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   667583篇
  免费   5046篇
  国内免费   1516篇
化学   328260篇
晶体学   9601篇
力学   35628篇
综合类   19篇
数学   95678篇
物理学   204959篇
  2021年   6213篇
  2020年   6725篇
  2019年   7699篇
  2018年   10515篇
  2017年   10740篇
  2016年   14665篇
  2015年   7728篇
  2014年   13319篇
  2013年   29139篇
  2012年   22891篇
  2011年   27079篇
  2010年   20724篇
  2009年   20646篇
  2008年   25745篇
  2007年   25564篇
  2006年   23336篇
  2005年   20760篇
  2004年   19389篇
  2003年   17594篇
  2002年   17557篇
  2001年   18236篇
  2000年   14212篇
  1999年   10998篇
  1998年   9759篇
  1997年   9532篇
  1996年   8900篇
  1995年   7936篇
  1994年   8027篇
  1993年   7811篇
  1992年   8115篇
  1991年   8662篇
  1990年   8375篇
  1989年   8267篇
  1988年   7973篇
  1987年   7820篇
  1986年   7406篇
  1985年   9312篇
  1984年   9841篇
  1983年   8296篇
  1982年   8648篇
  1981年   8093篇
  1980年   7628篇
  1979年   8389篇
  1978年   8590篇
  1977年   8630篇
  1976年   8630篇
  1975年   8234篇
  1974年   8048篇
  1973年   8271篇
  1972年   6349篇
排序方式: 共有10000条查询结果,搜索用时 31 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.
The Langevin dynamics and fluctuational-dissipative relationships for the hydrodynamic fluctuations for systems which are described in the third Barnett order with respect to the gradients of the hydrodynamic variables are generalized on the basis of a kinetic approach.  相似文献   
18.
19.
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   
20.
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   
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