全文获取类型
收费全文 | 5811篇 |
免费 | 794篇 |
国内免费 | 549篇 |
专业分类
化学 | 257篇 |
力学 | 701篇 |
综合类 | 152篇 |
数学 | 4838篇 |
物理学 | 1206篇 |
出版年
2024年 | 12篇 |
2023年 | 49篇 |
2022年 | 79篇 |
2021年 | 90篇 |
2020年 | 143篇 |
2019年 | 141篇 |
2018年 | 169篇 |
2017年 | 202篇 |
2016年 | 241篇 |
2015年 | 131篇 |
2014年 | 240篇 |
2013年 | 492篇 |
2012年 | 276篇 |
2011年 | 337篇 |
2010年 | 303篇 |
2009年 | 347篇 |
2008年 | 401篇 |
2007年 | 371篇 |
2006年 | 371篇 |
2005年 | 335篇 |
2004年 | 306篇 |
2003年 | 251篇 |
2002年 | 260篇 |
2001年 | 198篇 |
2000年 | 220篇 |
1999年 | 163篇 |
1998年 | 141篇 |
1997年 | 142篇 |
1996年 | 102篇 |
1995年 | 116篇 |
1994年 | 72篇 |
1993年 | 77篇 |
1992年 | 59篇 |
1991年 | 37篇 |
1990年 | 48篇 |
1989年 | 27篇 |
1988年 | 21篇 |
1987年 | 20篇 |
1986年 | 22篇 |
1985年 | 16篇 |
1984年 | 19篇 |
1983年 | 8篇 |
1982年 | 16篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1977年 | 13篇 |
1974年 | 7篇 |
1973年 | 7篇 |
排序方式: 共有7154条查询结果,搜索用时 31 毫秒
901.
Nguyen Ngoc Luan 《Applicable analysis》2013,92(9):1694-1704
This paper establishes several new facts on generalized polyhedral convex sets and shows how they can be used in vector optimization. Among other things, a scalarization formula for the efficient solution sets of generalized linear vector optimization problems is obtained. We also prove that the efficient solution set of a generalized linear vector optimization problem in a locally convex Hausdorff topological vector space is the union of finitely many generalized polyhedral convex sets and it is connected by line segments. 相似文献
902.
Yan Xiaoyan 《The Journal of mathematical sociology》2013,37(4):359-389
A definition of fuzzy clique in social networks is suggested which overcomes five limitations of current definitions. This definition is based on the networks in which the 0–1 strengths, the weighted strengths, and fuzzy strengths are all allowed. The fuzzy distance in such a network is defined. The node‐clique and clique‐clique coefficients are suggested. The core and the periphery of fuzzy cliques are discussed formally. A “cone like” property of the cores is discovered. The network structures are discussed using the new definition. A “no circle” property of networks is found. Basic fuzzy tools and the related algorithms are also discussed. Some examples are analyzed to demonstrate the theory. 相似文献
903.
904.
Hung-Yuan Chen 《代数通讯》2013,41(10):3709-3721
Let R be a noncommutative prime ring with extended centroid C, and let D: R → R be a nonzero generalized derivation, f(X 1,…, X t ) a nonzero polynomial in noncommutative indeterminates X 1,…, X t over C with zero constant term, and k ≥ 1 a fixed integer. In this article, D and f(X 1,…, X t ) are characterized if the Engel identity is satisfied: [D(f(x 1,…, x t )), f(x 1,…, x t )] k = 0 for all x 1,…, x t ∈ R. 相似文献
905.
Surjeet Kour 《代数通讯》2013,41(11):4100-4110
It is shown that the derivation y r ? x + (xy s + g)? y , where 0 ≤ r < s are integers, is a simple derivation of k[x, y], the polynomial ring in two variables over a field k of characteristic zero. 相似文献
906.
Masayoshi Yoshikawa 《代数通讯》2013,41(5):2046-2060
We will investigate the structure of noncommutative imprimitive association schemes of rank 6 and the representation of their adjacency algebras. From this investigation, we will construct new integral standard generalized table algebras with three parameters. These algebras are noncommutative, imprimitive, and 6-dimensional. 相似文献
907.
给出了解病态线性方程组的一种新的Jacobi迭代算法,并证明了算法的收敛性;通过具体算例说明了算法的实用性和有效性. 相似文献
908.
A new family of finite-dimensional simple modular Lie superalgebra ? is constructed based on results of Y. Z. Zhang and Q. C. Zhang [J. Algebra, 2009, 321: 3601–3619]. The simplicity and generators of ? are discussed and the derivation superalgebra of ? is characterized. Furthermore, the invariance of the nonnatural filtration of ? is determined by the method of minimal dimension of image spaces. 相似文献
909.
In this paper, a financial market with Markovian switching and inflation is described, and the problem of maximizing expected utility of consumption discounted by inflation is given. Then, by a generalized Itô formula for Markov-modulated processes, the verification theorems of optimal policies are derived. Finally, the optimal consumption and portfolio policies for the constant relative risk aversion utility are given explicitly, and an economic analysis is made by numerical examples. 相似文献
910.
《Numerical Functional Analysis & Optimization》2013,34(5-6):561-575
In this paper, we propose a method of calculating an element of B-differential, also an element of Clarke generalized Jacobian, for a vector-valued maximum function. This calculation is required in many existing numerical methods for the solution of nonsmooth equations and for the nonsmooth optimization. The generalization of our method to a vector-valued smooth composition of maximum functions is also discussed. Particularly, we propose a method of obtaining the set of B-differential for a vector-valued maximum of affine functions. 相似文献