全文获取类型
收费全文 | 408篇 |
免费 | 116篇 |
国内免费 | 29篇 |
专业分类
测绘学 | 16篇 |
大气科学 | 36篇 |
地球物理 | 191篇 |
地质学 | 263篇 |
海洋学 | 21篇 |
天文学 | 3篇 |
综合类 | 6篇 |
自然地理 | 17篇 |
出版年
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 10篇 |
2020年 | 19篇 |
2019年 | 29篇 |
2018年 | 11篇 |
2017年 | 19篇 |
2016年 | 23篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 21篇 |
2012年 | 24篇 |
2011年 | 33篇 |
2010年 | 17篇 |
2009年 | 33篇 |
2008年 | 28篇 |
2007年 | 21篇 |
2006年 | 22篇 |
2005年 | 27篇 |
2004年 | 11篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 6篇 |
2000年 | 25篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 8篇 |
1993年 | 12篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 1篇 |
1985年 | 3篇 |
排序方式: 共有553条查询结果,搜索用时 46 毫秒
1.
2D numerical modelling of impact cratering has been utilized to quantify an important depth-diameter relationship for different crater morphologies, simple and complex. It is generally accepted that the final crater shape is the result of a gravity-driven collapse of the transient crater, which is formed immediately after the impact. Numerical models allow a quantification of the formation of simple craters, which are bowl-shaped depressions with a lens of rock debris inside, and complex craters, which are characterized by a structural uplift. The computation of the cratering process starts with the first contact of the impactor and the planetary surface and ends with the morphology of the final crater. Using different rheological models for the sub-crater rocks, we quantify the influence on crater mechanics. To explain the formation of complex craters in accordance to the threshold diameter between simple and complex craters, we utilize the Acoustic Fluidization model. We carried out a series of simulations over a broad parameter range with the goal to fit the observed depth/diameter relationships as well as the observed threshold diameters on the Moon, Earth and Venus. 相似文献
2.
Delineation of groundwater protection zones by the backward particle tracking method: theoretical background and GIS-based stochastic analysis 总被引:1,自引:0,他引:1
Konstadinos N. Moutsopoulos Alexandra Gemitzi Vassilios A. Tsihrintzis 《Environmental Geology》2008,54(5):1081-1090
The backward particle tracking method, an effective and powerful tool that can be used to delineate groundwater protection
zones, is presented. The theoretical background and insights on the applicability of this method are provided. Moreover, the
present work enriches the backward particle tracking method with an uncertainty analysis concerning the porosity values, applying
a Monte Carlo (MC) approach, coupled with the use of geographical information systems (GIS). As an application example, a
wellfield in the Komotini area, Greece, is investigated. The present study may serve as a potential guideline for wellfield
delineation, particularly in areas like Greece where lack of data related to the hydrogeological system is often a problem. 相似文献
3.
4.
5.
6.
Khaled S. Balkhair 《Hydrogeology Journal》2006,14(7):1380-1382
7.
8.
Che Yong-tai Yu Jin-zi Zhang Shu-liang Fan Xue-fang Guo Jun-jie Zhang Tian-yuan Yang Jin-lan 《地震学报(英文版)》2002,15(2):226-233
A lot of slow fluctuations of water level have been observed in the original recording maps of subsurface fluid in Well Shuozhou,
Shanxi Province. Some typical recording maps of the “precursors” are introduced in the paper and the features of the “precursors”
recorded by the well are analyzed. The results show that 38% strong earthquakes possess this kind of record, which has a fluctuation
period arranging from several to tens of minutes and appear mostly two days before the earthquakes. Moreover, the mechanism,
transmission and responding conditions of well water level are discussed, as well as the scientific meaning and practical
value of the “precursor” of the well water level in earthquake predictions.
Foundation item: State Natural Science Foundation of China (19973011). 相似文献
9.
10.