全文获取类型
收费全文 | 25226篇 |
免费 | 2939篇 |
国内免费 | 2494篇 |
专业分类
化学 | 2449篇 |
晶体学 | 31篇 |
力学 | 2438篇 |
综合类 | 648篇 |
数学 | 17840篇 |
物理学 | 7253篇 |
出版年
2024年 | 37篇 |
2023年 | 218篇 |
2022年 | 398篇 |
2021年 | 444篇 |
2020年 | 536篇 |
2019年 | 539篇 |
2018年 | 598篇 |
2017年 | 753篇 |
2016年 | 845篇 |
2015年 | 622篇 |
2014年 | 1226篇 |
2013年 | 1693篇 |
2012年 | 1275篇 |
2011年 | 1562篇 |
2010年 | 1399篇 |
2009年 | 1684篇 |
2008年 | 1693篇 |
2007年 | 1774篇 |
2006年 | 1615篇 |
2005年 | 1528篇 |
2004年 | 1297篇 |
2003年 | 1152篇 |
2002年 | 1009篇 |
2001年 | 889篇 |
2000年 | 859篇 |
1999年 | 718篇 |
1998年 | 642篇 |
1997年 | 603篇 |
1996年 | 447篇 |
1995年 | 389篇 |
1994年 | 303篇 |
1993年 | 253篇 |
1992年 | 210篇 |
1991年 | 162篇 |
1990年 | 182篇 |
1989年 | 115篇 |
1988年 | 107篇 |
1987年 | 95篇 |
1986年 | 91篇 |
1985年 | 98篇 |
1984年 | 87篇 |
1983年 | 51篇 |
1982年 | 82篇 |
1981年 | 66篇 |
1980年 | 49篇 |
1979年 | 43篇 |
1978年 | 45篇 |
1977年 | 38篇 |
1976年 | 33篇 |
1973年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Pearson-χ~2距离的若干性质 总被引:18,自引:0,他引:18
李开灿 《数学的实践与认识》2003,33(1):49-53
本文对数理统计中常用的 Pearson- χ2距离的分析特性进行了讨论 ,得到了这一距离的一些解析性质 ,最后我们还给出了几个常用距离的关系 . 相似文献
72.
73.
Computability and computational complexity were first considered over the fields of real and complex numbers and generalized to arbitrary algebraic systems. This article approaches the theory of computational complexity over an arbitrary algebraic system by taking computability over the list extension for a computational model of it. We study the resultant polynomial complexity classes and mention some NP-complete problems. 相似文献
74.
We consider some types of packet discretization for continuous spectra in quantum scattering problems. As we previously showed, this discretization leads to a convenient finite-dimensional (i.e., matrix) approximation for integral operators in the scattering theory and allows reducing the solution of singular integral equations connected with the scattering theory to some suitable purely algebraic equations on an analytic basis. All singularities are explicitly singled out. Our primary emphasis is on realizing the method practically. 相似文献
75.
Patrizio Frosini 《Geometriae Dedicata》2004,108(1):105-110
In this paper we prove that for every real-valued Morse function φ on a smooth closed manifold ℳ and every neighborhood U of its critical points a suitable Riemannian metric μ
U
exists such that φ is linear outside
U 相似文献
76.
TieYong YangGuangjun 《分析论及其应用》2004,20(1):58-68
In this paper, we construct some continuous but non-differentiable functions defined by quinary decimal, that are Kiesswetter-like functions. We discuss their properties, then investigate the Hausdorff dimensions of graphs of these functions and give a detailed proof. 相似文献
77.
Abnormalities in the cochlear function usually cause broadening of the auditory filters which reduces the speech intelligibility. An attempt to apply a spectral enhancement algorithm has been undertaken to improve the identification of Polish vowels by subjects with cochlear-based hearing-impairment. The identification scores of natural (unprocessed) vowels and spectrally enhanced (processed) vowels has been measured for hearing-impaired subjects. It has been found that spectral enhancement improves vowel scores by about 10% for those subjects, however, a wide variation in individual performance among subjects has been observed. The overall vowels identification scores obtained were 85% for natural vowels and 96% for spectrally enhanced vowels. 相似文献
78.
In this paper, based on the Lame function and Jacobi elliptic function, the perturbation method is appliedto some nonlinear evolution equations to derive their multi-order solutions. 相似文献
80.
We show that functions which are invariant for suitable product semigroups (one of which is a quasi-Poisson semigroup on a general state space) decompose into a singular eigen-function and a mixture of products of minimal eigen-functions. 相似文献