全文获取类型
收费全文 | 999篇 |
免费 | 70篇 |
国内免费 | 130篇 |
专业分类
化学 | 12篇 |
力学 | 3篇 |
综合类 | 11篇 |
数学 | 1090篇 |
物理学 | 83篇 |
出版年
2024年 | 4篇 |
2023年 | 26篇 |
2022年 | 28篇 |
2021年 | 17篇 |
2020年 | 52篇 |
2019年 | 34篇 |
2018年 | 44篇 |
2017年 | 27篇 |
2016年 | 18篇 |
2015年 | 27篇 |
2014年 | 29篇 |
2013年 | 112篇 |
2012年 | 29篇 |
2011年 | 51篇 |
2010年 | 43篇 |
2009年 | 64篇 |
2008年 | 87篇 |
2007年 | 57篇 |
2006年 | 57篇 |
2005年 | 50篇 |
2004年 | 29篇 |
2003年 | 45篇 |
2002年 | 46篇 |
2001年 | 39篇 |
2000年 | 23篇 |
1999年 | 44篇 |
1998年 | 38篇 |
1997年 | 21篇 |
1996年 | 17篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有1199条查询结果,搜索用时 44 毫秒
51.
We establish a link between rational homotopy theory and the problem which vector bundles admit a complete Riemannian metric of nonnegative sectional curvature. As an application, we show for a large class of simply-connected nonnegatively curved manifolds that, if lies in the class and is a torus of positive dimension, then ``most' vector bundles over admit no complete nonnegatively curved metrics.
52.
Harald Biller 《Transactions of the American Mathematical Society》2003,355(1):407-432
Essential results about actions of compact Lie groups on connected manifolds are generalized to proper actions of arbitrary groups on connected cohomology manifolds. Slices are replaced by certain fiber bundle structures on orbit neighborhoods. The group dimension is shown to be effectively finite. The orbits of maximal dimension form a dense open connected subset. If some orbit has codimension at most , then the group is effectively a Lie group.
53.
Takae Tsuji 《Transactions of the American Mathematical Society》2003,355(9):3699-3714
For a prime number and a number field , let denote the projective limit of the -parts of the ideal class groups of the intermediate fields of the cyclotomic -extension over . It is conjectured that is finite if is totally real. When is an odd prime and is a real abelian field, we give a criterion for the conjecture, which is a generalization of results of Ichimura and Sumida. Furthermore, in a special case where divides the degree of , we also obtain a rather simple criterion.
54.
BaoShanWANG JiPingZHANG 《数学学报(英文版)》2003,19(1):29-34
In this paper,we shall mainly study the p-solvable finite group in terms of p-local rank,and a group theoretic characterization will be given of finite p-solvabel groups with p-local rank two.Theorem A Let G be a finite p-solvable group with p-local rank plr(G)=2 and Op(G)=1.If P is a Sylow p-subgrounp of G,then P has a normal subgroup Q such that P/Q is cyclic or a generalized quaternion 2-group and the p-rank of Q is at most two.Theorem B Let G be a finite p-solvable group with Op(G)=1.Then the p-length lp(G)≤plr(G);if in addition plr(G)=lp (G) and p≥5 is odd,then plr(G)=0 or 1. 相似文献
55.
Balázs Csikós 《Geometriae Dedicata》2001,86(1-3):59-79
Let f(x
1,..., x
N
) be a lattice polynomial in N variables, in which each variable occurs exactly once, B
1,..., B
N
be smoothly moving balls in the hyperbolic, Euclidean, or spherical space. Introducing a suitable modification of the Dirichlet–Voronoi decomposition, we prove a formula for the derivative of the volume of the domain f(B
1,..., B
N
). As an application of the formula, we show that the volume increases if the balls move continuously in such a way that the functions
ij
d
ij
increase for all 1 i < j N, where
ij
is a sign depending on f, d
ij
is the distance between the centers of B
I
and B
j
. 相似文献
56.
In this note, we give an example of a strongly convex algebraic complete Reinhardt domain which is not Lu Qi-Keng in for any
57.
In 1876, H. Brocard posed the problem of finding all integral solutions to n! + 1 = m2. In 1913, unaware of Brocard's query, S. Ramanujan gave the problem in the form, The number 1 + n! is a perfect square for the values 4, 5, 7 of n. Find other values. We report on calculations up to n = 109 and briefly discuss a related problem. 相似文献
58.
Shunlong Luo 《Journal of statistical physics》2007,128(5):1177-1188
The classical Fisher information is superadditive in the sense that the Fisher information of a bivariate probability density
is always not less than the sum of those of the marginals. The longstanding conjecture concerning the superadditivity of the
Wigner–Yanase–Dyson information is a quantum analogue of this property. It is remarkable that Hansen constructed a numerical
counterexample to the quantum case (J. Stat. Phys. 126: 643–648, 2007). However, the requirement of superadditivity of an information-theoretic quantity such as the Wigner–Yanase–Dyson information
seems so intuitive, it is desirable to identify conditions as general as possible such that the superadditivity holds. In
this paper, we establish the superadditivity in several physically significant cases. 相似文献
59.
60.
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