全文获取类型
收费全文 | 50468篇 |
免费 | 3331篇 |
国内免费 | 4620篇 |
专业分类
化学 | 22686篇 |
晶体学 | 441篇 |
力学 | 4155篇 |
综合类 | 513篇 |
数学 | 10569篇 |
物理学 | 20055篇 |
出版年
2024年 | 103篇 |
2023年 | 540篇 |
2022年 | 1259篇 |
2021年 | 1303篇 |
2020年 | 1338篇 |
2019年 | 1288篇 |
2018年 | 1091篇 |
2017年 | 1276篇 |
2016年 | 1390篇 |
2015年 | 1098篇 |
2014年 | 1736篇 |
2013年 | 3198篇 |
2012年 | 2007篇 |
2011年 | 2240篇 |
2010年 | 1789篇 |
2009年 | 2868篇 |
2008年 | 3079篇 |
2007年 | 3495篇 |
2006年 | 2987篇 |
2005年 | 2320篇 |
2004年 | 1949篇 |
2003年 | 2238篇 |
2002年 | 2626篇 |
2001年 | 1985篇 |
2000年 | 1876篇 |
1999年 | 1590篇 |
1998年 | 1549篇 |
1997年 | 884篇 |
1996年 | 850篇 |
1995年 | 735篇 |
1994年 | 785篇 |
1993年 | 581篇 |
1992年 | 650篇 |
1991年 | 431篇 |
1990年 | 413篇 |
1989年 | 320篇 |
1988年 | 282篇 |
1987年 | 275篇 |
1986年 | 246篇 |
1985年 | 232篇 |
1984年 | 230篇 |
1983年 | 140篇 |
1982年 | 187篇 |
1981年 | 184篇 |
1980年 | 119篇 |
1979年 | 149篇 |
1978年 | 127篇 |
1977年 | 118篇 |
1976年 | 74篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
112.
Bush连续不可微函数的分形性质 总被引:1,自引:0,他引:1
本文对用递推关系确定的Bush连续不可微函数,找出了迭代函数系(IFS),从而得到它的级数表达式和所具有的自仿射分形的有关性质.最后还计算出函数图象的Hausdorff 维数的准确值. 相似文献
113.
Alvaro P. Raposo Hans J. Weber David E. Alvarez-Castillo Mariana Kirchbach 《Central European Journal of Physics》2007,5(3):253-284
We briefly review the five possible real polynomial solutions of hypergeometric differential equations. Three of them are
the well known classical orthogonal polynomials, but the other two are different with respect to their orthogonality properties.
We then focus on the family of polynomials which exhibits a finite orthogonality. This family, to be referred to as the Romanovski
polynomials, is required in exact solutions of several physics problems ranging from quantum mechanics and quark physics to
random matrix theory. It appears timely to draw attention to it by the present study. Our survey also includes several new
observations on the orthogonality properties of the Romanovski polynomials and new developments from their Rodrigues formula. 相似文献
114.
Yu Zanping Zhou Zheyan School of Math.and Computer Science Fujian Normal University Fuzhou ) Shen Jianhe 《Annals of Differential Equations》2007,23(3):365-372
The paper aims to obtain existence and uniqueness of the solution as well as asymptotic estimate of the solution for singularly perturbed nonlinear third- order Robin boundary value problem with a turning point.In order to achieve this aim,existence and uniqueness of the solution for third-order nonlinear Robin boundary value problem is derived first based on the upper and lower solutions method under relatively weaker conditions.In this manner,the goal of this paper is gained by applying the existence and uniqueness results mentioned above. 相似文献
115.
V. A. Petrosyan 《Russian Chemical Bulletin》1995,44(8):1353-1364
The results of studies on electrosynthesis involving carb- and heteroanions generated by cathodic deprotonation of acids (CDA), carried out in the laboratory headed by the author, are surveyed. These studies resulted in the elaboration of efficient electrochemical versions of the known Michaelis-Becker, Wittig-Horner, and Perkin reactions; electrochemical analogs of homolytic aromatic substitution, alkylation, heterocyclization,etc. were developed. Based on CDA, convenient and promising methods for preparing variousN-, O-, P-, S-, andC-alkylated and arylated substances have been developed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1411–1422, August, 1995.The author is grateful to Professor V. A. Dorokhov, Professor V. P. Litvinov, and researchers from the laboratories of N. D. Zelinsky Institute of Organic Chemistry headed by them, who participated in joint studies.The work was carried out with financial support from the International Science Foundation (Grant No. MHYOO). 相似文献
116.
Asymptotic methods for contact problems are expounded. Some typical integral equations are considered 相似文献
117.
A. D. Krisch 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):417-423
There will be a review of the history of polarized proton beams, and a discussion of the unexpected and still unexplained
large transverse spin effects found in several high-energy proton-proton spin experiments at the ZGS, AGS and Fermilab. Next,
there will be a discussion of present and possible future experiments on the violent elastic collisions of polarized protons
at IHEP-Protvino's 70GeV U-70 accelerator in Russia and the new high-intensity 50GeV J-PARC facility being built at Tokai
in Japan. 相似文献
118.
José A. Anquela Teresa Cortés Miguel Gómez-Lozano Mercedes Siles-Molina 《Acta Mathematica Hungarica》2004,103(3):177-196
We investigate the basic properties of the different socles that can be considered in not necessarily semiprime associative
systems. Among other things, we show that the socle defined as the sum of minimal (or minimal and trivial) inner ideals is
always an ideal. When trivial inner ideals are included, this inner socle contains the socles defined in terms of minimal
left or right ideals.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
119.
It is well known that the mathematical models provide very important information for the research of human immunodeficiency virus-type 1 and hepatitis C virus (HCV). However, the infection rate of almost all mathematical models is linear. The linearity shows the simple interaction between the T cells and the viral particles. In this paper, we consider the classical mathematical model with saturation response of the infection rate. By stability analysis we obtain sufficient conditions on the parameters for the global stability of the infected steady state and the infection-free steady state. We also obtain the conditions for the existence of an orbitally asymptotically stable periodic solution. Numerical simulations are presented to illustrate the results. 相似文献
120.
从大型复杂武器装备系统的具体特点出发,运用基于神经网络的评价方法,构建了大型复杂武器装备质量综合评价模型。实证分析的结果表明该方法得出的结果与实际情况相符。 相似文献