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   179568篇
  免费   873篇
  国内免费   262篇
化学   89649篇
晶体学   2635篇
力学   9377篇
综合类   7篇
数学   20911篇
物理学   58124篇
  2020年   1848篇
  2019年   2288篇
  2018年   3395篇
  2017年   3523篇
  2016年   4157篇
  2015年   1852篇
  2014年   3586篇
  2013年   7047篇
  2012年   5532篇
  2011年   6586篇
  2010年   5510篇
  2009年   5635篇
  2008年   6360篇
  2007年   6323篇
  2006年   5617篇
  2005年   4980篇
  2004年   4821篇
  2003年   4366篇
  2002年   4521篇
  2001年   4999篇
  2000年   3691篇
  1999年   2823篇
  1998年   2603篇
  1997年   2457篇
  1996年   2253篇
  1995年   2048篇
  1994年   2005篇
  1993年   2038篇
  1992年   2073篇
  1991年   2380篇
  1990年   2314篇
  1989年   2384篇
  1988年   2264篇
  1987年   2294篇
  1986年   2125篇
  1985年   2656篇
  1984年   2670篇
  1983年   2316篇
  1982年   2371篇
  1981年   2275篇
  1980年   2076篇
  1979年   2393篇
  1978年   2547篇
  1977年   2639篇
  1976年   2729篇
  1975年   2536篇
  1974年   2467篇
  1973年   2634篇
  1972年   2152篇
  1971年   1973篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Special features of the absorption and fluorescence spectra of phenols (phenol and para-chlorophenol) in alkalized and acidified aqueous-micellar solutions are studied. It is established that the absorption band of the anionic phenol form is formed in aqueous-alkali media in the presence of ionogenic surfactants. The fluorescence intensity of the anionic phenol form solubilized in micelles is higher than that in water.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 76–80, November, 2004.  相似文献   
992.
993.
The symplectic, optical, and photon-number tomographic symbols of binomial states of the radiation field are studied. Explicit relations for all tomograms of the binomial states are obtained. Two measures for nonclassical properties of these states are discussed.  相似文献   
994.
Aerodynamic interaction of two bodies in a supersonic flow   总被引:1,自引:0,他引:1  
  相似文献   
995.
Certain feedback loops can be used in photorefractive optical schemes to implement periodic states and create spatial gratings characterized by extremely high or low diffraction efficiencies. This highly nonlinear phenomenon is studied both experimentally and numerically. An analytical method is developed for analyzing periodic states with the use of symmetries of time-dependent diffraction equations and fast feedback response. The method is applied to describe the properties of periodic states, including their spatial structure, diffraction-efficiency oscillation period and amplitude, and characteristics of feedback-controlled strong phase modulation.  相似文献   
996.
The double photoionization of helium at high photon energies is considered using a nonrelativistic approach. The central region of the energy spectrum and its contribution to the total process cross section and to the ratio between the double and single ionization cross sections are studied. Interelectronic interaction in the initial state is included exactly, whereas the interaction between the fast outgoing electrons is calculated by perturbation theory. A detailed derivation of the expression for the cross section ratio between double and single ionizations is given. The corresponding results obtained by other authors are analyzed and corrected.  相似文献   
997.
Main properties of the excited states of 118Sn manifesting themselves in cascade γ decay of its compound state are studied. As in heavier nuclei studied earlier, qualitative interpretation of the whole set of observed properties of the nucleus appears to be impossible without accounting for coexistence and interaction of quasiparticle and collective nuclear excitations and their considerable influence on the main parameters of the process under study. From Yadernaya Fizika, Vol. 67, No. 10, 2004, pp. 1845–1849. Original English Text Copyright ? 2004 by Khitrov, Panteleev, Sukhovoj, Honzátko, Tomandl. This article was submitted by the authors in English.  相似文献   
998.
999.
Processes of the inelastic magnetic and weak scattering of tritium-beta-source antineutrinos on the bound electrons of a germanium atom are considered. The results obtained by calculating the spectra and cross sections are presented for the energy-transfer range between 10 eV and 18 keV.  相似文献   
1000.
The precession motion of magnetization in a longitudinal alternating magnetic field for a system of two antiferromagnetically coupled magnetoactive layers is studied. New dynamic modes characterized by large precession amplitudes and doubling of the period are found. The modes can be efficiently controlled using an external magnetic bias field. A new effect consisting in the unsusceptibility of a magnetic subsystem to excitation by an alternating field has been revealed.  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