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   1338528篇
  免费   25738篇
  国内免费   7687篇
化学   657451篇
晶体学   20814篇
力学   75474篇
综合类   103篇
数学   244007篇
物理学   374104篇
  2021年   13482篇
  2020年   15900篇
  2019年   16016篇
  2018年   15026篇
  2017年   13647篇
  2016年   28824篇
  2015年   21031篇
  2014年   30398篇
  2013年   74292篇
  2012年   37586篇
  2011年   35631篇
  2010年   38460篇
  2009年   41088篇
  2008年   34902篇
  2007年   31093篇
  2006年   34027篇
  2005年   28888篇
  2004年   29350篇
  2003年   27641篇
  2002年   28182篇
  2001年   26210篇
  2000年   23333篇
  1999年   21868篇
  1998年   20836篇
  1997年   20847篇
  1996年   21009篇
  1995年   19076篇
  1994年   18548篇
  1993年   18073篇
  1992年   17687篇
  1991年   18037篇
  1990年   17240篇
  1989年   17364篇
  1988年   16874篇
  1987年   16920篇
  1986年   15733篇
  1985年   22255篇
  1984年   23581篇
  1983年   19840篇
  1982年   21569篇
  1981年   20822篇
  1980年   20140篇
  1979年   20186篇
  1978年   21604篇
  1977年   21149篇
  1976年   20803篇
  1975年   19484篇
  1974年   19110篇
  1973年   19596篇
  1972年   14096篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
152.
The electrical conductivity of hydrosols of ultradispersed diamonds was studied. The electromembrane method for cleaning and concentrating of ultradispersed diamonds in hydrosols was considered. The influence exerted by the concentration of the dispersed phase on the electrical characteristics of the cleaning process was analyzed. A mathematical relation making it possible to evaluate the output characteristics of the process and to determine the geometrical characteristics of the apparatus was proposed.  相似文献   
153.
The microhardness and content of carbon in electroplated gold coatings were studied as influenced by the operation time of citrate and citrate-phosphate gold-plating electrolytes. Such physicomechanical properties as porosity, microhardness, internal stress, plasticity, and microstructure of electroless-plated and electroplated nickel coatings were studied and analyzed.  相似文献   
154.
The radiation emitted by charged, scalar particles in a Schwarzschild field with maximal acceleration corrections is calculated classically and in the tree approximation of quantum field theory. In both instances the particles emit radiation that has characteristics similar to those of gamma-ray bursters.  相似文献   
155.
Surface relief formation at holographic recording on amorphous selenium films was demonstrated and investigated. The presence of this optical phase modulation component is essential for ensuring significant, stable and erasable optical recording in a-Se films at 290–320 K temperatures, where conventional photodarkening was known as insignificant and unstable. Photocrystallization can only be observed in super-exposed a-Se films at the given experimental conditions of hologram recording. Erasing behavior of surface relief gratings under heat treatment was also investigated in order to reveal further details of the mechanism. Photoinduced structural transformations within the amorphous phase, connected to local ordering under the condition of light-induced fluidity, are proposed as an explanation for the relief formation and erasing. The observed reversible optical recording process may be useful for the various optoelectronic applications of photoconductive a-Se layers. Received: 12 June 2000 / Accepted: 6 June 2001 / Published online: 30 August 2001  相似文献   
156.
This paper reports on the first experimental observation of quantum-well states and sp-type resonances in thin single-crystal gold, silver, and copper layers formed on single-crystal W(110) surfaces, which result from spatial localization of Bloch-type electronic wave functions in a quantum well with potential barriers at the vacuum/metal and metal/W(110) interfaces. The quantization of the valence-band electronic structure in Au/W(110), Ag/W(110), and Cu/W(110) systems was studied experimentally using angle-resolved photoelectron spectroscopy.  相似文献   
157.
The Al2O3−CdSe interface of a thin-film transistor is investigated in the frequency range 30 Hz-30 kHz under weak depletion and accumulation. The surface states are, most likely, located in the insulator Al2O3 with a concentration varying from 4·1018 to 1019 cm−3 eV−1. The surface states have a negligible influence on the thin-film transistor operation.  相似文献   
158.
159.
160.
The simple relation between representations of the covering groups of SL2 and GL2 makes it possible to fuse and extend the recent metaplectic results of Shimura, Waldspurger, Flicker, and ourselves. By giving a new (purely local andL-function theoretic) treatment of the Waldspurger-Shintani correspondence, we also simplify some of Waldspurger’s original results.  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