全文获取类型
收费全文 | 307篇 |
免费 | 51篇 |
国内免费 | 60篇 |
专业分类
测绘学 | 27篇 |
大气科学 | 16篇 |
地球物理 | 145篇 |
地质学 | 148篇 |
海洋学 | 30篇 |
天文学 | 2篇 |
综合类 | 16篇 |
自然地理 | 34篇 |
出版年
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 11篇 |
2020年 | 6篇 |
2019年 | 15篇 |
2018年 | 14篇 |
2017年 | 20篇 |
2016年 | 10篇 |
2015年 | 11篇 |
2014年 | 12篇 |
2013年 | 28篇 |
2012年 | 14篇 |
2011年 | 25篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 23篇 |
2007年 | 20篇 |
2006年 | 24篇 |
2005年 | 12篇 |
2004年 | 15篇 |
2003年 | 17篇 |
2002年 | 6篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 12篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1987年 | 1篇 |
1977年 | 5篇 |
排序方式: 共有418条查询结果,搜索用时 15 毫秒
1.
2.
3.
A new method of estimating the ratio between in situ rock stresses and tectonics based on empirical and probabilistic analyses 总被引:1,自引:0,他引:1
This paper describes a new procedure for assessing the ratio between in situ stresses in rock masses by means of K (K = σH / σv, being σH and σv principal stress) and tectonics for purposes of engineering geology and rock mechanics. The method combines the use of the logic decision tree and the empirical relationship between the Tectonic Stress Index, TSI, and a series of K in situ values obtained from an extensive database. The decision tree considers geological and geophysical factors affecting stress magnitudes both on the regional and local scale. The TSI index is defined by geological and geomechanical parameters. The method proposed provides an assessment of the magnitude of horizontal stresses of tectonic origin. Results for several regions of Europe are presented and the possible applications of the procedure are discussed. 相似文献
4.
Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification
An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. 相似文献
5.
6.
The 2004 Chuetsu earthquakes of Niigata (Japan) triggered numerous landslides, and the most widespread types of landslides
were highly disrupted, relatively shallow slides and soil (debris) flows. This paper presented a method to evaluate slope
instability using Newmark displacement on a pixel-by-pixel basis in a given area. The proposed method was able to integrate
Newmark displacement modeling and Monte Carlo simulations within geographical information systems. In the modeling, an empirical
attenuation relationship was utilized to calculate Arias intensity over this study area, and the variability of geotechnical
parameters was taken into account to calculate coseismic landslide displacement. Before deriving the displacement from related
inputs, the Monte Carlo simulations ran 1,500 times and generated 1,500 displacement values for each grid cell, and then means
and standard deviations of displacement were calculated and probabilistic distributions can be obtained. Finally, given 10 cm
as a threshold value of displacement, estimated probabilities of displacement exceeding 10 cm were shown as a map of seismic
landslide hazards. The resulting hazard map was classified into four categories from very low to high level. 相似文献
7.
Analyzing the tables and probability maps posted by Yan Y. Kagan and David D. Jackson in April 2002–September 2004 at http://scec.ess.ucla.edu/~ykagan/predictions_index.html and the catalog of earthquakes for the same period, the conclusion is drawn that the underlying method could be used for prediction of aftershocks, while it does not outscore random guessing when main shocks are considered. 相似文献
8.
9.
10.