全文获取类型
收费全文 | 4349篇 |
免费 | 770篇 |
国内免费 | 90篇 |
专业分类
测绘学 | 37篇 |
大气科学 | 21篇 |
地球物理 | 4363篇 |
地质学 | 560篇 |
海洋学 | 23篇 |
天文学 | 34篇 |
综合类 | 63篇 |
自然地理 | 108篇 |
出版年
2024年 | 13篇 |
2023年 | 27篇 |
2022年 | 58篇 |
2021年 | 79篇 |
2020年 | 83篇 |
2019年 | 106篇 |
2018年 | 115篇 |
2017年 | 110篇 |
2016年 | 95篇 |
2015年 | 146篇 |
2014年 | 201篇 |
2013年 | 188篇 |
2012年 | 191篇 |
2011年 | 200篇 |
2010年 | 179篇 |
2009年 | 243篇 |
2008年 | 280篇 |
2007年 | 207篇 |
2006年 | 253篇 |
2005年 | 217篇 |
2004年 | 202篇 |
2003年 | 158篇 |
2002年 | 162篇 |
2001年 | 145篇 |
2000年 | 165篇 |
1999年 | 171篇 |
1998年 | 193篇 |
1997年 | 147篇 |
1996年 | 165篇 |
1995年 | 168篇 |
1994年 | 102篇 |
1993年 | 111篇 |
1992年 | 74篇 |
1991年 | 46篇 |
1990年 | 42篇 |
1989年 | 28篇 |
1988年 | 53篇 |
1987年 | 12篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 21篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 1篇 |
1954年 | 6篇 |
排序方式: 共有5209条查询结果,搜索用时 15 毫秒
131.
地脉动测试技术若干问题的讨论 总被引:1,自引:0,他引:1
讨论了地脉动的测试技术以及测试工作中应该重视而且容易被忽视的问题 ,并就地脉动幅值域和频率域特性参数提出不同的看法 相似文献
132.
— We present a quantitative statistical test for the presence of a crossover c0 in the Gutenberg-Richter distribution of earthquake seismic moments, separating the usual power-law regime for seismic moments less than c0 from another faster decaying regime beyond c0. Our method is based on the transformation of the ordered sample of seismic moments into a series with uniform distribution under condition of no crossover. A simulation method allows us to estimate the statistical significance of the null hypothesis H0 of an absence of crossover (c0=infinity). When H0 is rejected, we estimate the crossover c0 using two different competing models for the second regime beyond c0 and the simulation method. For the catalog obtained by aggregating 14 subduction zones of the Circum-Pacific Seismic Belt, our estimate of the crossover point is log(c0)=28.14 ± 0.40 (c0 in dyne-cm), corresponding to a crossover magnitude mW=8.1 ± 0.3. For separate subduction zones, the corresponding estimates are substantially more uncertain, so that the null hypothesis of an identical crossover for all subduction zones cannot be rejected. Such a large value of the crossover magnitude makes it difficult to associate it directly with a seismogenic thickness as proposed by many different authors. Our measure of c0 may substantiate the concept that the localization of strong shear deformation could propagate significantly in the lower crust and upper mantle, thus increasing the effective size beyond which one should expect a change of regime. 相似文献
133.
During the 1999 Chi-Chi, Taiwan earthquake, many sand boiling phenomena were observed in central Taiwan, which caused severe ground settlement and structure damages. According to the installed accelerograms, the peak ground surface horizontal accelerations in the liquefaction-affected areas range from 774.42 to 121.3 gal. The writers carried out an extensive investigation of soil liquefaction in this earthquake. In this paper, we present results of the CPT exploration and post-earthquake liquefaction analysis. Two hundred and seventy five (275) cone penetration test data were collected from the liquefaction-affected areas, and 46 liquefaction case histories and 88 non-liquefaction case histories were derived that can be used to evaluate the accuracy of existing liquefaction evaluation models. In addition, the strength of the liquefied soils after earthquake and the implication of its liquefaction potential in the future event are discussed. 相似文献
134.
135.
Soil liquefaction and associated ground failures have been a major source of damage during the past earthquakes. The risk of liquefaction and associated ground deformation can be reduced by various ground-improvement methods including the stone column (gravel drain) technique. This paper presents the current state of the stone column technologies as a liquefaction countermeasure. A comprehensive review is provided aiming to: (a) identify key considerations for the general use of stone columns as a liquefaction countermeasure, (b) provide insights for design and construction, (c) compile the latest research developments, and (d) identify sources of useful information. Case histories of field applications and observed field performance are cited to portray different stone column applications and observed effectiveness. The paper identifies areas where more research is needed and includes recommendations for future research and development. 相似文献
136.
137.
Magnitude calibration of north Indian earthquakes 总被引:13,自引:0,他引:13
138.
139.
刍议国际地震保险投保率 总被引:1,自引:0,他引:1
地震灾难带来的损失日益增加的问题,让保险业至今难以应对。地震发生频率低、损失巨大而保险公司的承保能力又十分有限,加之,社会公众的投保意识薄弱,造成地震保险投保率过低。从地震灾情入手,介绍了国际地震保险开展情况,剖析了地震保险投保率过低的原因,并针对问题提出了解决措施。 相似文献
140.
以山西省祁县依法管理工程抗震设防要求为例,论述了强制性审核、确定一般工业、民用建设工程抗震设防要求的重要性及其深远意义。结合工作实际.总结了部分依法行政、规范管理和落实抗震设防要求的经验。 相似文献