merging and diverging traffic due to short distances between ramps, for example, 300–500 m. Based on the empirical analysis of traffic data collected on a typical segment of a congested urban expressway, this study proposes an extended generalized filter algorithm for the urban expressway traffic state estimation based on heterogeneous data. More specifically, the multiple sources of data include both fixed sensor data (e.g., inductive loops or radar data) and global positioning system (GPS) probe vehicle data. This study compares the proposed algorithm and the traditional algorithm for freeways using data collected on the segment of expressway in Beijing, China. Results demonstrate the advantage of the proposed method, as well as its feasibility and effectiveness. 相似文献
93.
地质雷达解释隧道衬砌空洞大小的定量研究 总被引:2,自引:0,他引:2
地质雷达作为一种无损检测技术方法,广泛应用于各项工程检测,但是其主要应用局限于定性的检测.通过对地质雷达检测隧道衬砌中空洞的定量分析,总结出定量计算空洞大小的方法,并得出计算空洞大小的公式.对温福线隧道多处空洞的打孔进行对比,其准判率大于95%,空洞大小的定量解释误差一般在10%左右,并分析了产生误差的原因. 相似文献
94.
95.
Jun Ni 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(8):1098-1119
In order to improve handling performance of a hybrid 8-Wheel-Drive vehicle, the handling performance control strategy was proposed. For armoured vehicle, besides handling stability in high speed, the minimum steer radius in low speed is also a key tactical and technical index. Based on that, the proposed handling performance control strategy includes ‘Handling Stability’ and ‘Radius Minimization’ control modes. In ‘Handling Stability’ control mode, ‘Neutralsteer Radio’ is defined to adjust the steering characteristics to satisfy different demand in different speed range. In ‘Radius Minimization’ control mode, the independent motors are controlled to provide an additional yaw moment to decrease the minimum steer radius. In order to verify the strategy, a simulation platform was built including engine and continuously variable transmission systems, generator and battery systems, independent motors and controllers systems, vehicle dynamic and tyre mechanical systems. The simulation results show that the handling performance of the vehicle can be enhanced significantly, and the minimum steer radius can be decreased by 20% which is significant improvement compared to the common level of main battle armoured vehicle around the world. 相似文献
96.
以某胀缩性裂隙边坡为例,基于非饱和土力学理论,利用有限元方法,对降雨入渗条件下胀缩性裂隙边坡稳定安全系数进行计算和分析,研究了裂隙的位置、深度和降雨的强度对胀缩性裂隙边坡稳定的影响规律.研究表明:裂隙位于坡面边坡稳定性最低,位于坡顶次之,位于坡脚偏于安全;整个降雨过程中边坡稳定安全系数随着裂隙开裂深度增大而逐渐降低;边坡稳定性随着降雨强度的增加显著降低,但随着降雨的持续,边坡安全系数趋于稳定. 相似文献
97.
98.
北京机场南线(京承高速公路—东六环路)公路工程位于北京市东北部,是首都机场扩建工程配套建设的三条高速公路之一。随着我国高速公路建设的迅速发展和机动车保有量的急剧增加,我国高速公路交通事故率呈上升趋势。道路交通安全问题已成为摆在我们面前的首要问题,而高速公路交通安全设施是有效减少交通事故的具体措施之一。高速公路交通安全设施的设计要充分体现"以人为本"的设计理念,将安全放在首位,体现对人的关注,体现人性化的要求,注重公路安全性、方便性、舒适性、愉悦性的和谐统一,为道路使用者提供安全保障和人性化的服务,切实提高公路交通的安全水平和服务水平。高速公路交通安全设施是高速公路的重要组成部分,是发挥公路经济效益、保障行驶安全必不可少的配套设施。该文通过机场南线交通设施设计的理念和设计原则,并以设计实例论证了交通安全以人为本的安全设施设计理念。 相似文献
99.
100.
The B2-L21 ordering transitions in Au-Cu-Al shape-memory alloys are studied by the Monte Carlo exchange simulations, where a set of
the first, the second and the third nearest-neighbor mixing potentials for Cu-Al in the Au-Cu-Al alloys are calculated from
first principals using the Connolly-Williams methods. To ensure the phase stability of the β-Au-Cu-Al, the investigation includes the range of compositions Au2Cu1−x
Al1+x
(−0.15 ⩽ x ⩽ 0.15). The B2-L21 transition temperatures are predicted, and are in agreement with the experimental results. The atomic ordering around vacancy
of the L21 structure is further discussed. 相似文献