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1.
Silica@copper (SiO2@Cu) core–shell nanoparticles were synthesized and well characterized by XRD, TEM, AFM, XPS, UV/Vis, TGA–MS, and ICP–AES techniques. The synthesized SiO2@Cu core–shell nanoparticles were employed as catalysts for the conjugate addition of amines to α,β‐unsaturated compounds in water to obtain β‐amino carbonyl compounds in excellent yields in shorter reaction times. Furthermore, the catalyst works well for hetero‐Michael addition reactions of heteroatom nucleophiles such as thiols to α,β‐unsaturated compounds. As the reaction is performed in water, it allows for easy recycling of the catalyst with consistent activity. 相似文献
2.
I.V. Markevich V.I. Kushnirenko L.V. Borkovska B.M. Bulakh 《Solid State Communications》2005,136(8):475-478
The mechanism of formation of a thin highly conductive layer, which is known to be present on ZnO surface, has been proposed. This process has been assumed to consist in accumulation of mobile shallow donors at crystal surface due to their drift in band-bending electric field caused by adsorbed oxygen. Experimental results that confirm this mechanism have been obtained. 相似文献
3.
Computations of the Diels-Alder (DA) reactions of azaphosphole representative namely, thiazolo[3,2-d][1,4,2]diazaphosphole with 1,3-butadiene and isoprene at the density functional theory level reveal concerted mechanisms via asynchronous transition states. The activation energies (B3LYP/6-311++G**// B3LYP/6-311G**), 16-19 kcal mol−1, are much smaller than the value (32.57 kcal mol−1) calculated for the DA reaction of the non-phosphorus analogue, imidazo[2,1-b]thiazole with 1,3-butadiene. An electron-withdrawing group at the 3-position of the dienophile enhances both stereo- and regioselectivities, which agree nicely with the experimental values. Inclusion of solvent effect (PCM model) reveals that the stereo- and regioselectivities are not affected appreciably. The relative stabilities of the transition structures corresponding to the endo/exo stereoisomers and meta (P/Me, 1:3)/para (P/Me, 1:4) regioisomers have been rationalized on the basis of the secondary molecular orbital interactions. 相似文献
4.
Syntheses of substituted pyrazolo[3,4-b]quinolines, 3,4-dihydro-4-oxopyriraido[4′,5′:4,5]theino[2,3-b]quinoline and 12-phenylpyrido[1′,2′:1,2[pyrimido[4,5-b]quinoline are described. 相似文献
5.
Neelima Gupta Vijaya Kabra Varsha Saxena Sama Jain Kalpana Bhatnager 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):851-861
A novel one-pot synthesis of four new classes of amidothiophosphoric esters and trisamidothiophosphoric esters is developed. (1-Alkyl-2-pyrimidinylidenamido)bis(diethylamido)thiophosphates, (1-alkyl-2-pyrimidinylidenamido)bis (O-2/4-methylphenyl)thiophosphates, (3-alkyl-2-thiazolinylidenamido)bis (diethylamido)thiophosphate and (3-alkyl-2-thiazolinylidenamido)bis(O-2/4-methylphenyl)thiophosphates are obtained from the nucleophilic substitution and oxidation of N-alkyl-2-cycloiminylidenaminodichlorophosphines generated in situ from the reaction of the corresponding N-alkyl-2-aminocycloiminium halide with phosphorus trichloride and triethylamine. The synthesized thiophosphoric esters have been investigated for fungicidal properties. 相似文献
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7.
B. M. Bulakh 《Fluid Dynamics》1983,18(3):454-456
The problem of the interaction of two or more particles moving in a viscous incompressible fluid at small Reynolds numbers (Re 1) has been well studied. The linearity of the Stokes equations makes it possible to develop effective methods of solution of the problem for two and many particles [1]. If the Reynolds number is not small, the inertia forces in the Navier-Stokes equations cannot be ignored, and the problem becomes nonlinear, i.e., much more complicated. The present note is devoted to the problem of the interaction of two spherical particles in a steady uniform flow of a viscous incompressible fluid when the Reynolds number is not small. Asymptotic expressions are obtained for the interaction forces between the particles when the distances between them are large compared with their radius.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 142–144, May–June, 1983. 相似文献
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10.
Powder XRD data of mixtures of title compounds are interpreted in terms of superlattices (SL). It is suggested that SL configurations
(orthorhombic-orthorhombic, orthorhombic-monoclinic, monoclinic-monoclinic) are realizable, because of discrete orientational
changes in the alignment of molecules of n-C28H58 hydrocarbon, through an angle mθ, wherem = 1, 2, 3 … and angle θ has an average value of 3.3°. Supporting literature evidence on the inclinations are discussed. 相似文献