全文获取类型
收费全文 | 295790篇 |
免费 | 3014篇 |
国内免费 | 1695篇 |
专业分类
化学 | 145559篇 |
晶体学 | 3971篇 |
力学 | 15440篇 |
综合类 | 61篇 |
数学 | 55381篇 |
物理学 | 80087篇 |
出版年
2020年 | 1754篇 |
2019年 | 1896篇 |
2018年 | 12631篇 |
2017年 | 12532篇 |
2016年 | 9534篇 |
2015年 | 3229篇 |
2014年 | 3805篇 |
2013年 | 9144篇 |
2012年 | 11266篇 |
2011年 | 19478篇 |
2010年 | 12044篇 |
2009年 | 12265篇 |
2008年 | 15087篇 |
2007年 | 17276篇 |
2006年 | 8553篇 |
2005年 | 8923篇 |
2004年 | 8315篇 |
2003年 | 7946篇 |
2002年 | 6937篇 |
2001年 | 6921篇 |
2000年 | 5330篇 |
1999年 | 3799篇 |
1998年 | 3212篇 |
1997年 | 3135篇 |
1996年 | 3203篇 |
1995年 | 2732篇 |
1994年 | 2791篇 |
1993年 | 2673篇 |
1992年 | 2879篇 |
1991年 | 2955篇 |
1990年 | 2752篇 |
1989年 | 2672篇 |
1988年 | 2615篇 |
1987年 | 2552篇 |
1986年 | 2575篇 |
1985年 | 3344篇 |
1984年 | 3401篇 |
1983年 | 2838篇 |
1982年 | 3086篇 |
1981年 | 2847篇 |
1980年 | 2651篇 |
1979年 | 2833篇 |
1978年 | 3030篇 |
1977年 | 3050篇 |
1976年 | 3074篇 |
1975年 | 2809篇 |
1974年 | 2917篇 |
1973年 | 2979篇 |
1972年 | 2334篇 |
1971年 | 1853篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
761.
A file ofn records can be sorted in linear time givenO(log(n)) processors. Four such algorithms are presented and analyzed. All of them have reasonable hardware requirements; no memory access conflicts are generated; a constant number of communication lines per processor are needed (except for one case); and the space requirements areO(n) orO(n log(log(n))). 相似文献
762.
Reported to the 5th All-Union Conference on High-Temperature Plasma Diagnostics (June 18–22, 1990, Minsk). 相似文献
763.
764.
A. A. Chistyakov I. L. Martynov K. E. Mochalov V. A. Oleinikov S. V. Sizova E. A. Ustinovich K. V. Zakharchenko 《Laser Physics》2006,16(12):1625-1632
The optical properties of CdSe/ZnS semiconductor nanocrystals with the core-shell structure are studied upon visible-laser excitation in a wide range of flux densities. It is demonstrated that the dimensional quantization effect is preserved in the films with a limiting high concentration of nanocrystals. A strong bathochromic shift of the absorption and luminescence peaks relative to the peak positions in the corresponding spectra of nanocrystals in films with a relatively low concentration of nanocrystals and solutions is caused by a high concentration of nanocrystals and the dipole moment related to the asymmetry of the nanoparticles. The shift is varied from 35 to 50 nm depending on the film thickness. The luminescence spectra of the films remain unchanged upon an increase in the laser intensity to 1 × 106 W/cm2. The laser action on the nanoparticle films is studied at intensities (5 × 106?1 × 109 W/cm2) higher than the damage threshold. 相似文献
765.
计算机模拟仿真射频磁控溅射实验制备薄膜及离于电池电极,研究了在特定实验条件下薄膜的生长过程,并分析了影响薄膜生长的部分因素。 相似文献
766.
767.
768.
769.
770.
Ion synthesis and laser annealing of Cu nanoparticles in Al2O3 总被引:1,自引:0,他引:1
A.L. Stepanov V.N. Popok D.E. Hole I.B. Khaibullin 《Applied Physics A: Materials Science & Processing》2002,74(3):441-446
Al2O3 samples with Cu nanoparticles, synthesised by ion implantation at 40 keV with a dose of 1×1017 ion/cm2 and a current density from 2.5 to 12.5 μA/cm2, were annealed using ten pulses from a KrF excimer laser with a single pulse fluence of 0.3 J/cm2. The copper depth distribution, formation and modification of metal nanoparticles under the ion implantation and laser treatment
were studied by Rutherford backscattering (RBS), energy dispersive X-ray (EDX) analysis, atomic force microscopy (AFM) and
optical spectroscopy. It was found that laser annealing leads to a reduction in the nanoparticle size without diffusion of
metal atoms into the bulk. The change in particle size and the possibility for oxidation of the copper particles are examined
in the framework of Mie theory. Calculations presented show that under excimer laser treatment, Cu nanoparticles are more
likely to be reduced in size than to undergo oxidation.
Received: 19 April 2001 / Accepted: 7 November 2001 / Published online: 23 January 2002 相似文献