全文获取类型
收费全文 | 28161篇 |
免费 | 3012篇 |
国内免费 | 2996篇 |
专业分类
化学 | 9742篇 |
晶体学 | 99篇 |
力学 | 2316篇 |
综合类 | 604篇 |
数学 | 14456篇 |
物理学 | 6952篇 |
出版年
2024年 | 42篇 |
2023年 | 256篇 |
2022年 | 614篇 |
2021年 | 589篇 |
2020年 | 743篇 |
2019年 | 728篇 |
2018年 | 758篇 |
2017年 | 1053篇 |
2016年 | 1174篇 |
2015年 | 943篇 |
2014年 | 1485篇 |
2013年 | 1817篇 |
2012年 | 1619篇 |
2011年 | 1810篇 |
2010年 | 1608篇 |
2009年 | 1841篇 |
2008年 | 1743篇 |
2007年 | 1917篇 |
2006年 | 1704篇 |
2005年 | 1561篇 |
2004年 | 1319篇 |
2003年 | 1165篇 |
2002年 | 1012篇 |
2001年 | 900篇 |
2000年 | 843篇 |
1999年 | 735篇 |
1998年 | 652篇 |
1997年 | 623篇 |
1996年 | 492篇 |
1995年 | 388篇 |
1994年 | 328篇 |
1993年 | 212篇 |
1992年 | 174篇 |
1991年 | 148篇 |
1990年 | 165篇 |
1989年 | 109篇 |
1988年 | 102篇 |
1987年 | 86篇 |
1986年 | 79篇 |
1985年 | 95篇 |
1984年 | 77篇 |
1983年 | 55篇 |
1982年 | 73篇 |
1981年 | 68篇 |
1980年 | 44篇 |
1979年 | 41篇 |
1978年 | 31篇 |
1977年 | 28篇 |
1976年 | 33篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
251.
I. P. Rochev 《Mathematical Notes》2007,81(1-2):247-259
We consider generalizations of Pólya’s theorem to the case of entire functions taking algebraic values at natural or integer points. 相似文献
252.
R. N. Miroshin 《Mathematical Notes》2007,82(3-4):357-365
Multiple integrals generalizing the iterated kernels of integral operators are expressed as single integrals in the case of a special representation of the kernel (this is our theorem). Besides integral equations, Markov processes involve these integrals as well. As a consequence of the theorem, we obtain transition probability densities of certain Markov processes. As an illustration, we consider nine examples. 相似文献
253.
In this article,the Hausdorff dimension and exact Hausdorff measure function of any random sub-self-similar set are obtained under some reasonable conditions.Several examples are given at the end. 相似文献
254.
255.
256.
本文给出了C^n中超球B上Hardy空间H^p,Bergman空间Lα^p,Bloch空间β,Besov空间Bp及Lipschitz空间Ak^p之间的系数乘子。 相似文献
257.
A family of skew Hadamard difference sets 总被引:1,自引:0,他引:1
Cunsheng Ding 《Journal of Combinatorial Theory, Series A》2006,113(7):1526-1535
In 1933 a family of skew Hadamard difference sets was described by Paley using matrix language and was called the Paley-Hadamard difference sets in the literature. During the last 70 years, no new skew Hadamard difference sets were found. It was conjectured that there are no further examples of skew Hadamard difference sets. This conjecture was proved to be true for the cyclic case in 1954, and further progress in favor of this conjecture was made in the past 50 years. However, the conjecture remains open until today. In this paper, we present a family of new perfect nonlinear (also called planar) functions, and construct a family of skew Hadamard difference sets using these perfect nonlinear functions. We show that some of the skew Hadamard difference sets presented in this paper are inequivalent to the Paley-Hadamard difference sets. These new examples of skew Hadamard difference sets discovered 70 years after the Paley construction disprove the longstanding conjecture on skew Hadamard difference sets. The class of new perfect nonlinear functions has applications in cryptography, coding theory, and combinatorics. 相似文献
258.
使用“对称性匹配簇-组态相互作用”方法,对Li2分子三重态的第一激发态、LiH分子的基态、单重态的第一和第二激发态的几何构型与谐振频率进行了优化计算.利用“群操作求和”方法分别对这4个态进行单点能扫描计算,并拟合出了相应各态的Murrell-Sorbie势能函数.使用多种方法对Li2H分子的基态结构进行优化,并用优选出的密度泛函(B3P86)方法对该分子进行了进一步的频率计算.结果发现Li2H分子的基态稳态结构为C2v构型,在此基础上用多体项展式理论导出了它的解析势能函数,其等值势能图准确再现了Li2H分子的结构特征和离解能.首次报导了该分子对称伸缩振动等值势能图中存在的两个对称鞍点,对应于反应LiH Li→Li2H,活化能大约为18.7×4.184 KJ/mol. 相似文献
259.
260.
In this work, a comparison of the interfacial electronic properties between a semiconducting oligomer and a variety of substrates with different properties—metal, semiconductor and oxide layers—is reported. The interface formation was studied by X-ray and Ultraviolet photoelectron spectroscopies (XPS, UPS). High purity oligomer films with thickness up to 10 nm were prepared by stepwise evaporation on the clean substrates under ultrahigh vacuum (UHV) conditions. Analysis of the oligomer and substrate related XPS spectra clarified the interfacial chemistry and band bending in the semiconducting materials. The valence band structure and the interfacial dipoles were determined by UPS. The barriers for hole injection were measured at the interfaces of the organic film with all substrates. The interfacial energy band diagrams were deduced in all cases from the combination of XPS and UPS results. Emphasis was given on the influence of the substrate work function (eΦ) on the electronic properties of these interfaces. 相似文献