全文获取类型
收费全文 | 218篇 |
免费 | 3篇 |
专业分类
化学 | 176篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 7篇 |
物理学 | 29篇 |
出版年
2022年 | 4篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 10篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 11篇 |
2007年 | 5篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 14篇 |
2001年 | 5篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 15 毫秒
161.
Alexander D. Dilman Vitalij V. Levin Pavel A. Belyakov Marina I. Struchkova Vladimir A. Tartakovsky 《Tetrahedron letters》2008,49(28):4352-4354
A method for the nucleophilic trifluoromethylation of arylidenemalononitriles using Me3SiCF3 is described. The reaction is carried out in dimethylformamide in the presence of AcONa as a Lewis base, and affords products of Michael addition in high yield. 相似文献
162.
Lipilin D. L. Churakov A. M. Strelenko Yu. A. Tartakovsky V. A. 《Russian Chemical Bulletin》2002,51(2):311-318
Tin(ii) chloride selectively reduces the aromatic nitro group to the amino group, the azoxy group remaining intact. This allows the preparation of 2-(R-NNO-azoxy)anilines from 2-(R-NNO-azoxy)nitrobenzenes bearing electron-donating or weak electron-withdrawing substituents (Me or Br) in the benzene ring and alkyl substituents at the distal N atom of the azoxy group. The presence of electron-withdrawing substituents at the azoxy group (for example, CO2Et) leads to a change in the direction of the reaction resulting in selective reduction of the azoxy group to the hydrazo group. 相似文献
163.
M. S. Klenov A. M. Churakov O. V. Anikin Yu. A. Strelenko V. A. Tartakovsky 《Russian Chemical Bulletin》2009,58(10):2047-2057
Salts of N-nitro-O-(4-nitrophenyl)hydroxylamine were synthesized by a new method of oxidative nitration, involving the reaction of O-(4-nitrophenyl)hydroxylamine with KNO2 or NaNO2 in the presence of PhI(OAc)2 or PhIO as oxidants. When using Na15NO2, the samples containing the nitro group labeled with the 15N isotope were obtained. Acidification of the appropriate salt gave N-nitro-O-(4-nitrophenyl)hydroxylamine. It is the first N-nitrohydroxylamine isolated in the H-form. Its thermal stability was investigated and the probable mechanism of decomposition
was suggested. From a comparison of the 14N and 15N NMR spectra of N-nitro-O-(4-nitrophenyl)hydroxylamine with those of its O- and N-methylated derivatives, its equilibrium with the aci-form (N=NOOH) was inferred. 相似文献
164.
V. A. Shlyapochnikov G. I. Oleneva N. O. Cherskaya O. A. Luk'yanov V. P. Gorelik O. V. Anikin V. A. Tartakovsky 《Russian Chemical Bulletin》1995,44(8):1449-1453
The vibrational and electronic spectra of dinitramide salts MN(NO2)2 (M=K, Na, Li, NH4, Fe, Ag, Mn, Mg, Rb, C(NH2)3) have been studied. The IR and Raman spectra of solutions and melts of the salts have been satisfactorily interpreted on the basis of the anion model withC
2v
symmetry. The complication of the spectra in the crystalline phase has been explained by restructurization of the anion that reduces its symmetry and makes the nitro groups nonequivalent.For part 6, seeIzv. Akad. Nauk, Ser. Khim., 1995, 113 [Russ. Chem. Bull.,44, 108 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1508–1512, August, 1995. 相似文献
165.
V. A. Tartakovsky A. S. Ermakov D. B. Vinogradov P. V. Bulatov 《Russian Chemical Bulletin》1998,47(4):652-655
Nitration ofN-3-chloroalkoxy-2-hydroxypropyl-N-alkylsulfamates gave the correspondingN-3-chloroalkoxy-2-nitroxypropyl-N-alkylnitramines. Azidation of the latter resulted inN-azido-3-azidoalkoxypropyl-N-alkylnitramines.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 673–676, April, 1998. 相似文献
166.
M. S. Klenov A. M. Churakov Yu. A. Strelenko V. A. Tartakovsky 《Russian Chemical Bulletin》2011,60(10):2051-2056
A new method for the synthesis of benzotetrazine-1,3-dioxides was developed from the 2-(tert-butyl-NNO-azoxy)-N-nitroaniline O-alkyl derivatives upon the action of strong acids (H2SO4, MeSO3H, CF3CO2H) or BF3·Et2O. A mechanism suggested for these reactions includes transformation of the N=N(O)OR group (R = Me, Pri) to the oxodiazonium ion (N=N=O)+, which intramolecularly reacts with the neighboring tert-butyl-NNO-azoxy group, furnishing the tetrazine-1,3-dioxide ring. 相似文献
167.
Sukhorukov AY Boyko YD Ioffe SL Khomutova YA Nelyubina YV Tartakovsky VA 《The Journal of organic chemistry》2011,76(19):7893-7900
Asymmetric synthesis of GlaxoSmithKline's highly potent phosphodiesterase inhibitor 1 has been accomplished in nine steps and 16% overall yield. The original strategy suggested involves as a key step the silylation of enantiopure six-membered cyclic nitronates 4 obtained by a highly stereoselective [4 + 2]-cycloaddition of an appropriate nitroalkene 5 to trans-1-phenyl-2-(vinyloxy)cyclohexane. Functionalization of the resulting 5,6-dihydro-4H-1,2-oxazine and subsequent stereoselective reduction of 1,2-oxazine ring in intermediate 2 furnished the pyrrolizidinone framework with the recovery of chiral auxiliary alcohol. 相似文献
168.
Konnov A. A. Klenov M. S. Churakov A. M. Strelenko Yu. A. Fedyanin I. V. Tartakovsky V. A. 《Russian Chemical Bulletin》2019,68(1):191-193
Russian Chemical Bulletin - The reaction of 2-[(2-azidophenyl)hydrazono]-2-(tert-butyl-NNO-azoxy)-N′-hydr oxyethanimidamide with sodium acetate in DMF aff ords... 相似文献
169.
Smirnov V. O. Tishkov A. A. Lyapkalo I. M. Ioffe S. L. Kachala V. V. Strelenko Yu. A. Tartakovsky V. A. 《Russian Chemical Bulletin》2001,50(12):2433-2440
Silylation of ,-bis(alkyloxycarbonyl)--aryl- and ,-bis(alkyloxycarbonyl)--alkyl-substituted aliphatic nitro compounds proceeds stereoselectively to give the corresponding N,N-bis(trimethylsilyloxy)aminocyclopropanes in high yields. These compounds can be used as synthetic equivalents of nitrosocyclopropanes. 相似文献
170.
We derive an approximate analytical solution, which describes the interface dynamics during the injection of supercritical
carbon dioxide into homogeneous geologic media that are fully saturated with a host fluid. The host fluid can be either heavier
(e.g., brine) or lighter (e.g., methane) than the injected carbon dioxide. Our solution relies on the Dupuit approximation
and explicitly accounts for the buoyancy effects. The general approach is applicable to a variety of phenomena involving variable-density
flows in porous media. In three dimensions under radial symmetry, the solution describes carbon dioxide injection; its two-dimensional
counterpart can be used to model seawater intrusion into coastal aquifers. We conclude by comparing our solutions with existing
analytical alternatives. 相似文献