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   368803篇
  免费   3833篇
  国内免费   1118篇
化学   179427篇
晶体学   4251篇
力学   19268篇
综合类   14篇
数学   65142篇
物理学   105652篇
  2020年   2457篇
  2019年   2597篇
  2018年   13513篇
  2017年   13367篇
  2016年   11107篇
  2015年   4096篇
  2014年   5269篇
  2013年   12401篇
  2012年   12991篇
  2011年   21202篇
  2010年   13401篇
  2009年   13429篇
  2008年   16882篇
  2007年   19033篇
  2006年   10267篇
  2005年   10325篇
  2004年   9780篇
  2003年   9329篇
  2002年   8220篇
  2001年   8107篇
  2000年   6396篇
  1999年   4836篇
  1998年   4331篇
  1997年   4245篇
  1996年   4158篇
  1995年   3795篇
  1994年   3932篇
  1993年   3661篇
  1992年   4133篇
  1991年   3991篇
  1990年   3932篇
  1989年   3702篇
  1988年   3746篇
  1987年   3710篇
  1986年   3483篇
  1985年   4679篇
  1984年   4953篇
  1983年   4124篇
  1982年   4261篇
  1981年   4178篇
  1980年   4164篇
  1979年   4142篇
  1978年   4447篇
  1977年   4364篇
  1976年   4398篇
  1975年   4066篇
  1974年   4093篇
  1973年   4223篇
  1972年   2959篇
  1971年   2489篇
排序方式: 共有10000条查询结果,搜索用时 31 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