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   4300篇
  免费   108篇
  国内免费   16篇
化学   3262篇
晶体学   35篇
力学   71篇
数学   176篇
物理学   880篇
  2023年   29篇
  2022年   30篇
  2021年   40篇
  2020年   43篇
  2019年   55篇
  2018年   36篇
  2017年   38篇
  2016年   66篇
  2015年   82篇
  2014年   82篇
  2013年   202篇
  2012年   191篇
  2011年   202篇
  2010年   108篇
  2009年   101篇
  2008年   196篇
  2007年   188篇
  2006年   213篇
  2005年   236篇
  2004年   219篇
  2003年   182篇
  2002年   217篇
  2001年   136篇
  2000年   105篇
  1999年   73篇
  1998年   53篇
  1997年   43篇
  1996年   66篇
  1995年   60篇
  1994年   60篇
  1993年   58篇
  1992年   81篇
  1991年   65篇
  1990年   57篇
  1989年   51篇
  1988年   46篇
  1987年   38篇
  1986年   51篇
  1985年   74篇
  1984年   62篇
  1982年   48篇
  1981年   29篇
  1980年   30篇
  1979年   47篇
  1978年   39篇
  1977年   44篇
  1976年   31篇
  1975年   29篇
  1974年   32篇
  1973年   34篇
排序方式: 共有4424条查询结果,搜索用时 0 毫秒
81.
82.
83.
Ultraviolet photoemission (UPS) and inner core reflectance spectra have been measured on SmSe(100) surface with synchrotron radiation. Besides the multiplet structures observed in UPS spectra for the Sm 4f, 5p and 5s excitations, the reflectance spectrum has revealed a multiplet structure associated with the Sm 4d→4f excitation. Each band of the UPS spectra has shown remarkably different hν dependence and the resonant behavior of the cross section. Sm 4f- and Se 4p-derived valence band features are unambiguously identified by the angle resolved UPS.  相似文献   
84.
85.
86.
87.
The novel electrohydrodynamically-assisted electrostatic precipitator (EHD ESP) was developed to suppress particle reentrainment for collection of low resistive diesel particulates. The collection efficiency was compared between vertically and horizontally oriented electrodes of the EHD ESP using 400 cc diesel engine. The particle size dependent collection efficiency was evaluated for the particle size ranging in 20 to 5000 nm using a scanning mobility particle sizer (SMPS) and a particle counter (PC). Both horizontally and vertically oriented EHD ESP showed an excellent suppression of particle reentrainment. However, the horizontally oriented electrode EHD ESP showed significantly improved for the particle size of 300–500 nm in comparison with vertically oriented electrode EHD ESP, resulting in more than 90% collection efficiency for all particle size range. The EHD ESP has high potential especially for highly concentrated marine diesel engine emission control.  相似文献   
88.
Magnetic minor hysteresis loops have been measured on A533B-type nuclear reactor pressure vessel steels with various combinations of Cu and Ni contents after neutron irradiation to a fluence up to 3.32 × 1019 n cm?2. A strong compositional dependence of minor-loop properties, which are indicators of internal stress, was found. The properties of high-Cu and high-Ni steel show a large increase in the low fluence regime below 0.4 × 1019 n cm?2, followed by a slow decrease, while those for low-Cu or low-Ni steel show a sudden decrease. The changes are roughly in linear proportion to the yield strength changes. The results were explained from the viewpoint of the formation and growth of Cu-rich precipitates and/or fine scale defects in the matrix and along pre-existing dislocations.  相似文献   
89.
We perform a Wilsonian renormalization group analysis for the nucleon–nucleon scattering in the P waves in the nuclear effective field theory including pions, in a similar way to the one done for the S-waves in our previous paper. We emphasize that the one-pion exchange interaction with large momentum transfer is of the same order as the leading contact interaction, so that there is no mismatch of the power counting. It is explicitly shown by obtaining consistent sets of renormalization group equations, that the cutoff dependence generated by the loop diagrams containing pion exchanges can be compensated by the cutoff dependence of the coupling constants of the contact interactions.  相似文献   
90.
Double charged pion photoproductions from the deuteron have been studied at Research Center for Electron Photon Science (ELPH), Tohoku University. Tagged photon beams in an energy range of 0.67 ≤ E γ ≤ 1.08 GeV were impinged on the liquid deuteron target. Produced charged particles were observed with the Neutral Kaon Spectrometer2 (NKS2). The γ dπ + π ? d process was clearly separated among the three charged tracks. We obtained the photon energy dependence of the normalized yields of this process.  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