首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1374篇
  免费   38篇
  国内免费   99篇
化学   7篇
晶体学   1篇
力学   23篇
综合类   16篇
数学   1251篇
物理学   213篇
  2024年   4篇
  2023年   12篇
  2022年   20篇
  2021年   13篇
  2020年   18篇
  2019年   23篇
  2018年   31篇
  2017年   31篇
  2016年   23篇
  2015年   12篇
  2014年   33篇
  2013年   116篇
  2012年   68篇
  2011年   55篇
  2010年   37篇
  2009年   75篇
  2008年   85篇
  2007年   86篇
  2006年   77篇
  2005年   59篇
  2004年   54篇
  2003年   45篇
  2002年   59篇
  2001年   51篇
  2000年   52篇
  1999年   46篇
  1998年   36篇
  1997年   30篇
  1996年   28篇
  1995年   18篇
  1994年   21篇
  1993年   20篇
  1992年   21篇
  1991年   16篇
  1990年   13篇
  1989年   10篇
  1988年   13篇
  1987年   15篇
  1986年   10篇
  1985年   9篇
  1984年   7篇
  1983年   3篇
  1982年   11篇
  1981年   8篇
  1980年   10篇
  1979年   3篇
  1978年   12篇
  1977年   3篇
  1976年   5篇
  1974年   3篇
排序方式: 共有1511条查询结果,搜索用时 0 毫秒
101.
We analyze the finite temperature behavior of the Sakai-Sugimoto model, which is a holographic dual of a theory which spontaneously breaks a U(Nf)L × U(Nf)R chiral flavor symmetry at zero temperature. The theory involved is a 4 + 1 dimensional supersymmetric SU(Nc) gauge theory compactified on a circle of radius R with anti-periodic boundary conditions for fermions, coupled to Nf left-handed quarks and Nf right-handed quarks which are localized at different points on the compact circle (separated by a distance L). In the supergravity limit which we analyze (corresponding in particular to the large Nc limit of the gauge theory), the theory undergoes a deconfinement phase transition at a temperature Td = 1/2πR. For quark separations obeying L > Lc ? 0.97 ∗ R the chiral symmetry is restored at this temperature, but for L < Lc ? 0.97 ∗ R there is an intermediate phase which is deconfined with broken chiral symmetry, and the chiral symmetry is restored at TχSB ? 0.154/L. All of these phase transitions are of first order.  相似文献   
102.
The concept of fuzzy scalar (inner) product that will be used in the fuzzy objective and inequality constraints of the fuzzy primal and dual linear programming problems with fuzzy coefficients is proposed in this paper. We also introduce a solution concept that is essentially similar to the notion of Pareto optimal solution in the multiobjective programming problems by imposing a partial ordering on the set of all fuzzy numbers. We then prove the weak and strong duality theorems for fuzzy linear programming problems with fuzzy coefficients.  相似文献   
103.
This paper gives a duality theorem for weak L-R smash products, which extends the duality theorem for weak smash products given by Nikshych.  相似文献   
104.
Fusion Operators and Cocycloids in Monoidal Categories   总被引:1,自引:0,他引:1  
The Yang–Baxter equation has been studied extensively in the context of monoidal categories. The fusion equation, which appears to be the Yang–Baxter equation with a term missing, has been studied mainly in the context of Hilbert spaces. This paper endeavours to place the fusion equation in an appropriate categorical setting. Tricocycloids are defined; they are new mathematical structures closely related to Hopf algebras.  相似文献   
105.
本文讨论定义在Banach空间上的,既具有等式约束又具有不等式约束的,非光滑(F,P)不变凸多目标规划的Wolfe对偶性,Mond-Weir型对偶性可类似讨论之。  相似文献   
106.
Necessary and sufficient conditions in constrained optimization   总被引:22,自引:0,他引:22  
Additional conditions are attached to the Kuhn-Tucker conditions giving a set of conditions which are both necessary and sufficient for optimality in constrained optimization, under appropriate constraint qualifications. Necessary and sufficient conditions are also given for optimality of the dual problem. Duality and converse duality are treated accordingly.  相似文献   
107.
A new iterative method for finding a zero of m-accretive operators is proposed. This method, involving a so-called perturbed mapping, provides a way to construct sunny nonexpansive retractions. Several strong convergence theorems for this method are established in a Banach space that is either uniformly smooth or reflexive with a weakly continuous duality map.  相似文献   
108.
We use surrogate analysis and constraint pairing in multidimensional knapsack problems to fix some variables to zero and to separate the rest into two groups – those that tend to be zero and those that tend to be one, in an optimal integer solution. Using an initial feasible integer solution, we generate logic cuts based on our analysis before solving the problem with branch and bound. Computational testing, including the set of problems in the OR-library and our own set of difficult problems, shows our approach helps to solve difficult problems in a reasonable amount of time and, in most cases, with a fewer number of nodes in the search tree than leading commercial software.  相似文献   
109.
Charge transport in two dimensions provides an ideal laboratory for investigating parameter space geometries. The Onsager relations for anisotropic transport in a parity-violating external field endow these spaces with a highly nontrivial complex (and Kähler) structure, which can be given a simple geometrical interpretation. A large class of Coulomb gases exhibiting this structure have a generalized Kramers-Wannier symmetry (complexfield duality) which is contained in the modular group. Knowledge of this symmetry and the degrees of freedom encoded in the Coulomb gas appear to be sufficient to determine the global phase diagram and the renormalization group fixed-point structure, including the critical exponents. This accounts for all the scaling behavior observed so far in the quantum Hall system.  相似文献   
110.
We find a universal SO(2) symmetry of a p-form Maxwell theory for both odd and even p. For odd p, it corresponds to the duality rotations but for even p, it defines a new set of transformations which is not related to duality rotations. In both cases, a symmetry group defines a subgroup of the O(2,1) group of R-linear canonical transformations which has also a natural representation on the level of quantization condition for p-brane dyons.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号