全文获取类型
收费全文 | 1045篇 |
免费 | 96篇 |
国内免费 | 16篇 |
专业分类
地球物理 | 817篇 |
地质学 | 151篇 |
海洋学 | 10篇 |
综合类 | 35篇 |
自然地理 | 144篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 22篇 |
2020年 | 22篇 |
2019年 | 4篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 17篇 |
2013年 | 26篇 |
2012年 | 17篇 |
2011年 | 15篇 |
2010年 | 20篇 |
2009年 | 35篇 |
2008年 | 32篇 |
2007年 | 62篇 |
2006年 | 55篇 |
2005年 | 68篇 |
2004年 | 63篇 |
2003年 | 51篇 |
2002年 | 52篇 |
2001年 | 53篇 |
2000年 | 66篇 |
1999年 | 54篇 |
1998年 | 45篇 |
1997年 | 45篇 |
1996年 | 46篇 |
1995年 | 46篇 |
1994年 | 44篇 |
1993年 | 31篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 11篇 |
1989年 | 20篇 |
1988年 | 14篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1984年 | 6篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1157条查询结果,搜索用时 15 毫秒
71.
Measuring of microseismic events has been carried out at the former potash mine of Hope since early 1984.Analysis of the data demonstrates an immediate temporal relationship between brine introduction and onset of microseismic activity. The spatial distribution of the sources indicates a dependence on brine level height. Sources are found preferentially immediately next to roads and workings. Source radii, estimated from the frequency ranges in the seismograms, varied with the cross-section of neighbouring cavities and had a similar, order of size.Events occurred rarely in the previously flooded mine sections Similarly, the zone below a depth of approx. 600 m below sea level was virtually inactive. 相似文献
72.
Anticipating the scale invariance of rock fracturing processes, we applied Keilis-Borok’s algorithm M8, originally designed
for identifying times of increased probability (TIPS) of occurrence of strong earthquakes (M < 8.0), retrospectively to Koyna
earthquakes which occurred in the region after the impoundment of the Shivaji Sagar reservoir in 1962. The algorithm which
enables diagnosis of TIPS from the 7th year onwards after the commencement of the earliest available data set showed that
the 5.3 magnitude earthquake of 20 September 1980 indeed occurred within a time of increased probability. This result, apart
from its potential application to recognizing future TIPS in the region, points to selfsimilarity between the premonitory
patterns of natural and induced earthquakes and to scale-invariant nature of their processes. Further, a typical precursory
rise in seismicity followed by a relative quiescence was also found to precede all the three larger earthquakes of the sequence. 相似文献
73.
74.
75.
76.
77.
根据新疆及苏联天山地区的地震目录和古地震研究成果,将整个天山地区的地震韵律划分为地震世、地震亚世、地震期、地震幕、地震阶五级,探讨了各级韵律的特征。估计了我国天山地区未来地震活动趋势。 相似文献
78.
Tilt and strainmeter data collected in the Friuli seismic area between 1977 and 1985 have been analyzed to study the stress-strain field and/or the elastic parameter variations in the area after the strong 1976 seismic event.We concentrated on three different frequency bands, respectively linked with the tidal waves, the seasonal effect and the secular one. The results from the first two bands point at an increase of the local rigidity modulus.Relevant stresses induced by the seasonal groundwater level variations have been found, thus supporting the hypothesis that they can act as triggering effects. The secular trend reveals significant tectonic stress modifications. It appears that the post-seismic tectonic stresses faded during 1981–1983, and were followed by a new loading phase.On leave from the Institute of Geodesy and Geophysics of the Chinese Academy of Sciences. Ph. D. student at the Institute of Geodesy and Geophysics, Trieste University. 相似文献
79.
Recent improvements in the seismological networks on the Ibero-Maghrebian region have permitted estimation of hypocentral location and focal mechanisms for earthquakes which occurred at South Spain, Alboran Sea and northern Morocco of deep and intermediate depth, with magnitudes between 3.5 and 4.5. Intermediate depth shocks, range from 60 to 100 km, with greater concentration located between Granada and Málaga. Fault-plane solutions of 5 intermediate shocks have been determined; they present a vertical plane in NE-SW or E-W direction. Seismic moments of about 1015 Nm and dimensions of about 1 km have been determined from digital records of Spanish stations.P-wave forms are complex. This may be explained by the crustal structure near the station, discontinuities in the upper mantle and inhomogeneities near the source. Deep activity at about 650 km has only 3 shocks since 1954 (1954, 1973, 1990). Shocks are located at a very small region. Fault-plane solutions show a consistent direction of the pressure axis dipping 45° in E direction. For the 1990 shock seismic moment is 1016 Nm and dimensions 2.6 km. TheP-waves are of simpler form with a single pulse. The intermediate and deep activities are not connected and no activity has been detected between 100 and 650 km. The intermediate shocks may be explained in terms of a recent subduction from Africa under Iberia in SE direction. The very deep activity must be related to a sunk detached block of lithospheric material still sufficiently cold and rigid to generate earthquakes. 相似文献
80.
本文以滑波理论为依据,总结了山西地震带的两种不同特点的滑坡。即:振荡式滑坡及触发式滑坡。虽然两种滑坡都可分为变形、解体、滑动、毁灭等四个阶段,但其动力不同。振荡式滑波的滑动面倾角小,因而滑力来源于强震振动,而触发式滑坡的滑动面倾角大,因而滑力来自滑体本身静荷载。对两种滑坡的研究对预防及减轻强震带来的次生灾害有重要的意义。 相似文献