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   38668篇
  免费   2339篇
  国内免费   2495篇
化学   20927篇
晶体学   722篇
力学   1857篇
综合类   230篇
数学   5245篇
物理学   14521篇
  2024年   30篇
  2023年   203篇
  2022年   588篇
  2021年   833篇
  2020年   844篇
  2019年   1095篇
  2018年   1487篇
  2017年   1634篇
  2016年   2010篇
  2015年   1276篇
  2014年   1942篇
  2013年   2799篇
  2012年   2759篇
  2011年   2840篇
  2010年   2734篇
  2009年   2750篇
  2008年   2788篇
  2007年   2632篇
  2006年   2384篇
  2005年   1644篇
  2004年   1319篇
  2003年   917篇
  2002年   1017篇
  2001年   914篇
  2000年   1029篇
  1999年   682篇
  1998年   669篇
  1997年   568篇
  1996年   243篇
  1995年   145篇
  1994年   121篇
  1993年   98篇
  1992年   64篇
  1991年   58篇
  1990年   60篇
  1989年   48篇
  1988年   36篇
  1987年   35篇
  1986年   30篇
  1985年   26篇
  1984年   12篇
  1983年   13篇
  1982年   9篇
  1981年   12篇
  1980年   10篇
  1979年   9篇
  1978年   6篇
  1977年   10篇
  1968年   10篇
  1936年   6篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
91.
The specific and nonspecific constituents of the total energy of intermolecular interasction in ethylene glycol, diethylene glycol, and formamide were determined for the range 288.15–323.15 K using a simulation approach. Diethylene glycol, like formamide and ethylene glycol, forms networks of hydrogen bonds. In ethylene glycol and formamide, the hydrogen bonds make a predominant contribution to the total interaction energy. The specific and nonspecific contributions in mixtures of the above solvents with dimethyl-formamide were calculated, and the results were discussed in combination with the data for aqueous dimethyl-formamide solutions.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1789–1796.Original Russian Text Copyright © 2004 by Zaichikov, KrestyaninovThis revised version was published online in April 2005 with a corrected cover date.  相似文献   
92.
93.
Interaction of ITA-31 polyimide binder with a series of industrial sorbents based on styrene and vinylpyridine derivatives was studied.  相似文献   
94.
Analysis of the mechanism of congruent dissociative evaporation of solid substances led to a suggestion that potassium permanganate can be used as a possible kinetic standard in thermal analysis.  相似文献   
95.
A new procedure was developed for preparing carbon films with magnetic metal nanoparticles by thermolysis of a polymer precursor. The conditions for preparing carbon films with required surface concentration of the metal nanoparticles and hence with dielectric or metallic properties were determined.  相似文献   
96.
A novel compound, biotinylated 18β-glycyrrhetinic acid (BGA), was synthesized. It is a compound of 18β-glycyrrhetinic acid linked with biotin. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 266–267, May–June, 2006. An erratum to this article is available at .  相似文献   
97.
The results of studies on the synthesis of defect magnesium oxides by MgO hydration in salt solutions are summarized. The incorporation of oxygen-containing salt anions into the anionic hydroxide/oxide framework is described. In this case, the anion residue whose oxygen atoms belong to the oxygen framework of the oxide is incorporated in the octahedral oxygen cell of the oxide to occupy the place of a virtual magnesium cation. A portion of cationic vacancies remains free, whereas a portion is occupied by the transformed anion residue with a positive charge other than 2+. As a result, defect magnesium oxides are formed as substitutional solid solutions. The structure and charge heterogeneity of defect oxides is responsible for their high catalytic activity.  相似文献   
98.
The concepts of the selective inhibition of reactions with the participation of HO 2· radicals by nitrobenzene in accordance with a cyclic mechanism were supported using cyclohexanol oxidation as an example. It was demonstrated that the nitroxyl radical generated from nitrobenzene selectively reacts with HO2 · to form hydrogen peroxide and nitrobenzene. A decrease in the rates of oxidation of esters, carboxylic acids, and ketones with specially chosen structures in the presence of nitrobenzene, as well as the detection of H2O2 and corresponding ,-unsaturated compounds among the reaction products, indicated that the degradation of -peroxyl radicals of the above compounds occurred under conditions of the liquid-phase oxidation of organic substances that result in the formation of the HO2· radical and an unsaturated compound.Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 814–820.Original Russian Text Copyright © 2004 by Nepomnyashchikh, Nosacheva, Perkel.  相似文献   
99.
For the mixtures of pectin of different esterification degrees and water, heat capacities in the range of 80–320 K have been measured, and DTA measurements have been carried out in the range 80–450 K. The effect of water on the physical transitions of pectin has been studied, and the solubility of water in pectins of different esterification degrees at the temperature of melting of a liquid component has been determined. On the basis on the experimental data, the physical state diagram of the pectin-water system has been constructed and analyzed for the whole range of component concentrations within a wide temperature interval.  相似文献   
100.
The equilibrium and kinetic characteristics of uranium sorption from simulated sulfuric acid leaching solutions by AMP, Lewatit K 6367, Purolite A 500, Purolite A 600, and AM-p gel-like and porous strongly basic anion exchangers were studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 736–740.Original Russian Text Copyright © 2005 by Kolomiets, Troshkina, Sheremet’ev, Konopleva.  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