全文获取类型
收费全文 | 471篇 |
免费 | 99篇 |
国内免费 | 304篇 |
专业分类
测绘学 | 25篇 |
大气科学 | 6篇 |
地球物理 | 214篇 |
地质学 | 545篇 |
海洋学 | 32篇 |
综合类 | 13篇 |
自然地理 | 39篇 |
出版年
2023年 | 2篇 |
2022年 | 14篇 |
2021年 | 14篇 |
2020年 | 25篇 |
2019年 | 18篇 |
2018年 | 33篇 |
2017年 | 30篇 |
2016年 | 36篇 |
2015年 | 51篇 |
2014年 | 39篇 |
2013年 | 48篇 |
2012年 | 43篇 |
2011年 | 65篇 |
2010年 | 44篇 |
2009年 | 42篇 |
2008年 | 40篇 |
2007年 | 42篇 |
2006年 | 46篇 |
2005年 | 32篇 |
2004年 | 31篇 |
2003年 | 26篇 |
2002年 | 22篇 |
2001年 | 22篇 |
2000年 | 21篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1986年 | 2篇 |
排序方式: 共有874条查询结果,搜索用时 156 毫秒
451.
452.
453.
454.
深埋隧道地震动力响应的复反应分析 总被引:11,自引:5,他引:11
复反应法是用来分析地震动力作用下岩土体动力性质的有限元方法之一。这种方法的主要特点是引入复模量概念, 使材料的阻尼比与频率无关, 这样能更好的模拟岩土体的动力性能。本文结合在建的某公路深埋隧道, 分析了隧址区山体的地震动作用特点, 探讨了隧道埋深与地震作用强度之间的关系。 相似文献
455.
G. A. Athanasopoulos 《Geotechnical and Geological Engineering》1995,13(2):93-104
Summary Values of the low-amplitude shear modulus, G
o, of a marl underlying the city of Kalamata, Greece, obtained by in situ crosshole and laboratory resonant column techniques are presented in the paper. It was found that the laboratory values were lower than their field counterparts and the difference was considered to be the result of (i) the temporary stress release following sampling and (ii) the mechanical disturbance associated with specimen preparation. By utilizing previous experimental results relating the field versus laboratory difference in the value of G
o to the age of the clay deposit, it became possible to estimate the age of the particular marl which was found to agree with the geologically expected age of the deposit. The approach taken in this study may, upon further improvement, become a useful technique for dating geological materials, especially those possessing cohesion. 相似文献
456.
Laboratory study of seismic free-field response of sand 总被引:2,自引:0,他引:2
This paper describes a new soil-structure interaction test box for use on a moderately large shaking table. The test box is designed to replicate, as nearly as possible, the free-field seismic response of a soil layer overlying a rigid base. Results from shaking table testing are presented which demonstrate the ability of the test box to serve as a large-scale shear device. The test box is unique in its ability to determine dynamic shear modulus for both high- and low-amplitude shear strain, and also to study the dynamic response of sand under low levels of confining stress. Dynamic shear modulus for standard Ottawa sand was measured over a wide range of shear strain amplitude and compared with data from the existing literature. Finally, based on results from the test box, a constitutive model is proposed which describes the free field response of a sand layer overlying bedrock and subjected to vertically propagating SH waves. The model is simple in form with a single parameter uniquely related to the friction angle of the sand. 相似文献
457.
458.
Relationships among eigenshape analysis, Fourier analysis, and analysis of coordinates 总被引:2,自引:0,他引:2
F. James Rohlf 《Mathematical Geology》1986,18(8):845-854
459.
460.
The deformation characteristics, shear moduli and damping ratios of reconstituted lacustrine carbonate silt samples were investigated in different kinds of laboratory tests. Material from a landslide that occurred in a seismically very active area in Slovenia was used in the tests. The initial values of this material's deformation characteristics and the extent to which these values change due to increasing shear strain depend on a number of factors, such as the degree of saturation, the initial void ratio, over-consolidation, and the effective stresses. The use of a volumetric threshold strain has proved to be the best way of describing the shear modulus reduction curve irrespective of any other factors, and it fits well with the data obtained in the experiments. The critical state and consolidation lines for the investigated material are presented in the paper as deformational characteristics at critical strain levels. The material's liquefaction potential was studied for certain in situ conditions. 相似文献