全文获取类型
收费全文 | 390332篇 |
免费 | 2748篇 |
国内免费 | 1036篇 |
专业分类
化学 | 203966篇 |
晶体学 | 5997篇 |
力学 | 18453篇 |
综合类 | 16篇 |
数学 | 45819篇 |
物理学 | 119865篇 |
出版年
2020年 | 3499篇 |
2019年 | 4178篇 |
2018年 | 6502篇 |
2017年 | 6571篇 |
2016年 | 8172篇 |
2015年 | 4435篇 |
2014年 | 7355篇 |
2013年 | 16447篇 |
2012年 | 13037篇 |
2011年 | 15206篇 |
2010年 | 11405篇 |
2009年 | 11469篇 |
2008年 | 14316篇 |
2007年 | 14168篇 |
2006年 | 12913篇 |
2005年 | 14068篇 |
2004年 | 13192篇 |
2003年 | 11099篇 |
2002年 | 9614篇 |
2001年 | 10415篇 |
2000年 | 8062篇 |
1999年 | 6091篇 |
1998年 | 5225篇 |
1997年 | 5330篇 |
1996年 | 4932篇 |
1995年 | 4204篇 |
1994年 | 4402篇 |
1993年 | 4347篇 |
1992年 | 4764篇 |
1991年 | 4893篇 |
1990年 | 4683篇 |
1989年 | 4739篇 |
1988年 | 4600篇 |
1987年 | 4573篇 |
1986年 | 4375篇 |
1985年 | 5644篇 |
1984年 | 5821篇 |
1983年 | 4763篇 |
1982年 | 5026篇 |
1981年 | 4879篇 |
1980年 | 4496篇 |
1979年 | 5039篇 |
1978年 | 5138篇 |
1977年 | 5292篇 |
1976年 | 5311篇 |
1975年 | 4968篇 |
1974年 | 4885篇 |
1973年 | 5110篇 |
1972年 | 3666篇 |
1971年 | 3340篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.
J. E. Fischer E. Werwa P. A. Heiney 《Applied Physics A: Materials Science & Processing》1993,56(3):193-196
We have used both reflection-geometry and grazing-incidence-geometry X-ray scattering to study thin films of C60 evaporated onto mica substrates via a hot-wall technique. The growth mode yields close-packed C60 planes, which are parallel to the substrate surface and which exhibit out-of-plane correlation lengths of 850 Å. In the film plane the C60 is at best pseudo-epitaxial, with a 0.9° distribution of crystallite orientations, a 450 Å in-plane correlation length, and a 3.7% lattice mismatch, better than obtained by other thin film techniques but far from the accepted definition of single crystal thin film epitaxy. 相似文献
22.
23.
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
24.
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
25.
26.
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
27.
28.
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
29.
30.
N. I. Khamidov B. T. Kadyrov N. T. Ul'chenko A. Sh. Isamukhamedov A. I. Glushenkova 《Chemistry of Natural Compounds》1994,30(4):430-433
The phsicochemical indices and the fatty-acid and triacylglycerol compositions of cottonseed and palm oils, of cottonseed
oil hydrogenate, and of compositions based on them have been determined with the aid of IR and UV spectroscopies, GLC analysis,
and chemical transformations. The compositions and amounts of the main classes of lipids in the initial oils and the hydrogenate
have been studied. It has been found that in the process of hydrogenation the amount of oxygenated components falls.
The work was conducted with the financial support of the Uzbek Fund for Fundamental Investigations. 相似文献