全文获取类型
收费全文 | 928篇 |
免费 | 25篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 23篇 |
大气科学 | 89篇 |
地球物理 | 179篇 |
地质学 | 269篇 |
海洋学 | 80篇 |
天文学 | 226篇 |
自然地理 | 90篇 |
出版年
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 14篇 |
2016年 | 15篇 |
2015年 | 23篇 |
2014年 | 21篇 |
2013年 | 45篇 |
2012年 | 28篇 |
2011年 | 32篇 |
2010年 | 24篇 |
2009年 | 46篇 |
2008年 | 40篇 |
2007年 | 38篇 |
2006年 | 48篇 |
2005年 | 26篇 |
2004年 | 34篇 |
2003年 | 31篇 |
2002年 | 24篇 |
2001年 | 20篇 |
2000年 | 22篇 |
1999年 | 16篇 |
1998年 | 17篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 16篇 |
1993年 | 16篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 18篇 |
1984年 | 15篇 |
1983年 | 22篇 |
1982年 | 18篇 |
1981年 | 22篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 16篇 |
1977年 | 13篇 |
1975年 | 14篇 |
1974年 | 12篇 |
1973年 | 8篇 |
1972年 | 9篇 |
1971年 | 10篇 |
1969年 | 6篇 |
排序方式: 共有956条查询结果,搜索用时 843 毫秒
1.
2.
R. A.Street KeithHorne T. A.Lister A.Penny Y.Tsapras A.Quirrenbach N.Safizadeh J.Cooke D.Mitchell A.Collier Cameron 《Monthly notices of the Royal Astronomical Society》2002,330(3):737-754
We report on the discovery of 25 variable stars plus 13 suspected variables found in the field of the open cluster NGC 6819. The stars were identified from time-series photometric data obtained on the Isaac Newton Telescope, La Palma, during two observing runs covering the 19 nights between 1999 June 22–30 and 1999 July 22–31 . The variables found include 12 eclipsing binaries with an additional three suspected, nine BY Draconis systems, plus four variables of other types, including one star believed to be a Cepheid. Three of the 15 eclipsing binaries are believed to be cluster members. Details of a further 10 suspected variable stars are also included. 相似文献
3.
We present solutions for the effective stress induced by gas flow through a porous solid into a borehole resulting from sudden pressure reduction. Tensile effective stress that exceeds the strength of the solid will lead to borehole failure. This has applications to the intentional creation of cavities, relevant to the efficient recovery of coalbed methane, and the avoidance of borehole stability problems in conventional gas production. 相似文献
4.
5.
6.
7.
Barry Y. Welsh 《Astrophysics and Space Science》1983,90(2):437-444
High resolution optical observations (FWHM ~ 10–13 km s?1) of the I-S gas towards the early-type stars HD 164 794, HD 164816, and HD 165052 in the M8 Nebula are presented. A high velocity componentV LSR=?26 km s?1 has been detected in all 3 stars' spectra. A line profile fitting analysis has been carried out on the observed Caii and Nai absorption lines to determine cloud component column densities and to subsequently determine the physical and chemical conditions of the associated I-S gas. 相似文献
8.
Barry Wolf 《Pure and Applied Geophysics》1967,67(1):76-82
Summary A study is made of the scattered field which results when a Love wave is incident on a layer having an irregular surface. To obtain this solution a perturbation method is used. It is shown that the scattered field may be described by a superposition of Love waves and non-propagating disturbances. As an illustrative example, the result is applied to obtain the scattering by a triangular trough. 相似文献
9.
10.