全文获取类型
收费全文 | 5945篇 |
免费 | 322篇 |
国内免费 | 28篇 |
专业分类
化学 | 4758篇 |
晶体学 | 20篇 |
力学 | 114篇 |
数学 | 575篇 |
物理学 | 828篇 |
出版年
2024年 | 6篇 |
2023年 | 62篇 |
2022年 | 94篇 |
2021年 | 109篇 |
2020年 | 135篇 |
2019年 | 155篇 |
2018年 | 124篇 |
2017年 | 106篇 |
2016年 | 242篇 |
2015年 | 186篇 |
2014年 | 196篇 |
2013年 | 306篇 |
2012年 | 523篇 |
2011年 | 596篇 |
2010年 | 269篇 |
2009年 | 204篇 |
2008年 | 444篇 |
2007年 | 440篇 |
2006年 | 447篇 |
2005年 | 412篇 |
2004年 | 291篇 |
2003年 | 253篇 |
2002年 | 209篇 |
2001年 | 61篇 |
2000年 | 33篇 |
1999年 | 29篇 |
1998年 | 31篇 |
1997年 | 32篇 |
1996年 | 28篇 |
1995年 | 23篇 |
1994年 | 16篇 |
1993年 | 22篇 |
1992年 | 15篇 |
1991年 | 16篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1967年 | 6篇 |
排序方式: 共有6295条查询结果,搜索用时 15 毫秒
251.
Ozeki and Prodinger showed that the odd power sum of the first several consecutive Fibonacci numbers of even order is equal to a polynomial evaluated at a certain Fibonacci number of odd order. We prove that this polynomial and its derivative both vanish at 1, and will be an integer polynomial after multiplying it by a product of the first consecutive Lucas numbers of odd order. This presents an a?rmative answer to a conjecture of Melham. 相似文献
252.
253.
Long-range dependent random fields with spectral densities, which are unbounded at some frequencies, are investigated. We demonstrate new examples of covariance functions, which do not exhibit a regular varying asymptotic behavior at infinity. However, the variances of averaged functionals of these fields are regularly varying. The limit theorems for weighted functionals of cyclic long-range dependent fields are obtained. The order of normalizing constants and relations between the weight functions and singularities in non-degenerative asymptotics are discussed. 相似文献
254.
255.
256.
Nonlinear Dynamics - This paper presents a tool for analyzing the motion of two-link nonholonomic swimmers. We refer to these systems as Land-sharks, which are a generalization of the well known... 相似文献
257.
Compound‐specific amino acid δ15N values in archaeological shell: Assessing diagenetic integrity and potential for isotopic baseline reconstruction 下载免费PDF全文
258.
259.
Matthew Hernandez 《偏微分方程通讯》2015,40(3):387-437
We construct and justify leading order weakly nonlinear geometric optics expansions for nonlinear hyperbolic initial value problems, including the compressible Euler equations. The technique of simultaneous Picard iteration is employed to show approximate solutions tend to the exact solutions in the small wavelength limit. Recent work [2] by Coulombel et al. studied the case of reflecting wave trains whose expansions involve only real phases. We treat generic boundary frequencies by incorporating into our expansions both real and nonreal phases. Nonreal phases introduce difficulties such as approximately solving complex transport equations and result in the addition of boundary layers with exponential decay. This also prevents us from doing an error analysis based on almost periodic profiles as in [2]. 相似文献
260.
Christopher M. Timperley Matthew J. Waters 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):423-430
The synthesis and physical properties of the first fluorinated dialkyl phosphoramidates of structure (RCH 2 O) 2 P(O)NHCH 2 R F , where R = CH 3 , CF 3 or CCl 3 and R F = CF 3 or C 2 F 5 , are described. They were obtained by treatment of the respective dialkyl phosphorochloridates with trifluoroethylamine or pentafluoropropylamine in ether in the presence of triethylamine. 相似文献