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71.
A. N. Vasil’ev A. N. Lyshchikov O. E. Nasakin Ya. S. Kayukov V. A. Tafeenko 《Russian Journal of Organic Chemistry》2005,41(2):279-282
Reduction of alkyl-2-amino-5,6-dialkyl-3-cyanopyridine-4-carboxylates with sodium borohydride in protic solvents gave rise to 4-amino-3-imino-6,7-dialkyl-1,3-dihydrofuro[3,4-c]pyridines that at hydrolysis in acid medium afforded the corresponding lactones.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 288–291.Original Russian Text Copyright © 2005 by Vasil’ev, Lyshchikov, Nasakin, Kayukov, Tafeenko. 相似文献
72.
Bredikhina Z. A. Pashagin A. V. Savel"ev D. V. Bredikhin A. A. 《Russian Chemical Bulletin》2001,50(3):436-439
Nonracemic -blockers, viz., (S)-propranolol and (S)-timolol, were prepared from (S)-glycidol in three steps consisting in the reaction with SOCl2 followed by the reaction of the resulting (4S)-4-chloromethyl-2-oxo-1,3,2-dioxathiolanes with the corresponding phenol and the final cleavage of (4R)-aryloxymethyl sulfites under the action of amines in DMF. 相似文献
73.
74.
Imtiaz Ahmad M. Arsala Khan M. Shakirullah M. Ishaq Yousaf Iqbal Saeed ur Rehman 《中国化学会会志》2004,51(4):729-734
Influence of pretreatments, i.e., demineralization and pre‐soaking in some solvents on the yields of liquefied products obtained from hydro‐depolymerization of Pakistani coal in a pool of hydrogen has been discussed. Results of hydrogenation experiments demonstrated that demineralizing the coal sample prior to liquefaction caused the yields to decrease compared with the virgin coal samples. The contribution of mineral matter of coal has been evaluated by comparing the yields of liquid products of virgin and leached samples. Increase in the yields obtained from the hydrogenation experiments of swollen coal samples was not satisfactorily significant. 相似文献
75.
The review considers problems related to the formation, in the living organism, of nitric oxide, a versatile and vitally important regulator of cell metabolism. The pathways of formation of endogenous nitric oxide from L-arginine are discussed and the main approaches to increasing the NO concentration by introducing various types of exogenous nitric oxide donors into the organism and chemical and biological characteristics of these donors are considered. Primary attention is devoted to the known drugs that were shown to release NO under hydrolytic, oxidative, or reductive conditions. The solution of problems related to the elucidation of the mechanisms of drug action requires that the formation of nitric oxide be taken into account. 相似文献
76.
A fast transient fluorescence technique was used to study latex film formation induced by organic solvent vapor. Mixtures of pyrene (P)- and naphthalene (N)-labeled and/or pure naphthalene-labeled latex films were prepared separately from poly(methyl methacrylate) (PMMA) particles. Then these pure and mixed latex films were exposed to vapor of various chloroform-heptane mixtures in seven different experiments. In both films, fluorescence lifetimes from N were monitored during vapor-induced film formation. It was observed that N lifetimes decreased as the vapor exposure time is increased. A Stern-Volmer kinetic analysis was used for low quenching efficiencies to interpret the decrease in N lifetimes. A Prager-Tirrell model was employed to obtain back-and-forth frequencies, nu, of reptating PMMA chains during latex film formation induced by solvent vapor. In both pure and mixed latex films, nu values were found to be correlated with the chloroform content in the vapor mixture. It was observed that polymer interdiffusion obeyed a t1/2 law during film formation. 相似文献
77.
