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   1308026篇
  免费   29897篇
  国内免费   12171篇
化学   648223篇
晶体学   20519篇
力学   75398篇
综合类   419篇
数学   241090篇
物理学   364445篇
  2021年   14619篇
  2020年   16972篇
  2019年   17218篇
  2018年   12789篇
  2016年   28512篇
  2015年   21868篇
  2014年   31792篇
  2013年   76162篇
  2012年   37070篇
  2011年   31832篇
  2010年   37177篇
  2009年   40101篇
  2008年   31317篇
  2007年   26222篇
  2006年   33202篇
  2005年   25344篇
  2004年   27242篇
  2003年   26156篇
  2002年   27569篇
  2001年   24966篇
  2000年   22807篇
  1999年   21916篇
  1998年   21102篇
  1997年   20984篇
  1996年   21328篇
  1995年   19394篇
  1994年   18804篇
  1993年   18283篇
  1992年   17749篇
  1991年   18057篇
  1990年   17270篇
  1989年   17307篇
  1988年   16812篇
  1987年   16851篇
  1986年   15728篇
  1985年   22172篇
  1984年   23533篇
  1983年   19798篇
  1982年   21521篇
  1981年   20759篇
  1980年   20099篇
  1979年   20091篇
  1978年   21513篇
  1977年   21059篇
  1976年   20717篇
  1975年   19380篇
  1974年   19014篇
  1973年   19496篇
  1972年   14016篇
  1967年   12270篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
A semiempirical model is proposed for the calculation of electrical, magnetic and thermal parameters of the plasma of a high-frequency induction discharge. The model is based on solving a system of two-dimensional Maxwell equations written for a cylindrical coordinate system.  相似文献   
952.
A method of teaching of one of the divisions of electrodynamics devoted to relativity theory is suggested. The presentation is based on the four-dimensional formalism, which allows a number of fundamental physical phenomena to be considered from a unified position. The content is in full conformity with the approved standard programs for students and postgraduates of radio physical and radio technical specialities of universities. The methods can be useful to the teachers, scientific workers, and engineers concerned with other directions and specialities.  相似文献   
953.
954.
A possibility of application of semiconductor lasers of the visible range as exciting sources for Raman spectroscopy is studied. An experimental set-up for measuring Raman spectra of polycrystalline dielectrics and broad-gap semiconductors excited by a semiconductor laser with a wavelength of 640 nm was created. The conditions under which the spectral width of the lasing line of a semiconductor laser was within 10-3 cm-1 in the continuous mode with a power of 10 mW are realized. The characteristics of various types of exciting sources used in Raman spectroscopy are compared. The results of studies of the characteristic Raman spectra excited with a semiconductor laser in polycrystalline sulfur are presented.  相似文献   
955.
956.
A physical multidimensional local model of the propagation process of a laser pulse in air having no analogy to famous models in laser physics is constructed. It is based on the representations of classical wave mechanics characteristic of the theory of scalar wave fields.  相似文献   
957.
958.
The study of the effect of a perfectly conducting plane placed at a certain distance from the surface of a potassium niobate crystal on the characteristics of the generalized Rayleigh and Gulyaev-Bleustein surface waves is continued. In addition, the effect of an infinitely thin conducting layer applied to the surface of the piezoelectric on the characteristics of these waves is analyzed. It is found that a variation in the conductance of this layer can produce a result that completely differs from the result obtained when a perfectly conducting plane is moved toward the surface, although the extreme states of these actions (electrically open and short-circuited surfaces) are identical. A possible physical explanation of this difference is proposed.  相似文献   
959.
Measurements of response, gain, and noise immunity are carried out for an underwater compensated additive receiving array with randomly spaced hydrophones that is moored at the bottom of a man-made lake with multimode sound propagation. The in-sea locating ability of a similar array is demonstrated with the sources of noiselike signals at frequencies of 5–100 Hz. A dedicated numerical processor is developed and tested for processing the signals received by a random underwater array.  相似文献   
960.
A phenomenological model for describing the production of Centauro events in relativistic heavy-ion collisions is discussed. The model provides quantitative predictions for kinematical variables, for the baryon number, and for the masses of a Centauro fireball and of its decay products. A Centauro fireball decays predominantly into nucleons, strange hyperons, and possibly strangelets. Centauro events in Pb + Pb collisions at the LHC energy are simulated for the CASTOR detector. The signatures of these events are discussed in detail.  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