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   197篇
  免费   10篇
测绘学   7篇
大气科学   13篇
地球物理   76篇
地质学   78篇
海洋学   10篇
天文学   16篇
综合类   1篇
自然地理   6篇
  2023年   2篇
  2022年   1篇
  2021年   4篇
  2020年   4篇
  2019年   9篇
  2018年   12篇
  2017年   3篇
  2016年   9篇
  2015年   7篇
  2014年   14篇
  2013年   17篇
  2012年   7篇
  2011年   8篇
  2010年   7篇
  2009年   12篇
  2008年   8篇
  2007年   12篇
  2006年   5篇
  2005年   6篇
  2004年   3篇
  2003年   7篇
  2002年   7篇
  2001年   4篇
  2000年   4篇
  1999年   6篇
  1998年   2篇
  1997年   4篇
  1995年   3篇
  1994年   2篇
  1993年   4篇
  1992年   5篇
  1991年   3篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1976年   1篇
排序方式: 共有207条查询结果,搜索用时 31 毫秒
201.
A refined substructure technique in the frequency domain is developed, which permits consideration of the interaction effects among adjacent containers through the supporting deformable soil medium. The tank‐liquid systems are represented by means of mechanical models, whereas discrete springs and dashpots stand for the soil beneath the foundations. The proposed model is employed to assess the responses of adjacent circular, cylindrical tanks for harmonic and seismic excitations over wide range of tank proportions and soil conditions. The influence of the number, spatial arrangement of the containers and their distance on the overall system's behavior is addressed. The results indicate that the cross‐interaction effects can substantially alter the impulsive components of response of each individual element in a tank farm. The degree of this impact is primarily controlled by the tank proportions and the proximity of the predominant natural frequencies of the shell‐liquid‐soil systems and the input seismic motion. The group effects should be not a priori disregarded, unless the tanks are founded on shallow soil deposit overlying very stiff material or bedrock. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
202.

Volume Contents

Contents of Volume 29  相似文献   
203.
Pavlides  S.B.  Papadopoulos  G.  Ganas  A. 《Natural Hazards》2002,27(1-2):61-84
On 7 September 1999 the Athens Metropolitan area (Greece) was hit by a moderate size (Ms = 5.9) earthquake. The severely damaged area is localized in the northwestern suburbs of the city, at the foothills of Mt. Parnitha (38.1°N, 23.6°E), about 18 km from the historic centre of Athens. In this paper, we present our results on the surface expression of the seismogenic structure. Methods applied were: field observations, geological mapping, fault geometry and kinematics, evaluation of macroseismic data, interpretation of LANDSAT images, construction of a DEM and application of shading techniques. Aftershock distribution and fault plane solutions were also considered. Our results suggest that the earthquake source is located within the NW-SE trending valley bearing a few outcrops of Neogene-Quaternary sediments across the south foothills of Mt. Parnitha, never known in the past to have been activated by such strong earthquakes. The earthquake occurred along a 10 km long normal fault, striking N110°–133° and dipping 64°–85°SW, extending from the Fili Fort (4th century BC) in the NNW to the Fili town and then to Ano Liossia, to the SSE. Tensional stress field with 3 axis almost horizontal striking NNE-NE prevails in the area. The fault strike and the extensional direction (3) are compatible with the focal mechanism of the main shock.  相似文献   
204.
The static displacement field of the Athens 1999 earthquake has been numerically modeled by a BEM method and analysed from SAR interferometry images with compatible results: (a) for a fault that reaches the surface the subsidence field coincides with the hangingwall domain of the Fili neotectonic normal fault with maximum amplitude, d max, 5.5–7 cm, which is consistent with the possibly co-seismic displacement of 6–10 cm observed in the field, the average fault dislocation of 5–8 cm found by the application of circular source models, and the displacement up to 6 cm predicted by empirical relations between magnitude and displacement; the field of uplift covers the footwall domain of the fault with d max1.5 cm;d gradually decreases with distance from the fault at a gradient of 0.4 cm/km, (b) for a blind fault d max is only 1.8 and 0.3 cm in the hangingwall and footwall, respectively, and the decay gradient becomes 0.15 cm/km, (c) the total deformation area is 15 km × 15 km and the Fili fault, with a preferred mean dip of 60°, constitutes the natural boundary between the subsidence and uplift areas. The macroseismic field pattern is similar with that of the static ground deformation. The majority of intensity values VI (MM and EMS-98 scales), are distributed within the hangingwall of the Fili fault, while the highest intensities (VIII and IX) concentrate very close to the Fili fault within its hangingwall domain. A gradual decrease of the intensities with the distance from the Fili fault is evident. Because of the similarity between the intensity distribution pattern and the static ground deformation pattern, we make the hypothesis that the latter predicts well enough the main characteristics of the former although the ground displacement is dominated by relatively low frequency as compared to the ground acceleration.  相似文献   
205.
定量分析地震活动的活跃与平静特征   总被引:1,自引:0,他引:1  
黄建平  马丽  陈时军 《中国地震》2005,21(3):417-428
在对中国大陆、中国台湾、新西兰、意大利和葡萄牙等不同地区的原始地震目录做震源深度和震级记录完整时间分析及删除余震的基础上,通过聚类分析方法定量考察各个研究区域内中强地震的活跃与平静特征,得到了这些地区地震活跃时段Ta、活跃时段内相邻地震间隔时间t和平静时段Tq的分布及其置信区间。并用时间间隔分析法,在假设“地震活动时间分布的活跃与平静特征是一平稳随机过程”条件下,计算了各研究区域在活跃时段内发生的理论地震数目N′和各地区全部实际地震发生的概率P。结果发现地震活动时间分布的活跃与平静特征不服从平稳随机过程。  相似文献   
206.
The implementation of a geographic information system (GIS)/fuzzy spatial decision support system in the selection of sites for drinking-water pumping boreholes is described. Groundwater is the main source of domestic supply and irrigation in Korinthia prefecture, south-eastern Greece. Water demand has increased considerably over the last 30 years and is mainly met by groundwater abstracted via numerous wells and boreholes. The definition of the most “suitable” site for the drilling of new boreholes is a major issue in this area. A method of allocating suitable locations has been developed based on multicriteria analysis and fuzzy logic. Twelve parameters were finally involved in the model, prearranged into three categories: borehole yield, groundwater quality, and economic and technical constraints. GIS was used to create a classification map of the research area, based on the suitability of each point for the placement of new borehole fields. The coastal part of the study area is completely unsuitable, whereas high values of suitability are recorded in the south-western part. The study demonstrated that the method of multicriteria analysis in combination with fuzzy logic is a useful tool for selecting the best sites for new borehole drilling on a regional scale. The results could be used by local authorities and decision-makers for integrated groundwater resources management.  相似文献   
207.
Mineralogy and Petrology - Seventy samples from major plutons (mainly granitic) of Western Anatolia (Turkey) have been analyzed by γ-ray spectrometry to determine the specific activities of...  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