全文获取类型
收费全文 | 12124篇 |
免费 | 114篇 |
国内免费 | 93篇 |
专业分类
化学 | 5229篇 |
晶体学 | 15篇 |
力学 | 718篇 |
综合类 | 61篇 |
数学 | 4102篇 |
物理学 | 2206篇 |
出版年
2024年 | 117篇 |
2023年 | 704篇 |
2022年 | 477篇 |
2021年 | 475篇 |
2020年 | 1478篇 |
2019年 | 1092篇 |
2018年 | 949篇 |
2017年 | 788篇 |
2016年 | 758篇 |
2015年 | 588篇 |
2014年 | 771篇 |
2013年 | 2872篇 |
2012年 | 524篇 |
2011年 | 56篇 |
2010年 | 46篇 |
2009年 | 39篇 |
2008年 | 68篇 |
2007年 | 49篇 |
2006年 | 39篇 |
2005年 | 94篇 |
2004年 | 102篇 |
2003年 | 42篇 |
2002年 | 25篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 10篇 |
1998年 | 18篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 12篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Honglin Wu 《Linear and Multilinear Algebra》2013,61(6):609-623
For a symmetric 0–1 matrix A, we give the number of ones in A 2 when rank(A) = 1, 2, and give the maximal number of ones in A 2 when rank(A) = k (3 ≤ k ≤ n). The sufficient and necessary condition under which the maximal number is achieved is also obtained. For generic 0–1 matrices, we only study the cases of rank 1 and rank 2. 相似文献
992.
Regarding the generalizations of the Bessel inequality in Hilbert spaces which are due to Bombieri and Boas–Bellman, we obtain a version of the Bessel inequality and some generalizations of this inequality in the framework of Hilbert C *-modules. 相似文献
993.
In the theory of the separation of roots of algebraic equations, the well-known Routh–Hurwitz–Fujiwara theorem enables us to separate the complex roots of a polynomial with complex coefficients in terms of the inertia of a related Hermitian matrix. Unfortunately, it fails if the polynomial has a nontrivial factor which is symmetric with respect to the imaginary axis. In this article, we present a method to overcome the fault and formulate the inertia of a scalar polynomial with complex coefficients in terms of the inertia of several Hermitian matrices based on a factorization of a monic symmetric polynomial into products of monic symmetric polynomials with only simple roots in the complex plane and on computing the inertia of each factor by means of a subtle perturbation. 相似文献
994.
995.
Mikko Pelto 《Discrete Applied Mathematics》2013,161(16-17):2597-2603
996.
Igal Sason 《Statistics & probability letters》2013,83(10):2422-2431
New lower bounds on the total variation distance between the distribution of a sum of independent Bernoulli random variables and the Poisson random variable (with the same mean) are derived via the Chen–Stein method. The new bounds rely on a non-trivial modification of the analysis by Barbour and Hall (1984) which surprisingly gives a significant improvement. A use of the new lower bounds is addressed. 相似文献
997.
In this paper, we consider the inviscid 3D Boussinesq system in Besov spaces and obtain the lower bound for the lifespan of solutions. 相似文献
998.
999.
This paper deals with some relevant properties of Runge–Kutta (RK) methods and symplectic partitioned Runge–Kutta (PRK) methods. First, it is shown that the arithmetic mean of a RK method and its adjoint counterpart is symmetric. Second, the symplectic adjoint method is introduced and a simple way to construct symplectic PRK methods via the symplectic adjoint method is provided. Some relevant properties of the adjoint method and the symplectic adjoint method are discussed. Third, a class of symplectic PRK methods are proposed based on Radau IA, Radau IIA and their adjoint methods. The structure of the PRK methods is similar to that of Lobatto IIIA–IIIB pairs and is of block forms. Finally, some examples of symplectic partitioned Runge–Kutta methods are presented. 相似文献
1000.
C.M. da Fonseca Dan A. Mazilu Irina Mazilu H. Thomas Williams 《Applied Mathematics Letters》2013,26(12):1206-1211
A straightforward model for deposition and evaporation on discrete cells of a finite array of any dimension leads to a matrix equation involving a Sylvester–Kac type matrix. The eigenvalues and eigenvectors of the general matrix are determined for an arbitrary number of cells. A variety of models to which this solution may be applied are discussed. 相似文献