全文获取类型
收费全文 | 2153篇 |
免费 | 203篇 |
国内免费 | 245篇 |
专业分类
化学 | 157篇 |
晶体学 | 4篇 |
力学 | 147篇 |
综合类 | 62篇 |
数学 | 1607篇 |
物理学 | 624篇 |
出版年
2024年 | 7篇 |
2023年 | 34篇 |
2022年 | 30篇 |
2021年 | 48篇 |
2020年 | 70篇 |
2019年 | 58篇 |
2018年 | 43篇 |
2017年 | 49篇 |
2016年 | 69篇 |
2015年 | 59篇 |
2014年 | 126篇 |
2013年 | 124篇 |
2012年 | 81篇 |
2011年 | 102篇 |
2010年 | 113篇 |
2009年 | 119篇 |
2008年 | 138篇 |
2007年 | 166篇 |
2006年 | 132篇 |
2005年 | 116篇 |
2004年 | 107篇 |
2003年 | 112篇 |
2002年 | 116篇 |
2001年 | 81篇 |
2000年 | 78篇 |
1999年 | 89篇 |
1998年 | 65篇 |
1997年 | 66篇 |
1996年 | 47篇 |
1995年 | 28篇 |
1994年 | 35篇 |
1993年 | 20篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1957年 | 1篇 |
排序方式: 共有2601条查询结果,搜索用时 15 毫秒
131.
132.
For an integer n3 and any positive number , we establish the existence of smooth functions K on
n
{0} with |K–1|, such that the equation
has a smooth positive solution which blows up at the origin (i.e., u does not have slow decay near the origin). Furthermore, we show that in some situations K can be extended as a Lipschitz function on
n
. These provide counter-examples to a conjecture of C.-S. Lin when n>4, and a question of Taliaferro.
Mathematics Subject Classification (2000)Primary 35J60; Secondary 53C21 相似文献
133.
We construct two examples of spaces homeomorphic to R
n
(n3) each of which has a closed geodesic and admits no isoperimetric inequality. The first is a complete polyhedral metric space of nonpositive curvature, and the second is an incomplete Riemannian space with nonpositive sectional curvatures. 相似文献
134.
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.
135.
YunYanYANG 《数学学报(英文版)》2003,19(1):63-68
In this paper,we derive an elementary identity for smooth solutions of the following equation:△u(x) K(x)e^2u(x)=0 in R^2 and use it to get some global properties of the solutions. 相似文献
136.
A class of subsets of
d
which can berepresented as locally finite unions of sets with positive reach isconsidered. It plays a role in PDE's on manifolds with singularities.For such a set, the unit normal cycle (determining the d – 1curvature measures) is introduced as a (d – 1)-currentsupported by the unit normal bundle and its properties are established.It is shown that, under mild additional assumptions, the unit normalcycle (and, hence, also the curvature measures) of such a set can beapproximated by that of a close parallel body or, alternatively, by themirror image of that of the closure of the complement of the parallelbody (which has positive reach). Finally, the mixed curvature measuresof two sets of this class are introduced and a translative integralgeometric formula for curvature measures is proved. 相似文献
137.
Paolo Lisca 《Proceedings of the American Mathematical Society》2001,129(11):3437-3444
Let be a closed, oriented -manifold. The set of homotopy classes of positive, fillable contact structures on is a subtle invariant of , known to always be a finite set. In this paper we study under the assumption that carries metrics with positive scalar curvature. Using Seiberg-Witten gauge theory, we prove that two positive, fillable contact structures on are homotopic if and only if they are homotopic on the complement of a point. This implies that the cardinality of is bounded above by the order of the torsion subgroup of . Using explicit examples we show that without the geometric assumption on such a bound can be arbitrarily far from holding.
138.
Shiffman proved his famous first theorem, that if A R3 is a compact minimal annulus bounded by two convex Jordan curves in parallel (say horizontal) planes, then A is foliated by strictly convex horizontal Jordan curves. In this article we use Perron's method to construct minimal annuli which have a planar end and are bounded by two convex Jordan curves in horizontal planes, but the horizontal level sets of the surfaces are not all convex Jordan curves or straight lines. These surfaces show that unlike his second and third theorems, Shiffman's first theorem is not generalizable without further qualification. 相似文献
139.
FANG FUQUAN 《数学年刊B辑(英文版)》2000,(4)
1. IntroductionBy [111, a hypersurface in a symmetric space is called equifocal if every normal geodesicperpendiculajr to it is closed of constant length, say l, and contains Zg focal points for somepositive integer g. This is a natural generalization of isoparametric hypersurfaces in sphereswhere the illteger g is the number of distinct principal curvatures. In this note we considerequifocal hypersurfaces in simply connected rank one symmetric spaces, i.e. the complexprojective space CP", th… 相似文献
140.
Large volume growth and finite topological type 总被引:5,自引:0,他引:5
D. Ordway B. Stephens D. G. Yang 《Proceedings of the American Mathematical Society》2000,128(4):1191-1196
It is shown in this paper that a complete noncompact -dimensional Riemannian manifold with nonnegative Ricci curvature, sectional curvature bounded from below, and large volume growth is of finite topological type provided that the volume growth rate of the complement of the cone of rays from a fixed base point is less than .