全文获取类型
收费全文 | 12870篇 |
免费 | 303篇 |
国内免费 | 181篇 |
专业分类
化学 | 912篇 |
晶体学 | 88篇 |
力学 | 139篇 |
综合类 | 25篇 |
数学 | 10723篇 |
物理学 | 1467篇 |
出版年
2023年 | 26篇 |
2022年 | 64篇 |
2021年 | 91篇 |
2020年 | 60篇 |
2019年 | 290篇 |
2018年 | 314篇 |
2017年 | 195篇 |
2016年 | 115篇 |
2015年 | 139篇 |
2014年 | 325篇 |
2013年 | 622篇 |
2012年 | 459篇 |
2011年 | 720篇 |
2010年 | 573篇 |
2009年 | 839篇 |
2008年 | 913篇 |
2007年 | 947篇 |
2006年 | 799篇 |
2005年 | 606篇 |
2004年 | 475篇 |
2003年 | 340篇 |
2002年 | 341篇 |
2001年 | 311篇 |
2000年 | 314篇 |
1999年 | 346篇 |
1998年 | 281篇 |
1997年 | 243篇 |
1996年 | 298篇 |
1995年 | 281篇 |
1994年 | 289篇 |
1993年 | 202篇 |
1992年 | 180篇 |
1991年 | 126篇 |
1990年 | 120篇 |
1989年 | 135篇 |
1988年 | 88篇 |
1987年 | 94篇 |
1986年 | 74篇 |
1985年 | 103篇 |
1984年 | 90篇 |
1983年 | 54篇 |
1982年 | 83篇 |
1981年 | 69篇 |
1980年 | 77篇 |
1979年 | 43篇 |
1978年 | 56篇 |
1977年 | 48篇 |
1976年 | 43篇 |
1975年 | 14篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
In this article, we mainly deal with the boundary value problem for harmonic function with values in Clifford algebra: where is a Liapunov surface in , the Dirac operator , are unknown functions with values in a universal Clifford algebra Under some assumptions, we show that the boundary value problem is solvable. 相似文献
952.
Uniqueness of complete spacelike hypersurfaces via their higher order mean curvatures in a conformally stationary spacetime 下载免费PDF全文
Henrique Fernandes de Lima Marco Antonio Lázaro Velásquez 《Mathematische Nachrichten》2014,287(11-12):1223-1240
We study complete noncompact spacelike hypersurfaces immersed into conformally stationary spacetimes, that is, Lorentzian manifolds endowed with a timelike conformal vector field V. In this setting, by using as main analytical tool a suitable maximum principle for complete noncompact Riemannian manifolds, we establish new characterizations of totally umbilical hypersurfaces in terms of their higher order mean curvatures. For instance, supposing an appropriated restriction on the norm of the tangential component of the vector field V, we are able to show that such hypersurfaces must be totally umbilical provided that either some of their higher order mean curvatures are linearly related or one of them is constant. Applications to the so‐called generalized Robertson‐Walker spacetimes are given. In particular, we extend to the Lorentzian context a classical result due to Jellett 29 . 相似文献
953.
We study necessary and sufficient conditions on a bounded operator T defined on the Hilbert space to be an isometry and show that, under suitable hypotheses, it suffices to restrict T to a smaller class of functions (e.g., if , to the cone of positive and decreasing functions). We also consider the problem of characterizing the sets for which the orthogonal projection of the operator T on is also an isometry. Finally, we illustrate our results with several examples involving classical operators on different settings. 相似文献
954.
We prove the existence of solution for a class of ‐Laplacian equations where the nonlinearity has a critical growth. Here, we consider two cases: the first case involves the situation where the variable exponents are periodic functions. The second one involves the case where the variable exponents are nonperiodic perturbations. 相似文献
955.
In this paper we deal with the hyponormality of Toeplitz operators with matrix‐valued symbols. The aim of this paper is to provide a tractable criterion for the hyponormality of bounded‐type Toeplitz operators (i.e., the symbol is a matrix‐valued function such that Φ and are of bounded type). In particular, we get a much simpler criterion for the hyponormality of when the co‐analytic part of the symbol Φ is a left divisor of the analytic part. 相似文献
956.
We prove a multiplier theorem for certain Laplacians with drift on Damek–Ricci spaces, which are a class of Lie groups of exponential growth. Our theorem generalizes previous results obtained by W. Hebisch, G. Mauceri and S. Meda on Lie groups of polynomial growth. 相似文献
957.
A Steiner system is called a Steiner quintuple systems of order v. The smallest order for which the existence, or otherwise, of a Steiner quintuple system is unknown is 21. In this article, we prove that, if an S(4, 5, 21) exists, the order of its full automorphism group is 1, 2, 3, 4, 5, 6, 7, or 10. 相似文献
958.
《Journal of the Egyptian Mathematical Society》2014,22(1):31-35
In this paper, we study new generalized integral operators for the classes of p-valent functions associated with generalized multiplier transformations. 相似文献
959.
In 1996 I.Kh. Sabitov proved that the volume of a simplicial polyhedron in a 3-dimensional Euclidean space is a root of certain monic polynomial with coefficients depending on the combinatorial type and on edge lengths of the polyhedron only. Moreover, the coefficients of this polynomial are polynomials in edge lengths of the polyhedron. This result implies that the volume of a simplicial polyhedron with fixed combinatorial type and edge lengths can take only finitely many values. In particular, this yields that the volume of a flexible polyhedron in a 3-dimensional Euclidean space is constant. Until now it has been unknown whether these results can be obtained in dimensions greater than 3. In this paper we prove that all these results hold for polyhedra in a 4-dimensional Euclidean space. 相似文献
960.