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   700213篇
  免费   5378篇
  国内免费   2003篇
化学   340186篇
晶体学   9882篇
力学   38238篇
综合类   27篇
数学   112839篇
物理学   206422篇
  2021年   5833篇
  2020年   6288篇
  2019年   7173篇
  2018年   19330篇
  2017年   19181篇
  2016年   19144篇
  2015年   8029篇
  2014年   12576篇
  2013年   28163篇
  2012年   24989篇
  2011年   35204篇
  2010年   24501篇
  2009年   24890篇
  2008年   30260篇
  2007年   31953篇
  2006年   22049篇
  2005年   20676篇
  2004年   19666篇
  2003年   18313篇
  2002年   17240篇
  2001年   17696篇
  2000年   13700篇
  1999年   10553篇
  1998年   9122篇
  1997年   9007篇
  1996年   8507篇
  1995年   7576篇
  1994年   7617篇
  1993年   7358篇
  1992年   7877篇
  1991年   8278篇
  1990年   7991篇
  1989年   7910篇
  1988年   7704篇
  1987年   7437篇
  1986年   7165篇
  1985年   9152篇
  1984年   9566篇
  1983年   7994篇
  1982年   8228篇
  1981年   7787篇
  1980年   7368篇
  1979年   7997篇
  1978年   8219篇
  1977年   8181篇
  1976年   8158篇
  1975年   7789篇
  1974年   7579篇
  1973年   7955篇
  1972年   5850篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
V. A. Steklov Mathematics Institute, USSR Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 79, No. 3, pp. 347–358, June, 1989.  相似文献   
13.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 46–50, January, 1991.  相似文献   
14.
15.
A systematic study on the electrochemical behavior of diosmin in Britton-Robinson buffer (pH 2.0-10.0) at a glassy carbon electrode (GCE) was made. The oxidation process of the drug was found to be quasi-reversible with an adsorption-controlled step. The adsorption stripping response was evaluated with respect to various experimental conditions, such as the pH of the supporting electrolyte, the accumulation potential and the accumulation time. The observed anodic peak current at +0.73 V vs. Ag/AgCl reference electrode increased linearly over two orders of magnitude from 5.0x10(-8) M to 9.0x10(-6) M. A limit of detection down to 3.5x10(-8) M of diosmin at the GCE was achieved with a mean recovery of 97+/-2.1%. Based on the electrochemical data, an open-circuit accumulation step in a stirred sample solution of BR at pH 3.0 was developed. The proposed method was successfully applied to the determination of the drug in pharmaceutical formulations. The results compared favorably with the data obtained via spectrophotometric and HPLC methods.  相似文献   
16.
Ionic conductivity of dry quaternary ammonium polymer, polydiallyldimethylammonium with Cl and H2PO4 counter ions was studied in a wide range of frequencies (10−2-107 Hz) and temperatures (300-470 K). The data were analysed within the formalism of permittivity. WAXS, and thermal properties of this polymer were investigated prior to conductivity measurements.  相似文献   
17.
18.
Systems for automatic detection and correction of spelling errors in natural language texts are considered. The development of such systems for both English and Russian (and for inflected languages in general, including all Slavic languages) is discussed. An approach associated with morphological analysis of the wordforms in the given text is described. The topics considered in the paper include the main methods of automatic spelling correction, levels of automation of the spelling error correction process, the effect of the type of computer used, the use of spelling error correctors in a stand-alone mode and in combination with word-processing software, and the maintenance of auxiliary dictionaries.Translated from Itogi Nauki i Tekhniki, Seriya Teoriya Veroyatnostei, Matematicheskaya Statistika, Teoreticheskaya Kibernetika, Vol. 28, pp. 111–139, 1988.  相似文献   
19.
Consider a projective algebraic variety W which is an irreducible component of the set of all common zeros of a family of homogeneous polynomials of degrees less than d in n + 1 variables over a field of zero characteristic. Consider a dominant rational morphism from W to W′ given by homogeneous polynomials of degree d′. We suggest algorithms for constructing objects in general position related to this morphism. They generalize some algorithms from the first part of the paper to the case dim W > dim W′. These algorithms are deterministic and polynomial in (dd′)n and the size of the input. Bibliography: 12 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 325, 2005, pp. 181–224.  相似文献   
20.
The nonlinear theory of thermally stimulated depolarization currents is developed. The theory explains the processes of hetero- and homocharge relaxation in complex crystals with hydrogen bonds and allows the relaxation oscillator parameters to be calculated using the quadratic approximation for the external electric field.  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