Polyparaxylylene-CdS nanocomposite films: Optical spectra, photoluminescence, and surface topography
I. V. Klimenko E. P. Krinichnaya T. S. Zhuravleva S. A. Zav’yalov E. I. Grigor’ev I. A. Misurkin S. V. Titov B. A. Loginov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(12):2041-2046
For polyparaxylylene-CdS nanocomposite films prepared by solid-phase cryochemical synthesis, the dependences of the optical absorption spectra, photoluminescence intensity, and surface topography on the CdS concentration were examined. It was revealed that the most significant changes, such as the shift of the position of the exciton absorption band by ~1 eV and the increase of the surface roughness (the magnitude of variation of heights h max ? h min along a surface profile) occur within a CdS concentration range of from ~5 to ~8 vol %. The average size of the nanoparticles was determined from the position of the exciton absorption maximum: 2R np ? ? 3 nm at c ≤ 5 vol % and 2R np ≥ 5?7 nm at c ≥ 10 vol %. The formation of 3-nm particles at low CdS concentrations was confirmed by the existence of exciton photoluminescence with maximum at 370 nm. Exciton luminescence was not observed at c ≥ 10 vol %. By contrast, at all c values, photoluminescence with maxima at ~520 and ~570 nm, which is usually assigned to interstitial S and Cd atoms, correspondingly, and a the weak emission of unknown nature with a maximum at 545 nm were observed. 相似文献
78.
A. D. Vasil’ev N. N. Golovnev M. S. Molokeev T. D. Churilov 《Journal of Structural Chemistry》2005,46(2):363-370
Synthesis of a complex formed by ciprofloxacin (cfH) and copper(II) chloride is described; its crystal structure is reported and analyzed in comparison to related compounds. The obtained compound (cfH3)CuCl4·H2O (cfH 3 2+ — double protonated cfH molecule) crystallizes as platelets of P21/c symmetry having the unit cell parameters a = 13.491(1) Å, b = 11.0459(7) Å, c = 16.299(1) Å; β = 111.392(7)°. Carbonyl oxygen O(1) is protonated, and hydrogen atom combined with it forms an intramolecular hydrogen bond with carboxylic O(2) oxygen (O(1)?O(2) = 2.642(5) Å). Terminal nitrogen atom N(3) of the piperazinyl group is also protonated, and two its hydrogen atoms participate in hydrogen bonds of N-H?Cl type. The structure also has hydrogen bonds O-H?O, O-H?Cl with the participation of water molecules which occupy hydrophilic channels. Molecular ions cfH 3 2+ make couples with intrapair π?π interactions. 相似文献
79.
Summary Surface sediments and sediment cores from two bays in the Adriatic sea (Punat Bay and Soline Bay, Croatia) have been analyzed
for a number of elements, in particular: Ti, V, Mn, Fe, Cu, Zn, As and Pb, by using XRF. Maps of elemental distribution in
surface sediments show increased concentrations for some elements present in antifouling paints (Cu, Zn, Pb) near the service
areas in the villages or marinas. Core profiles for these elements were used to evaluate the environmental impact of newly
constructed marinas. Source partition indicates the influence of other sources located in near by villages. The critical factor
in these considerations was shown to be water exchange with the open sea. 相似文献
80.
Kulikov R. N. Kostenko E. V. Kuznetsova M. A. Novopashina D. S. Chernonosov A. A. Vorob"ev P. E. Ven"yaminova A. G. Zenkova M. A. Vlassov V. V. 《Russian Chemical Bulletin》2003,52(1):247-257
The site-specific modification of the 5"-terminal fragment of PGY1/MDR1 mRNA by oligodeoxyribonucleotide conjugates bearing residues of bleomycin A5 (Blm), cobalt(ii) tetracarboxyphthalocyanine (Phcn), 4-[N-(2-chloroethyl)-N-methylamino]benzylamine (RCl), or perfluoroarylazide (Az) was studied. Conjugates of oligonucleotides complementary to the RNA sequences 123—138 and 155—166 selectively modify RNA in the vicinity of these regions. The highest efficacy (up to 50%) was achieved in reactions with alkylating and perfluoroarylazide conjugates of oligonucleotides. Conjugates of perfluoroarylazide with 2"-O-modified oligonucleotides are much more efficient than analogous conjugates with oligodeoxyribonucleotides (extents of RNA modification are 40—50% and 20%, respectively). 相似文献