全文获取类型
收费全文 | 167篇 |
免费 | 3篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 24篇 |
大气科学 | 24篇 |
地球物理 | 24篇 |
地质学 | 57篇 |
海洋学 | 8篇 |
天文学 | 33篇 |
自然地理 | 3篇 |
出版年
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 11篇 |
2015年 | 2篇 |
2014年 | 9篇 |
2013年 | 11篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 4篇 |
2009年 | 8篇 |
2008年 | 4篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1966年 | 1篇 |
1963年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有173条查询结果,搜索用时 15 毫秒
171.
Koen Kemel Axel Brandenburg Nathan Kleeorin Dhrubaditya Mitra Igor Rogachevskii 《Solar physics》2013,287(1-2):293-313
The negative effective magnetic-pressure instability operates on scales encompassing many turbulent eddies, which correspond to convection cells in the Sun. This instability is discussed here in connection with the formation of active regions near the surface layers of the Sun. This instability is related to the negative contribution of turbulence to the mean magnetic pressure that causes the formation of large-scale magnetic structures. For an isothermal layer, direct numerical simulations and mean-field simulations of this phenomenon are shown to agree in many details, for example the onset of the instability occurs at the same depth. This depth increases with increasing field strength, such that the growth rate of this instability is independent of the field strength, provided the magnetic structures are fully contained within the domain. A linear stability analysis is shown to support this finding. The instability also leads to a redistribution of turbulent intensity and gas pressure that could provide direct observational signatures. 相似文献
172.
Mechanics of Sediment Transport. Edited by B. Mutlu Sumer and A. Muller. Proceedings of Euromech 156, Istanbul, 12–14 July 1982. Rotterdam: A. A. Balkema, 1983. 285 pp. $45.00. Gear Drive Systems: Design and Application, Peter Lynwander, New York and Basel: Marcel Dekker, Inc., 1983. Price: $49.50. 相似文献
173.
Abhas Mitra 《Astrophysics and Space Science》2011,333(1):351-356
We consider a spherically symmetric general relativistic perfect fluid in its comoving frame. It is found that, by integrating the local energy momentum conservation equation, a general form of g 00 can be obtained. During this study, we get a cue that an adiabatically evolving uniform density isolated sphere having ρ(r,t)=ρ 0(t), should comprise “dust” having p 0(t)=0; as recently suggested by Durgapal and Fuloria (J. Mod. Phys. 1:143, 2010) In fact, we offer here an independent proof to this effect. But much more importantly, we find that for the homogeneous and isotropic Friedmann-Robertson-Walker (FRW) metric having p(r,t)=p 0(t) and ρ(r,t)=ρ 0(t), \(g_{00} = e^{-2p_{0}/(p_{0} +\rho_{0})}\). But in general relativity (GR), one can choose an arbitrary t→t ?=f(t) without any loss of generality, and thus set g 00(t ?)=1. And since pressure is a scalar, this implies that p 0(t ?)=p 0(t)=0 in the Big-Bang model based on the FRW metric. This result gets confirmed by the fact the homogeneous dust metric having p(r,t)=p 0(t)=0 and ρ(r,t)=ρ 0(t) and the FRW metric are exactly identical. In other words, both the cases correspond to the same Einstein tensor \(G^{a}_{b}\) because they intrinsically have the same energy momentum tensor \(T^{a}_{b}=\operatorname {diag}[\rho_{0}(t), 0,0, 0]\). 相似文献