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   508篇
  免费   16篇
  国内免费   1篇
化学   350篇
晶体学   33篇
力学   7篇
数学   24篇
物理学   111篇
  2024年   2篇
  2023年   4篇
  2022年   13篇
  2021年   19篇
  2020年   10篇
  2019年   14篇
  2018年   14篇
  2017年   17篇
  2016年   21篇
  2015年   13篇
  2014年   28篇
  2013年   38篇
  2012年   29篇
  2011年   40篇
  2010年   13篇
  2009年   21篇
  2008年   30篇
  2007年   26篇
  2006年   17篇
  2005年   21篇
  2004年   15篇
  2003年   8篇
  2002年   10篇
  2001年   4篇
  2000年   4篇
  1998年   2篇
  1997年   7篇
  1995年   4篇
  1994年   2篇
  1993年   3篇
  1992年   6篇
  1989年   5篇
  1988年   4篇
  1986年   5篇
  1985年   4篇
  1984年   4篇
  1983年   3篇
  1982年   8篇
  1981年   11篇
  1980年   2篇
  1979年   3篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
  1966年   5篇
  1962年   1篇
  1960年   2篇
  1957年   1篇
  1948年   2篇
  1946年   1篇
排序方式: 共有525条查询结果,搜索用时 218 毫秒
11.
Thetrans-dioxo ruthenium (VI) complex, [P(C6H5)3C6H5CH2]+[Ru(O)2OAcCl2] or tetrapropylammonium perruthenate catalyzes the oxidation of secondary alcohols to ketones byN-methylmorpholine-N-oxide (NMO). Kinetic studies showed the formation of a complex between catalyst and substrate (alcohol) as the first step in the mechanism.  相似文献   
12.
The kinetics of polymerization of acrylonitrile initiated by the redox systems cyanoacetic acid/Mn(OAc)3 and cyanoacetic acid/tris(benzoylacetonato)manganese(III) in dimethylsulphoxide as solvent have been investigated over the range 20–35°. The kinetics of oxidation are consistent with the formation of intermediate complexes between the reactants, followed by electron transfer. Manganous ions inhibit the reaction by competitive complexation. The primary radicals are very efficient as initiators of polymerization which is terminated by mutual interaction of macroradicals. Mechanisms have been proposed to explain the kinetics; rate and equilibrium constants have been evaluated.  相似文献   
13.
14.
15.
The one-electron oxidation of toluidine blue by specific oxidising radicals such as Cl 2 , Tl(II), N3, Br 2 etc. has been studied by employing the pulse radiolysis technique. The Br 2 radical was found to be less efficient in oxidising toluidine blue as compared to Cl 2 ., Tl+2 and N3. The semioxidised species exhibited only onepK a indicating the presence of two conjugate acid-base forms whose spectral and kinetic features were evaluated. Reaction of OH radicals with the dye gave rise to a transient species which exhibited spectral and kinetic features different from that of the semioxidised species indicating that the mode of reaction of OH is different.  相似文献   
16.
The synthesis of fluorescent 2,10-derivatives of the title chromophore are described. The substituents contain amino-reactive N-hydroxysuccinimde ester and thiol-reactive iodoacetamide groups for attachment to biomolecules. A phosphate derivative was also prepared as an enzyme substrate.  相似文献   
17.
18.
Currently, the existing microbial radionuclides transformations processes are not completely understood. Bacteria, however, solubilize radionuclides by direct enzymatic reduction, or indirectly by its metabolites and by facilitating electrochemical redox systems. Microbes exchange electrons from proteins, organelles, metabolites to metals and electrodes have strengthened the novel bioremediation methods. In contrast, MRCs based on this redox behavior has offered considerable value over traditional treatment because of growing renewable and conception of energy incentives methods. Moreover, MRCs provides a flexible platform that enables us to access integrated treatment process of generating power and for recovering valuable resources from the contaminated sites.  相似文献   
19.
20.
Ten-membered heterocycles of the type PhN(PCl2){OC6H2(R)2 (μ-S(CH2))((R)2─C6H2O─)} (R = Me, iPr or tBu) have been prepared and their transition metal chemistry is explored. Functionalised phosphines react with transition metals to give interesting metallacycles. Several Group 6, ruthenium, platinum metals and novel titanium(IV) metallacycles have been structurally characterized.  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