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101.
The known triterpene tetraoside holothurin A has been isolated from the Pacific Ocean holothurianHolothuria squamifera. By using two independent methods — enzymatic cleavage and two-stage Smith degradation — 22,25-epoxyholost-9(11)-ene-3,12,17-triol, C30H46O6, which is the native aglycone of holothurin A, was obtained. The structure of the native aglycone has been established on the basis of the results of IR, mass, and PMR spectroscopy.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 448–451, July–August, 1984. 相似文献
102.
M. A. Surmeneva R. A. Surmenev V. F. Pichugin N. N. Koval’ A. D. Teresov A. A. Ivanova I. Yu. Grubova V. P. Ignatov O. Primak M. Epple 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2013,7(5):944-951
Silicon-containing hydroxyapatite coatings 400–700 nm in thickness are prepared by means of radio-frequency (RF) magnetron sputtering on a heated (to 200°C) titanium substrate chemically etched and treated with a pulsed electron beam. The morphology and phase composition of the coating are studied. The morphology and roughness of the composite “calcium-phosphate coating-titanium substrate” differ depending on the treatment procedure of the substrate before deposition. The scratch test method is used to assess the adhesion strength of the coatings formed at different values of bias potential applied to the substrate. It is observed that the adhesion strength of the coating changes with decreasing crystallite size. 相似文献
103.
V. Yu. Baranovskii V. G. Ganev V. B. Petkova Kh. Ch. Voicheva M. V. Dimitrov 《Colloid Journal》2012,74(6):645-648
IR spectroscopy and viscometry data have shown that poly(acrylic acid) and poly(methacrylic acid) form complexes with agar-agar in aqueous solutions as they do with other polysaccharides. The polyacid-agar-agar complexes are typical hydrogels. The swelling index of hydrogels based on the poly(methacrylic acid)-agar-agar complex has been found to be markedly lower than that of poly(acrylic acid)-agaragar complex. The hydrogels based on the complex of cross-linked poly(acrylic acid) with agar-agar can be of practical interest as polymeric carriers for drugs. 相似文献
104.
105.
Optics and Spectroscopy - The paper presents a brief review of recent works concerning the modeling of X-ray lasers in cluster flows and in nanostructured targets. Calculations of the atomic... 相似文献
106.
M. B. Gazizov S. Yu. Ivanova R. A. Khairullin Yu. S. Kirillina K. S. Gazizova 《Russian Journal of General Chemistry》2018,88(11):2243-2250
A new procedure has been developed for the simultaneous preparation of terephthalaldehyde and 4-(dibromomethyl)benzaldehyde by catalytic debromophosphoryl- and phosphonyloxylation of 1,4-bis- (dibromomethyl)benzene with P(IV) acid methyl esters. The reaction of 4-(dibromomethyl)benzaldehyde with ortho esters in the presence of sulfuric acid gave the corresponding acetals, whereas in the presence of ZnCl2 terephthalaldehyde bis-acetals were formed. 4-(Dibromomethyl)benzaldehyde and its acetal were converted to methyl 4-(dibromomethyl)- and 4-(dimethoxymethyl)benzoates which were phosphorylated by the action of chlorophosphines, as well as by successive treatment with phosphorus(III) chloride and P(III) esters. 相似文献
107.
Transformations of granules based on kaolin and phosphoric acid under the conditions of vapor-phase crystallization at 170°C were studied. Specific features of the individual and cooperative action of a water vapor and a template dipropylamine on the granules were determined. It is shown that the regulation of competing processes of formation of dense non-porous phases (tridymite, cristobalite, berlinite) and microporous crystalline silicoaluminophosphates of structural types ATL and ATN can be carried out by creating transport pores in the volume of the initial granules. The formation of transport pores was provided by using of porogens (hydroxyethyl cellulose and carbon nanospheres) with the subsequent calcination of the granules. The presence of 40- and 60- nm macropores in the porous structure favored intensification of mass-exchange processes occurring within the granules under the vapor-phase crystallization conditions. This led to an increase in the selectivity of crystallization of the materials with crystal structure types AEL and ATN. The morphology of the crystals with the AEL and ATN structure and their chemical composition depend on the porogen used to prepare the starting granules. 相似文献
108.
109.
A. V. Rudnev N. I. Ivanova N. G. Vanifatova T. G. Dzherajan 《Moscow University Chemistry Bulletin》2014,69(4):175-179
The effect of the time of ultrasonic treatment and concentration of aqueous Tween 80 on the stability of calcium hydroxyapatite suspensions was studied. The optimal conditions under which the system becomes stable were found using capillary-zone electrophoresis, dynamic light scattering, and scanning electron microscopy. The possibility of evaluating the system stability was shown based on studying the electrophoretic behavior of particles. 相似文献
110.
Plasma Chemistry and Plasma Processing - The yield of redox reactions (Fe2+ oxidation and Mn7+ reduction in aqueous solutions) under the action of hot plasma radiation in liquid and species formed... 相似文献