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WYETH Paul 《中国科学:化学》2010,(3)
Silks represent some of the most precious ancient and historic textile artefacts in collections worldwide.Their optimum preservation demands an appreciation of their characteristics.One important concern,especially with regard to ancient Chinese silks,is whether the fabrics have been degummed.Silks with remnant sericin gum coating the fibroin fibres would require different conservation protocol.In previous research on aged silks,the presence of sericin has been inferred from amino acid analysis of hydrolysa... 相似文献
105.
106.
I. I. Boiko Yu. N. Solntsev N. A. Krutikov V. P. Lutsik T. N. Boiko 《Chemistry of Heterocyclic Compounds》1982,18(9):886-888
A number of previously unknown 2,6-diarylpyrylium tetrafluoroborates was obtained by the reaction of substituted acetophenones with ethyl orthoformate and boron trifluoride etherate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1168–1169, September, 1982. 相似文献
107.
M. V. Vovk P. S. Lebed A. N. Chernega V. V. Pirozhenko V. I. Boiko I. F. Tsymbal 《Chemistry of Heterocyclic Compounds》2004,40(1):47-57
The interaction of 1-chloroalkyl isocyanates, 1-chloroalkylcarbodiimides, 1,1-dichloroalkyl isocyanates, and N-(1-chloroethylidene)-O-methylurethanes with 2-cyanomethylpyridine has been investigated. An effect of organic base has been detected on the regioselectivity of the cyclocondensation of 1-chloroalkyl isocyanates, which leads to 2,3-dihydro-1H-pyrido[1,2-c]pyrimidin-1-one or the isomeric 2,3-dihydro-1H-pyrido[1,2-c]pyrimidin-3-one. Irrespective of the cyclization conditions 1-chloroalkylcarbodiimides react with the formation of 1-imino-2,3-dihydro-1H-pyrido[1,2-c]pyrimidines. One type of product, a 1H-pyrido[1,2-c]pyrimidin-1-one, was also isolated from 1,1-dichloroalkyl isocyanates and N-(1-chloroalkylidene)urethanes. 相似文献
108.
A. Yu. Bobrovsky N. I. Boiko K. Shaumburg V. P. Shibaev 《Colloid and polymer science》2000,278(7):671-676
A number of new photosensitive copolyacrylates of different composition were obtained by the copolymerization of chiral photochromic
benzilidene-p-menthane- 3-one acrylic monomers with a smectogenic monomer containing a hexyloxyphenylbenzoate mesogenic group. The chiral,
photochromic monomers differ by the length of the aliphatic spacer and the aromatic fragment. It was found that the introduction
of a small number of chiral units into the copolymers (5 mol%) leads to the “degeneration” of the smectic C phase, which characterizes
the hexyloxyphenylbenzoate homopolymer, and to the formation of the smectic A phase. An unusual effect of chiral nematic phase
induction was observed for copolymers containing chiral side groups with two ring aromatic fragments. It should be pointed
out that the chiral nematic phase does not occur in the case of the homopolymers of both initial comonomers. An explanation
of this effect, based on the consideration of the chemical structure of the chiral and hexyloxyphenylbenzoate units, was suggested.
The optical properties of cholesteric copolymers were investigated; the helical twisting power of the chiral groups of different
structures was calculated. The possibility of using such copolymers as new photosensitive materials was demonstrated.
Received: 16 December 1999/Accepted: 1 February 2000 相似文献
109.
Fedorov B. S. Golovina N. I. Fadeev M. A. Strukov G. V. Kedrov V. V. Shilov G. V. Boiko G. N. Atovmyan L. O. 《Russian Chemical Bulletin》2001,50(3):520-524
Previously unknown N-(2-nitroxyethyl)isonicotinamide was synthesized by the reaction of isonicotinoyl chloride with 2-nitroxyethylamine and was used as a ligand in the reactions with PdCl2 and PtCl2 to prepare new complexes, viz., trans-bis[(2-nitroxyethyl)isonicotinamide-N]dichloropalladium(ii) and cis-bis[(2-nitroxyethyl)isonicotinamide-N]dichloroplatinum(ii), respectively. The structures of the ligand and the resulting complexes were established by X-ray diffraction analysis. 相似文献
110.
The small-angle X-ray scattering in calomel (univalent mercury chloride Hg2Cl2) single crystals at low temperatures has been investigated. Data on the size of superstructural ferroelectric domains have been obtained for the first time. Lang measurements with anomalous X-ray transmission have made it possible to trace the temperature dynamics of crystal lattice of the high-temperature D4h phase of Hg2Cl2 from 300 K to the Curie temperature (186 K) and the formation of ferroelastic domains in the temperature range of 186–100 K. The lowering of paraphase symmetry in the closest vicinity of the phase transition temperature is indicative of tricritical point transition. 相似文献