全文获取类型
收费全文 | 239605篇 |
免费 | 2299篇 |
国内免费 | 781篇 |
专业分类
化学 | 133717篇 |
晶体学 | 3463篇 |
力学 | 9021篇 |
综合类 | 7篇 |
数学 | 27648篇 |
物理学 | 68829篇 |
出版年
2021年 | 1897篇 |
2020年 | 2153篇 |
2019年 | 2530篇 |
2018年 | 3424篇 |
2017年 | 3312篇 |
2016年 | 4676篇 |
2015年 | 2683篇 |
2014年 | 4232篇 |
2013年 | 10503篇 |
2012年 | 7994篇 |
2011年 | 9812篇 |
2010年 | 6829篇 |
2009年 | 6497篇 |
2008年 | 9350篇 |
2007年 | 9503篇 |
2006年 | 8876篇 |
2005年 | 8205篇 |
2004年 | 7308篇 |
2003年 | 6604篇 |
2002年 | 6420篇 |
2001年 | 6295篇 |
2000年 | 4994篇 |
1999年 | 3716篇 |
1998年 | 3286篇 |
1997年 | 3327篇 |
1996年 | 3208篇 |
1995年 | 2618篇 |
1994年 | 2706篇 |
1993年 | 2732篇 |
1992年 | 2855篇 |
1991年 | 2896篇 |
1990年 | 2778篇 |
1989年 | 2762篇 |
1988年 | 2716篇 |
1987年 | 2670篇 |
1986年 | 2585篇 |
1985年 | 3394篇 |
1984年 | 3589篇 |
1983年 | 2866篇 |
1982年 | 3220篇 |
1981年 | 3080篇 |
1980年 | 2835篇 |
1979年 | 3049篇 |
1978年 | 3161篇 |
1977年 | 3164篇 |
1976年 | 3102篇 |
1975年 | 2951篇 |
1974年 | 2919篇 |
1973年 | 3051篇 |
1972年 | 2010篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
921.
V. P. Bubnov I. S. Krainskii E. E. Laukhina E. B. Yagubskii 《Russian Chemical Bulletin》1994,43(5):746-750
The effect of the parameters of the electric arc (helium pressure, current and voltage, clearance between electrodes) and of the peculiarities of the setup design (arrangement of electrodes, distance between the arc and the cooling surface, temperature of the soot condensation surface) on the yield of fullerenes has been studied. Conditions for producing soot with a C60 and C70 content up to 43% (toluene extract) have been found.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 805–809, May, 1994.The authors are grateful to N. G. Spitsyna and A. V. Dubovitskii for the determination of the content of C60 and C70 fullerenes in the extract.The work was financially supported by the Russian Foundation for Basic Research (Project 93-03-18705). 相似文献
922.
923.
E. F. Kvashina 《Russian Chemical Bulletin》1994,43(12):2121-2121
The interaction of ditoluenetitanium with CO{in2} has been studied. Based on hydrolysis, thermolysis, and IR spectral data, the conclusion is drawn that a low-valent titanium oxalate is formed.This study was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-5538).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2241–2242, December, 1994. 相似文献
924.
Potassium salts of O-substitutedN-nitrohydroxylamines were synthesized by nitration of O-substituted.N-acetylhydroxylamines followed by treatment of the reaction products with potassium methoxide.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 178–179, January, 1994. 相似文献
925.
926.
927.
Flaked capillary columns with an OV-101/CE-Na{in3}PO{in4} hydrophobic-hydrophilic sorbent have been suggested. This sorbent provides for the analysis of polar and nonpolar substances, including amines and aminoalcohols, in aqueous and organic solvents. The efficiency of new columns was demonstrated for the analysis of 25 organic substances of various classes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2169–2173, December, 1994.The work was financially supported by the Russian Foundation for Basic Research, Project No. 93-03-4969. 相似文献
928.
929.
Sulfonyldiazene-N-oxides2 and3 were obtained by treatment of sulfamide with nitroso compounds1 in the presence of 1,3-dibromoisocyanurate (DBI) in neutral and acid media.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 681–683, April, 1994. 相似文献
930.
E. K. Merabet H. K. Yuen W. A. Grote K. L. Deppermann 《Journal of Thermal Analysis and Calorimetry》1994,42(5):895-906
A new sensitive isothermal titration microcalorimeter using polyvinylidene difluoride (PVDF) as detector has been developed. Heat pulses of less than 0.4 μJ can be detected and the baseline noise level (p-p) is 40 nW. The calorimeter is constructed with one reaction cell (0.7 ml) insulated by several radiation shields inside a vacuum chamber. The performance of the instrument was examined by measuring the heat of protonation of Tris with HCl. The enthalpy of reaction was found to be ?49±1 kJ·mol?1, in good agreement with the reported value of ?47.5 kJ·mol?1. 相似文献