全文获取类型
收费全文 | 275篇 |
免费 | 145篇 |
国内免费 | 100篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 1篇 |
地球物理 | 330篇 |
地质学 | 158篇 |
海洋学 | 1篇 |
天文学 | 3篇 |
综合类 | 24篇 |
出版年
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2011年 | 18篇 |
2010年 | 4篇 |
2009年 | 24篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 17篇 |
2005年 | 33篇 |
2004年 | 105篇 |
2003年 | 56篇 |
2002年 | 58篇 |
2001年 | 31篇 |
2000年 | 13篇 |
1999年 | 18篇 |
1998年 | 27篇 |
1997年 | 30篇 |
1996年 | 23篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 15篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有520条查询结果,搜索用时 15 毫秒
441.
Sun Cichang Wang Xusheng Liu Qingfang Tao Yulu Yu Ping and Feng RuiInstitute of Geophysics SSB Beijing China Department of Geophysics Peking University Beijing China Seismnlogical Bureau of Hunan Province Changsha China Center for Seismological Data Information SSB Beijing China 《中国地震研究》1998,(2)
Cross-well electromagnetic tomography has been used to monitor the changes of the abso rption coefficient of electromagnetic waves before and after earthquakes for 5 years at Dahuichang fault since 1992.It has been found that 3 months before the occurrence of moderately strong earthquakes(ML≥4.0,△<210 km),several special changes in tomogram appeared as follows:The mean-value of the absorption coefficient dropped about 10% compared with the annually decreasing tendency; the mean difference of pixels suddenly decreased or increased in different directions; and the entropy of the paragenic matrix in a tomogram decreased and the number of low absorption pixels increased.It is inferred that such changes in electromagnetic tomograms are attributed to the variation of micro-cracks and porosity in rocks.Electromagnetic tomography can be studied as a new technique to detect earthquake precursors. 相似文献
442.
Gao Yuan Wu Zhongliang and Zhou HuilanGraduate School of USTC Academia Sinica Beijing ChinaCenter for Analysis Prediction China Seismological Bureau Beijing ChinaInstitute of Geophysics China Seismological Bureau Beijing China 《中国地震研究》1998,(3)
Four earthquakes with M > 6.0 occurred in Qinghai Province, China froth 1988 to 1990. Using broadband data from GDSN, the source ruptures of these earthquakes and tectonic surroundings were studied using waveform modelling combined with background data of geological tectonics. Through the analysis of apparent source time function (aSTF) and apparent time difference (aTD), the complexity of sources was discussed, and in view of source analysis, the result further supports the conclusion that the compressive stress axis of tectonic stress field in northeastern Qinghai-Xizang (Tibetan) plateau is at the NE direction, is nearly horizontal, turns counter-clockwise to the NEE or N to S direction, and is nearly horizontal close to the northern Qinghai-Xizang plateau. 相似文献
443.
Ren Qingfang Zhang Xiankang Zhang Chengke Zhao Jinren and Zhou Xuesong Research Center of Exploration Geophysics CSB Zhengzhou China 《中国地震研究》1998,(4)
1-D and 2-D calculation and interpretation are carried out with the DSS data from the western section of Heze-Changzhi profile and the southern section of Zhengzhou-Jinan profile. 2-D velocity structure is determined in Tangyin graben and its adjacent area. The result shows that velocity structure of the crust and upper mantle is obviously different in vertical and lateral directions. Crustal thickness varies apparently in this area, and there are local low velocity blocks in the interior crust. The swelling M-discontinuity corresponds to Tangyin graben and Moho depth at the highest swelling position is 31 km. Toward the east, its depth gradually increases to 32 km in Xunxian swelling; toward the west, M-discontinuity becomes a steep zone at the piedmont uplift of Taihang Mountain and reaches 40 km at depth near Changzhi. Through analyzing the relationship between historical earthquakes and deep structure in North China, we infer that seismic risk exists in Tangyin graben and its adjacent area. 相似文献
444.
