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   420057篇
  免费   3113篇
  国内免费   1068篇
化学   192298篇
晶体学   5854篇
力学   23556篇
综合类   9篇
数学   78956篇
物理学   123565篇
  2020年   2248篇
  2019年   2492篇
  2018年   19026篇
  2017年   19555篇
  2016年   13001篇
  2015年   4306篇
  2014年   4902篇
  2013年   11440篇
  2012年   15201篇
  2011年   29139篇
  2010年   17933篇
  2009年   18111篇
  2008年   24034篇
  2007年   28764篇
  2006年   9800篇
  2005年   15344篇
  2004年   12066篇
  2003年   11776篇
  2002年   9083篇
  2001年   7785篇
  2000年   6275篇
  1999年   4575篇
  1998年   4126篇
  1997年   4051篇
  1996年   3954篇
  1995年   3571篇
  1994年   3668篇
  1993年   3379篇
  1992年   3800篇
  1991年   3820篇
  1990年   3731篇
  1989年   3607篇
  1988年   3714篇
  1987年   3608篇
  1986年   3419篇
  1985年   4528篇
  1984年   4785篇
  1983年   4021篇
  1982年   4161篇
  1981年   4077篇
  1980年   4055篇
  1979年   4031篇
  1978年   4334篇
  1977年   4173篇
  1976年   4254篇
  1975年   3925篇
  1974年   3956篇
  1973年   4150篇
  1972年   2901篇
  1971年   2411篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Russian Journal of Applied Chemistry - In September 1975, the head of Russian electrochemists, Academician A.N. Frumkin (1895–1976), in his report at the XI Mendeleev Congress on General and...  相似文献   
12.
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial...  相似文献   
13.
Makarov  G. N. 《JETP Letters》2022,115(11):660-666
JETP Letters - Using the spectroscopic data on the 235UF6 and 238UF6 molecules and on the lasing frequencies of CF4 and para-H2 lasers and recent results, a method has been proposed to increase the...  相似文献   
14.
Knyazev  Yu. V.  Kazak  N. V.  Gavrichkov  V. A.  Polukeev  S. I.  Ovchinnikov  S. G. 《JETP Letters》2022,116(8):567-573
JETP Letters - Changes in the magnetic properties of FeBO3 single crystals in the course of spin crossover occurring with increasing pressure up to 63 GPa are studied both experimentally and...  相似文献   
15.
Chemistry of Heterocyclic Compounds - 2-Imino-2,5-dihydrofurans are a highly valuable class of heterocyclic compounds that show versatile biological activity and are used in diverse fields of...  相似文献   
16.
Siberian Mathematical Journal - Let $ \{(A_{i},B_{i})\}_{i=1}^{m} $ be a set pair system. Füredi, Gyárfás, and Király called it $ 1 $ -cross intersecting if $...  相似文献   
17.
The recognition of boron compounds is well developed as boronic acids but untapped as organotrifluoroborate anions (R−BF3). We are exploring the development of these and other designer anions as anion-recognition motifs by considering them as substituted versions of the parent inorganic ion. To this end, we demonstrate strong and reliable binding of organic trifluoroborates, R−BF3, by cyanostar macrocycles that are size-complementary to the inorganic BF4 progenitors. We find that recognition is modulated by the substituent's sterics and that the affinities are retained using the common K+ salts of R−BF3 anions.  相似文献   
18.
19.
Russian Physics Journal - The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have...  相似文献   
20.
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials.  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