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141.
Chernyshev KA Krivdin LB Larina LI Konkova TV Demina MM Medvedeva AS 《Magnetic resonance in chemistry : MRC》2007,45(8):661-666
Configurational assignment of five carbon, silicon and germanium containing propynal oximes has been carried out by means of experimental measurements and high-level ab initio calculations of their 13C-1H, 13C-13C and 15N-1H spin-spin coupling constants. The title compounds were shown to exist in the nonequilibrium mixture of E and Z isomers with the energy difference of less than 0.3 kcal/mol calculated at the MP2/6-311G** level. 相似文献
142.
K. A. Chernyshev L. I. Larina E. A. Chirkina V. G. Rozinov L. B. Krivdin 《Russian Journal of Organic Chemistry》2011,47(12):1859-1864
Theoretical and experimental studies on magnetic shielding of the phosphorus nucleus in trichloro-[2-(1H-pyrazol-1-yl)ethenyl]phosphonium hexachlorophosphate(V) and 1,1,1,1-tetrachloro-1H-1λ6-pyrazolo-[1,2-a][1,2,3]diazaphosphol-8-ium-1-ide showed that intramolecular coordination of the phosphorus atom in the chlorophosphonium group to the nitrogen atom in the pyrazole ring leads to upfield shift of the phosphorus signal (to δP 170 ppm) and that the contribution of the spin-orbital contribution to the 31P chemical shift reaches 15%. Relativistic effects and effects of the medium are determining in the theoretical calculation of 31P NMR chemical shifts. 相似文献
143.
Experimental and computational studies of nJ(77Se, 1H) selenium-proton couplings in selenoglycosides
Kövér KE Kumar AA Rusakov YY Krivdin LB Illyés TZ Szilágyi L 《Magnetic resonance in chemistry : MRC》2011,49(4):190-194
Selenoglycosides are important starting materials in synthetic carbohydrate chemistry and play a role in biological interactions as well. Both aspects are influenced by the conformation around the glycosidic bond. Here, we present a combined experimental and computational approach to measure and evaluate (n)J((77)Se, (1)H) coupling constants for their use in conformational analysis. The measurements were carried out using a modified CPMG-HSQMBC pulse scheme which yields pure absorption antiphase multiplets to allow accurate determination of the (n)J(XH) values regardless of the size of the proton-proton couplings. Theoretical calculations were performed at the Second-Order Polarization Propagator Approach (SOPPA) level. Population-averaged values calculated for geminal and vicinal couplings are in a good agreement with experiment indicating an adequate theoretical level of the calculations. Experimental observations and computations alike have indicated that two-bond (77)Se-(1)H couplings, (2)J((77)Se, (1)H), in a H1-C1-Se-X moiety are very sensitive to the torsion angle around the C1-Se-bond and will, therefore, be useful for conformational studies. 相似文献
144.
Svetlana F. Malysheva Nina K. Gusarova Natal'ya A. Belogorlova Tamara V. Kashik Leonid B. Krivdin Sergei V. Fedorov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1838-1844
A facile, one-pot vinylation of secondary phosphine chalcogenides with alkyl(or aryl) vinyl sulfoxides has been elaborated. The vinylation comprises the nucleophilic addition of secondary phosphine chalcogenides to the vinyl sulfoxides (~50 mol% KOH, dioxane, 25–40°C, 1 h) followed by the elimination of sulfenic acids from the adducts (additional equivalent of KOH, 60–70°C, 1.5–2.0 h), the yields of target tertiary vinyl phosphine chalcogenides reaching 92%. 相似文献
145.
S. V. Fedorov Yu. Yu. Rusakov L. B. Krivdin 《Russian Journal of Organic Chemistry》2014,50(2):160-164
Calculation was carried out of chemical shifts in 13C NMR spectra for a series of fluoromethanes CH n F4?n (n = 0–4) by the methods of the electron density functional theory GIAO-DFT taking in consideration the solvent effect in the framework of the polarizable continuum model Tomasi IEF-PCM. The best results were obtained at the use of Keal-Tozer KT3 functional combined with Pople standard basis sets 6-311G(d,p) and 6-311++G(d,p), and also with Jensen special set pcS-2 containing tight p-functions. The optimum reference in the calculation of chemical shifts in 13C NMR spectra for the fluoromethanes series is TMS. 相似文献
146.
K. A. Chernyshev L. B. Krivdin G. N. Rozentsveig I. V. Ushakova I. B. Rozentsveig G. G. Levkovskaya 《Russian Journal of Organic Chemistry》2008,44(1):76-85
The second-order polarization propagator approach (SOPPA) was used to calculate 13C-1H, 13C-13C, and 15N-1H coupling constants for a series of N-(polychloroethylidene)arenesulfonamides and N’-arylsulfonylformimidamides, and their configuration with respect to the C=N bond was determined by comparing the calculated
data with the experimental values. All the examined compounds were found to exist in solution exclusively as the corresponding
E isomers. The most favorable conformations and relative energies of the E and Z isomers in the gas phase were determined in terms of the second-order perturbation theory (MP2/6-311G**). N’-Arylsulfonylformimidamides are characterized by restricted internal rotation of the dialkylamino group about the C-N bond
having an increased order.
Original Russian Text ? K.A. Chernyshev, L.B. Krivdin, G.N. Rozentsveig, I.V. Ushakova, I.B. Rozentsveig, G.G. Levkovskaya,
2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 1, pp. 82–91.
Dedicated to Full Member of the Russian Academy of Sciences G.A. Tolstikov on his 75th anniversary 相似文献
147.
E. V. Kondrashov E. V. Rudyakova I. B. Rozentsveig I. V. Ushakova G. N. Rozentsveig V. A. Savosik K. A. Chernyshev L. B. Krivdin G. G. Levkovskaya 《Russian Journal of Organic Chemistry》2008,44(1):86-94
N-(Polychloroethylidene)arene-and -trifluoromethanesulfonamides reacted with indole and N-substituted indoles to give the corresponding N-[2,2-dichloro(or 2,2,2-trichloro)-1-(1H-indol-3-yl)ethyl]-substituted sulfonamides. Unlike N-(2,2,2-trichloroethylidene)trifluoromethanesulfonamide, less electrophilic N-(poly-chloroethylidene)arenesulfonamides failed to react with 1-(4-nitrophenyl)-1H-indole. Previously unknown N,N’-bis(2,2-dichloroethylidene)biphenyl-4,4’-disulfonamide reacted with 1-benzyl-1H-indole at both azomethine fragments. Likewise, reactions of 1,6-bis(1H-indol-1-yl)hexane and 1,4-bis(1H-indol-1-ylmethyl)-benzene with N-sulfonyl trichloroacetaldehyde imines involved both indole rings in the former. 相似文献