全文获取类型
收费全文 | 1324篇 |
免费 | 51篇 |
国内免费 | 186篇 |
专业分类
力学 | 12篇 |
综合类 | 20篇 |
数学 | 1501篇 |
物理学 | 28篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 9篇 |
2021年 | 9篇 |
2020年 | 19篇 |
2019年 | 17篇 |
2018年 | 41篇 |
2017年 | 49篇 |
2016年 | 32篇 |
2015年 | 8篇 |
2014年 | 36篇 |
2013年 | 190篇 |
2012年 | 39篇 |
2011年 | 43篇 |
2010年 | 57篇 |
2009年 | 108篇 |
2008年 | 100篇 |
2007年 | 67篇 |
2006年 | 77篇 |
2005年 | 64篇 |
2004年 | 60篇 |
2003年 | 80篇 |
2002年 | 76篇 |
2001年 | 55篇 |
2000年 | 59篇 |
1999年 | 49篇 |
1998年 | 57篇 |
1997年 | 42篇 |
1996年 | 33篇 |
1995年 | 17篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1982年 | 6篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有1561条查询结果,搜索用时 31 毫秒
271.
L. V. Korobenko V. Zh. Sakbaev 《Computational Mathematics and Mathematical Physics》2009,49(6):1037-1053
The choice of a differential diffusion operator with discontinuous coefficients that corresponds to a finite flow velocity and a finite concentration is substantiated. For the equation with a uniformly elliptic operator and a nonzero diffusion coefficient, conditions are established for the existence and uniqueness of a solution to the corresponding Cauchy problem. For the diffusion equation with degeneration on a half-line, it is proved that the Cauchy problem with an arbitrary initial condition has a unique solution if and only if there is no flux from the degeneration domain to the ellipticity domain of the operator. Under this condition, a sequence of solutions to regularized problems is proved to converge uniformly to the solution of the degenerate problem in L 1(R) on each interval. 相似文献
272.
设R是含有恒等元1的半环,C是R上的中心子半环.Tn(R)是R上的n阶上三角矩阵C-代数.证明了当R是一个幂等元都是中心元的半环时,映射Φ:Tn(R)→Tn(R)是乘法半群自同构当且仅当存在Tn(R)中的可逆矩阵G和R中的半环自同构τ使得A=(aij)n×n∈Tn(R),均有Φ(A)=G-1τ(A)G.这里τ(A)=(τ(aij))n×n,n2. 相似文献
273.
In this paper, we prove that the 2D Navier-Stokes equations possess a global attractor in Hk(Ω,R2) for any k ≥ 1, which attracts any bounded set of Hk(Ω,R2) in the H^k-norm. The result is established by means of an iteration technique and regularity estimates for the linear semigroup of operator, together with a classical existence theorem of global attractor. This extends Ma, Wang and Zhong's conclusion. 相似文献
274.
We survey a great number of results obtained during four decades of investigations on lattices of semigroup varieties and formulate several open problems. 相似文献
275.
Let S° be an inverse semigroup with semilattice biordered set E° of idempotents and E a weakly inverse biordered set with a subsemilattice Ep = { e ∈ E | arbieary f ∈ E, S(f , e) loheain in w(e)} isomorphic to E° by θ:Ep→E°. In this paper, it is proved that if arbieary f, g ∈E, f ←→ g→→ f°θD^s° g°θand there exists a mapping φ from Ep into the symmetric weakly inverse semigroup P J(E∪ S°) satisfying six appropriate conditions, then a weakly inverse semigroup ∑ can be constructed in P J(S°), called the weakly inverse hull of a weakly inverse system (S°, E, θ, φ) with I(∑) ≌ S°, E(∑) ∽- E. Conversely, every weakly inverse semigroup can be constructed in this way. Furthermore, a sufficient and necessary condition for two weakly inverse hulls to be isomorphic is also given. 相似文献
276.
设n是一个正整数, Cn(r)是B={0,1}上所有n阶r 循环矩阵组成之集, Gn=∪〖DD(〗n-1〖〗r=0〖DD)〗Cn(r). 对于半群Gn中任一个固定的r 循环矩阵C,在Gn中定义一个新的运算“*”:A,B∈Gn, AB=ACB. 则(Gn,)构成一个半群, 称(Gn,)为(带有三明治矩阵C的)广义循环布尔矩阵三明治半群, 并记为Gn(C).刻画了半群Gn(C)中的完全正则元,并给出了求Gn(C)中所有完全正则元的算法. 相似文献
277.
Hugo D. Fernández Sare B. Miara M.L. Santos 《Mathematical Methods in the Applied Sciences》2012,35(18):2157-2165
In this paper, we consider a piezoelectric dissipative system in which a dissipation term is given through the mechanical part of the stress tensor. The abstract Cauchy problem associated to this system generates a semigroup of linear operators. We establish the analyticity of this semigroup that, in turn, implies the exponential decay of the corresponding energy and the strong regularity of the solutions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
278.
Existence and regularity of solutions to model for liquid mixture of 3He-4He is considered in this paper. First, it is proved that this system possesses a unique global weak solution in H1(ω,C×R) by using Galerkin method. Secondly, by using an iteration procedure, regularity estimates for the linear semigroups, it is proved that the model for liquid mixture of 3He-4He has a unique solution in Hk(ω,C×R) for all k ≥ 1. 相似文献
279.
We are concerned with an inverse problem for a degenerate linear evolution equation of first-order. Both hyperbolic and parabolic cases will be considered. We indicate sufficient conditions for the existence and uniqueness of a solution. All the results can be applied to inverse problems for equations from mathematical physics. As a possible application of the abstract theorems, some examples of partial differential equations are given. 相似文献
280.