全文获取类型
收费全文 | 340篇 |
免费 | 3篇 |
专业分类
化学 | 297篇 |
晶体学 | 4篇 |
力学 | 4篇 |
数学 | 14篇 |
物理学 | 24篇 |
出版年
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 9篇 |
2013年 | 15篇 |
2012年 | 23篇 |
2011年 | 31篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 19篇 |
2005年 | 18篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有343条查询结果,搜索用时 31 毫秒
1.
2.
Abakumov G. A. Druzhkov N. O. Kurskii Yu. A. Shavyrin A. S. 《Russian Chemical Bulletin》2003,52(3):712-717
Products of thermal transformation of substituted N-aryl-o-quinoneimines were studied using NMR spectroscopy. The formation of 4aH-phenoxazine, which was further dimerized by the Diels—Alder reaction, was established. 相似文献
3.
M. P. Shurygina S. A. Chesnokov M. A. Lopatin V. K. Cherkasov G. A. Abakumov 《Russian Chemical Bulletin》2004,53(11):2485-2489
A study of the kinetics of photoreduction of 9,10-phenanthrenequinone in the presence of hydrogen donors (para-substituted N,N-dimethylanilines and polymethylbenzenes) showed that plots of the quantum yield of photoreduction (H) and apparent reaction rate constant (k
H) vs. oxidation potential of hydrogen donors are extreme. In the presence of amines, k
H and H increase, as a whole, whereas they decrease in the presence of polymethylbenzenes. In coordinates H-G
e (G
e is the change in the free energy of electron transfer) for pairs quinone-H donor, H increases with G
e approaching to zero. For the amine series, this effect is mainly in the exothermic region of G
e (G
e < 0). For the series of polymethylbenzenes, this increase is observed in the endothermic region (G
e > 0).__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2381–2385, November, 2004. 相似文献
4.
G. A. Abakumov V. I. Nevodchikov N. O. Druzhkov L. N. Zakharov L. G. Abakumova Yu. A. Kurskii V. K. Cherkasov 《Russian Chemical Bulletin》1997,46(4):771-776
New di-o-quinones of the biphenyl series, namely, 2,2′-dialkyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinones, were synthesized. Their structures were established by IR and NMR spectroscopy. The molecular
structure of 2,2′-dimethyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinone was established by X-ray structural analysis. The structure is characterized by orthogonal
(the torsion angle is 82.9°) mutual arrangement ofo-benzoquinone fragments. ESR studies demonstrated that chemical reduction of diquinone proceeds in four oneelectron stages
to form paramagnetic mono- and trianions as intermediates. Quinopyrocatechols, which are intermediates in the synthesis of
di-o-quinones, were isolated and characterized.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 804–809, April, 1997. 相似文献
5.
The reaction of decacarbonyldimanganese Mu2(CO)10 (1) With thallium(t) 3,6-di-tert-butyl-o-benzosemiquinolate (2) in solution was studied by ESR spectroscopy. Irradiation of solutions containing1 and2 in organic solvents with visible light at 220–280 K leads totrinuclear MnTlMn complex (3). An analysis of hyperfine structure parameters indicates that3 is a semiquinone complex of thallium. A possible mechanism of the formation of complex3 and its molecular structure was discussed.Translated fromIzveshya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 95–98, January, 1996. 相似文献
6.
G. A. Abakumov V. K. Cherkasov T. N. Kocherova N. O. Druzhkov Yu. A. Kurskii L. G. Abakumova 《Russian Chemical Bulletin》2006,55(7):1195-1199
Reactions of 3,6-di(tert-butyl)-o-benzoquinone with primary amines occur by the nucleophilic 1,4-addition mechanism and lead to the corresponding 2-hydroxy-p-quinonimines, which exist in solutions in equilibrium with tautomeric 4-amino-o-quinones. The thermodynamic parameters of this prototropic isomerism were determined by NMR spectroscopy. In the case of
a secondary amine (piperidine), a derivative of 4-amino-o-quinone was obtained; the corresponding o-semiquinone complexes were studied in solution by ESR spectroscopy.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1151–1155, July, 2006. 相似文献
7.
A. V. Piskunov A. V. Lado G. A. Abakumov V. K. Cherkasov O. V. Kuznetsova G. K. Fukin E. V. Baranov 《Russian Chemical Bulletin》2007,56(1):97-103
Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL2 (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions
in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ2MgLn (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et2O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy2]2 and SQ2Mg·DME complexes were established by X-ray diffraction.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007. 相似文献
8.
G. A. Abakumov N. O. Druzhkov Yu. A. Kurskii L. G. Abakumova A. S. Shavyrin G. K. Fukin A. I. Poddel’skii V. K. Cherkasov L. S. Okhlopkova 《Russian Chemical Bulletin》2005,54(11):2571-2577
Cyclization of substituted quinone imines and diazabutadiene derivatives of aminophenols affords 4aH-phenoxazine or 4H-1,4-benzoxazine derivatives, which are finally transformed into the following fused heterocycles: the stable 1,4,6,8-tetra(tert-butyl)phenoxazin-10-yl radical and 7a,14a,15a, 15b-tetrahydro-14,16-dioxa-5,9-diaza-8,15-ethenohexaphene and 5a,6,11a, 12-tetrahydro[1,4]benzoxazino[3,2-b][1,4]benzoxazine derivatives. The influence of the substituents on the pathways of the reactions of intermediate benzoxazines
and phenoxazines, such as oxidation, [2+4] dimerization, and the closure of the second ring, was studied. The structures of
the fused heterocycles were determined by X-ray diffraction, NMR spectroscopy, and ESR.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2491–2496, November, 2005. 相似文献
9.
A. V. Safronova L. N. Bochkarev N. E. Stolyarova I. K. Grigorieva I. P. Malysheva G. V. Basova G. K. Fukin E. V. Baranov Yu. A. Kurskii G. A. Abakumov 《Russian Chemical Bulletin》2006,55(2):218-221
New germanium-containing tungsten carbyne complexes Ph3GeC≡W(CH2R)3 (R = But or SiMe3) were synthesized by the reaction of the alkoxy derivative Ph3GeC≡W(OBut)3 with alkyllithium reagents RCH2Li. The new compounds were isolated in individual form as crystals in 95 and 90% yields, respectively, and were characterized
by elemental analysis, 1H and 13C NMR spectroscopy, and X-ray diffraction. X-ray diffraction study showed that the coordination environment of the W and Ge
atoms in the Ph3GeC≡ W(CH2But)3 and Ph3GeC≡W(CH2SiMe3)3 complexes can be described as a distorted tetrahedron.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 213—216, February, 2006. 相似文献
10.
Chesnokov S. A. Cherkasov V. K. Abakumov G. A. Kurskii Yu. A. Shurygina M. P. Mamysheva O. N. Shavyrin A. S. 《Russian Chemical Bulletin》2003,52(3):718-724
Photoreduction of o-benzoquinones in the presence of p-bromo-N,N-dimethylaniline under irradiation ( > 500 nm) affords the corresponding pyrocatechols and hydroxyphenyl ethers. The latter are unstable and, in turn, decompose in the dark reaction to pyrocatechols. The ratio between pyrocatechol and hydroxyphenyl ether formed upon the photoreaction is determined by the structure of o-quinone, namely, the presence and bulk of substituents in positions 3 and 6 of the ring. The yield of pyrocatechol is maximal (60—65%) if the substituents are the same (H and H, But and But) or insignificantly differ (Pri and But), regardless of its bulk. 相似文献