全文获取类型
| 收费全文 | 4212篇 |
| 免费 | 1185篇 |
| 国内免费 | 194篇 |
专业分类
| 测绘学 | 6篇 |
| 大气科学 | 60篇 |
| 地球物理 | 4071篇 |
| 地质学 | 992篇 |
| 海洋学 | 219篇 |
| 天文学 | 12篇 |
| 综合类 | 41篇 |
| 自然地理 | 190篇 |
出版年
| 2024年 | 6篇 |
| 2023年 | 22篇 |
| 2022年 | 75篇 |
| 2021年 | 92篇 |
| 2020年 | 148篇 |
| 2019年 | 175篇 |
| 2018年 | 138篇 |
| 2017年 | 183篇 |
| 2016年 | 166篇 |
| 2015年 | 178篇 |
| 2014年 | 299篇 |
| 2013年 | 227篇 |
| 2012年 | 147篇 |
| 2011年 | 210篇 |
| 2010年 | 194篇 |
| 2009年 | 277篇 |
| 2008年 | 293篇 |
| 2007年 | 242篇 |
| 2006年 | 252篇 |
| 2005年 | 230篇 |
| 2004年 | 189篇 |
| 2003年 | 184篇 |
| 2002年 | 198篇 |
| 2001年 | 143篇 |
| 2000年 | 148篇 |
| 1999年 | 131篇 |
| 1998年 | 140篇 |
| 1997年 | 128篇 |
| 1996年 | 165篇 |
| 1995年 | 156篇 |
| 1994年 | 104篇 |
| 1993年 | 97篇 |
| 1992年 | 64篇 |
| 1991年 | 43篇 |
| 1990年 | 36篇 |
| 1989年 | 26篇 |
| 1988年 | 21篇 |
| 1987年 | 11篇 |
| 1986年 | 6篇 |
| 1985年 | 3篇 |
| 1984年 | 12篇 |
| 1983年 | 1篇 |
| 1982年 | 1篇 |
| 1981年 | 2篇 |
| 1980年 | 4篇 |
| 1979年 | 4篇 |
| 1978年 | 4篇 |
| 1977年 | 9篇 |
| 1976年 | 1篇 |
| 1954年 | 6篇 |
排序方式： 共有5591条查询结果，搜索用时 15 毫秒
991.
992.
993.
994.
INTRODUCTIONShort-termearthquake prediction is one of the most challenging targets in earth science today.Manyrecent reports have presented examples fromseveral regions of the world by which associationsbetween possible electromagnetic precursors and earthquakes become more and more plausible(Eftaxias ,et al .,2003) . At the same time ,electromagnetic abnormity,as one of the short-termearthquake precursors ,is recognized by more and more experts in some countries . Pre-earthquakeelectroma… 相似文献
995.
Conventionally, evaluation of liquefaction potential of loose saturated cohesionless deposits as specified in Japanese design codes employs peak ground acceleration (PGA). However, recent large-scale earthquakes in Japan revealed that liquefaction at some sites did not occur even though large PGAs were recorded at or near these sites. As an alternative approach, an evaluation procedure based on peak ground motion parameters, i.e. incorporating both PGA and the peak ground velocity (PGV), is proposed. By performing parametric studies using one-dimensional seismic response analysis and formulating regression models, seismic-induced shear stresses within the deposit are expressed in terms of peak ground motion parameters at the surface, and these are used to calculate the factor of safety against liquefaction. Application to case histories in Japan indicates that the proposed two-parameter equation can adequately account for the occurrence and non-occurrence of liquefaction at various sites as compared to the conventional PGA-based approach. Moreover, analyses of several strong motion records at various sites show that liquefaction may occur when PGA≥150 gal and PGV≥20 kine, indicating that these values can serve as thresholds in assessing the possible occurrence of liquefaction. 相似文献
996.
997.
Worldwide experience repeatedly shows that damages in structures caused by earthquakes are highly dependent on site condition and epicentral distance. In this paper, a 21-storey shear wall-structure built in the 1960s in Hong Kong is selected as an example to investigate these two effects. Under various design earthquake intensities and for various site conditions, the fragility curves or damage probability matrix of such building is quantified in terms of the ductility factor, which is estimated from the ratio of storey yield shear to the inter-storey seismic shear. For high-rise buildings, a higher probability of damage is obtained for a softer site condition, and damage is more severe for far field earthquakes than for near field earthquakes. For earthquake intensity of VIII, the probability of complete collapse (P) increases from 1 to 24% for near field earthquakes and from 1 to 41% for far field earthquakes if the building is moved form a rock site to a site consisting a 80 m thick soft clay. For intensity IX, P increases from 6 to 69% for near field earthquake and from 14 to 79% for far field earthquake if the building is again moved form rock site to soft soil site. Therefore, site effect is very important and not to be neglected. Similar site and epicentral effects should also be expected for other types of high-rise structures. 相似文献
998.
Takamatsu is a harbor city of 330,000 people on the northern shore of Shikoku Island, southwest Japan. Earthquakes in the Nankai Trough, typically of magnitude M 8+, have been considered the primary source of seismic hazard for the island and Takamatsu. A major active fault system, the Median Tectonic Line, runs across the Shikoku from east to west near the north shore. There is no documented historical seismicity associated with this major fault system in Shikoku or with associated faults such as the 20 km Nagao Fault near Takamatsu. Therefore the trenches were cut across some of the more important faults to expose the record of past seismicity. Additional data on past seismicity is derived from paleo-liquefaction studies in the Takamatsu plain. This paper describes the trenching and paleo-seismic studies and discusses the implications of the findings for seismic hazard in Takamatsu. 相似文献
999.
Flow and deformation failure of sandy slopes 总被引：2，自引：0，他引：2
The effects of earthquake induced pore pressure on seismic and post seismic stability conditions of cohesionless slopes are investigated with reference to the infinite slope scheme. In cohesionless slopes the shear strength reduction caused by pore pressure build-up may lead the slope to a deformation failure or to a flow failure if liquefaction conditions are approached. Two critical values of the seismic induced pore pressure ratio are introduced to evaluate the effect of shear strength reduction on the slope failure mechanism. The results are given in the form of stability charts and a procedure for the evaluation of the seismic stability condition is described. The procedure gives useful information about the failure mechanism that slopes may exhibit and the displacement analysis which should be carried out. 相似文献
1000.