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   269408篇
  免费   2562篇
  国内免费   637篇
化学   143530篇
晶体学   3743篇
力学   12005篇
综合类   9篇
数学   29992篇
物理学   83328篇
  2019年   2375篇
  2018年   3155篇
  2017年   3153篇
  2016年   4602篇
  2015年   2779篇
  2014年   4407篇
  2013年   10848篇
  2012年   8289篇
  2011年   10143篇
  2010年   7208篇
  2009年   6996篇
  2008年   9502篇
  2007年   9646篇
  2006年   9018篇
  2005年   8189篇
  2004年   7541篇
  2003年   6824篇
  2002年   6737篇
  2001年   7377篇
  2000年   5705篇
  1999年   4395篇
  1998年   3888篇
  1997年   3878篇
  1996年   3626篇
  1995年   3377篇
  1994年   3526篇
  1993年   3223篇
  1992年   3689篇
  1991年   3689篇
  1990年   3615篇
  1989年   3472篇
  1988年   3585篇
  1987年   3481篇
  1986年   3302篇
  1985年   4384篇
  1984年   4644篇
  1983年   3889篇
  1982年   3950篇
  1981年   3859篇
  1980年   3838篇
  1979年   3811篇
  1978年   4143篇
  1977年   4065篇
  1976年   4134篇
  1975年   3803篇
  1974年   3867篇
  1973年   4013篇
  1972年   2828篇
  1971年   2356篇
  1970年   2170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