全文获取类型
收费全文 | 640篇 |
免费 | 207篇 |
国内免费 | 403篇 |
专业分类
测绘学 | 54篇 |
大气科学 | 38篇 |
地球物理 | 185篇 |
地质学 | 805篇 |
海洋学 | 91篇 |
天文学 | 13篇 |
综合类 | 43篇 |
自然地理 | 21篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 16篇 |
2021年 | 29篇 |
2020年 | 43篇 |
2019年 | 40篇 |
2018年 | 42篇 |
2017年 | 38篇 |
2016年 | 60篇 |
2015年 | 50篇 |
2014年 | 69篇 |
2013年 | 47篇 |
2012年 | 66篇 |
2011年 | 71篇 |
2010年 | 51篇 |
2009年 | 77篇 |
2008年 | 52篇 |
2007年 | 66篇 |
2006年 | 73篇 |
2005年 | 59篇 |
2004年 | 45篇 |
2003年 | 32篇 |
2002年 | 35篇 |
2001年 | 25篇 |
2000年 | 27篇 |
1999年 | 25篇 |
1998年 | 21篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1250条查询结果,搜索用时 562 毫秒
1.
2.
In urban environments, one major concern with deep excavations in soft clay is the potentially large ground deformations in and around the excavation. Excessive movements can damage adjacent buildings and utilities. There are many uncertainties associated with the calculation of the ultimate or serviceability performance of a braced excavation system. These include the variabilities of the loadings, geotechnical soil properties, and engineering and geometrical properties of the wall. A risk‐based approach to serviceability performance failure is necessary to incorporate systematically the uncertainties associated with the various design parameters. This paper demonstrates the use of an integrated neural network–reliability method to assess the risk of serviceability failure through the calculation of the reliability index. By first performing a series of parametric studies using the finite element method and then approximating the non‐linear limit state surface (the boundary separating the safe and ‘failure’ domains) through a neural network model, the reliability index can be determined with the aid of a spreadsheet. Two illustrative examples are presented to show how the serviceability performance for braced excavation problems can be assessed using the reliability index. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
3.
You Yage
YuZhi Associated Professor Guangzhou Institute of Energy Conversion Chinese Academy of Sciences Guangzhou
. Professor Guangzhou Institute of Energy Conversion Chinese Academy of Sciences Guangzhou 《中国海洋工程》1995,(4)
In this paper, the extreme wave loads on an on-shore wave power device are investigated. First, boundary element method is applied to solve the three dimensional potential problem based on the small amplitude wave assumption. Then the motion of the Oscillating Water Column (OWC) inside the device and its laods on the device are calculated in time domain. Several protective techniques often applied are simulated by changing the constraint of the upper end of the chamber of the device. Numerical results are used to judge the effectiveness of these techniques. The investigation shows that damping can not effectively restrain the motion of OWC when the period of incident wave is long, which may cause dangerous loads on the structure. The shut chamber can effectively restrain the motion of OWC, but alternatively cause high pressure in the chamber. A Contracting opening with a Taper (CT) can exhaust a great amount of kinetic energy of OWC, and significantly decrease the loads. It is a promising protective tec 相似文献
4.
5.
6.
7.
8.
以沈阳市某深基坑支护及降水工程在密集建筑群中施工为例,介绍了该支护工程的设计与施工,阐述了该工程变形监测方法并对其结果进行了分析,总结了在沈阳地区密集建筑群中进行基坑开挖的设计与施工经验。 相似文献
9.
10.
土钉墙技术在长春市北方大厦基坑工程中的应用实践 总被引:2,自引:1,他引:2
结俣长春市北方大厦基坑支护工程实际,着重介绍了土钉墙支护方案的设计,施工及应用情况,为土钉墙支护技术在长春市深基开挖工程中的推广应用积累了经验。 相似文献