全文获取类型
收费全文 | 1538篇 |
免费 | 730篇 |
国内免费 | 387篇 |
专业分类
测绘学 | 66篇 |
大气科学 | 28篇 |
地球物理 | 114篇 |
地质学 | 1587篇 |
海洋学 | 53篇 |
天文学 | 696篇 |
综合类 | 81篇 |
自然地理 | 30篇 |
出版年
2024年 | 7篇 |
2023年 | 9篇 |
2022年 | 42篇 |
2021年 | 52篇 |
2020年 | 45篇 |
2019年 | 63篇 |
2018年 | 53篇 |
2017年 | 61篇 |
2016年 | 80篇 |
2015年 | 77篇 |
2014年 | 95篇 |
2013年 | 88篇 |
2012年 | 122篇 |
2011年 | 128篇 |
2010年 | 102篇 |
2009年 | 198篇 |
2008年 | 128篇 |
2007年 | 146篇 |
2006年 | 176篇 |
2005年 | 141篇 |
2004年 | 129篇 |
2003年 | 114篇 |
2002年 | 92篇 |
2001年 | 82篇 |
2000年 | 87篇 |
1999年 | 97篇 |
1998年 | 64篇 |
1997年 | 43篇 |
1996年 | 29篇 |
1995年 | 24篇 |
1994年 | 26篇 |
1993年 | 17篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有2655条查询结果,搜索用时 31 毫秒
271.
272.
On the X-ray spectra of luminous, inhomogeneous accretion flows 总被引:1,自引:0,他引:1
A. Merloni J. Malzac A. C. Fabian R. R. Ross 《Monthly notices of the Royal Astronomical Society》2006,370(4):1699-1712
273.
274.
275.
Andrzej A. Zdziarski 《Monthly notices of the Royal Astronomical Society》2005,360(3):816-824
We develop a formalism to calculate energy-dependent fractional variability (rms) in accretion flows. We consider rms spectra resulting from radial dependences of the level of local variability (as expected from the propagation of disturbances in accretion flows) assuming the constant shape of the spectrum emitted at a given radius. We consider the cases when the variability of the flow is either coherent or incoherent between different radial zones. As an example of local emission, we consider blackbody, Wien and thermal Comptonization spectra. In addition to numerical results, we present a number of analytical formulae for the resulting rms. We also find an analytical formula for the disc Wien spectrum, which we find to be a very good approximation to the disc blackbody. We compare our results to the rms spectrum observed in an ultrasoft state of GRS 1915+105. 相似文献
276.
277.
278.
279.
S. S. Komissarov 《Monthly notices of the Royal Astronomical Society》2005,359(3):801-808
In this paper we report the results of axisymmetric relativistic magnetohydrodynamic (MHD) simulations for the problem of a Kerr black hole immersed in a rarefied plasma with 'uniform' magnetic field. The long-term solution shows properties that are significantly different from those of the initial transient phase studied recently by Koide. The topology of magnetic field lines within the ergosphere is similar to that of the split-monopole model with a strong current sheet in the equatorial plane. Closer inspection reveals a system of isolated magnetic islands inside the sheet and ongoing magnetic reconnection. No regions of negative hydrodynamic 'energy at infinity' are seen inside the ergosphere and the so-called MHD Penrose process does not operate. However, the rotational energy of the black hole continues to be extracted via the purely electromagnetic Blandford–Znajek mechanism. In spite of this, no strong relativistic outflows from the black hole are seen to be developing. Combined with results of other recent simulations, our results signal a potential problem for the standard MHD model of relativistic astrophysical jets should they be found at distances as small as a few tens of gravitational radii from the central black hole. 相似文献
280.