全文获取类型
收费全文 | 346篇 |
免费 | 21篇 |
国内免费 | 62篇 |
专业分类
力学 | 1篇 |
综合类 | 5篇 |
数学 | 412篇 |
物理学 | 11篇 |
出版年
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 14篇 |
2019年 | 13篇 |
2018年 | 16篇 |
2017年 | 17篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 51篇 |
2012年 | 12篇 |
2011年 | 12篇 |
2010年 | 7篇 |
2009年 | 17篇 |
2008年 | 20篇 |
2007年 | 30篇 |
2006年 | 20篇 |
2005年 | 22篇 |
2004年 | 17篇 |
2003年 | 23篇 |
2002年 | 15篇 |
2001年 | 14篇 |
2000年 | 22篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有429条查询结果,搜索用时 703 毫秒
81.
《Fortschritte der Physik》2017,65(5)
The complete classification of the nilpotent orbits of SO(2,2)2 in the representation (2,2,2,2) , achieved in 14 , is applied to the study of multi‐center, asymptotically flat, extremal black hole solutions to the STU model. These real orbits provide an intrinsic characterization of regular single‐center solutions, which is invariant with respect to the action of the global symmetry group SO(4,4), underlying the stationary solutions of the model, and provide stringent regularity constraints on multi‐centered solutions. The known almost‐BPS and composite non‐BPS solutions are revisited in this setting. We systematically provide, for the relevant SO(2,2)2‐nilpotent orbits of the global Noether charge matrix, regular representatives thereof. This analysis unveils a composition law of the orbits according to which those containing regular multi‐centered solutions can be obtained as combinations of specific single‐center orbits defining the constituent black holes. Some of the SO(2,2)2‐orbits of the total Noether charge matrix are characterized as “intrinsically singular” in that they cannot contain any regular solution. 相似文献
82.
殷霞 《数学的实践与认识》2012,42(5):164-169
研究了有限群的结构问题,利用子群c-半置换和完全c-半置换的定义和性质,通过对有限群sylow子群的2-极大子群的研究,获得了有限群幂零、p-幂零的充分条件和另外两个决定群结构的充要条件. 相似文献
83.
研究了广义半交换环的幂零结构,定义了一类新的环类,即幂零$\alpha$-半交换环.说明了$\alpha$-半交换环与半交换环, $\alpha$-半交换环和$\alpha$-刚性环等环密切相关,通过构造反例说明了幂零$\alpha$-半交换环未必是$\alpha$-半交换环.研究了幂零$\alpha$-半交换环的各种性质,推广和统一了与环的半交换性质有关的若干结论. 相似文献
84.
R是素GPI-环,若多项式f(x1,…,xd)在R上是幂零的,则或f(x1…,xd)是R的恒 等式,或R是有限域上的有限矩阵环 相似文献
85.
We give a necessary and sufficient condition for the nilpotent operators to be similiar to irreducible operators, and give
an answer to D. A. Herrero Conjectures for nilpotent operators. 相似文献
86.
This paper derives some optimization results for bilinear systems using a higher-order method by characterizing them over matrix Lie groups. In the derivation of the results, first a bilinear system is transformed to a left-invariant system on matrix Lie groups. Then, the product of exponential representation is used to express this system in canonical form. Next, the conditions for optimality are obtained by the principles of variational calculus. It is demonstrated that closed-form analytical solutions exist for classes of bilinear systems whose Lie algebra are nilpotent. 相似文献
87.
Hamid-Reza Fanaï 《Geometriae Dedicata》2000,80(1-3):187-200
In this text, we consider the solvmanifolds obtained by an abelian extension of two-step nilmanifolds and obtain Einstein metrics (with negative scalar curvature) near to the symmetric spaces. 相似文献
88.
某些幂零子群与可解性 总被引:2,自引:1,他引:1
本文利用某些幂子群的半正规性,讨论有限群的可解性,所得结果统一推广了王品超、赵耀庆的若干结果。 相似文献
89.
A group G is generically trivial if and only if, for all prime numbers p the localization of G with respect to p is trivial. Taking off from a theorem of Casacuberta and Castellet , we prove that a virtually nilpotent group E is generically trivial if and only if E is perfect. Inspired by this result, we introduce the concept of almost generically trivial groups. Those are groups G such that, for only finitely many primes p the localization of G with respect to p is not trivial. We prove that a virtually nilpotent group E with finitely generated abelianization is almost generically trivial if and only if the abelianization of E is finite. 相似文献
90.