全文获取类型
收费全文 | 2132篇 |
免费 | 205篇 |
国内免费 | 267篇 |
专业分类
化学 | 72篇 |
晶体学 | 3篇 |
力学 | 141篇 |
综合类 | 66篇 |
数学 | 1902篇 |
物理学 | 420篇 |
出版年
2024年 | 6篇 |
2023年 | 32篇 |
2022年 | 28篇 |
2021年 | 46篇 |
2020年 | 69篇 |
2019年 | 54篇 |
2018年 | 48篇 |
2017年 | 50篇 |
2016年 | 70篇 |
2015年 | 58篇 |
2014年 | 117篇 |
2013年 | 127篇 |
2012年 | 72篇 |
2011年 | 95篇 |
2010年 | 106篇 |
2009年 | 124篇 |
2008年 | 143篇 |
2007年 | 178篇 |
2006年 | 129篇 |
2005年 | 124篇 |
2004年 | 114篇 |
2003年 | 109篇 |
2002年 | 117篇 |
2001年 | 78篇 |
2000年 | 80篇 |
1999年 | 93篇 |
1998年 | 67篇 |
1997年 | 72篇 |
1996年 | 51篇 |
1995年 | 29篇 |
1994年 | 33篇 |
1993年 | 19篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1957年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有2604条查询结果,搜索用时 15 毫秒
31.
The authors study rotational hypersurfaces with constant Gauss-Kronecker curvature in Rn. They solve the ODE associated with the generating curve of such hypersurface using integral expressions and obtain several geometric properties of such hypersurfaces. In particular, they discover a class of non-compact rotational hypersurfaces with constant and negative Gauss-Kronecker curvature and finite volume, which can be seen as the higher-dimensional generalization of the pseudo-sphere. 相似文献
32.
Michael Weiss 《Proceedings of the American Mathematical Society》1996,124(2):615-622
Upper bounds obtained by Gromov on the Betti numbers of certain closed Riemannian manifolds are shown to be upper bounds on the minimum number of cells in --spaces dominating such manifolds.
33.
Philippe Rukimbira 《Annals of Global Analysis and Geometry》1993,11(2):165-171
Let (M, ) be an R-contact manifold, then the set of periodic points of the characteristic vector field is a nonempty union of closed, totally geodesic odd-dimensional submanifolds. Moreover, the R-metric cannot have nonpositive sectional curvature. We also prove that no R-contact form can exist on any torus. 相似文献
34.
Jean Barge 《K-Theory》1993,7(1):9-16
In this paper we construct a canonical 2-cocycle on the groupP SL(2,k) with values in the Witt groupW(k) of the fieldk. This allows us to produce anatural homomorphism :H
2(SL(2,k); Z)I
2(k), whereI
2(k) is the square of the fundamental ideal. We prove that this homomorphism is in fact a lift of Milnor's symbol. 相似文献
35.
Joris Proost 《Journal of Solid State Electrochemistry》2005,9(10):660-664
A thermodynamic framework has been provided for the interpretation of combined cyclic voltammetry and surface stress measurements, the latter being obtained from wafer curvature or beam deflection measurements of a solid electrode as a function of applied potential (so-called voltstressograms). Firstly, the derivation of electrocapillarity equations for solid electrodes has been critically reviewed by starting from the Gibbs adsorption equation appropriate for solid–electrolyte interfaces. This allowed us to demonstrate the critical importance of elastic surface strain in the thermodynamic boundary conditions of the partial derivatives intervening in the interpretation of voltstressograms. From these considerations, it was shown for the first time that the electrocapillarity equations for solid electrodes are not appropriate for describing the variation of surface stress with potential obtained from wafer curvature measurements, because such measurements are intrinsically incompatible with the constant strain condition implied in the electrocapillarity equations. An alternative explanation is provided for the experimentally observed proportionality between the current density, measured in cyclic voltammograms, and the first derivative of surface stress with respect to potential, obtained from voltstressograms. 相似文献
36.
In this paper, we prove some inequalities between intrinsic and extrinsic curvature invariants, namely the normalized -Casorati curvatures and the scalar curvature of statistical submanifolds in Kenmotsu statistical manifolds of constant -sectional curvature that are endowed with semi-symmetric metric connection. Furthermore, we investigate the equality cases of these inequalities. We also describe an illustrative example. 相似文献
37.
刻画了有限集合N上全变换半群Tn 与对称逆半群ISn 之间的所有同态. 相似文献
38.
39.
Timothy Buttsworth 《Mathematische Nachrichten》2019,292(4):747-759
Let G be a three‐dimensional unimodular Lie group, and let T be a left‐invariant symmetric (0,2)‐tensor field on G. We provide the necessary and sufficient conditions on T for the existence of a pair consisting of a left‐invariant Riemannian metric g and a positive constant c such that , where is the Ricci curvature of g. We also discuss the uniqueness of such pairs and show that, in most cases, there exists at most one positive constant c such that is solvable for some left‐invariant Riemannian metric g. 相似文献
40.