地震面波频散的层析成像 总被引:5,自引:0,他引:5
本文较详细地介绍了群速度频散测定的多重滤波法,以及LSQR反演方法运用于网格频散反演和地球内部结构反演的地震面波频散的层析成像方法。给出了计算程序框图及数值模拟结果 相似文献
445.
A numerical study of 1-D nonlinear P-wave propagation in solid 总被引:3,自引:0,他引:3
IntroductionBecauseoftheextensivedistributionofruptures,micro-cracksandcrystalfracturesintheearth,therelationshipsbetweenthestressandstrainarenolongerlinear,infact,theyarenonlinear.Inordertoinvestigateandusethenonlinearcharacteristicsofsolidmediumintheearth,weshouldconsidertheinfluenceofnonlinearresponseduringthecourseofseismicmodelingandinversion.Thisisoneoftheimportantstudyfieldsthathavebeenpaidgreatattentionsinthere-centyearsintheworld(Minster,etal,1991;ZHANG,TENG,1993).Thenonlinearchar… 相似文献
446.
Introduction Increasing evidences show that the properties of candidate earthquake precursors seem to befocal mechanism dependent (Tsuruoka, et al, 1995; Reasenberg, 1999; Wan, et al, 2002). Test ofearthquake precursors without the classification of earthquakes could be misleading (Wu, 1999,Nature debates, http://helix.nature.com/debates/). In this paper we use the reported earthquakeprecursors for some earthquakes in China (ZHANG, 1988; 1990a, b; 1999; 2000; CHEN, 2002a, b;2003) to… 相似文献
447.
An equivalent-boundary method for the shell analysis of buried pipelines under fault movement 总被引:2,自引:0,他引:2
Introduction The history of research work on the response of buried pipeline under the fault movement hasbeen about 30 years. Several simplified design methods have been proposed to obtain the maxi-mum stress or strain in pipe. These methods include the theoretical method and the finite elementmethod (FEM). In the theoretical method, the pipe is usually modeled as a cable (Newmark, Hall1975; Kennedy, et al, 1977) or a beam (Wang, Wang, 1995; LIU, ZHANG, 2002). These theoreti-cal me… 相似文献
448.
Paleomagnetic study on the Early Triassic red beds from Jiaocheng, Shanxi Province ——Local rotation and tectonic significance 总被引:1,自引:0,他引:1
SHI Ruiping HUANG Baochun ZHU Rixiang& REN ShoumaiInstitute of Geology Geophysics Chinese Academy of Sciences Beijing China Correspondence should be addressed to Shi Ruiping 《中国科学D辑(英文版)》2004,(2)
Paleomagnetic and rock magnetic study has been conducted on the Early Triassic red beds of Liujiagou Formation from Jiaocheng, Shanxi Province. Hematite was shown as the main magnetic mineral. After eradicating an initial viscous component at room temperature to -100℃- 200℃, thermal demagnetization shows that most samples contain two remanence components, intermediate-temperature remanence component at 250℃-500℃ and high-temperature component at 500℃-680℃. The intermediate-temperature component has a negative fold test at the 95% confidence level. And the pole position of the intermediate-temperature component in geographic coordinates is correlated with the Middle Jurassic reference pole of the North China Block (NCB) within the 95% confidence, suggesting that it might be a remagnetiza-tion component acquired during the Yanshanian period. The high-temperature component contains both reversal and normal polarities with positive fold test and C-level positive reversal test at the 95% confidence lev 相似文献
449.
在已有的地表地质构造、浅层探测与深部探测等资料基础上,利用高精度地震局域网的数字地震记录,分析了延庆矾山次级盆地北缘断裂上的微、小地震活动特征, 及其与地表活断层和深部地壳结构关系. 通过对地震局域网获得的微、小地震的精确位置、震源机制解及其特点的分析,厘定了地表活断层延庆矾山盆地北缘断裂属旋转平面状正断层,揭示了延怀盆地区浅表地质与深部构造的相互关系,以及地壳脆韧性变形随深度的转换特征. 相似文献
450.