全文获取类型
收费全文 | 159958篇 |
免费 | 13036篇 |
国内免费 | 10469篇 |
专业分类
化学 | 80487篇 |
晶体学 | 1752篇 |
力学 | 7571篇 |
综合类 | 632篇 |
数学 | 16355篇 |
物理学 | 45055篇 |
无线电 | 31611篇 |
出版年
2023年 | 2088篇 |
2022年 | 3115篇 |
2021年 | 4158篇 |
2020年 | 4221篇 |
2019年 | 4348篇 |
2018年 | 4514篇 |
2017年 | 4571篇 |
2016年 | 5766篇 |
2015年 | 4797篇 |
2014年 | 6465篇 |
2013年 | 8709篇 |
2012年 | 9457篇 |
2011年 | 9809篇 |
2010年 | 7791篇 |
2009年 | 7921篇 |
2008年 | 8415篇 |
2007年 | 7837篇 |
2006年 | 7244篇 |
2005年 | 6458篇 |
2004年 | 5395篇 |
2003年 | 4880篇 |
2002年 | 4936篇 |
2001年 | 4362篇 |
2000年 | 3517篇 |
1999年 | 3055篇 |
1998年 | 2709篇 |
1997年 | 2411篇 |
1996年 | 2333篇 |
1995年 | 1905篇 |
1994年 | 1903篇 |
1993年 | 1766篇 |
1992年 | 1664篇 |
1991年 | 1623篇 |
1990年 | 1509篇 |
1989年 | 1331篇 |
1988年 | 1168篇 |
1987年 | 1090篇 |
1986年 | 1071篇 |
1985年 | 1126篇 |
1984年 | 1049篇 |
1983年 | 920篇 |
1982年 | 897篇 |
1979年 | 869篇 |
1978年 | 862篇 |
1977年 | 848篇 |
1976年 | 967篇 |
1975年 | 852篇 |
1974年 | 895篇 |
1973年 | 895篇 |
1972年 | 777篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Yu. A. Morozov 《Technical Physics》2004,49(5):603-608
The effect of random frequency fluctuations due to spontaneous emission and generation-recombination noise on the shape of
the emission line of a semiconductor laser with pseudorandom modulation of the pump current is studied numerically. The roles
of spontaneous emission and chirp modulation in forming the lasing spectrum are separated out. The dependence of the output
spectral characteristics of the laser on the parameters and type of modulation is analyzed. 相似文献
912.
913.
Yu. V. Pyatkov V. V. Pashkevich W. H. Trzaska G. G. Adamian N. V. Antonenko D. V. Kamanin V. A. Maslov V. G. Tishchenko A. V. Unzhakova 《Physics of Atomic Nuclei》2004,67(9):1726-1730
An analysis of the preferable fission path manifesting itself as a fine structure of the total kinetic energy-mass distribution of the fission fragments compelled us to put forward an absolutely new shape of the fissioning system on the descent from the fission barrier. It is a multicomponent nuclear molecule constituted by two magic clusters and a torus-like neck between. 相似文献
914.
The classes ofL
1-matrices,L
2-matrices,L
3-matrices andW-matrices are introduced to study solvability of a linear complementarity problem via solving a linear program. Three sufficient
conditions are presented to guarantee that a linear complementarity problem is solvable via a linear program. The new sufficient
conditions are weaker than the ones introduced by Mangasarian. This fact is also illustrated by an example.
Partially supported by NSFC.
This author is also with College of Business Administration of Human University as a Lotus chair professor. 相似文献
915.
基于VHDL实现单精度浮点数的加/减法运算 总被引:1,自引:0,他引:1
研究了单精度浮点数加/减法的结构及其设计方法,并在Aldec公司的Active—HDL软件环境下,采用VHDL语言进行设计,并进行了仿真验证,计算精度可以达到10^-7。 相似文献
916.
Tsarev Yu. V. Dmitriev A. E. Kostrov V. V. 《Russian Journal of Applied Chemistry》2003,76(11):1772-1775
Stages of synthesis of a copper-containing catalyst for electrocatalytic oxidation of acetone in waste gases were studied. The course of the extrusion and calcination and their influence on electrocatalytic oxidation of acetone on the catalyst synthesized were analyzed. 相似文献
917.
The influence of the sequence of Cu and Pd introduction into zeolite matrice when preparing Cu, Pd-zeolite catalysts on their acidity and degree of metal reduction was studied. The mutual influence of Cu and Pd on their reducibility was analyzed. The selectivity of Cu, Pd-zeolite catalysts in conversion of synthesis gas to different products was elucidated. 相似文献
918.
919.
920.
By using microlocal analysis, the propagation of weak singularities in Cauchy problems for quasilinear thermoelastic systems in three space variables are investigated. First, paradifferential operators are employed to decouple the quasilinear thermoelastic systems. Second, by investigating the decoupled hyperbolic-parabolic systems and using the classical bootstrap argument, the property of finite propagation speeds of singularities in Cauchy problems for the quasilinear thermoelastic systems is obtained. Finally, it is shown that the microlocal weak singularities for Cauchy problems of the thermoelastic systems are propagated along the null bicharacteristics of the hyperbolic operators. 相似文献