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   3890篇
  免费   739篇
  国内免费   1491篇
测绘学   235篇
大气科学   241篇
地球物理   1309篇
地质学   3163篇
海洋学   496篇
天文学   108篇
综合类   412篇
自然地理   156篇
  2018年   4篇
  2017年   8篇
  2016年   10篇
  2015年   21篇
  2014年   8篇
  2013年   41篇
  2012年   18篇
  2011年   476篇
  2010年   257篇
  2009年   409篇
  2008年   134篇
  2007年   218篇
  2006年   399篇
  2005年   444篇
  2004年   1003篇
  2003年   611篇
  2002年   381篇
  2001年   249篇
  2000年   155篇
  1999年   134篇
  1998年   151篇
  1997年   178篇
  1996年   107篇
  1995年   83篇
  1994年   47篇
  1993年   169篇
  1992年   114篇
  1991年   68篇
  1990年   22篇
  1989年   36篇
  1988年   14篇
  1987年   11篇
  1986年   8篇
  1979年   3篇
  1978年   3篇
  1977年   4篇
  1976年   8篇
  1974年   3篇
  1973年   3篇
  1970年   3篇
  1969年   3篇
  1950年   8篇
  1943年   6篇
  1940年   8篇
  1937年   14篇
  1934年   7篇
  1933年   7篇
  1928年   4篇
  1927年   4篇
  1924年   3篇
排序方式: 共有6120条查询结果,搜索用时 15 毫秒
201.
矿产资源管理信息系统设计与开发   总被引:1,自引:0,他引:1  
基于GIS的矿产资源管理信息系统采用地理信息系统(GIS)技术、SQL Server数据库技术以及网络技术,实现了矿产资源信息图形数据与属性数据统一管理,为矿产资源管理工作提供了现代化的科学管理手段和决策支持。本文介绍了系统的设计与实现、系统包含的工作模块、各个模块的功能结构以及采用的技术特点。  相似文献   
202.
In this paper,a variational method is presented for solving theclassical gravimetric,satellite gravimetric and satellite altimetric mixed typeboudary value problem to obtain the potential coefficients.According to thisprinciple,classical gravimetric data(height measured by geometric levelling orheight triangulation),satellite gravimetric data(height measured by satellitegeodesy technique)and satellite altimetric data can be used jointly to calculate thepotential coefficients.  相似文献   
203.
204.
We propose the pseudo-periodicity method and its quantitative prediction indexes for the occurrence time of earlier strong aftershock. We conducted tests of regressive prediction, and the R-value of the tests is 0.45, indicating that this method is effective for prediction.  相似文献   
205.
Results of analysis of variation of cross fault short-baseline and short-range leveling in Western Yunnan Earthquake Test Site (WYETS), results show that among five observation stations of cross fault short-baseline and short-range leveling in WYETS before the Lijiang MS7.0 Earthquake occurred in February 1996 only Yongsheng observation station (epicentral distance 82 km) located at Chenghai fault shows great variation about one year before the earthquake. And the nearest observation station, Lijiang (epicentral distance 42 km); presents great coseismic variation, but does not show obvious anomalous variation before the earthquake. There are no significant variations related to the earthquake at the other three observation stations. Two methods are used in analysis of the observed data and some valuable results have been obtained.  相似文献   
206.
Lithospheric Geothermal Structure in Yunnan, China   总被引:2,自引:0,他引:2  
In this paper,the characteristics of the lateral variations of the deep heat flow and Hthospheric geotemperature distribution in Yunnan have been studied,and the lithospheric geothermal structure has been divided into three types,i.e.the geothermal structure in the typical modern tectonically active region,transitional geological region and stable geological region.Finally,the relationship between the geotherm and seismicitv has been discussed.  相似文献   
207.
Using the single-zircon evaporation technique and U-Pb method, the authors have conducted an isotope geochonological study of the Huilanshan granulite and Shima garnet-bearing plagioclase gneiss (" country rocks" of the Shima eclogite) in the Dabie Mountains. The study shows that these rocks have peak metamorphic ages of 443-455 Ma, which are essentially consistent with that of the Caledonian high-ultrahigh pressure eclogites. This indicates the existence of the Caledonian collisional orogeny in the Dabie Mountains.  相似文献   
208.
Zircon and apatite fission-track dating indicates that the exhumation of the Dabie Mountains tended to be accelerated in the Cenozoic and that the exhumation of the eastern Dabie Mountains was more and more intense from south to north, which is in accordance with the more and more intense dissection from south to north, as is reflected by the modern geomorphologic features of the Dabie Mountains. The accelerated exhumation during the Cenozoic was related to the high elevation of the Dabie Mountains resulting from Late Cretaceous-Palaeogene detachment faulting and subsequent fault-block uplift and subsidence. The average elevation at that time was at least about 660 m higher than that at the present. The intense exhumation lagged behind intense uplift.  相似文献   
209.
210.
The Hori’s inverse method based on spectral decomposition was applied to estimate coseismic slip distribution on the rupture plane of the 14 November 2001 MS8.1 Kunlun earthquake based on GPS survey results.The inversion result shows that the six sliding models can be constrained by the coseismic GPS data.The established slips mainly concentrated along the eastern segment of the fault rupture,and the maximum magnitude is about 7 m.Slip on the eastern segment of the fault rupture represents as purely left-la...  相似文献   
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