首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   45168篇
  免费   538篇
  国内免费   314篇
测绘学   917篇
大气科学   2258篇
地球物理   8920篇
地质学   17529篇
海洋学   4261篇
天文学   9960篇
综合类   117篇
自然地理   2058篇
  2022年   528篇
  2021年   795篇
  2020年   866篇
  2019年   938篇
  2018年   1857篇
  2017年   1704篇
  2016年   1859篇
  2015年   806篇
  2014年   1604篇
  2013年   2494篇
  2012年   1854篇
  2011年   2194篇
  2010年   2058篇
  2009年   2320篇
  2008年   2077篇
  2007年   2249篇
  2006年   2044篇
  2005年   1127篇
  2004年   1098篇
  2003年   1059篇
  2002年   1003篇
  2001年   933篇
  2000年   792篇
  1999年   553篇
  1998年   576篇
  1997年   573篇
  1996年   447篇
  1995年   470篇
  1994年   461篇
  1993年   393篇
  1992年   395篇
  1991年   395篇
  1990年   435篇
  1989年   355篇
  1988年   344篇
  1987年   378篇
  1986年   291篇
  1985年   460篇
  1984年   479篇
  1983年   435篇
  1982年   394篇
  1981年   377篇
  1980年   368篇
  1979年   326篇
  1978年   357篇
  1977年   303篇
  1976年   270篇
  1975年   273篇
  1974年   237篇
  1973年   288篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
92.
Sattar  Ashim  Goswami  Ajanta  Kulkarni  Anil V. 《Natural Hazards》2019,98(2):817-817
Natural Hazards - The article was published with the citation “Worni et al. (2012)”. The author group of the article would like readers to know that this information should instead...  相似文献   
93.
This paper presents an integrated measurement technique based on DC methods (vertical electrical sounding, electrical resistivity tomography) which was used to identify faults and determine their geoelectric parameters in the western part of the Chuya basin. New information on the structure of the Chagan River valley located in the zone of the disastrous 27 September 2003 Chuya earthquake has been obtained from the results of these methods. Geoelectric cross-sections of the sedimentary sequence and the upper part of the basement were obtained from VES data, showing the block structure of the study area. Electrical resistivity tomography sections confirm the presence of a major fault between basement blocks of different heights and indicate the presence of faults bounding the valley on its right side and in the southwestern part.  相似文献   
94.
This work is based on the results of 2-D and 3-D surveys in the Tuapse Basin and field works in the Crimea-Caucasus region. Seven zones were outlined in the model of sedimentation starting from the eroded mountain structure of the Greater Caucasus down to deep water sediments of the Tuapse Basin. The slope and deep-water sediments of channels and fan complexes are characterized. Volume models of the sedimentation system in the Black Sea are shown for the first time.  相似文献   
95.
96.
Results of numerical simulations using the WRF-ARW nonhydrostatic model are presented for eight episodes of intense convection over European Russia in the summer of 2007. The calculations were performed on four nested grids with horizontal grid meshes of 27, 9, 3, and 1 km. Convection was parametrized on the first two grids and explicitly resolved on the other two. It has been found that simulations on finer grids with explicit calculation of convective flows make it possible to reproduce heavy rainfalls and strong-wind zones in the areas of intense convection. A preliminary verification of the short-range predictions of convective systems shows that the maximum 12-h precipitation totals and the maximum winds at 10 m are close, in the order of magnitude, to the observed values. Prediction of convection centers is the weakest point. Difficulties in the model verification associated with the absence of data with high space-time resolution are discussed.  相似文献   
97.
Marine disperse grounds from the shelf of the North Caspian Sea were studied using various test methods. The strain modulus and the coefficient of transverse strain were specified by triaxial compression and compression tests. Empirical correlations were found for the strain modulus as a result of both tests for different types of grounds.  相似文献   
98.
99.
Aftershocks have the potential to cause collapse of a structure that has been already damaged by the preceding main shock. Seismic safety of a structure should therefore be ascertained through a damage analysis using the anticipated main shock and few larger-aftershock motions. Simulation of aftershock motions needs characterization of the seismic hazard due to aftershocks, and therefore it will be useful to develop a conditional scaling model that can predict the response spectrum of an anticipated aftershock motion consistent with the design spectrum of the main shock motion anticipated at the same station. In this study an attempt is made to develop a conditional scaling model for the pseudo spectral velocity spectrum via linear regression analysis on the aftershock and main shock recordings for the 1999 Chi–Chi earthquake. It is shown that it may be possible to obtain a simpler and approximate version of the conditional model from an unconditional model. Damage-causing potential of a ground motion also depends on its strong motion duration (SMD) and therefore a conditional scaling model is developed for SMD of the aftershock motion in several narrow frequency-bands. The model is developed for the larger-aftershock motions and it is shown that a reasonable replacement of such a model may be obtainable directly from an unconditional model. Finally, a simple weighted averaging scheme is proposed to obtain the composite SMD from the SMDs for different frequency bands by using the pseudo spectral acceleration spectrum of the motion.  相似文献   
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号