全文获取类型
收费全文 | 4296篇 |
免费 | 185篇 |
国内免费 | 198篇 |
专业分类
化学 | 131篇 |
力学 | 257篇 |
综合类 | 9篇 |
数学 | 3731篇 |
物理学 | 551篇 |
出版年
2024年 | 5篇 |
2023年 | 45篇 |
2022年 | 56篇 |
2021年 | 49篇 |
2020年 | 85篇 |
2019年 | 112篇 |
2018年 | 98篇 |
2017年 | 86篇 |
2016年 | 76篇 |
2015年 | 88篇 |
2014年 | 204篇 |
2013年 | 442篇 |
2012年 | 236篇 |
2011年 | 274篇 |
2010年 | 232篇 |
2009年 | 375篇 |
2008年 | 344篇 |
2007年 | 291篇 |
2006年 | 221篇 |
2005年 | 149篇 |
2004年 | 154篇 |
2003年 | 165篇 |
2002年 | 120篇 |
2001年 | 84篇 |
2000年 | 94篇 |
1999年 | 76篇 |
1998年 | 78篇 |
1997年 | 82篇 |
1996年 | 65篇 |
1995年 | 45篇 |
1994年 | 47篇 |
1993年 | 31篇 |
1992年 | 31篇 |
1991年 | 12篇 |
1990年 | 17篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 17篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有4679条查询结果,搜索用时 359 毫秒
1.
《Discrete Mathematics》2022,345(10):112984
Let G be a generalized dicyclic group with identity 1. An inverse closed subset S of is called minimal if and there exists some such that . In this paper, we characterize distance-regular Cayley graphs of G under the condition that S is minimal. 相似文献
2.
Let χ be an order c multiplicative character of a finite field and a binomial with . We study the twisted classical and T-adic Newton polygons of f. When , we give a lower bound of Newton polygons and show that they coincide if p does not divide a certain integral constant depending on .We conjecture that this condition holds if p is large enough with respect to by combining all known results and the conjecture given by Zhang-Niu. As an example, we show that it holds for . 相似文献
3.
In this paper, we study generalized Douglas–Weyl(α, β)-metrics. Suppose that a regular(α, β)-metric F is not of Randers type. We prove that F is a generalized Douglas–Weyl metric with vanishing S-curvature if and only if it is a Berwald metric. Moreover, by ignoring the regularity, if F is not a Berwald metric, then we find a family of almost regular Finsler metrics which is not Douglas nor Weyl. As its application, we show that generalized Douglas–Weyl square metric or Matsumoto metric with isotropic mean Berwald curvature are Berwald metrics. 相似文献
4.
非线性互补问题的一种全局收敛的显式光滑Newton方法 总被引:2,自引:0,他引:2
本针对Po函数非线性互补问题,给出了一种显式光滑Newton方法,该方法将光滑参数μ进行显式迭代而不依赖于Newton方向的搜索过程,并在适当的假设条件下,证明了算法的全局收敛性。 相似文献
5.
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.
6.
矩阵方程A^TXB=C的正定和半正定解 总被引:5,自引:1,他引:4
何楚宁 《高校应用数学学报(A辑)》1997,(4):475-480
给出了矩阵方程A^TXB=C在正定和半正定矩阵类中有解的充要条件及解的一般表达式。 相似文献
7.
The theory of tree-growing (RECPAM approach) is developed for outcome variables which are distributed as the canonical exponential family. The general RECPAM approach (consisting of three steps: recursive partition, pruning and amalgamation), is reviewed. This is seen as constructing a partition with maximal information content about a parameter to be predicted, followed by simplification by the elimination of ‘negligible’ information. The measure of information is defined for an exponential family outcome as a deviance difference, and appropriate modifications of pruning and amalgamation rules are discussed. It is further shown how the proposed approach makes it possible to develop tree-growing for situations usually treated by generalized linear models (GLIM). In particular, Poisson and logistic regression can be tree-structured. Moreover, censored survival data can be treated, as in GLIM, by observing a formal equivalence of the likelihood under random censoring and an appropriate Poisson model. Three examples are given of application to Poisson, binary and censored survival data. 相似文献
8.
G. Dattoli 《Journal of Mathematical Analysis and Applications》2002,269(2):716-725
Bilateral generating functions are those involving products of different types of polynomials. We show that operational methods offer a powerful tool to derive these families of generating functions. We study cases relevant to products of Hermite polynomials with Laguerre, Legendre and other polynomials. We also propose further extensions of the method which we develop here. 相似文献
9.
本文在一类 Lp位势V(x)下建立了广义Schrodinger算子H=(-Δ)m+V(x)在C∞0(Rn)上的本质自伴性,给出了H的本质谱的分布. 相似文献
10.
This paper is concerned with the implementation and testing of an algorithm for solving constrained least-squares problems. The algorithm is an adaptation to the least-squares case of sequential quadratic programming (SQP) trust-region methods for solving general constrained optimization problems. At each iteration, our local quadratic subproblem includes the use of the Gauss–Newton approximation but also encompasses a structured secant approximation along with tests of when to use this approximation. This method has been tested on a selection of standard problems. The results indicate that, for least-squares problems, the approach taken here is a viable alternative to standard general optimization methods such as the Byrd–Omojokun trust-region method and the Powell damped BFGS line search method. 相似文献