全文获取类型
收费全文 | 1239篇 |
免费 | 270篇 |
国内免费 | 133篇 |
专业分类
测绘学 | 102篇 |
大气科学 | 120篇 |
地球物理 | 726篇 |
地质学 | 353篇 |
海洋学 | 105篇 |
天文学 | 23篇 |
综合类 | 57篇 |
自然地理 | 156篇 |
出版年
2024年 | 6篇 |
2023年 | 17篇 |
2022年 | 14篇 |
2021年 | 23篇 |
2020年 | 39篇 |
2019年 | 45篇 |
2018年 | 42篇 |
2017年 | 58篇 |
2016年 | 56篇 |
2015年 | 56篇 |
2014年 | 71篇 |
2013年 | 83篇 |
2012年 | 63篇 |
2011年 | 61篇 |
2010年 | 51篇 |
2009年 | 66篇 |
2008年 | 68篇 |
2007年 | 85篇 |
2006年 | 94篇 |
2005年 | 74篇 |
2004年 | 70篇 |
2003年 | 49篇 |
2002年 | 59篇 |
2001年 | 35篇 |
2000年 | 37篇 |
1999年 | 41篇 |
1998年 | 40篇 |
1997年 | 36篇 |
1996年 | 35篇 |
1995年 | 26篇 |
1994年 | 32篇 |
1993年 | 22篇 |
1992年 | 16篇 |
1991年 | 19篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1954年 | 4篇 |
排序方式: 共有1642条查询结果,搜索用时 15 毫秒
51.
This paper presents relative secular variations of the total intensity of the geomagnetic field against a background of results of magnetic anomaly interpretation along seismic profile P4. Profile P4 crosses a Variscan folding zone in the Paleozoic Platform (PLZ), the Trans-European Suture Zone (TESZ), and the Polish part of the East European Craton (EEC). Secular geomagnetic field variations
measured in 1966–2000 along a line adjacent to seismic profile P4 were analysed. The study of secular variations, reduced to the base recordings at the Belsk Magnetic Observatory, showed that the growth of geomagnetic field at the East European Craton was slower than in the Trans-European Suture Zone and the Paleozoic Platform.A 2D crustal magnetic model was interpreted as a result of magnetic modelling, in which seismic, geological and geothermal data were also used. The modelling showed that there were significant differences in the magnetic model for geotectonic units, which had been earlier determined based on deep seismic survey data. It should be noted that a fundamental change of trend of the relative secular variations was observed at the slope of the Precambrian Platform. After analysing the geomagnetic field observed along profile P4, the hypothesis that the contact between Phanerozoic and Precambrian Europe lies in Poland's territory can be proven. 相似文献
52.
The relative importance of the contribution of the lower crust and of the lithospheric mantle to the total strength of the continental lithosphere is assessed systematically for realistic ranges of layer thickness, composition, and temperature. Results are presented as relative strength maps, giving the ratio of the lower crust to upper mantle contribution in terms of crustal thickness and surface heat flow. The lithosphere shows a “jelly sandwich” rheological layering for low surface heat flow, thin to average crustal thickness, and felsic or wet mafic lower crustal compositions. On the other hand, most of the total strength resides in the seismogenic crust in regions of high surface heat flow, crust of any thickness, and dry mafic lower crustal composition. 相似文献
53.
54.
Introduction The acceleration response spectrum and peak ground acceleration are the necessary and im-portant parameters in earthquake-resistant design at present. They are still active research field. With the increase of digital high accurate strong motion observation data, especially the earth-quakes of Loma Prieta (M=7.0) in 1989; Landers (M=7.3) in 1992; Big Bear (M=6.4) in 1994 and Northridge (M=6.7) in 1994 in USA; Kozani (M=6.6) earthquake and afteshocks in 1995 in Greece; Dinar… 相似文献
55.
A Possible Detection of the 26 December 2004 Great Sumatra-Andaman Islands Earthquake with Solution Products of the International GNSS Service 总被引:1,自引:0,他引:1
J. Kouba 《Studia Geophysica et Geodaetica》2005,49(4):463-483
The main goal of this work is to critically review the IGS solution products and Precise Point Positioning (PPP) in order
to demonstrate their potential to contribute to studies of large earthquakes such as the one that devastated Southeast Asia
on December 26th, 2004. In view of a possible detection of the Mw 9.0 Sumatra-Andaman Islands Earthquake of December 26, 2004,
position solutions, ranging from intervals of years to one second, of four International GNSS Service (IGS) stations within
3000 km of the epicenter were examined. The IGS combined, cumulative solution product (IGS04P51), consisting of epoch and
station velocity solutions and based on data spans of several years prior to the earthquake, was used as a reference. Four
IGS combined weekly position solutions (igs04P1301-4), two weeks before and after the earthquake, were utilized for the weekly
solution resolution. PPP static and kinematic solutions with IGS Final combined orbits and clocks were used for the mean daily
and instantaneous 5-min and 1-sec epoch solutions, respectively. The most significant changes, detected by both weekly and
daily solutions occurred in longitude. The nearest IGS station ntus, about 1000 km east of the epicenter, moved westward about
15 mm, while the more distant Indian station iisc (∼ 2300 km NW from the epicenter), shifted about 15 mm eastward. In spite
of position errors caused by interpolation of the 5-min IGS clocks, the 1-sec solutions, based on separate data sets, available
only for two stations (iisc, dgar), still showed seismic surface waves, in particular at the Indian station iisc. Precise
daily IGS combined polar motion and length-of-day products, after correcting for the atmospheric effects, also likely detected,
statistically significant, anomalistic excitations on December 26, 2004 that could be caused by this great earthquake. 相似文献
56.
57.
58.
59.
60.