全文获取类型
收费全文 | 9206篇 |
免费 | 335篇 |
国内免费 | 816篇 |
专业分类
化学 | 796篇 |
晶体学 | 2篇 |
力学 | 273篇 |
综合类 | 88篇 |
数学 | 7739篇 |
物理学 | 1459篇 |
出版年
2024年 | 8篇 |
2023年 | 98篇 |
2022年 | 123篇 |
2021年 | 153篇 |
2020年 | 135篇 |
2019年 | 221篇 |
2018年 | 209篇 |
2017年 | 222篇 |
2016年 | 185篇 |
2015年 | 172篇 |
2014年 | 293篇 |
2013年 | 1212篇 |
2012年 | 355篇 |
2011年 | 447篇 |
2010年 | 424篇 |
2009年 | 579篇 |
2008年 | 675篇 |
2007年 | 648篇 |
2006年 | 495篇 |
2005年 | 390篇 |
2004年 | 412篇 |
2003年 | 367篇 |
2002年 | 361篇 |
2001年 | 245篇 |
2000年 | 241篇 |
1999年 | 201篇 |
1998年 | 219篇 |
1997年 | 226篇 |
1996年 | 176篇 |
1995年 | 119篇 |
1994年 | 116篇 |
1993年 | 89篇 |
1992年 | 73篇 |
1991年 | 49篇 |
1990年 | 42篇 |
1989年 | 38篇 |
1988年 | 30篇 |
1987年 | 20篇 |
1986年 | 34篇 |
1985年 | 38篇 |
1984年 | 36篇 |
1983年 | 14篇 |
1982年 | 45篇 |
1981年 | 20篇 |
1980年 | 22篇 |
1979年 | 28篇 |
1978年 | 17篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1936年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
3.
4.
Clemens G. Raab Georg Regensburger Jamal Hossein Poor 《Journal of Pure and Applied Algebra》2021,225(5):106564
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials. 相似文献
5.
6.
In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result. 相似文献
7.
8.
Summary This paper is concerned with the problem of developing numerical integration algorithms for differential equations that, when
viewed as equations in some Euclidean space, naturally evolve on some embedded submanifold. It is desired to construct algorithms
whose iterates also evolve on the same manifold. These algorithms can therefore be viewed as integrating ordinary differential
equations on manifolds. The basic method “decouples” the computation of flows on the submanifold from the numerical integration
process. It is shown that two classes of single-step and multistep algorithms can be posed and analyzed theoretically, using
the concept of “freezing” the coefficients of differential operators obtained from the defining vector field. Explicit third-order
algorithms are derived, with additional equations augmenting those of their classical counterparts, obtained from “obstructions”
defined by nonvanishing Lie brackets. 相似文献
9.
M. M. Kostreva 《Journal of Optimization Theory and Applications》1989,62(1):63-76
Murty's algorithm for the linear complementarity problem is generalized to solve the optimality conditions for linear and convex quadratic programming problems with both equality and inequality constraints. An implementation is suggested which provides both efficiency and tight error control. Numerical experiments as well as field tests in various applications show favorable results.The author thanks K. G. Murty for his encouragement and helpful comments. 相似文献
10.
Algebra matrix and similarity classification of operators 总被引:1,自引:0,他引:1
ZHANG Zilong & LI Yucheng Department of Mathematics Hebei Normal University Shijiazhuang China 《中国科学A辑(英文版)》2006,49(3):398-409
In this paper, by the Gelfand representation theory and the Silov idempotents theorem, we first obtain a central decomposition theorem related to a unital semi-simple n-homogeneous Banach algebra, and then give a similarity classification of two strongly irreducible Cowen-Douglas operators using this theorem. 相似文献