全文获取类型
收费全文 | 706篇 |
免费 | 1篇 |
专业分类
化学 | 622篇 |
力学 | 16篇 |
数学 | 6篇 |
物理学 | 63篇 |
出版年
2022年 | 10篇 |
2021年 | 16篇 |
2020年 | 14篇 |
2019年 | 20篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 28篇 |
2015年 | 8篇 |
2014年 | 14篇 |
2013年 | 75篇 |
2012年 | 34篇 |
2011年 | 35篇 |
2010年 | 25篇 |
2009年 | 23篇 |
2008年 | 32篇 |
2007年 | 23篇 |
2006年 | 27篇 |
2005年 | 32篇 |
2004年 | 26篇 |
2003年 | 17篇 |
2002年 | 17篇 |
2001年 | 12篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1973年 | 8篇 |
1972年 | 8篇 |
1971年 | 9篇 |
1970年 | 3篇 |
1969年 | 8篇 |
1968年 | 4篇 |
排序方式: 共有707条查询结果,搜索用时 15 毫秒
1.
2.
A. A. Sobanov A. V. Zolotukhin I. V. Galkina V. I. Galkin R. A. Cherkasov 《Russian Journal of General Chemistry》2006,76(3):421-429
A complex spectral (UV, IR, and 31P NMR), preparative, and kinetic investigation of the mechanism of the noncatalytic variant of the Pudovik reaction in the series of imines was carried out. The reaction proceeds through a four-center cyclic transition state. The transition state is highly labile, which determines its high sensitivity to the structure of the reagents, the nature of the solvent and catalyst, and some other factors. The necessary condition for the hydrophosphorylation of imines to occur is the participation of proton-donor reagents and acidic admixtures, specifically hydrolysis products of dialkyl hydrogen phosphites, such as monoalkyl dihydrogen phosphates and phosphorous acid, which act as acid catalysts. When the starting reagents are thoroughly purified and no such catalysts are present, the Pudovik reaction fails to occur in the imine series. 相似文献
3.
4.
5.
R. A. Cherkasov V. I. Galkin N. G. Khusainova O. A. Mostovaya A. R. Garifzyanov G. Kh. Nuriazdanova N. S. Krasnova E. A. Berdnikov 《Russian Journal of Organic Chemistry》2005,41(10):1481-1484
New and previously known β-aminoethylphosphonates were synthesized by addition of primary and secondary amines to vinylphosphonates, and their IR and NMR spectra were examined. Diethyl 2-diethylaminoethylphosphonate and diethyl 2-morpholinoethylphosphonate were found to be stronger bases than the corresponding aminomethylphosphonates, but all these are weaker bases than their precursors, nonphosphorylated amines. Distribution constants of β-aminophosphonates between water and some organic solvents were determined and compared with those of their α-amino homologs. 相似文献
6.
A. R. Garifzyanov N. V. Shirshova R. A. Cherkasov 《Russian Journal of General Chemistry》2005,75(4):537-540
Transport of some inorganic acids (HCl, HBr, HClO4, HNO3, H2SO4, and H2PO4) through hydrophobic impregnated membranes with aminophosphoryl compounds of the general formula R
2
1
P(O)CH2 ⋅ NR2R3 [R1 = C4H9(C2H5)CHCH2O, R2 = C4H9, R3 = C8H17; R1 = R3 = C8H17, R2 = H; R1 = C10H2, R2 = R3 = C2H5; R1 = C10H21, R2 + R3 = (CH2)2O(CH2)2; R1 = C8H17, R2 = H, R3 = 2-quinolyl] and dodecylamine as carriers was studied. The membrane phases were solutions of the carriers in phenylcyclohexane and tridecane. General regularities that correlate the structure of an aminophosphoryl compounds to its transport properties toward inorganic acids were established. The largest flows are characteristic of perchloric, nitric, and hydrobromic acids.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 575–578.Original Russian Text Copyright © 2005 by Garifzyanov, Shirshova, Cherkasov. 相似文献
7.
L. P. Stepovik M. V. Gulenova I. M. Martynova N. S. Skvortsov V. K. Cherkasov 《Russian Journal of General Chemistry》2005,75(7):1098-1107
Trialkyl(aryl)silanes and -germanes effectively react with metal (Al, Ti) tert-butylate-tert-butyl-hydroperoxide under mild conditions (room temperature, benzene or tetrachloromethane) mainly by the element-hydrogen bond. The character of the products depends on the nature of the element, the structure of the radical bound to it, and the solvent. The process is radical in nature. It includes the stages of formation of element-centered radicals and their reaction with the oxygen generated by the system. The intermediate organometallic peroxides can also acts as oxidants for the element (Si, Ge)-hydrogen bonds.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1161–1170.Original Russian Text Copyright © 2005 by Stepovik, Gulenova, Martynova, Skvortsov, Cherkasov. 相似文献
8.
A. I. Kuramshin I. V. Pavlova R. A. Cherkasov 《Russian Journal of Organic Chemistry》2005,41(9):1271-1279
New carbonyl π-complexes of tungsten(0) with cyclohexanone, cyclohexanethione, and N-cyclo-hexylideneaniline were synthesized. Geometric and electronic parameters of the ligands, as well as energy parameters of the complex formation process, were determined by quantum-chemical calculations. Hydrophosphorylation with diethyl phosphonate changed the reactivity of coordinated N-cyclohexylideneaniline, while no analogous effect was observed for cyclohexanone and cyclohexanethione. 相似文献
9.
M. V. Gulenova L. P. Stepovik V. K. Cherkasov 《Russian Journal of General Chemistry》2006,76(6):980-988
Oxidation of the isopropoxy group in the Zr(i-PrO)4·i-PrOH complex involves both direct reaction with tert-butyl hydroperoxide and intermediate formation of zirconium peroxy compound. Zirconium tetra-tert-butoxide reacts with tert-bytyl hydroperoxide to form metal-containing peroxide and trioxide. Decomposition of the latter leads to oxygen evolution and is accompanied by radical formation. The alkoxyl and peroxyl radicals formed were identified by ESR spectroscopy. The nature of the oxidant (oxygen, zirconium-containing peroxide and-trioxide) in the Zr(OBu-t)4-t-BuOOH system is determined by the structure of the substrate molecule. 相似文献
10.
A. R. Garifzyanov G. Kh. Nuriazdanova S. V. Zakharov R. A. Cherkasov 《Russian Journal of General Chemistry》2004,74(12):1885-1889
Two-phase potentiometric titration was used to determine partition constants for a series of -aminophosphonates (RO)2P(O)CH2NR1R2 [R = Alk (C2-C5), R1, R2 = Me, Et, (CH2)5] between water and organic solvents, such as chloroform, carbon tetrachloride, toluene, octane, n-octanol, nitrobenzene, o-xylene, and cyclohexane. Correlations between the partition constants and the number of carbon atoms in substrate molecules were obtained. Solvent effects on partition constants were discussed, and solution parameters of -aminophosphonates were calculated.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004, pp. 1998–2002.Original Russian Text Copyright © 2004 by Garifzyanov, Nuriazdanova, Zakharov, Cherkasov.This revised version was published online in April 2005 with a corrected cover date. 相似文献