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   337631篇
  免费   3197篇
  国内免费   1232篇
化学   175973篇
晶体学   5695篇
力学   15098篇
综合类   6篇
数学   36654篇
物理学   108634篇
  2019年   2590篇
  2018年   3254篇
  2017年   3145篇
  2016年   5004篇
  2015年   3263篇
  2014年   5112篇
  2013年   14212篇
  2012年   10387篇
  2011年   13058篇
  2010年   8973篇
  2009年   8757篇
  2008年   11957篇
  2007年   11992篇
  2006年   11558篇
  2005年   10669篇
  2004年   9693篇
  2003年   8673篇
  2002年   8527篇
  2001年   9822篇
  2000年   7521篇
  1999年   6028篇
  1998年   5134篇
  1997年   5015篇
  1996年   4786篇
  1995年   4516篇
  1994年   4234篇
  1993年   4302篇
  1992年   4591篇
  1991年   4707篇
  1990年   4441篇
  1989年   4437篇
  1988年   4453篇
  1987年   4364篇
  1986年   4106篇
  1985年   5577篇
  1984年   5903篇
  1983年   4804篇
  1982年   5250篇
  1981年   5018篇
  1980年   4980篇
  1979年   5081篇
  1978年   5270篇
  1977年   5119篇
  1976年   5231篇
  1975年   4884篇
  1974年   4758篇
  1973年   5014篇
  1972年   3351篇
  1971年   2695篇
  1968年   2516篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The Fokker–Planck-type kinetic equation is constructed with the help of the evolution equation for the transverse energy of channelized particles, which in its turn is derived beyond the framework of perturbation theory proceeding from the condition of nonconcervation of the adiabatic invariant.  相似文献   
92.
We discuss some variant superfield representations which can arise by the replacement of some of the usual fields in a multiplet with p-form gauge fields.  相似文献   
93.
We study the asymptotics of some regression functions which occur in the study of high rejections of homogeneous Gaussian random fields.Translated from Statisticheskie Metody Otsenivaniya i Proverki Gipotez, pp. 143–148, 1988.  相似文献   
94.
95.
96.
Specific features of the initiated oxidation of polyethylene and its low-molecular-weight analogue tridecane, associated with the occurrence of the process in the short-chain mode, were studied.  相似文献   
97.
An equation for the standard enthalpy of solvation of a compound in a binary solvent is derived. The enthalpies of solvation in water-methanol mixtures are estimated for 1,3-propane-and 1,6-hexanediols, 1,2,4-butane-and 1,3,5-pentanetriols, 2-methoxy-and 2-propoxyethanols, and diethylene glycol. The enthalpy of solvation of 1,2-dimethoxyethane in the water-methanol mixed solvent is determined experimentally.  相似文献   
98.
The thermal and dielectric behaviors of poly(vinylidene fluoride-trifluoroethylene) copolymers near the ferroelectric-to-paraelectric phase transition are investigated for samples with 20, 25, 30, and 40 mol% trifluoroethylene (TrFE). The data suggest that the transition becomes continuous for a particular composition near 50 mol% TrFE. Experimental data are sensitive to thermal history (kinetics of crystallization, and kinetics and cycling over the structural transition). It is found that several anomalies are present at the structural change, and in particular the 30 mol% TrFE sample shows the most marked anomalies. These phenomena can be attributed to defects, but another possibility would be the existence of an intemediate supplementary phase. Both hypotheses are discussed.  相似文献   
99.
Summary High-purity indium was analysed by spark source mass spectrometry, using electrical and photoplate detection. For the calibration of the differences in elemental sensitivity, a standard sample was prepared in which 10 impurities were determined by graphite furnace atomic absorption spectrometry. In this way accuracies of less than 40% were obtained for relatively homogeneous elements at ppm and sub-ppm level. About 40 elements could be determined with detection limits of 10 to 30 ppb. Two pattern recognition methods, principal component analysis and clustering analysis, were applied to obtain information on trace element distribution, which indicated that a number of elements were strongly spatially correlated in the analysed sample.
Chemische Analyse und Verteilungsbestimmung von Spurenelementen in Indium-Matrix durch Funkenquellen-Massenspektrometrie

On leave from: Department of Chemistry, Nanjing Normal University, Nanjing, People's Republic of China  相似文献   
100.
The purpose of this note is to describe a procedure for transferring familiar estimates for transition probabilities on RN to transition probabilities on compact manifolds.  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