全文获取类型
收费全文 | 11675篇 |
免费 | 1790篇 |
国内免费 | 1797篇 |
专业分类
化学 | 4667篇 |
晶体学 | 219篇 |
力学 | 338篇 |
综合类 | 104篇 |
数学 | 1340篇 |
物理学 | 8594篇 |
出版年
2024年 | 19篇 |
2023年 | 91篇 |
2022年 | 301篇 |
2021年 | 308篇 |
2020年 | 239篇 |
2019年 | 298篇 |
2018年 | 288篇 |
2017年 | 433篇 |
2016年 | 458篇 |
2015年 | 444篇 |
2014年 | 693篇 |
2013年 | 1025篇 |
2012年 | 785篇 |
2011年 | 713篇 |
2010年 | 653篇 |
2009年 | 781篇 |
2008年 | 862篇 |
2007年 | 880篇 |
2006年 | 786篇 |
2005年 | 680篇 |
2004年 | 559篇 |
2003年 | 510篇 |
2002年 | 445篇 |
2001年 | 403篇 |
2000年 | 377篇 |
1999年 | 334篇 |
1998年 | 280篇 |
1997年 | 285篇 |
1996年 | 218篇 |
1995年 | 180篇 |
1994年 | 142篇 |
1993年 | 132篇 |
1992年 | 125篇 |
1991年 | 75篇 |
1990年 | 60篇 |
1989年 | 76篇 |
1988年 | 108篇 |
1987年 | 42篇 |
1986年 | 24篇 |
1985年 | 26篇 |
1984年 | 26篇 |
1983年 | 7篇 |
1982年 | 18篇 |
1981年 | 21篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1977年 | 5篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1971年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
太赫兹半导体探测器研究进展 总被引:4,自引:0,他引:4
太赫兹(THz)探测器是THz技术应用的关键器件之一.基于半导体的全固态THz量子阱探测器(THzQWIP)具有探测响应速度快、制作工艺成熟、体积小和易集成等优点.文章简要介绍了THz探测器的分类和特点,重点介绍了THzQWIP的工作原理和研究进展. 相似文献
142.
143.
144.
E.H. El Abdalaoui F. Parreau A.A. Prikhod'ko 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2006,42(6):671-681
It is shown that for any family of probability measures in Ornstein type constructions, the corresponding transformation has almost surely a singular spectrum. This is a new generalization of Bourgain's theorem [J. Bourgain, On the spectral type of Ornstein class one transformations, Israel J. Math. 84 (1993) 53–63], same result is proved for Rudolph's construction [D. Rudolph, An example of a measure-preserving map with minimal self-joining and applications, J. Anal. Math. 35 (1979) 97–122]. 相似文献
145.
146.
分布耦合系数对线性啁啾光栅色散的影响 总被引:7,自引:1,他引:6
本文从光栅反向耦合波方程出发,经相位共轭变换用Runge-Kuta-Gil方法对其数值求解。针对线性啁啾光栅耦合系数变化服从不同的分布,分析了各种分布对光栅反射谱特性和色散特性的影响。 相似文献
147.
148.
Najate Bensari-zizi Claude Alamichel 《International Journal of Infrared and Millimeter Waves》1989,10(1):137-151
About 2500 lines of CH3
35Cl have been assigned. The strong xy Coriolis resonance between thev
2 andv
5 modes is quite visible between thev
4+v
4
±1
perpendicular band, centered around 4383 cm–1, and thev
4
±1
+v
5
±1
perpendicular component, centered around 4475 cm–1, with a crossing of upper energy levels allowing the observation of lines which are normally forbidden. Although not yet observed with certainty, because of the great density of lines of the spectrum, thev
4
1
+v
5
±1
parallel component is nevertheless detectable by its effects onv
2+v
4
±1
which is linked by Coriolis resonance to both components ofv
4+v
5. Moreover the spectrum is much complicated by many other resonances with weak bands which occur at level crossings: it is the case ofv
2+3v
6
±1
, connected tov
2+v
4
±1
by the well known Darling Dennison resonance which couplesv
4
±1
and 3v
6
±1
, and also ofv
5
±1
+3v
6
±1
connected tov
4
±1
+v
5
±1
by the same resonance; but this last case is complicated by an anharmonic resonance betweenv
5
±1
+3v
6
±1
and 2v
3+3v
6
1
. Two more perturbations occur on the K=–1 side ofv
2+v
4: a weak Coriolis resonance gives rise to one subband ofv
1+v
2 at a level crossing withv
2+v
4, and thev
1+v
5 band (linked of course tov
1+v
2 by the Coriolis resonance between thev
2 andv
5 modes) is quite visible and perturbs several subbands ofv
2+v
4 of high values of K through an anharmonic resonance. Moreover, the complex (3v
5
±1
,v+2v
5
0
, 2v
2+v
5
±1
, 3v
2,v
2+2v
5
±2
, 3v
5
±3
) system of Coriolis-connected bands is linked to the bands studied in the present work by two Fermi resonances: one betweenv
2+2v
5
0
andv
1+v
2, and the other one betweenv
1+v
5 and 3v
5
±1
, whose several subbands have been observed on the low part of the spectrum. The values of all the band centres and of the different coupling constants have been estimated, but all these interactions make the line assignments and the interpretation of the spectrum very difficult. 相似文献
149.
Application of the refined Wiener-Hermite expansion with moderate to high Reynolds numbers Re to homogeneous, isotropic turbulence is presented. The results show a defect to Kolmogorov's five-thirds law, increase in the absolute value of the exponent comparable with many theoretical predictions. Midrange spectra up to fluctuation Reynolds numbers of 108 show little, if any, dependence of the defect on Re, as long as the initial spectra do not deviate too far from their equilibrium states. The renormalization scheme has also been proven to have no effect on the final shape of the spectrum. 相似文献
150.
聚乙烯单晶的退火效应 总被引:1,自引:1,他引:1
用混合晶红外光谱法和SAXS、DSC和LAM等方法研究了聚乙烯单晶在75℃、90℃和105℃退火前后的结构变化,发现在90℃以下和105℃以上退火,遵循不同的退火机制 相似文献