全文获取类型
收费全文 | 4303篇 |
免费 | 757篇 |
国内免费 | 688篇 |
专业分类
测绘学 | 328篇 |
大气科学 | 285篇 |
地球物理 | 1391篇 |
地质学 | 1819篇 |
海洋学 | 484篇 |
天文学 | 72篇 |
综合类 | 568篇 |
自然地理 | 801篇 |
出版年
2024年 | 13篇 |
2023年 | 49篇 |
2022年 | 120篇 |
2021年 | 158篇 |
2020年 | 182篇 |
2019年 | 185篇 |
2018年 | 146篇 |
2017年 | 146篇 |
2016年 | 183篇 |
2015年 | 165篇 |
2014年 | 228篇 |
2013年 | 281篇 |
2012年 | 221篇 |
2011年 | 235篇 |
2010年 | 195篇 |
2009年 | 213篇 |
2008年 | 240篇 |
2007年 | 282篇 |
2006年 | 259篇 |
2005年 | 224篇 |
2004年 | 213篇 |
2003年 | 204篇 |
2002年 | 160篇 |
2001年 | 179篇 |
2000年 | 169篇 |
1999年 | 127篇 |
1998年 | 136篇 |
1997年 | 135篇 |
1996年 | 121篇 |
1995年 | 97篇 |
1994年 | 96篇 |
1993年 | 83篇 |
1992年 | 62篇 |
1991年 | 49篇 |
1990年 | 27篇 |
1989年 | 32篇 |
1988年 | 40篇 |
1987年 | 23篇 |
1986年 | 19篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1954年 | 8篇 |
排序方式: 共有5748条查询结果,搜索用时 62 毫秒
171.
172.
173.
Introduction Sichuan-Yunnan region, located in the east margin of Qinghai-Xizang (Tibetean) Plateau, is a transitional zone between the rapidly upheaving Tibetean Plateau and relatively steady Yangtze Platform. Under the pressure exerted by the northward movement of Indian Plate, Sichuan-Yunnan region has been undergone strong deformation and regmagenesis, becoming one of the regions with the most intensive seismicity in the world. The research on the tectonics and seismicity there is alw… 相似文献
174.
M. Malinowski 《Studia Geophysica et Geodaetica》2005,49(4):485-500
The aim of this paper is to show the application of short-period surface waves recorded during deep seismic sounding experiment
for constraining shallow velocity structure of the crust. Phase velocity of fundamental mode Rayleigh waves, observed along
the CELEBRATION 2000 experiment profile CEL09, were obtained by a p-ω method and has been subsequently inverted for one-dimensional
shear velocity models for the top 2 km. Multiple filter technique applied to one shot gather was used to carry out a joint
inversion of phase and group velocity data and to provide γR data to be used for Qβ inversion. Validity of obtained VS and Qβ models was confirmed by the reflectivity method. Noticeably, no clear dispersive wawes were observed in the Tepla-Barrandian
Unit. Quasi-2D model based on the individual 1D VS models is well correlated with the surface geology. Lower VS are observed in the Saxothuringian Zone in comparison to the Moldanubian Zone. In the vicinity of the Central Bohemian and
Moldanubian Plutons, the near-surface VS values are relatively low, but below 1 km depth, they are higher than in surrounding areas. We interpret it as the result
of the weathering and cracks within the granitoid rocks. 相似文献
175.
Roberto Sulpizio Daniela Mele Pierfrancesco Dellino Luigi La Volpe 《Bulletin of Volcanology》2005,67(8):743-767
The combined use of field investigation and laboratory analyses allowed the detailed stratigraphic reconstruction of the Pollena eruption (472 AD) of Somma-Vesuvius. Three main eruptive phases were recognized, related either to changes in the eruptive processes and/or to relative changes of melt composition. The eruption shows a pulsating behavior with deposition of pyroclastic fall beds and generation of dilute and dense pyroclastic density currents (PDC). The eruptive mechanisms and transportation dynamics were reconstructed for the whole eruption. Column heights were between 12 and 20 km, corresponding to mass discharge rates (MDR) of 7×106 kg/s and 3.4×107 kg/s. Eruptive dynamics were driven by magmatic fragmentation of a phono-tephritic to tephri-phonolitic magma during Phases I and II, whereas phreatomagmatic fragmentation dominated Phase III. Magma composition varies between phonolitic and tephritic-phonolitic, with melt viscosity likely not in excess of 103 Pa s. The volume of the pyroclastic fall deposits, calculated by using of proximal isopachs, is 0.44 km3. This increases to 1.38 km3 if ash volumes are extrapolated on a log thickness vs. square root area diagram using one distal isopach and column height.Editorial responsibility: R Cioni 相似文献
176.
177.
178.
179.
180.