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   3639篇
  免费   98篇
  国内免费   3篇
化学   2396篇
晶体学   39篇
力学   72篇
数学   267篇
物理学   966篇
  2023年   37篇
  2022年   63篇
  2021年   61篇
  2020年   88篇
  2019年   106篇
  2018年   70篇
  2017年   60篇
  2016年   128篇
  2015年   74篇
  2014年   122篇
  2013年   236篇
  2012年   235篇
  2011年   289篇
  2010年   175篇
  2009年   149篇
  2008年   220篇
  2007年   184篇
  2006年   163篇
  2005年   140篇
  2004年   112篇
  2003年   77篇
  2002年   77篇
  2001年   61篇
  2000年   58篇
  1999年   46篇
  1998年   29篇
  1997年   23篇
  1996年   38篇
  1995年   29篇
  1994年   35篇
  1993年   43篇
  1992年   29篇
  1991年   27篇
  1989年   19篇
  1988年   21篇
  1987年   27篇
  1986年   21篇
  1985年   19篇
  1984年   31篇
  1983年   20篇
  1982年   22篇
  1981年   30篇
  1980年   19篇
  1979年   27篇
  1978年   16篇
  1977年   18篇
  1976年   16篇
  1975年   15篇
  1973年   11篇
  1957年   13篇
排序方式: 共有3740条查询结果,搜索用时 0 毫秒
81.
82.
A micropattern-induced transition in the mechanism of vortex motion and vortex mobility is observed in high-Tc thin films. The competition between the anomalous Hall effect and the guidance of vortices by rows of microholes (antidots) lead to a sudden change in the direction of vortex motion that is accompanied by a change in the critical current density and microwave losses. The latter effect demonstrates the difference in vortex mobility in different phases of vortex motion in between and within the rows of antidots.  相似文献   
83.
84.
Highly conducting and transparent thin films of tungsten (W)-doped indium oxide were obtained using pulsed laser deposition to study the effect of growth temperature and oxygen pressure on structural, optical and electrical properties. The transparency of the films is seen to largely depend on the growth temperature. The electrical properties, however, are found to depend strongly on both the growth temperature and the oxygen pressure. High mobility (up to 358 cm2 V−1 s−1), low resistivity (1.1 × 10−4 Ω cm), and relatively high transmittance (∼90%) tungsten-doped indium oxide films have been prepared at a growth temperature of 500 °C and an oxygen pressure of 1 × 10−6 bar.  相似文献   
85.
An ab initio calculation has been carried out to investigate the biaxial strain ( - 10.71% < ε < 9.13%) effect on elastic, electronic and optical properties of CuAlO(2). All the elastic constants (c(11), c(12), c(13), c(33)) except c(44) decrease (increase) during tensile (compressive) strain. The band gap is found to decrease in the presence of tensile as well as compressive strain. The relative decrease of the band gap is asymmetric with respect to the sign of the strain. Significant differences between the parallel and perpendicular components of the dielectric constant and the optical properties have been observed due to anisotropic crystal structure. It is further noticed that these properties are easily tunable by strain. Importantly, the collective oscillation of the valence electrons has been identified for light polarized perpendicular to the c-axis. From calculations, it is clear that the tensile strain can enhance the hole mobility as well as the transparency of CuAlO(2).  相似文献   
86.
The scaled factorial moments and the multifractal moments have been investigated in different??-intervals to study the dynamical fluctuation of pions produced in 200 AGeV32S-Ag/Br interaction. In order to investigate the detail characteristics of intermittency behaviour, theF-moments are extracted up to the eighth order of moments in differentM-intervals. The analysis indicates a non-thermal phase transition and different regime of particle production during the hadronisation process.  相似文献   
87.
The purpose of the paper is to present the variation of total ozone concentration over Dumdum at Kolkata, India during different seasons. It is concluded that the trend of ozone concentration during different seasons are different. A critical analysis is done and following important results are obtained.
(i)  The total ozone concentration increases during the pre-monsoon and winter periods. During pre-monsoon period rate of formation of ozone increases sharply with the rise of surface temperature.  相似文献   
88.
Generation, collection, and characterization of gold, silver, and palladium nanoparticles and nano-agglomerates (collectively “nanoparticles”) have been explored. The nanoparticles were generated with a spark aerosol generator (Palas GFG-1000). They were collected using a deposition cell under diffusion and thermophoresis. The shapes and sizes of the deposited particles were measured using transmission electron microscopy (TEM). TEM images showed that the particles were in the range of 8–100 nm in diameter, and their shapes varied from nearly spherical to highly non-spherical. Thermophoresis enhanced the deposition of nanoparticles (over the diffusive or the isothermal deposition) in all cases. Further, the size distributions of the nanoparticles generated in the gas phase (aerosol) were measured using a scanning mobility particle sizer (SMPS 3080, TSI) spectrometer. The SMPS results show that an increase in the spark frequency of the generator shifted the size distributions of the nanoparticles to larger diameters, and the total particle mass production rate increased linearly with increase in the spark frequency. The computational fluid dynamics code Fluent (Ansys) was used to model the flow in the deposition cell, and the computed results conform to the observations.  相似文献   
89.
90.
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