全文获取类型
收费全文 | 836篇 |
免费 | 30篇 |
国内免费 | 69篇 |
专业分类
化学 | 18篇 |
力学 | 19篇 |
综合类 | 2篇 |
数学 | 844篇 |
物理学 | 52篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 14篇 |
2020年 | 15篇 |
2019年 | 21篇 |
2018年 | 22篇 |
2017年 | 15篇 |
2016年 | 15篇 |
2015年 | 12篇 |
2014年 | 24篇 |
2013年 | 98篇 |
2012年 | 46篇 |
2011年 | 49篇 |
2010年 | 51篇 |
2009年 | 51篇 |
2008年 | 59篇 |
2007年 | 43篇 |
2006年 | 42篇 |
2005年 | 44篇 |
2004年 | 30篇 |
2003年 | 31篇 |
2002年 | 39篇 |
2001年 | 27篇 |
2000年 | 18篇 |
1999年 | 24篇 |
1998年 | 20篇 |
1997年 | 24篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有935条查询结果,搜索用时 750 毫秒
41.
We make a conjecture that the number of isolated local minimum points of a 2n-degree or (2n+1)-degree r-variable polynomial is not greater than n
r when n 2. We show that this conjecture is the minimal estimate, and is true in several cases. In particular, we show that a cubic polynomial of r variables may have at most one local minimum point though it may have 2r critical points. We then study the global minimization problem of an even-degree multivariate polynomial whose leading order coefficient tensor is positive definite. We call such a multivariate polynomial a normal multivariate polynomial. By giving a one-variable polynomial majored below a normal multivariate polynomial, we show the existence of a global minimum of a normal multivariate polynomial, and give an upper bound of the norm of the global minimum and a lower bound of the global minimization value. We show that the quartic multivariate polynomial arising from broad-band antenna array signal processing, is a normal polynomial, and give a computable upper bound of the norm of the global minimum and a computable lower bound of the global minimization value of this normal quartic multivariate polynomial. We give some sufficient and necessary conditions for an even order tensor to be positive definite. Several challenging questions remain open. 相似文献
42.
Christopher Meaney 《Proceedings of the American Mathematical Society》2003,131(10):3123-3128
We show that for below certain critical indices there are functions whose Jacobi or Laguerre expansions have almost everywhere divergent Cesàro and Riesz means of order .
43.
T. Ehrhardt 《Acta Mathematica Hungarica》2003,99(3):233-262
We give another proof of the Szeg\H{o}–Widom Limit Theorem. This proof relies on a new Banach algebra method that can be directly
applied to the asymptotic computation of the Toeplitz determinants. As a by-product, we establish an interesting identity
for operator determinants of Toeplitz operators, namely if
are certain matrix valued functions defined on the unit circle, then
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
44.
Zinoviy Grinshpun 《Proceedings of the American Mathematical Society》2003,131(5):1591-1600
We prove the following theorem. Any isometric operator , that acts from the Hilbert space with nonnegative weight to the Hilbert space with nonnegative weight , allows for the integral representation
where the kernels and satisfy certain conditions that are necessary and sufficient for these kernels to generate the corresponding isometric operators.
where the kernels and satisfy certain conditions that are necessary and sufficient for these kernels to generate the corresponding isometric operators.
45.
Pavel Rehak 《Czechoslovak Mathematical Journal》2001,51(2):303-321
We study oscillatory properties of the second order half-linear difference equation
. It will be shown that the basic facts of oscillation theory for this equation are essentially the same as those for the linear equation
. We present here the Picone type identity, Reid Roundabout Theorem and Sturmian theory for equation (HL). Some oscillation criteria are also given. 相似文献
46.
Peter Scott Gadde A. Swarup 《Transactions of the American Mathematical Society》2001,353(12):4973-5001
We introduce the notion of a `canonical' splitting over or for a finitely generated group . We show that when happens to be the fundamental group of an orientable Haken manifold with incompressible boundary, then the decomposition of the group naturally obtained from canonical splittings is closely related to the one given by the standard JSJ-decomposition of . This leads to a new proof of Johannson's Deformation Theorem.
47.
We prove some new degeneracy results for integral points and entire curves on surfaces; in particular, we provide the first examples, to our knowledge, of a simply connected smooth variety whose sets of integral points are never Zariski-dense. Some of our results are connected with divisibility problems, i.e. the problem of describing the integral points in the plane where the values of some given polynomials in two variables divide the values of other given polynomials. 相似文献
48.
Ming-Chien Yang 《Applied mathematics and computation》2010,216(12):3754-3760
The n-dimensional star graph Sn is an attractive alternative to the hypercube graph and is a bipartite graph with two partite sets of equal size. Let Fv and Fe be the sets of faulty vertices and faulty edges of Sn, respectively. We prove that Sn − Fv − Fe contains a fault-free cycle of every even length from 6 to n! − 2∣Fv∣ with ∣Fv∣ + ∣Fe∣ ? n − 3 for every n ? 4. We also show that Sn − Fv − Fe contains a fault-free path of length n! − 2∣Fv∣ − 1 (respectively, n! − 2∣Fv∣ − 2) between two arbitrary vertices of Sn in different partite sets (respectively, the same partite set) with ∣Fv∣ + ∣Fe∣ ? n − 3 for every n ? 4. 相似文献
49.
The classical Three Gap Theorem asserts that for a natural number n and a real number p, there are at most three distinct distances between consecutive elements in the subset of [0,1) consisting of the reductions
modulo 1 of the first n multiples of p. Regarding it as a statement about rotations of the circle, we find results in a similar spirit pertaining to isometries
of compact Riemannian manifolds and the distribution of points along their geodesics.
相似文献
50.
In this paper, we study a second order variational problem for locally convex hypersurfaces, which is the affine invariant analogue of the classical Plateau problem for minimal surfaces. We prove existence, regularity and uniqueness results for hypersurfaces maximizing affine area under appropriate boundary conditions.