全文获取类型
收费全文 | 26524篇 |
免费 | 3112篇 |
国内免费 | 2721篇 |
专业分类
化学 | 3347篇 |
晶体学 | 36篇 |
力学 | 2534篇 |
综合类 | 685篇 |
数学 | 18169篇 |
物理学 | 7586篇 |
出版年
2024年 | 42篇 |
2023年 | 232篇 |
2022年 | 451篇 |
2021年 | 502篇 |
2020年 | 588篇 |
2019年 | 577篇 |
2018年 | 637篇 |
2017年 | 808篇 |
2016年 | 927篇 |
2015年 | 693篇 |
2014年 | 1332篇 |
2013年 | 1791篇 |
2012年 | 1368篇 |
2011年 | 1654篇 |
2010年 | 1462篇 |
2009年 | 1790篇 |
2008年 | 1783篇 |
2007年 | 1857篇 |
2006年 | 1694篇 |
2005年 | 1614篇 |
2004年 | 1351篇 |
2003年 | 1202篇 |
2002年 | 1049篇 |
2001年 | 907篇 |
2000年 | 882篇 |
1999年 | 739篇 |
1998年 | 660篇 |
1997年 | 629篇 |
1996年 | 463篇 |
1995年 | 406篇 |
1994年 | 320篇 |
1993年 | 258篇 |
1992年 | 212篇 |
1991年 | 163篇 |
1990年 | 188篇 |
1989年 | 119篇 |
1988年 | 115篇 |
1987年 | 96篇 |
1986年 | 88篇 |
1985年 | 101篇 |
1984年 | 88篇 |
1983年 | 56篇 |
1982年 | 80篇 |
1981年 | 70篇 |
1980年 | 46篇 |
1979年 | 48篇 |
1978年 | 43篇 |
1977年 | 38篇 |
1976年 | 33篇 |
1973年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
21.
CONG Fuzhong & LI YongSchool of Mathematics Information Science Shandong Institute of Business Technology Yantai China Office of Mathematics Changchun Flight Academy of the Air Force Changchun China Department of Mathematics Jilin University Changchun China 《中国科学A辑(英文版)》2004,47(5):675-686
An effective stability result for generalized Hamiltonian systems is obtained by applying the simultaneous approximation technique due to Lochak. Among these systems, dimensions of action variables and angle variables might be distinct. 相似文献
22.
We study initial boundary value problems for linear scalar evolutionpartial differential equations, with spatial derivatives ofarbitrary order, posed on the domain {t > 0, 0 < x <L}. We show that the solution can be expressed as an integralin the complex k-plane. This integral is defined in terms ofan x-transform of the initial condition and a t-transform ofthe boundary conditions. The derivation of this integral representationrelies on the analysis of the global relation, which is an algebraicrelation defined in the complex k-plane coupling all boundaryvalues of the solution. For particular cases, such as the case of periodic boundaryconditions, or the case of boundary value problems for even-orderPDEs, it is possible to obtain directly from the global relationan alternative representation for the solution, in the formof an infinite series. We stress, however, that there existinitial boundary value problems for which the only representationis an integral which cannot be written as an infinite series.An example of such a problem is provided by the linearized versionof the KdV equation. Similarly, in general the solution of odd-orderlinear initial boundary value problems on a finite intervalcannot be expressed in terms of an infinite series. 相似文献
23.
本文考虑广义C-R组^[1](H)的解f=u iv jw∈C^2的一些性质,提出与之相关的两个边值问题,用积分方程方法和调和函数性质证明了边值问题解的存在唯一性,并写出解的积分表达式. 相似文献
24.
25.
We present a practical polynomial-time algorithm for computing the
zeta function of a Kummer curve over a finite field of small
characteristic. Such algorithms have recently been obtained using a
method of Kedlaya based upon Monsky–Washnitzer cohomology, and are of
interest in cryptography. We take a different approach.
The problem is reduced to that of computing the L-function
of a multiplicative character sum. This latter task is achieved via a
cohomological formula based upon the work of Dwork and Reich. We show,
however, that our method and that of Kedlaya are very closely related.Dedicated to the memory of Gian-Carlo Rota 相似文献
26.
Lionel Thibault Nadia Zlateva 《Proceedings of the American Mathematical Society》2005,133(10):2939-2948
Using a quantitative version of the subdifferential characterization of directionally Lipschitz functions, we study the integrability of subdifferentials of such functions over arbitrary Banach space.
27.
The paper presents a new formulation of the integral boundary element method (BEM) using subdomain technique. A continuous approximation of the function and the function derivative in the direction normal to the boundary element (further ‘normal flux’) is introduced for solving the general form of a parabolic diffusion‐convective equation. Double nodes for normal flux approximation are used. The gradient continuity is required at the interior subdomain corners where compatibility and equilibrium interface conditions are prescribed. The obtained system matrix with more equations than unknowns is solved using the fast iterative linear least squares based solver. The robustness and stability of the developed formulation is shown on the cases of a backward‐facing step flow and a square‐driven cavity flow up to the Reynolds number value 50 000. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
28.
29.
For vector quasivariational inequalities involving multifunctions in topological vector spaces, an existence result is obtained without a monotonicity assumption and with a convergence assumption weaker than semicontinuity. A new type of quasivariational inequality is proposed. Applications to quasicomplementarity problems and traffic network equilibria are considered. In particular, definitions of weak and strong Wardrop equilibria are introduced for the case of multivalued cost functions. 相似文献
30.
By extracting combinatorial structures in well-solved nonlinear combinatorial optimization problems, Murota (1996,1998) introduced the concepts of M-convexity and L-convexity to functions defined over the integer lattice. Recently, Murota–Shioura (2000, 2001) extended these concepts to polyhedral convex functions and quadratic functions in continuous variables. In this paper, we consider a further extension to more general convex functions defined over the real space, and provide a proof for the conjugacy relationship between general M-convex and L-convex functions.Mathematics Subject Classification (1991): 90C10, 90C25, 90C27, 90C35This work is supported by Grant-in-Aid of the Ministry of Education, Culture, Sports, Science and Technology of Japan 相似文献