全文获取类型
收费全文 | 10269篇 |
免费 | 2328篇 |
国内免费 | 1048篇 |
专业分类
测绘学 | 52篇 |
大气科学 | 75篇 |
地球物理 | 7721篇 |
地质学 | 3520篇 |
海洋学 | 784篇 |
天文学 | 10篇 |
综合类 | 455篇 |
自然地理 | 1028篇 |
出版年
2024年 | 37篇 |
2023年 | 136篇 |
2022年 | 273篇 |
2021年 | 336篇 |
2020年 | 440篇 |
2019年 | 482篇 |
2018年 | 394篇 |
2017年 | 365篇 |
2016年 | 333篇 |
2015年 | 398篇 |
2014年 | 515篇 |
2013年 | 534篇 |
2012年 | 592篇 |
2011年 | 617篇 |
2010年 | 493篇 |
2009年 | 568篇 |
2008年 | 585篇 |
2007年 | 717篇 |
2006年 | 743篇 |
2005年 | 597篇 |
2004年 | 612篇 |
2003年 | 529篇 |
2002年 | 426篇 |
2001年 | 322篇 |
2000年 | 374篇 |
1999年 | 314篇 |
1998年 | 312篇 |
1997年 | 252篇 |
1996年 | 283篇 |
1995年 | 222篇 |
1994年 | 208篇 |
1993年 | 182篇 |
1992年 | 118篇 |
1991年 | 79篇 |
1990年 | 55篇 |
1989年 | 54篇 |
1988年 | 46篇 |
1987年 | 34篇 |
1986年 | 24篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 16篇 |
1954年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
83.
利用高分辨率卫星影像进行地震损失评价所需的城市特征识别 总被引:2,自引:0,他引:2
高分辨率卫星影像已经在一些国家的民用领域得到应用。利用高分辨率卫星影像来收集地震损失评价所需要的各类城市信息不仅高效和有较好的时间分辨率,而且它可以减少以往所必需的大量的代价高昂且费力的城市调查。基于在印度城市台拉登所做的研究,讨论了如何利用高分辨率卫星影像进行城市特征识别的一些问题,同时也简单论述了利用GIS/RS软件综合所得的数据以便用于地震损失评价的方法。 相似文献
84.
R.M.W. Musson 《Bulletin of Earthquake Engineering》2004,2(1):101-112
Three sites in the UK are taken, representative of low, medium and high hazard levels (by UK standards). For each site, the
hazard value at 10−4 annual probability is computed using a generic seismic source model, and a variety of ground motion parameters: peak ground
acceleration (PGA), spectral acceleration at 10 Hz and 1 Hz, and intensity. Disaggregation is used to determine the nature
of the earthquakes most likely to generate these hazard values. It is found (as might be expected) that the populations are
quite different according to which ground motion parameter is used. When PGA is used, the result is a rather flat magnitude
distribution with a tendency to low magnitude events (\le 4.5 ML) which are probably not really hazardous. Hazard-consistent scenario earthquakes computed using intensity are found
to be in the range 5.8–5.9 ML, which is more in accord with the type of earthquake that one expects to be a worst-case event
in the UK.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
85.
IntroductionItisdefinitelystipulatedintheLawofthePeople'sRepublicofChinaonProtectingagainstandMitigatingEarthquakeDisastersthattheseismicsafetyevaluationmustbemadeformajorprojects(includinglifelineprojects)and,accordingtotheresultsobtained,theseismicresistancerequirementsshouldbedetermined.Thenecessityofseismicsafetyevaluationhasbeenrecog-nizedgradually,butthetopicontheeffectofsafetyevaluationhasnotbeenreferredmuch.Gener-allyspeaking,althoughmostpeopleapprovethesocialeffectofsafetyevaluatio… 相似文献
86.
A Markov method of analysis is presented for obtaining the seismic response of cable‐stayed bridges to non‐stationary random ground motion. A uniformly modulated non‐stationary model of the random ground motion is assumed which is specified by the evolutionary r.m.s. ground acceleration. Both vertical and horizontal components of the motion are considered to act simultaneously at the bridge supports. The analysis duly takes into account the angle of incidence of the earthquake, the spatial correlation of ground motion and the quasi‐static excitation. A cable‐stayed bridge is analysed under a set of parametric variations in order to study the non‐stationary response of the bridge. The results of the numerical study indicate that (i) frequency domain spectral analysis with peak r.m.s. acceleration as input could provide more r.m.s. response than the peak r.m.s. response obtained by the non‐stationary analysis; (ii) the longitudinal component of the ground motion significantly influences the vertical vibration of the bridge; and (iii) the angle of incidence of the earthquake has considerable influence on the deck response. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
87.
本文以动三轴试验和原位测试数据为基础,以天津地区砂性土为例,探讨砂性土振动液化机理及孔隙水压力变化规律,采用多种方法分析判别砂性土液化,为高烈度地区重要工程建筑抗震设计提供重要数据。 相似文献
88.
The Zhangjiakou–Penglai seismotectonic zone (ZPSZ) lies in the northern part of North China and extends along the Zhangjiakou–Beijing–Tianjin–Bohai Bay–Penglai–Yellow Sea. It is about 900 km long and some 250 km wide in a northwest direction. The great Sanhe-Pinggu (MS=8.0) earthquake occurred on September 1679 and the Tangshan (MS=7.8) earthquake on July 1976 caused serious economic and life losses. According to some differences in crust structure and regional tectonic stress field, the ZPSZ is divided into western and eastern segment by the 117°E line for study on long-term seismic hazard analysis. An analysis of Gutenberg–Richter's empirical relation of earthquake-frequency and time process of historic and recent earthquakes along the eastern and western segments shows that the earthquake activity obeys a Poisson process, and these calculations indicate that the earthquake occurrence probability of MS=6.0–6.9 is 0.77–0.83 in the eastern segment and the earthquake occurrence probability of MS=7.0–7.9 is 0.78–0.80 in the western segment of the ZPSZ during a period from 2005 to 2015. 相似文献
89.
90.
Imaging the Dead Sea Transform with scattered seismic waves 总被引:2,自引:0,他引:2