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   537922篇
  免费   4166篇
  国内免费   1291篇
化学   271432篇
晶体学   7722篇
力学   26792篇
综合类   17篇
数学   70009篇
物理学   167407篇
  2021年   5041篇
  2020年   5482篇
  2019年   6232篇
  2018年   8900篇
  2017年   9125篇
  2016年   11904篇
  2015年   6348篇
  2014年   10583篇
  2013年   23678篇
  2012年   18948篇
  2011年   22140篇
  2010年   16608篇
  2009年   16497篇
  2008年   20722篇
  2007年   20564篇
  2006年   18669篇
  2005年   18775篇
  2004年   17707篇
  2003年   15161篇
  2002年   13917篇
  2001年   14749篇
  2000年   11364篇
  1999年   8773篇
  1998年   7613篇
  1997年   7474篇
  1996年   6934篇
  1995年   6260篇
  1994年   6273篇
  1993年   6024篇
  1992年   6381篇
  1991年   6870篇
  1990年   6581篇
  1989年   6491篇
  1988年   6326篇
  1987年   6137篇
  1986年   5874篇
  1985年   7412篇
  1984年   7778篇
  1983年   6535篇
  1982年   6821篇
  1981年   6332篇
  1980年   6007篇
  1979年   6510篇
  1978年   6744篇
  1977年   6633篇
  1976年   6589篇
  1975年   6309篇
  1974年   6134篇
  1973年   6427篇
  1972年   4709篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The paper concerns several diagnostic techniques, which have been used in pulsed-power plasma experiments, i.e. Plasma-Focus and Z-Pinch devices, and which can be adapted to studies of Magnetic Confinement Fusion (MCF) facilities, e.g. Stellarators and Tokamaks. The application of Nuclear Track Detectors (NTDs) for time-integrated ion measurements in MCF experiments is described and the use of such detectors for time-resolved ion measurements is discussed. The application of special ?erenkov-type detectors for time resolved measurements of fast runaway electrons is considered. Also discussed is the use of selected nuclear reactions for measurements of fusion products, e.g. fast neutrons.  相似文献   
992.
Quantum operations with a charge solid-state qubit whose logical states are formed by two spatially separated localized states of an electron in the double-dot structure are studied theoretically. We show that it is possible to perform various one-qubit rotations making use of the microwave pulses tuned to the resonances between the localized states and the excited state delocalized over the nanostructure. An explicit analytic expression for the time-dependent electron state vector is derived, and the appropriate pulse parameters are determined.  相似文献   
993.
It is shown that the introduction of heavy inert gas impurities into the condensed phase of a lighter inert gas can significantly change the kinetic properties of the latter at high pressures. The electronic structure of the ordered Ar15Xe solid solution is calculated. Doping of the condensed phase of a light inert gas with atoms of a heavier inert gas may become a new convenient tool in high-pressure experiments.  相似文献   
994.
The possibility of applying the physical principles underlying the operation of a solid-state terahertz oscillator to plasma gas-discharge media is analyzed. A new method of electromagnetic wave generation in the terahertz frequency range is proposed. It is based on the excitation of plasma-oscillation current by a static electric field in a laser spark produced by an axicon lens, followed by the radiation of an electromagnetic pulse through the Cherenkov mechanism.  相似文献   
995.
Multilayer silicon structures with built-in layers of Ge nanoclusters were studied experimentally by Raman light scattering. The built-in layers were formed by the pulsed action of a low-energy beam of intrinsic ions during molecular-beam epitaxy. It is found that the ion-stimulated nucleation and the subsequent growth make it possible to obtain Ge nanoclusters almost free of Si.  相似文献   
996.
Capture of an ensemble of polymeric microspheres in a water suspension under the action of optical gradient forces in the field of interfering laser beams has been investigated for the case of two-, three-, and four-beam interference. The self-diffraction and diffraction of radiation on induced ordered spatial distribution of particles have been obtained.  相似文献   
997.
Abnormalities in the cochlear function usually cause broadening of the auditory filters which reduces the speech intelligibility. An attempt to apply a spectral enhancement algorithm has been undertaken to improve the identification of Polish vowels by subjects with cochlear-based hearing-impairment. The identification scores of natural (unprocessed) vowels and spectrally enhanced (processed) vowels has been measured for hearing-impaired subjects. It has been found that spectral enhancement improves vowel scores by about 10% for those subjects, however, a wide variation in individual performance among subjects has been observed. The overall vowels identification scores obtained were 85% for natural vowels and 96% for spectrally enhanced vowels.  相似文献   
998.
Optics and Spectroscopy - The fluorescence of the nematic liquid crystal n-butyl-n′-methoxyazoxybenzene (BMAOB) in the form of a layer and in porous glasses with pores of different diameter...  相似文献   
999.
We construct commuting rank 2 formally self-adjoint ordinary differential operators corresponding to a curve of genus 2.  相似文献   
1000.
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