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   46404篇
  免费   1316篇
  国内免费   16篇
化学   28088篇
晶体学   238篇
力学   761篇
综合类   2篇
数学   8778篇
物理学   9869篇
  2023年   332篇
  2022年   281篇
  2021年   458篇
  2020年   665篇
  2019年   608篇
  2018年   952篇
  2017年   869篇
  2016年   1683篇
  2015年   1388篇
  2014年   1342篇
  2013年   3032篇
  2012年   2863篇
  2011年   2678篇
  2010年   1789篇
  2009年   1497篇
  2008年   2363篇
  2007年   2141篇
  2006年   1909篇
  2005年   1971篇
  2004年   1705篇
  2003年   1416篇
  2002年   1230篇
  2001年   952篇
  2000年   957篇
  1999年   665篇
  1998年   513篇
  1997年   433篇
  1996年   577篇
  1995年   411篇
  1994年   484篇
  1993年   445篇
  1992年   469篇
  1991年   396篇
  1990年   443篇
  1989年   363篇
  1988年   367篇
  1987年   329篇
  1986年   320篇
  1985年   446篇
  1984年   413篇
  1983年   324篇
  1982年   326篇
  1981年   345篇
  1980年   279篇
  1979年   272篇
  1978年   273篇
  1977年   262篇
  1976年   277篇
  1974年   254篇
  1973年   263篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Ferric ferrocyanides synthesized from different sources of ferric cations and ferrocyanide anions and those derived from ferrous ferricyanide, ferrous ferrocyanide and ferric ferricyanide have been studied using Mössbauer and XRD techniques. Structural information of the effect of the provenance on the properties of the final compound is obtained. Significant correlations between isomer shift and quadrupole splitting of inner and outer iron cations have been observed.  相似文献   
82.
83.
84.
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   
85.
86.
This paper describes a robust and fast fitting procedure applicable for relaxing processes that cannot be understood as a discrete sum of single processes but require an activation energy distribution. The method is based on a set of closed-form expressions that allow the computation of the relaxation parameters directly from the isochronal curves obtained experimentally. The usefulness of this method is checked by analyzing the isochronal curves given by a theoretical energy distribution and the magnetic disaccommodation spectra observed in yttrium iron garnet (YIG) samples. PACS 02.60.Ed; 75.60.Lr; 75.50.Gg  相似文献   
87.
Summary. We prove that - under certain conditions - measurable solutions $f$ of the functional equation $f(x)=h(x,y,f(g_{1}(x,y)),\ldots,f(g_{n}(x,y))),\quad(x,y)\in D \subset \mathbb{R}^{s} \times \mathbb{R}^{l}$ are continuous, even if $1\le l\le s$. As a tool we introduce new classes of functions which - roughly speaking - interpolate between continuous and Lebesgue measurable functions. Connection between these classes are also investigated.  相似文献   
88.
The aim of the paper is to investigate the limit behaviour of the least squares estimator of the shift parameter of nearly unstable, nearly stable, and nearly explosive AR(1) models. Both zero start and stationary cases are treated. Connection with the maximum likelihood estimator of the shift parameter of continuous time AR(1) processes is also discussed.  相似文献   
89.
I. Jánossy 《Pramana》2003,61(2):435-445
It is suggested that liquid crystal—polymer interfaces are coupled systems, in which the components mutually influence the orientational state of each other. The photo-orientation process at liquid crystal-polymer interfaces provides a striking example of such a coupling. Experiments show that the anisotropic structure generated by polarised light at a polymer surface is strongly affected by the phase of the liquid crystal covering the polymer. Photo-orientation is significantly more efficient when the liquid crystal is in the isotropic phase than when it exhibits orientational order. The observations are interpreted by assuming that in the smectic and nematic phases the liquid crystal stabilises to a large extent polymer chain-segments aligned parallel to the director, while it blocks the photo-induced formation of chain-segments in the perpendicular direction. Other situations, in which the coupling between the liquid crystal and the polymer can be important, are also discussed briefly.  相似文献   
90.
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