全文获取类型
| 收费全文 | 107852篇 |
| 免费 | 1553篇 |
| 国内免费 | 649篇 |
专业分类
| 测绘学 | 2518篇 |
| 大气科学 | 7122篇 |
| 地球物理 | 20308篇 |
| 地质学 | 40597篇 |
| 海洋学 | 9421篇 |
| 天文学 | 24087篇 |
| 综合类 | 359篇 |
| 自然地理 | 5642篇 |
出版年
| 2022年 | 710篇 |
| 2021年 | 1157篇 |
| 2020年 | 1235篇 |
| 2019年 | 1392篇 |
| 2018年 | 4442篇 |
| 2017年 | 4016篇 |
| 2016年 | 3882篇 |
| 2015年 | 1591篇 |
| 2014年 | 2971篇 |
| 2013年 | 5110篇 |
| 2012年 | 3811篇 |
| 2011年 | 5658篇 |
| 2010年 | 5052篇 |
| 2009年 | 6224篇 |
| 2008年 | 5268篇 |
| 2007年 | 5756篇 |
| 2006年 | 4040篇 |
| 2005年 | 3018篇 |
| 2004年 | 2937篇 |
| 2003年 | 2836篇 |
| 2002年 | 2763篇 |
| 2001年 | 2282篇 |
| 2000年 | 2201篇 |
| 1999年 | 1735篇 |
| 1998年 | 1775篇 |
| 1997年 | 1647篇 |
| 1996年 | 1268篇 |
| 1995年 | 1368篇 |
| 1994年 | 1191篇 |
| 1993年 | 1099篇 |
| 1992年 | 1034篇 |
| 1991年 | 1063篇 |
| 1990年 | 1039篇 |
| 1989年 | 904篇 |
| 1988年 | 824篇 |
| 1987年 | 994篇 |
| 1986年 | 866篇 |
| 1985年 | 1072篇 |
| 1984年 | 1196篇 |
| 1983年 | 1158篇 |
| 1982年 | 1071篇 |
| 1981年 | 1001篇 |
| 1980年 | 915篇 |
| 1979年 | 867篇 |
| 1978年 | 836篇 |
| 1977年 | 721篇 |
| 1976年 | 704篇 |
| 1975年 | 711篇 |
| 1974年 | 679篇 |
| 1973年 | 771篇 |
排序方式： 共有10000条查询结果，搜索用时 46 毫秒
71.
72.
73.
74.
75.
76.
77.
Subglacial and subaqueous sediments deposited near the margin of a Late-glacial ice-dammed lake near Achnasheen, northern Scotland, are described and interpreted. The subglacial sediments consist of deformation tills and glacitectonites derived from pre-existing glaciolacustrine deposits, and the subaqueous sediments consist of ice-proximal outwash and sediment flow deposits, and distal turbidites. Sediment was delivered from the glacier to the lake by two main processes: (1) subglacial till deformation, which fed debris flows at the grounding line; and (2) meltwater transport, which fed sediment-gravity flows on prograding outwash fans. Beyond the ice-marginal environment, deposition was from turbidity currents, ice-rafting and settling of suspended sediments. The exposures support the conclusion that the presence of a subglacial deforming layer can exert an important influence on sedimentation at the grounding lines of calving glaciers. 相似文献
78.
Measurement of variations in the radial velocities of stars due to the reflex orbital motion of the star around the planetary-system barycenter constitutes a powerful method of searching for substellar or planetary mass companions. After several years of patient data acquisition, radial-velocity searches for planetary systems around other stars are now beginning to bear fruit. In late 1995 and early 1996, three candidate systems were announced with Jovian-mass planets around solar-type stars. The current paradigm for low-mass star formation suggests that planetary systems should be able to form in the circumstellar disks surrounding young stellar objects. These newly discovered systems, and other discoveries which will soon follow them, will test critically our understanding of the processes of star- and planet-formation. We review the techniques used in these radial-velocity searches and their results to date. We then discuss planned improvements in the surveys, and the prospects for the next 20 years. 相似文献
79.
H. A. Harutyunian 《Astrophysics》1996,39(4):370-374
The Voigt function and its derivatives are represented by means of series in Hermite polynomials. The equations obtained can be used both for numerical calculations of these functions and for analytical research.Translated from Astrofizika, Vol. 39, No. 4, pp. 619–625, October–December, 1996. 相似文献
80.