全文获取类型
收费全文 | 1388963篇 |
免费 | 29671篇 |
国内免费 | 7744篇 |
专业分类
化学 | 696180篇 |
晶体学 | 20904篇 |
力学 | 76151篇 |
综合类 | 113篇 |
数学 | 246125篇 |
物理学 | 386905篇 |
出版年
2021年 | 13515篇 |
2020年 | 15920篇 |
2019年 | 16034篇 |
2018年 | 15836篇 |
2017年 | 14489篇 |
2016年 | 29203篇 |
2015年 | 21039篇 |
2014年 | 30366篇 |
2013年 | 74218篇 |
2012年 | 40730篇 |
2011年 | 40745篇 |
2010年 | 39686篇 |
2009年 | 41671篇 |
2008年 | 39249篇 |
2007年 | 36017篇 |
2006年 | 38170篇 |
2005年 | 33170篇 |
2004年 | 32943篇 |
2003年 | 30388篇 |
2002年 | 30702篇 |
2001年 | 29704篇 |
2000年 | 25486篇 |
1999年 | 22868篇 |
1998年 | 21153篇 |
1997年 | 21070篇 |
1996年 | 21160篇 |
1995年 | 19175篇 |
1994年 | 18642篇 |
1993年 | 18188篇 |
1992年 | 18229篇 |
1991年 | 18495篇 |
1990年 | 17696篇 |
1989年 | 17770篇 |
1988年 | 17395篇 |
1987年 | 17303篇 |
1986年 | 16208篇 |
1985年 | 22614篇 |
1984年 | 23859篇 |
1983年 | 20054篇 |
1982年 | 21660篇 |
1981年 | 20895篇 |
1980年 | 20221篇 |
1979年 | 20467篇 |
1978年 | 21755篇 |
1977年 | 21363篇 |
1976年 | 21059篇 |
1975年 | 19771篇 |
1974年 | 19434篇 |
1973年 | 19905篇 |
1972年 | 14395篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
861.
M. A. Mikhaleva B. M. Bolotin T. A. Kizner E. S. Serebrykova 《Chemistry of Heterocyclic Compounds》1994,30(1):79-81
We have synthesized 5-alkyl(alkoxy)-2-(o-lzydroxy-p-alkoxyphenyl)pyrimidines and considered the effect of the OH group on the inesomorphism. We have found that in binuclear o-hydroxyarylpyrimidines, an ortho OH group forming an intramolecular hydrogen bond increases Tmp, inhibits the appearance of nematic properties, and promotes the appearance of a smectic A.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 30, No. 1, pp. 90–92, January, 1994. 相似文献
862.
By changing the conditions of the electrohydraulic treatment of aqueous plant heterodisperse systems comparatively high degradation
of the lignin component of plant tissue has been achieved. In addition to free monosaccharides, their reduced forms have been
detected in the aqueous phase.
Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89
14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 795–798, November–December, 1994. 相似文献
863.
G. N. Dalimova Kh. A. Abduazimov R. K. Rakhmanberdieva V. G. Gorokhova L. N. Petrushenko B. A. Babkin N. A. Koshilev 《Chemistry of Natural Compounds》1994,30(3):400-403
On the basis of the results of acid hydrolysis, chromatographic analysis of the hydrolysates, and a study of IR spectra, it has been established that the suspended particles liberated under the action of electrohydraulic shocks on heterodisperse water—plant systems consist of small fragments of the lignocarbohydrate complex of the plant tissue. 相似文献
864.
865.
A. Sh. Isamukhamedov N. P. Goncharova A. I. Glushetskova 《Chemistry of Natural Compounds》1994,30(2):170-174
The influence of sunflowerseed and cottonseed oils and also of fractions of normal and oxidized triacylglycerols isolated from them on cytochrome P-450 from rat liver microsomes has been investigated. 相似文献
866.
867.
868.
A. Aitmambetov S. N. Shinkaruk S. P. Bondarenko V. P. Khilya 《Chemistry of Natural Compounds》1994,30(4):453-456
6-Halogeno-1,3-benzodioxane analogs of chalcones have been synthesized by various methods. Flavanone and flavone analogs of silandrin and hydnocarpin have been obtained from them. The structures of the new flavonoids have been shown by their PMR spectra. 相似文献
869.
The electron-impact mass spectra of a number of phenylpropanoids and iridoid glycosides containing a phenylethanoid fragment in their structure have been studied. This has revealed features of the formation of fragments of 4-hydroxyphenylethyl and 3,4-dihydroxyphenylethyl alcohols and also of fragments of phenylethylamine and indolylethylamine derivatives present in the structures of the compounds investigated. 相似文献
870.