全文获取类型
| 收费全文 | 10819篇 |
| 免费 | 989篇 |
| 国内免费 | 1861篇 |
专业分类
| 测绘学 | 299篇 |
| 大气科学 | 490篇 |
| 地球物理 | 931篇 |
| 地质学 | 4757篇 |
| 海洋学 | 992篇 |
| 天文学 | 5086篇 |
| 综合类 | 359篇 |
| 自然地理 | 755篇 |
出版年
| 2024年 | 32篇 |
| 2023年 | 85篇 |
| 2022年 | 246篇 |
| 2021年 | 265篇 |
| 2020年 | 316篇 |
| 2019年 | 369篇 |
| 2018年 | 289篇 |
| 2017年 | 293篇 |
| 2016年 | 301篇 |
| 2015年 | 349篇 |
| 2014年 | 583篇 |
| 2013年 | 647篇 |
| 2012年 | 626篇 |
| 2011年 | 739篇 |
| 2010年 | 765篇 |
| 2009年 | 1055篇 |
| 2008年 | 1001篇 |
| 2007年 | 888篇 |
| 2006年 | 834篇 |
| 2005年 | 728篇 |
| 2004年 | 587篇 |
| 2003年 | 505篇 |
| 2002年 | 393篇 |
| 2001年 | 341篇 |
| 2000年 | 314篇 |
| 1999年 | 288篇 |
| 1998年 | 192篇 |
| 1997年 | 71篇 |
| 1996年 | 76篇 |
| 1995年 | 55篇 |
| 1994年 | 60篇 |
| 1993年 | 74篇 |
| 1992年 | 29篇 |
| 1991年 | 31篇 |
| 1990年 | 39篇 |
| 1989年 | 25篇 |
| 1988年 | 26篇 |
| 1987年 | 11篇 |
| 1986年 | 17篇 |
| 1985年 | 23篇 |
| 1984年 | 21篇 |
| 1983年 | 18篇 |
| 1982年 | 15篇 |
| 1981年 | 6篇 |
| 1980年 | 12篇 |
| 1979年 | 2篇 |
| 1978年 | 6篇 |
| 1977年 | 15篇 |
| 1877年 | 1篇 |
| 1875年 | 1篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
81.
82.
83.
R. F. Griffin 《Journal of Astrophysics and Astronomy》1990,11(4):533-540
Photoelectric radial-velocity measurements show that HD 118670 is a double-lined spectroscopic binary in an orbit which is
not quite circular and whose period is about 48 days. Spectral types of K0 V and K7 V would satisfy the photometry and the
mass ratio; the mass function would then suggest the possibility of eclipses. However, actual spectral classification indicates
a luminosity somewhat above the main sequence 相似文献
84.
85.
86.
87.
88.
89.
M. R. Bate S. H. Lubow G. I. Ogilvie K. A. Miller 《Monthly notices of the Royal Astronomical Society》2003,341(1):213-229
We analyse the non-linear, three-dimensional response of a gaseous, viscous protoplanetary disc to the presence of a planet of mass ranging from 1 Earth mass (1 M⊕ ) to 1 Jupiter mass (1 MJ ) by using the zeus hydrodynamics code. We determine the gas flow pattern, and the accretion and migration rates of the planet. The planet is assumed to be in a fixed circular orbit about the central star. It is also assumed to be able to accrete gas without expansion on the scale of its Roche radius. Only planets with masses M p ≳ 0.1 MJ produce significant perturbations in the surface density of the disc. The flow within the Roche lobe of the planet is fully three-dimensional. Gas streams generally enter the Roche lobe close to the disc mid-plane, but produce much weaker shocks than the streams in two-dimensional models. The streams supply material to a circumplanetary disc that rotates in the same sense as the orbit of the planet. Much of the mass supply to the circumplanetary disc comes from non-coplanar flow. The accretion rate peaks with a planet mass of approximately 0.1 MJ and is highly efficient, occurring at the local viscous rate. The migration time-scales for planets of mass less than 0.1 MJ , based on torques from disc material outside the Roche lobes of the planets, are in excellent agreement with the linear theory of type I (non-gap) migration for three-dimensional discs. The transition from type I to type II (gap) migration is smooth, with changes in migration times of about a factor of 2. Starting with a core which can undergo runaway growth, a planet can gain up to a few MJ with little migration. Planets with final masses of the order of 10 MJ would undergo large migration, which makes formation and survival difficult. 相似文献
90.