全文获取类型
| 收费全文 | 3840篇 |
| 免费 | 699篇 |
| 国内免费 | 77篇 |
专业分类
| 测绘学 | 38篇 |
| 大气科学 | 16篇 |
| 地球物理 | 3777篇 |
| 地质学 | 505篇 |
| 海洋学 | 16篇 |
| 天文学 | 146篇 |
| 综合类 | 32篇 |
| 自然地理 | 86篇 |
出版年
| 2023年 | 21篇 |
| 2022年 | 47篇 |
| 2021年 | 51篇 |
| 2020年 | 63篇 |
| 2019年 | 66篇 |
| 2018年 | 87篇 |
| 2017年 | 93篇 |
| 2016年 | 84篇 |
| 2015年 | 124篇 |
| 2014年 | 176篇 |
| 2013年 | 162篇 |
| 2012年 | 162篇 |
| 2011年 | 177篇 |
| 2010年 | 167篇 |
| 2009年 | 231篇 |
| 2008年 | 269篇 |
| 2007年 | 195篇 |
| 2006年 | 231篇 |
| 2005年 | 198篇 |
| 2004年 | 186篇 |
| 2003年 | 141篇 |
| 2002年 | 156篇 |
| 2001年 | 142篇 |
| 2000年 | 152篇 |
| 1999年 | 153篇 |
| 1998年 | 180篇 |
| 1997年 | 133篇 |
| 1996年 | 151篇 |
| 1995年 | 158篇 |
| 1994年 | 88篇 |
| 1993年 | 85篇 |
| 1992年 | 55篇 |
| 1991年 | 45篇 |
| 1990年 | 37篇 |
| 1989年 | 27篇 |
| 1988年 | 47篇 |
| 1987年 | 7篇 |
| 1986年 | 3篇 |
| 1985年 | 2篇 |
| 1984年 | 21篇 |
| 1983年 | 3篇 |
| 1982年 | 2篇 |
| 1981年 | 1篇 |
| 1980年 | 4篇 |
| 1979年 | 11篇 |
| 1978年 | 6篇 |
| 1977年 | 10篇 |
| 1954年 | 6篇 |
排序方式： 共有4616条查询结果，搜索用时 31 毫秒
81.
82.
Shantanu Joshi Amit Prashant Arghya Deb Sudhir K. Jain 《Soil Dynamics and Earthquake Engineering》2011
Presently available simplified analytical methods and semi-empirical methods for the analysis of buried pipelines subjected to fault motion are suitable only for the strike-slip and the normal-slip type fault motions, and cannot be used for the reverse fault crossing case. A simple finite element model, which uses beam elements for the pipeline and discrete nonlinear springs for the soil, has been proposed to analyse buried pipeline subjected to reverse fault motion. The material nonlinearities associated with pipe-material and soil, and geometric nonlinearity associated with large deformations were incorporated in the analysis. Complex reverse fault motion was simulated using suitable constraints between pipe-nodes and ground ends of the soil spring. Results of the parametric study suggest that the pipeline's capacity to accommodate reverse fault offset can be increased significantly by choosing a near-parallel orientation in plan with respect to the fault line. Further improvement in the response of the pipeline is possible by adopting loose backfill, smooth and hard surface coating, and shallow burial depth in the fault crossing region. For normal or near normal orientations, pipeline is expected to fail due to beam buckling at very small fault offsets. 相似文献
83.
Though rocking shallow foundations could be designed to possess many desirable characteristics such as energy dissipation, isolation, and self-centering, current seismic design codes often avoid nonlinear behavior of soil and energy dissipation beneath foundations. This paper compares the effectiveness of energy dissipation in foundation soil (during rocking) with the effectiveness of structural energy dissipation devices during seismic loading. Numerical simulations were carried out to systematically study the seismic energy dissipation in structural elements and passive controlled energy dissipation devices inserted into the structure. The numerical model was validated using shaking table experimental results on model frame structures with and without energy dissipation devices. The energy dissipation in the structure, drift ratio, and the force and displacement demands on the structure are compared with energy dissipation characteristics of rocking shallow foundations as observed in centrifuge experiments, where shallow foundations were allowed to rock on dry sandy soil stratum during dynamic loading. For the structures with energy dissipating devices, about 70–90% of the seismic input energy is dissipated by energy dissipating devices, while foundation rocking dissipates about 30–90% of the total seismic input energy in foundation soil (depending on the static factor of safety). Results indicate that, if properly designed (with reliable capacity and tolerable settlements), adverse effects of foundation rocking can be minimized, while taking advantage of the favorable features of foundation rocking and hence they can be used as efficient and economical seismic energy dissipation mechanisms in buildings and bridges. 相似文献
84.
85.
M. Erdik K. ŞeşetyanM.B. Demircioğlu U. HancılarC. Zülfikar 《Soil Dynamics and Earthquake Engineering》2011
This article summarizes the work done over the last decades regarding the development of new approaches and setting up of new applications for earthquake rapid response systems that function to estimate earthquake losses in quasi-real time after an earthquake. After a critical discussion of relevant earthquake loss estimation methodologies, the essential features and characteristics of the available loss estimation software are summarized. Currently operating near-real-time loss estimation tools can be classified under two main categories depending on the size of area they cover: global and local systems. For the global or regional near-real-time loss estimation systems: GDACS, WAPMERR, PAGER, and NERIES-ELER methodologies are presented together with their loss estimations for the 2009 Abruzzo (L’Aquila) earthquake in Italy. Examples are provided for the local rapid earthquake loss estimation systems, including the Taiwan Earthquake Rapid Reporting System, Real-time Earthquake Assessment Disaster System in Yokohama, Real Time Earthquake Disaster Mitigation System of the Tokyo Gas Co., and Istanbul Earthquake Rapid Response System. 相似文献
86.
87.
The paper analyzes the radon data of nearly two decades on the Jiayuguan fault zone,discusses the main influencing factors,and puts forward the relationship between radon and air temperature,ground temperature and rainfall.We summarized the earthquake reflecting effect for ML≥5.0 about 400km within the Jiayuguan station,and reached the conclusion that it has better earthquake-reflecting ability before an earthquake,usually appearing as abnormal changes in sustained low value.By extracting the annual trend of radon in Jiayuguan station over many years,we discovered that the annual trend of radon has a close relationship with the seismic activity in surrounding areas,namely,if the annual variation of radon is larger,the seismic activity in surrounding areas is stronger;Otherwise,if the annual variation of radon is relatively stable,the seismic activity in the vicinity is weak. 相似文献
88.
89.
90.