全文获取类型
收费全文 | 86479篇 |
免费 | 7099篇 |
国内免费 | 5596篇 |
专业分类
化学 | 27980篇 |
晶体学 | 1848篇 |
力学 | 3776篇 |
综合类 | 414篇 |
数学 | 20291篇 |
物理学 | 44865篇 |
出版年
2023年 | 226篇 |
2022年 | 397篇 |
2021年 | 450篇 |
2020年 | 804篇 |
2019年 | 1106篇 |
2018年 | 1065篇 |
2017年 | 832篇 |
2016年 | 629篇 |
2015年 | 620篇 |
2014年 | 1362篇 |
2013年 | 2615篇 |
2012年 | 1436篇 |
2011年 | 2013篇 |
2010年 | 2571篇 |
2009年 | 7136篇 |
2008年 | 8229篇 |
2007年 | 6718篇 |
2006年 | 6173篇 |
2005年 | 4254篇 |
2004年 | 4067篇 |
2003年 | 4229篇 |
2002年 | 6022篇 |
2001年 | 3924篇 |
2000年 | 3701篇 |
1999年 | 3464篇 |
1998年 | 2892篇 |
1997年 | 2006篇 |
1996年 | 1805篇 |
1995年 | 2280篇 |
1994年 | 2188篇 |
1993年 | 1635篇 |
1992年 | 1128篇 |
1991年 | 846篇 |
1990年 | 700篇 |
1989年 | 621篇 |
1988年 | 582篇 |
1987年 | 417篇 |
1985年 | 952篇 |
1984年 | 626篇 |
1983年 | 491篇 |
1982年 | 649篇 |
1981年 | 797篇 |
1980年 | 724篇 |
1979年 | 567篇 |
1978年 | 587篇 |
1977年 | 540篇 |
1976年 | 543篇 |
1975年 | 321篇 |
1974年 | 357篇 |
1973年 | 465篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
We consider concentrated vorticities for the Euler equation on a smooth domain in the form of supported on well-separated vortical domains , , of small diameters . A conformal mapping framework is set up to study this free boundary problem with being part of unknowns. For any given vorticities and small , through a perturbation approach, we obtain such piecewise constant steady vortex patches as well as piecewise smooth Lipschitz steady vorticities, both concentrated near non-degenerate critical configurations of the Kirchhoff–Routh Hamiltonian function. When vortex patch evolution is considered as the boundary dynamics of , through an invariant subspace decomposition, it is also proved that the spectral/linear stability of such steady vortex patches is largely determined by that of the 2N-dimensional linearized point vortex dynamics, while the motion is highly oscillatory in the 2N-codim directions corresponding to the vortical domain shapes. 相似文献
2.
3.
4.
5.
6.
7.
Inner derivations and norm equality 总被引:3,自引:0,他引:3
Mohamed Barraa Mohamed Boumazgour 《Proceedings of the American Mathematical Society》2002,130(2):471-476
We characterize when the norm of the sum of two bounded operators on a Hilbert space is equal to the sum of their norms.
8.
9.
M. Georgelin A. Pocheau 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(2):169-174
The polycrystalline perovskitelike manganese oxides La1-xAxMnO (A = Na, and K, ) have been fabricated by sol-gel technique. For all the compositions explored in this work, the average manganese oxidation
state is practically constant, at for A = Na, and for A = K, respectively. A close relationship is confirmed to hold between the Curie temperature (Tc) and the bond distance of Mn-O. Results of magnetic measurements show that these materials can be utilized as suitable candidates
for magnetic refrigerants with wide applied temperature span, for their significant entropy change and the easily tuned Curie
temperature.
Received: 12 September 1997 / Revised: 18 December 1997 / Accepted: 21 January 1998 相似文献
10.
C. Waldtmann H.-U. Everts B. Bernu C. Lhuillier P. Sindzingre P. Lecheminant L. Pierre 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(4):501-507
We study the exact low energy spectra of the spin 1/2 Heisenberg antiferromagnet on small samples of the kagomé lattice of up to N=36 sites. In agreement with the conclusions of previous authors, we find that these low energy spectra contradict the hypothesis
of Néel type long range order. Certainly, the ground state of this system is a spin liquid, but its properties are rather
unusual. The magnetic () excitations are separated from the ground state by a gap. However, this gap is filled with nonmagnetic () excitations. In the thermodynamic limit the spectrum of these nonmagnetic excitations will presumably develop into a gapless
continuum adjacent to the ground state. Surprisingly, the eigenstates of samples with an odd number of sites, i.e. samples with an unsaturated spin, exhibit symmetries which could support long range chiral order. We do not know if these
states will be true thermodynamic states or only metastable ones. In any case, the low energy properties of the spin 1/2 Heisenberg
antiferromagnet on the kagomé lattice clearly distinguish this system from either a short range RVB spin liquid or a standard chiral spin liquid. Presumably
they are facets of a generically new state of frustrated two-dimensional quantum antiferromagnets.
Received: 27 November 1997 / Accepted: 29 January 1998 相似文献