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21.
Ya. V. Fattakhov M. F. Galyautdinov T. N. L’vova I. B. Khaibullin 《Technical Physics》1997,42(12):1457-1459
The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface
upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures
is discussed.
Zh. Tekh. Fiz. 67, 97–99 (December 1997) 相似文献
22.
Elizabeth S. Senger 《School science and mathematics》1997,97(3):139-149
Thirteen fifth graders were given an assignment to invent their own numeration systems, following a unit on bases and a look at early events in the history of numbers. The task presented options that required the students to make decisions (such as whether to use a base, which base to use, design of symbols, etc.), and build a rationale for the elements of their system. Analyses of patterns embedded in their invented systems provided an assessment of student understanding of numeration. The progression of more and less complex thinking related to the student's choice of a base other than 10, consistency of logic throughout the system in words and symbols, rationale for change, and perception of real life examples that would change if the system was adopted. The invention task is presented as another way to make connections. 相似文献
23.
I. M. Karnaukh A. S. Moskovkin G. V. Ponomarev 《Chemistry of Heterocyclic Compounds》1994,30(1):20-25
The mass spectral behavior of 1, 2-di (mesoetioporphyr inyl-1)- and 1, 2-di (mesooctaethylporphyrlnyl) ethanes and ethylenes, their Cu and Ni complexes, as well as Ni Schiff bases of 1, 2-di (mesooctaethylporphyrinyl)ethane complexes, under ionization by electron impact and bombardment by accelerated atoms, was studied. Peaks of molecular ions, for which the basic decomposition pathways were established on the basis of an analysis of the parent and daughter ions, were observed in the electron impact mass spectra of all these compounds.For Communication 29, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 24–29, January, 1994. 相似文献
24.
S. V. Litvinenko V. I. Savich L. D. Bobrovnik 《Chemistry of Heterocyclic Compounds》1994,30(3):340-344
We have developed a method for synthesis of N-(3-clzloro-2-quinoxalyl)sulfonamides by reaction of 2,3-dichloroquinoxaline with substituted arylsufonamides. Based on the IR spectra, we have established that in the solid state, the synthesized compounds exist in the form of amide tautomers. Alkylation of these compounds leads to N-metliyl-N-(3-chloro-2-quinoxalyl)arylsulfonamides. We demonstrate the possibility of nucleophilic substitution of the halogen upon treatment with O- and N-nucleophiles. The use of bifunctional nucleophiles leads to condensed quinoxalines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 30, No. 3, pp. 387–392, March, 1994. 相似文献
25.
26.
M. A. Mikhaleva B. M. Bolotin T. A. Kizner E. S. Serebrykova 《Chemistry of Heterocyclic Compounds》1994,30(1):79-81
We have synthesized 5-alkyl(alkoxy)-2-(o-lzydroxy-p-alkoxyphenyl)pyrimidines and considered the effect of the OH group on the inesomorphism. We have found that in binuclear o-hydroxyarylpyrimidines, an ortho OH group forming an intramolecular hydrogen bond increases Tmp, inhibits the appearance of nematic properties, and promotes the appearance of a smectic A.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 30, No. 1, pp. 90–92, January, 1994. 相似文献
27.
28.
A. Aitmambetov S. N. Shinkaruk S. P. Bondarenko V. P. Khilya 《Chemistry of Natural Compounds》1994,30(4):453-456
6-Halogeno-1,3-benzodioxane analogs of chalcones have been synthesized by various methods. Flavanone and flavone analogs of silandrin and hydnocarpin have been obtained from them. The structures of the new flavonoids have been shown by their PMR spectra. 相似文献
29.
N. I. Khamidov B. T. Kadyrov N. T. Ul'chenko A. Sh. Isamukhamedov A. I. Glushenkova 《Chemistry of Natural Compounds》1994,30(4):430-433
The phsicochemical indices and the fatty-acid and triacylglycerol compositions of cottonseed and palm oils, of cottonseed
oil hydrogenate, and of compositions based on them have been determined with the aid of IR and UV spectroscopies, GLC analysis,
and chemical transformations. The compositions and amounts of the main classes of lipids in the initial oils and the hydrogenate
have been studied. It has been found that in the process of hydrogenation the amount of oxygenated components falls.
The work was conducted with the financial support of the Uzbek Fund for Fundamental Investigations. 相似文献
30.
Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 891475.
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 679–680, September–October, 1994. 相似文献