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   1547篇
  免费   278篇
  国内免费   220篇
测绘学   91篇
大气科学   65篇
地球物理   790篇
地质学   637篇
海洋学   145篇
天文学   87篇
综合类   82篇
自然地理   148篇
  2024年   5篇
  2023年   21篇
  2022年   66篇
  2021年   50篇
  2020年   72篇
  2019年   72篇
  2018年   60篇
  2017年   57篇
  2016年   61篇
  2015年   80篇
  2014年   82篇
  2013年   90篇
  2012年   79篇
  2011年   104篇
  2010年   82篇
  2009年   101篇
  2008年   74篇
  2007年   102篇
  2006年   115篇
  2005年   94篇
  2004年   78篇
  2003年   69篇
  2002年   59篇
  2001年   70篇
  2000年   46篇
  1999年   50篇
  1998年   34篇
  1997年   46篇
  1996年   26篇
  1995年   35篇
  1994年   16篇
  1993年   12篇
  1992年   10篇
  1991年   7篇
  1990年   5篇
  1989年   4篇
  1988年   6篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1979年   1篇
排序方式: 共有2045条查询结果,搜索用时 15 毫秒
121.
In recent years, more and more studies are focused on the performance in seismic design instead of the strength of structures. People have realized that the structure deformation (displacement) can describe the damage more properly and directly than the strength (force). The displacement design spectra need to be constructed within more wide range of the period and the damping for the displacement-based seismic design.  相似文献   
122.
中国高放废物处置库选址中灵敏地质特征的初步确认   总被引:5,自引:0,他引:5  
本文首先根据中国、瑞士和日本3国高放废物处置概念的相似性,建立中国第一处置库系统性能评价模型;然后通过对9个地质变量在8个事件中的灵敏度分析,初步确认出3个灵敏地质物征。此项研究对中国目前高放废物处置库选址工作有一定的指导意义。  相似文献   
123.
孙凤贤 《安徽地质》2001,11(3):230-234
论述航运局综合楼地基所在处的地形地貌、水文地质、工程地质条件;分析地基基础盲目施工诱发造成建筑场地工程地质灾害和危及周国民居安全的原因,提出防治措施,合理施工,治理塌陷,并取得较好效益。  相似文献   
124.
An integrated geophysical survey which combines vertical seismic profile method, shallow reflection seismic method, electric sounding, soil temperature measurement and radioactive gas measurement was used to investigate Zhaoshuling landslide in the new site of Badong County and to assess the stability of the landslide. By rational use of these methods together with borehole geological profile and other geological information, the spatial distribution of the landslide body, the formations and structures within and without the landslide body were determined and the stability of the landslide was also assessed, thus making great contribution to the successful and rational investigation and assessment of the landslide.  相似文献   
125.
This paper points to the need for seismic risk and vulnerability assessment of infrastructure systems, most notably tall structures and coastal facilities, in Kuwait and other Arabian Gulf countries. Building codes in the region currently lack seismic provisions, despite evidence of a potential threat from large-magnitude earthquakes originating from the southern part of the Zagros fold belt. The historical record of Iranian earthquakes that may have caused significant ground motion in the Gulf region is examined, as are reports of coastal damage from tsunamis. Various specific tasks, expected to constitute research priorities of a Joint Center for Risk Research, a cooperative research program involving Princeton and Kuwait Universities, are outlined.  相似文献   
126.
An electrical substation consists of a complex set of equipment items that are interconnected through conductor buses or cables. If the connections are not sufficiently flexible, significant dynamic interaction may occur between the connected equipment items during a seismic excitation. This interaction is believed to be responsible for some of the observed substation equipment damage in recent earthquakes. This paper investigates the interaction between two equipment items connected by a linear spring‐dashpot or spring‐dashpot‐mass element representing a conductor bus. It is found that the interaction between the two equipment items may significantly amplify the response of the higher‐frequency equipment item. The influences of various key parameters on the interaction effect are quantified. Means for reducing the adverse interaction effect are described. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
127.
SOURCE RADIATION AND RESPONSES OF WAVE PROPAGATION   总被引:2,自引:0,他引:2  
Recordings of seismic waves propagating from earthquake source to a station at the earth's surface are a system response function.The convolution operator in time domain can be simplified as a multiplication operator in frequency domain.We discuss in frequency domain the separation of source,path and site effects for global scaling of earthquake source radiation.Also discussed are source scaling model,faulting mechanism,and the H/V inversion problems with crustal and near surface structures.Gross features of apparent source spectra appear to be not much region-dependent although there may be difference between tectonic styles within a region of tectonic mixture for which we need further study as data accumulate.Vertical spectra may be a better approach to approximate source radiation,as it has less crustal amplification effects than horizontal spectra.The H/V ratio is evidently a comprehensive indicator of amplification effects from near surface to deep structure.This gives it potential as an inversion tool to deduce site crustal structure.  相似文献   
128.
详细分析了GRASS的三种数据结构,为设计GRASS与其它系统数据格式转换接口提供了基础。  相似文献   
129.
张广顺  张玉香 《气象》1996,22(9):15-18
该文论述了中国遥感卫星辐射校正场筹建的必要性,辐射校正的基本原理和我国的辐射校正场建设的构想。  相似文献   
130.
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