全文获取类型
收费全文 | 115020篇 |
免费 | 2902篇 |
国内免费 | 1416篇 |
专业分类
化学 | 50667篇 |
晶体学 | 1083篇 |
力学 | 7643篇 |
综合类 | 110篇 |
数学 | 36546篇 |
物理学 | 23289篇 |
出版年
2023年 | 417篇 |
2022年 | 344篇 |
2021年 | 604篇 |
2020年 | 841篇 |
2019年 | 795篇 |
2018年 | 11019篇 |
2017年 | 10845篇 |
2016年 | 7491篇 |
2015年 | 2165篇 |
2014年 | 1789篇 |
2013年 | 2991篇 |
2012年 | 6684篇 |
2011年 | 13273篇 |
2010年 | 7332篇 |
2009年 | 7403篇 |
2008年 | 8918篇 |
2007年 | 10929篇 |
2006年 | 2327篇 |
2005年 | 3121篇 |
2004年 | 3037篇 |
2003年 | 3180篇 |
2002年 | 2158篇 |
2001年 | 1146篇 |
2000年 | 1001篇 |
1999年 | 764篇 |
1998年 | 616篇 |
1997年 | 462篇 |
1996年 | 646篇 |
1995年 | 431篇 |
1994年 | 382篇 |
1993年 | 444篇 |
1992年 | 366篇 |
1991年 | 295篇 |
1990年 | 238篇 |
1989年 | 235篇 |
1988年 | 219篇 |
1987年 | 214篇 |
1986年 | 217篇 |
1985年 | 264篇 |
1984年 | 206篇 |
1983年 | 175篇 |
1982年 | 170篇 |
1981年 | 152篇 |
1980年 | 135篇 |
1979年 | 149篇 |
1978年 | 136篇 |
1977年 | 108篇 |
1976年 | 110篇 |
1973年 | 120篇 |
1968年 | 103篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
71.
72.
Zygmunt Bak 《Czechoslovak Journal of Physics》2002,52(1):A25-A28
We consider RKKY interaction in a quasi 2D system with nonparabolic dispersion. In our paper we calculate the RKKY range function assuming the in-layer confinement via effective dimensionality approach. We show, that indirect magnetic exchange in our system can be modelled by the effective spectral dimension which equals one. 相似文献
73.
74.
75.
76.
Graham Smith 《The Journal of the Operational Research Society》1989,40(9):761-770
Courses which teach discrete-event simulation are based on many different simulation languages. The requirements for a language to support teaching simulation are discussed. In particular, it is recommended that such languages separate into distinct modules those aspects of simulation which are taught as separate topics. Implementation of the separation is discussed. The SEESIM language, developed as a teaching aid, is described, and examples of its use are given. Straightforward use of SEESIM can be learned quickly, yet the language provides facilities for a staged introduction to advanced concepts of simulation. 相似文献
77.
浅析二阶齐次线性变系数微分方程的一个可积类型 总被引:1,自引:0,他引:1
姬志飞 《应用数学与计算数学学报》2006,20(1):125-128
本文讨论了二阶齐次线性变系数微分方程的特殊形式,给出了这种微分方程的一个可积类型. 相似文献
78.
J Ashenfelter 《Pramana》2002,59(5):713-717
The ESTU began operation in 1988 and achieved the design voltage of 20 MV in 1990. Since that time, improvements to the gas
handling system, negative ion injector, accelerator terminal and control system have greatly increased its capability and
reliability. Today, the ESTU can efficiently produce an extensive assortment of stable ions at wide-ranging energies in support
of low-energy nuclear physics. 相似文献
79.
A pressure sensitive paint (PSP) measurement has been known as a pressure field measurement technique based on the oxygen quenching phenomenon of luminescence of specific luminophores. A PSP measurement was applied for pressure field measurement in a low-solidity circular cascade diffuser of a single-stage transonic centrifugal compressor with 5 in pressure ratio for HFC134a gas. The oxygen concentration was about 500 ppm. Ru (bath-phen) was adsorbed on a silica-gel thinlayer chromatography sheet, and the sheet was pasted onto the side-wall between the cascade vanes. A drastic change in luminescent intensity was recognized during a surge condition. Also the pressure variations based on luminescent intensity agreed well with the pressure fluctuations measured using a semiconductor pressure sensor with high-frequency-response. It was shown that a PSP measurement worked well to investigate the unsteady pressure fields in a circular cascade diffuser of a transonic centrifugal compressor. Moreover, the time response of PSP becomes clear as a problem to be overcome for the present. 相似文献
80.
Lubomír Kubáček 《Applications of Mathematics》2006,51(6):565-582
Some remarks to problems of point and interval estimation, testing and problems of outliers are presented in the case of multivariate
regression model.
This work was supported by the Council of Czech Government J14/98:153100011. 相似文献