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1.
Summary Two new saponins have been isolated from the rhizomes ofD. caucasica: the water-soluble caucasosaponin—a rhamnosotriglucoside of 25 D-22-spirost-22-en-3-ol—and the water insoluble caucasoprosapogenin—a glucosotrioside of 25 D-22-spirost-5-en-3-ol-, and also the previously known rhamnosidodiglucoside of 25 D-22-spirost-5-en-3-ol—gracillin.Khimiya Prirodnykh Soedinenii, Vol. 3, No. 4, pp. 237–241, 1967 相似文献
2.
Yuliya E. Ryzhkova Fedor V. Ryzhkov Michail N. Elinson Oleg I. Maslov Artem N. Fakhrutdinov 《Molecules (Basel, Switzerland)》2023,28(1)
Chromeno[2,3-b]pyridines are substances demanded in medicinal and material chemistry. PASE (pot, atom, and step economy) and in particular one-pot approaches are key green chemistry techniques that are applied for the synthesis of heterocyclic compounds. In this case, the PASE approach was extended with ‘component economy’, as solvent was used also as reactant (solvent-involved reaction). This approach was adopted for the one-pot synthesis of previously unknown O-substituted 5-alkoxy-5H-chromeno[2,3-b]pyridines via two-step transformation, namely the reaction of salicylaldehydes and malononitrile dimer, with the subsequent addition of alcohol. The mechanistic studies revealed the possibility of concurrent reaction. The studies aided in optimizing the reaction conditions for the best yields (77–93%). Thus, the one-pot reaction proceeds efficient and quickly, and the work-up procedure (only simple filtering) is very convenient. The structure of synthesized chromeno[2,3-b]pyridines was confirmed by 2D NMR spectroscopy. 相似文献
3.
4.
E. Yu. Safronova A. V. Parshina E. A. Ryzhkova O. V. Bobreshova A. B. Yaroslavtsev 《Russian Journal of Inorganic Chemistry》2016,61(12):1512-1517
Hybrid materials based on perfluorinated sulfo cation-exchange MF-4SC membrane and nanoparticles of cesium hydrogen phosphotungstate and silicotungstate heteropolyanions were obtained. These membranes with a gradual dopant distribution along the length were used to develop potentiometric sensors for determination of amino-containing organic cations in aqueous solutions at pH < 7. A relationship between the membrane transport characteristics and sensing properties was elucidated. 相似文献
5.
Reactions induced in thin films of α-d-glucose and N-acetylglucosamine by low-energy electron exposure at incident electron energies (E0) between 5 eV and 15 eV have been investigated by high-resolution electron energy loss spectroscopy (HREELS). The reactions of α-d-glucose upon electron exposure were also studied in the presence of molecular oxygen. Electron exposure leads to characteristic changes of the vibrational spectra indicating that OH groups are lost with the formation of CC double bonds taking place preferentially above the ionisation threshold of the investigated molecules. At lower E0, OH groups are equally decomposed suggesting that dissociative electron attachment contributes to the reactions but formation of double bonds is not observed. The results show that different reaction channels are effective depending on E0 and that the outcome of electron-driven chemistry in saccharides may be controlled by changing from the subionisation regime to E0 above the ionisation threshold. Generally, low-energy electron exposure in the absence of O2 produces a material with lower oxygen content, i.e. leads to a reduction of the saccharide. In the case of N-acetylglucosamine, removal of the amide group from the sugar is also important at subionisation energies. In contrast, as shown for α-d-glucose, low-energy electron exposure in the presence of O2 leads to oxidation of the sugar even at cryogenic temperature. 相似文献
6.
In the self-consistent-field approximation, a statistical theory is constructed for the atomic distribution in the near-surface region of a binary alloy which is able to disintegrate from the atomically smooth free surface of the crystal. The form of the surface-segregation functions of the components is found, in closed form, taking the relaxation of the coordination energies and the atomicinteraction energies at the surface into account. The possibility of the existence of metastable nonmonotonic concentrational profiles at the crystal surface is demonstrated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 51–56, December, 1981. 相似文献
7.
In the self-consistent field approximation, without allowance for correlation, a static theory of the ordering of ternary alloys is constructed which makes it possible to take into account the long-range nature of the interatomic interaction forces in substitutional and interstitial alloys. The theory enables one to take into account the possible existence in the alloy of two subsets of points differing by the species of atoms that occupy them. The stability of the disordered state in such alloys is analyzed and an expression obtained for the temperature at which the disordered state loses stability.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 61–64, November, 1980. 相似文献
8.
L. P. Grankina V. I. Lozovoi E. F. Ryzhkova V. I. Ryzhkov 《Russian Physics Journal》1982,25(8):721-725
Analytical form for the functions describing atomic distribution of the components in the subsurface layer of a ternary alloy has been found in a closed form in the self-consistent field approximation, without taking correlation into account. The functions obtained allow one to construct concentration profiles of the components near the surface, to calculate the component surface concentration, and to investigate the dependence of the composition on the surface of the alloy crystal on temperature, and surface relaxation of coordination numbers and energies of the nearest neighbor interatomic interaction in an alloy. An analysis of the character of temperature dependencies of the composition on the surface has been performed for various alloys.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 47–52, August, 1982. 相似文献
9.
10.
A. V. Ryzhkova F. V. Podgornov W. Haase 《Bulletin of the Lebedev Physics Institute》2009,36(12):375-376
The possibility of controlling two-dimensional motion of dielectric microparticles in the channel filledwith nematic liquid
crystalwas experimentally shown. It was found that particle motion along the electric field occurs by means of the electrophoresis
phenomenon. Particle motion along electrodes perpendicularly to the electric field is caused by the combination of two effects,
i.e., the backflow and Quincke rotation. 相似文献