全文获取类型
收费全文 | 1029篇 |
免费 | 78篇 |
专业分类
公路运输 | 261篇 |
综合类 | 344篇 |
水路运输 | 199篇 |
铁路运输 | 224篇 |
综合运输 | 79篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 28篇 |
2021年 | 32篇 |
2020年 | 51篇 |
2019年 | 30篇 |
2018年 | 25篇 |
2017年 | 25篇 |
2016年 | 32篇 |
2015年 | 48篇 |
2014年 | 92篇 |
2013年 | 62篇 |
2012年 | 82篇 |
2011年 | 93篇 |
2010年 | 70篇 |
2009年 | 66篇 |
2008年 | 62篇 |
2007年 | 95篇 |
2006年 | 72篇 |
2005年 | 39篇 |
2004年 | 27篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有1107条查询结果,搜索用时 31 毫秒
991.
传统冲击回波法多采用单通道检测,但土木工程结构往往尺寸较大,采用单通道检测效率较低。为了提高检测效率,本文提出了双通道冲击回波采集的方法,并采用ABAQUS有限元软件建模分析了不同通道距离工况下冲击回波的响应特性,为多通道冲击回波方法的进一步应用奠定了基础。研究结果表明:对于无缺陷结构,两个通道间的距离对冲击回波峰值频率位置几乎没有影响;对于有缺陷模型结构,当两通道均布置在缺陷上方时,频率峰值位置受两通道距离影响较小,当有一个通道位于缺陷上方时,该通道峰值频率表现为两个冲击回波峰值频率的叠加。 相似文献
992.
李世辉 《城市轨道交通研究》2019,22(4):81-85
新建车站零距离穿越既有地铁车站结构,势必会对其运营安全及结构变形产生不可忽视的影响。以南京某工程为实例,明挖基坑开挖通过与既有车站结构间增设一排隔离桩、对称开挖,暗挖施工采用上下台阶法进行开挖、左右导洞对称施工。根据有限元数值分析基坑开挖引起的临近地表沉降和既有车站结构的变形,沉降最大值为9.8 mm,既有结构新增最大沉降量2.9 mm,累计沉降量8.3 mm,可确保既有结构的安全。 相似文献
993.
Dong Y.-P.Sun B.-L. 《铁道工程学报》2018,(11):87-91
Research purposes: At present, the urban subway is developing rapidly in our country, among which there are many problems. This paper takes a seven-story frame structure office building as research object. In view of the phenomenon that the dome subsidence and the land subsidence rate exceed the early warning in the field construction of the left line tunnel, combing theoretical analysis with the MIDAS-GTS numerical simulation, we took the "building-stratum-tunnel" as the research object, analyzed the influence of small distance tunnel construction process of mine method on the adjacent buildings, and analyzed the influence difference of the construction sequence of the left and right lines. Finally we put forward the relevant engineering technical measures. Research conclusions:(1) The tunnel construction makes the building in the tensile zone, and the structure is easy to be damaged. When the structure is far away from the influence of the excavation, the order of tunnel excavation is not significant. (2) When the surrounding rock is broken and close to the building, it is better to excavate the tunnel far away from the side of the building. At the same time, we should pay attention to taking the reinforcement measures near the side of the building and the intermediate rock column. (3) The research results can be applied to the field of shield construction in subway, and have a good guiding effect on the shield tunnel passing through buildings at close distance. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved. 相似文献
994.
《铁道标准设计通讯》2017,(4):126-131
为探究小净距隧道群洞穿越不同地层施工引起的力学响应,基于青岛地区土岩复合地层特殊地质条件,通过数值计算并结合现场测试数据,分析小净距地铁隧道群洞施工引起的地表沉降、应力特征、拱顶变形规律。结合工程实际,将隧道群洞施工划分为4个不同阶段并依此分析,结果表明:隧道群在其阶段Ⅳ施工后引起地表沉降变形较大,其他阶段地表沉降无明显变化;不同开挖阶段对夹岩的扰动程度存在差异,阶段Ⅳ施工使夹岩主应力出现剧烈变化,且夹岩最薄弱处最不利状态发生于阶段Ⅳ,但无剪切破坏现象;隧道拱顶沉降最大增量在该条隧道开挖后出现,上线隧道施工显著影响其他隧道拱顶沉降,且能够引起中线隧道拱顶抬升。研究成果为同类工程的施工稳定性分析提供了现场指导和技术支持。 相似文献
995.
996.
997.
钟碧羿 《电力机车与城轨车辆》2010,33(6)
车门是地铁车辆的一个重要组成部分,文章通过与广州地铁三号线项目车辆的车门控制系统比较,分析了广三线北延项目车辆车门控制的功能特点,介绍了车门控制系统的设计要点。 相似文献
998.
999.
1000.
The objective of the work was to evaluate the potential user response to distance and time based road pricing of a sample
of individuals drawn randomly from a group of volunteers in Dublin. The road use pricing charge levels were selected to match
the marginal external costs of car transport i.e. those costs not currently paid by the car user. Such costs include marginal
external costs of congestion, air pollution and noise. The project formed part of the EU DGXVII EUROPRICE project where one
of the objectives was to evaluate the impact of road use pricing on private transport demand. Estimates of the marginal external
costs of car travel had been previously made for Dublin in an EU DGVII project entitled TRENEN II STRAN and the results were
used to select the road pricing charges in the trial. The distance travelled and travel time of a particular individual's
work trip were noted. Charges per unit distance and time were applied so that the individual would incur a total charge for
their average peak period work trip of 6.4 euro; the average marginal external cost of a peak period trip in Dublin, as estimated
by the TRENEN model. Although the sample of individuals was relatively small, the indications from the results are worthy
of note and further investigation on a larger sample. A significant reduction in the number of peak period trips was evident,
of the order of 22%, resulting from trip suppression and transfer to other modes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献