全文获取类型
收费全文 | 1117篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 353篇 |
晶体学 | 9篇 |
力学 | 79篇 |
数学 | 175篇 |
物理学 | 504篇 |
出版年
2021年 | 21篇 |
2020年 | 13篇 |
2019年 | 24篇 |
2018年 | 37篇 |
2017年 | 30篇 |
2016年 | 38篇 |
2014年 | 20篇 |
2013年 | 35篇 |
2012年 | 34篇 |
2011年 | 28篇 |
2010年 | 31篇 |
2009年 | 27篇 |
2008年 | 31篇 |
2007年 | 34篇 |
2006年 | 50篇 |
2005年 | 26篇 |
2004年 | 22篇 |
2003年 | 23篇 |
2002年 | 22篇 |
2001年 | 26篇 |
2000年 | 26篇 |
1999年 | 12篇 |
1998年 | 25篇 |
1997年 | 13篇 |
1996年 | 17篇 |
1995年 | 18篇 |
1994年 | 10篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 24篇 |
1989年 | 10篇 |
1988年 | 19篇 |
1987年 | 23篇 |
1986年 | 15篇 |
1985年 | 27篇 |
1984年 | 22篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1976年 | 12篇 |
1975年 | 17篇 |
1974年 | 15篇 |
1973年 | 11篇 |
1970年 | 14篇 |
1969年 | 10篇 |
1968年 | 15篇 |
1967年 | 13篇 |
排序方式: 共有1120条查询结果,搜索用时 15 毫秒
11.
Komarov A. V. Yakovlev I. P. Novikov D. V. Zakhs V. E. 《Russian Journal of General Chemistry》2003,73(12):1936-1941
4-Hydroxy-5-methyl(phenyl)-2-styryl-6H-1,3-oxazin-6-ones react with hydrazine and phenylhydrazine to give the corresponding 3,5-substituted triazoles. Treatment of the title compounds with ethanol and methanol leads to formation of N-cinnamoylmalonamates. The structure of the products was confirmed by the IR and 1H and 13C NMR spectra. 相似文献
12.
13.
Lensovet Leningrad Technological Institute. Plastpolimer Okhta Scientific-Production Association. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 4, pp. 22–28, July–August, 1991. 相似文献
14.
15.
V. S. Bogdanov S. V. Baranin A. Dib I. P. Yakovlev V. A. Dorokhov 《Russian Chemical Bulletin》1992,41(9):1693-1699
Mono- and binuclear boron chelates have been synthesized by the action of butylthiodibutylborane on the ethyl esters of 4-[N-(R-pyrid-2-yl)carbamoyl]-3-amino-2-cyanobuten-2-ic acids (codimers of N-(R-pyrid-2-yl) amides and the ethyl ester of cyanoacetic acid). Complexes of this type can exist in solution in the form of two tautomers: acetamide acid derivatives or the corresponding ketene N,O-acetals.N. D. Zelinski Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2162–2170, September, 1992. 相似文献
16.
UV absorption spectra of acetyl fluoride-h3 and -d3 (CH3COF and CD3COF) molecules in the region of S1S0 electronic transitions are investigated. The origins (00
0 or 140±
0) of these transitions are observed at 39912 and 39904 cm–1, respectively, and some of the fundamental frequencies of these molecules in the s0 and S1 states are determined. In particular, the systems of torsion and inversion (out-of-plane C=O vibrations) energy levels are studied. The geometric parameters of an acetyl fluoride-h3 molecule in the S1 state are estimated by the theoretical simulation of the rotational contours of the 00
0 (140±
0) band. These data are used to evaluate the potential barriers to internal rotation in the S0 and S1 states, which were found to be 360 and 560 cm–1 for acetyl fluoride-h3 and 380 and 770 cm–1 for acetyl fluoride-d3, respectively, as well as the potential barriers to inversion in the S1 states, which were found to be 2090 and 2370 cm–1 for acetyl fluoride-h3 and acetyl fluoride-d3, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1957–1964, November, 1994.In conclusion, the authors would like to acknowledge T. S. Kuznetsova for the synthesis and purification of the AF samples.The research presented here was supported in part by the International Science Foundation under grant No. MJ 1000. 相似文献
17.
A. V. Yakovlev A. I. Finaenov S. L. Zabud’kov E. V. Yakovleva 《Russian Journal of Applied Chemistry》2006,79(11):1741-1751
Results obtained in synthesis of thermally expanded graphite by chemical and electrochemical methods with sulfuric and nitric acids are summarized. The possibility of controlling the properties of thermally expanded graphite compounds in electrochemical synthesis is demonstrated. The existing and promising application areas of thermally expanded graphite are analyzed. 相似文献
18.
A.B. Zolotoy O.A. Dyachenko L.O. Atovmyan I.P. Yakovlev V.O. Reichsfeld 《Journal of organometallic chemistry》1980,190(3):267-276
The structure of 5-ethyl-5,10-dihydro-10,10-diphenylphenazasiline has been determined from three-dimensional X-ray data collected by counter methods. The compound in the monoclinic space group P21/b with a 10.782(5), b 22.642(9), c 8.830(4) Å and γ 74°41′(2). The observed and calculated densities (Z = 4) are 1.22 and 1.21 g cm-3, respectively. Anisotropic(Si, N, C)-isotropic block-diagonal least squares refinement gave a conventional R factor of 3.9% for 1871 reflections with I>2σ(I). The central six-membered ring of the tricyclic system adopts a boat conformation; the dihedral angle between the benzo-group planes is 157.3°. The CSiC angle in the heterocycle is 101.1(1)°; the mean SiC bond length is 1.850(2) Å (in the cycle) and 1.862(2) Å (with Ph group). The nitrogen atom is displaced 0.05 Å from the plane of the adjacent carbon atoms; the sum of the angle about N is 359.7°. 相似文献
19.
Yu. V. Yakovlev N. N. Dogadkin O. I. Kutchinskaja 《Journal of Radioanalytical and Nuclear Chemistry》1975,28(1-2):201-207
A calculation method of self-shielding coefficients of interesting elements in samples of any forms is given for the neutron
activation analysis of cadmium and its compounds. The determination of ten elements in cadmium telluride using radiochemical
separation and γ spectrometry is described.
相似文献
20.
V. M. Yakovlev D. V. Ovchinnikov I. G. Fokeeva 《Russian Journal of Applied Chemistry》2005,78(2):336-338
The dissociation energy of heteronuclear diatomic molecules with polar covalent bonds was calculated by the modified Pauling procedure taking into account the presence of an unpaired electron on one of the atoms.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 341–343.Original Russian Text Copyright © 2005 by Yakovlev, Ovchinnikov, Fokeeva. 相似文献