首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1358471篇
  免费   25809篇
  国内免费   7824篇
化学   678881篇
晶体学   20508篇
力学   75062篇
综合类   110篇
数学   241954篇
物理学   375589篇
  2021年   13527篇
  2020年   15930篇
  2019年   16063篇
  2018年   13454篇
  2016年   28206篇
  2015年   20859篇
  2014年   30458篇
  2013年   74327篇
  2012年   38890篇
  2011年   36712篇
  2010年   37788篇
  2009年   40104篇
  2008年   35811篇
  2007年   31729篇
  2006年   36689篇
  2005年   29996篇
  2004年   30836篇
  2003年   28767篇
  2002年   29605篇
  2001年   29221篇
  2000年   25226篇
  1999年   22664篇
  1998年   21058篇
  1997年   21050篇
  1996年   21106篇
  1995年   19182篇
  1994年   18618篇
  1993年   18162篇
  1992年   18219篇
  1991年   18486篇
  1990年   17677篇
  1989年   17744篇
  1988年   17277篇
  1987年   17280篇
  1986年   16234篇
  1985年   22626篇
  1984年   23836篇
  1983年   20009篇
  1982年   21669篇
  1981年   20896篇
  1980年   20243篇
  1979年   20422篇
  1978年   21743篇
  1977年   21337篇
  1976年   21053篇
  1975年   19759篇
  1974年   19403篇
  1973年   19903篇
  1972年   14360篇
  1967年   12570篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Isochronous relaxation of tensile stresses is measured in a bulk Pd40Cu30Ni10P20 metallic glass in the initial state and after certain thermal treatments. The results of measurements are used to find the energy spectrum of irreversible structural relaxation, from which the temperature dependence of shear viscosity is then calculated. This dependence is also found independently from measurements of creep in the same glass. The calculated viscosity is shown to agree well with the experimental data.  相似文献   
912.
A suspension of ultrafine-dispersed nanodiamond was used for introducing (in particular, selectively) high-density centers of diamond nucleation on various substrates. High-quality doped diamond films to be used as electrochemistry electrodes were deposited from the gas phase in a microwave discharge on certain substrates treated using ultrafine-dispersed nanodiamond. A uniform distribution of nucleation centers with concentrations greater than 1010 cm-2 on silicon substrates was obtained. Electrochemical current-potential curves were measured for continuous films. Diamond meshes of different transparency were grown using selective nucleation. Successful production of high-quality doped diamond meshes gives grounds to consider them the most promising electrodes for use in electrochemistry.  相似文献   
913.
The translational nonequilibrium zone in a shock wave is considered for a gas consisting of light particles and a small addition of heavy particles. The gas is taken to be two-dimensional, and long-range forces are assumed to be absent. In the framework of this approximation, a program for molecular dynamics simulation of the gas is developed. It is applied to calculate a particle distribution function in the shock wave, to analyze the time evolution of the distribution function, and to study its dependence on the gas composition.  相似文献   
914.
The properties of nonrectifying AuGe/GaAs (Al0.4Ga0.6As) contacts exposed to heat treatment, 60Co γ radiation, and γ radiation combined with the application of an electrical bias are studied. A correlation between the type of interfacial interaction in the contacts and their resistance is found. Results obtained are explained in terms of a diffusion model with a movable boundary of the metal layer.  相似文献   
915.
The structure, composition, and mechanical properties of iron-alloyed TiC-TiNi composite materials are studied. When the titanium carbide framework is sintered with iron and then impregnated with titanium nickelide, iron atoms are found to diffuse into the matrix and form the B2 structure that is inhomogeneous (gradient) in chemical composition and properties and exhibits various temperatures of martensitic transformation. The latter fact shows up in the broadening of the martensitic transformation hysteresis and its shift toward low temperatures with increasing iron content. At room temperature, the strength properties of gradient-matrix TiC-TiNi composites are shown to increase with iron concentration.  相似文献   
916.
Russian Physics Journal -  相似文献   
917.
918.
The problem of dimensionality of time is considered. The space-time curvature is shown to result not only from the presence of the gravitational field but also from a certain other field whose potential is a positive value.  相似文献   
919.
It has been studied how the conditions of machining and the elastic tensile stresses affect the magnetic properties of amorphous metal wires of composition Fe75Si10B15 produced by drawing from a melt. The magnetic characteristics of wires subjected to both thermal treatment and treatment with a continuous electric current of different magnitude have been investigated. The residual induction of wires is their magnetic parameter most sensitive to the conditions of treatment. The dependences of the residual induction on temperature and on the magnitude of the treating electric current are qualitatively similar. The greatest changes in residual induction are observed in the range of treating electric currents from 0.5 to 0.8 A, which can be associated with the processes of structural relaxation and crystallization occurring in the wires. The run of the dependence of the residual induction on the magnitude of tensile stresses is nonmonotonic in character and is determined by the level of internal hardening stresses of the test wires.  相似文献   
920.
It is shown that the Kapitza effect in charge-ordered layered crystals can be explained for the case of a parallelism of magnetic field and measuring current when the Landau quantization and its effect on the charge-carrier scattering are considered. There is a linear correlation between the magnetic field and longitudinal resistance under the assumption that the scattering of charge carriers by acoustic phonons is dominant, and the band-to-band transitions are suppressed. The relations for the Kapitza coefficient are derived for different degrees of electron gas degeneracy and different values of interaction resulting in layered charge ordering.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号