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1.
Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of a series of substituted N-(1,3-thiazol-2-yl)-pyrimidin-2-amines and N-(pyrimidin-2-yl)thioureas by...  相似文献   
2.
Inimage processing (e.g., inastronomy), the desired black-and-white image is, from the mathematical viewpoint, aset. Hence, to process images, we need to process sets. To define a generic set, we need infinitely many parameters; therefore, if we want to represent and process sets in the computer, we must restrict ourselves to finite-parameter families of sets that will be used to approximate the desired sets. The wrong choice of a family can lead to longer computations and worse approximation. Hence, it is desirable to find the family that it isthe best in some reasonable sense. In this paper, we show how the problems of choosing the optimal family of sets can be formalized and solved. As a result of the described general methodology, forastronomical images, we get exactly the geometric shapes that have been empirically used by astronomers and astrophysicists; thus, we have atheoretical explanation for these shapes.  相似文献   
3.
It is proved that both the prediction problem and the problem of reconstructing the state from the observations in quantum mechanics are NP-hard.  相似文献   
4.
IR lattice vibration spectra were used to monitor the changes in the structure of zeolite Na-Y upon its dealumination with ethylenediaminetetraacetic acid (EDTA) or with HCl. The terminal Si-O(H,Na) bonds thus formed (which are detectable by characteristic absorbance at v 900–950 cm–1) are energetically less uniform when EDTA has been used as the dealuminating agent. This inhomogeneity is connected with the local deformations of zeolite structure which result in lowering the symmetry of silicon-oxygen tetrahedra. As a consequence, two novel bands appear at v 1090 cm–1 and 1200 cm–1 in addition to the fundamental absorption bands, vas (TO4) (T = Si, Al), at 1030 cm–1 and 1145 cm–1. A mechanism of dealumination is proposed, which takes into account the topochemical peculiarities involved in the chelation of the framework aluminum ions with EDTA.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskay, No. 2, pp. 284–287, February, 1993.  相似文献   
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The chemical method of preparation of oxide precursors was used to obtain sulfide-conducting ionic salts of CaY2S4, BaSm2S4 and heterogeneous additives of ZrS2 and SiS2, accordingly. The sintering modes for obtaining the heterogeneous systems of CaY2S4–ZrS2 and BaSm2S4–SiS2 were chosen. Samples were characterized using the methods of X-ray phase analysis and microprobe analysis. The methods of thermogravimetric and differential thermal analysis were used to determine thermal stability of samples. The temperature and concentration dependences of conductivity and average ionic transport numbers were studied. The range of compositions of heterogeneous mixtures is determined in which conductivity considerably exceeds conductivity of the basic sulfide-conducting solid electrolytes.  相似文献   
7.
The process of nonanol-1 oxidation is studied on the nickel oxide electrode with the use of chemically bound active oxygen forms (AOF) electrochemically generated in situ from O2, H2O2, and H2O. The effect of electrolysis conditions (AOF generation schemes, current density, passed charge) on the yield of pelargonic acid is studied. The oxidation proceeds most efficiently at the current density of 5–10 mA cm?2 as the theoretical charge is passed in the paired electrolysis mode. The current efficiency with respect to pelargonic acid is 83.7%; the substance yield is 83.8%. In addition to pelargonic acid, several oxidation side-products are found in the electrolyte. Their content increases with the increase in the charge passed as a result of further oxidation of pelargonic acid.  相似文献   
8.
The achievements and prospects in the use of aqueous hydrogen peroxide solutions prepared by cathodic reduction of oxygen in carbon black gas-diffusion and graphite electrodes for indirect oxidation of organic and inorganic substrates in situ are analyzed. Specific examples demonstrate the efficiency of using hydrogen peroxide solutions for in situ indirect electrocatalytic oxidation of organic and inorganic substrates to target products (indirect electrochemical synthesis), for decomposition (mineralization) of organic and inorganic pollutants in industrial waters and wastewaters, and for preparation of organic peroxy acids and inorganic peroxy solvates.  相似文献   
9.
Conclusions Heterocyclic compounds of the 2-imidazoline, benzimidazole and benzoxazole series, containing the ferrocenyl radical, were obtained from the hydrochlorides of the iminoesters of ferrocenecarboxylic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1567–1569, July, 1971.  相似文献   
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