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1.
Physics of Atomic Nuclei - In this paper, the analysis of the relation between the multiplication factor of neutrons of the multiplying system measured in critical experiments and the system... 相似文献
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Emily S. Tepe Ellen S. Deutsch MD Quiana Sampson Stephen Lawless James S. Reilly Robert Thayer Sataloff 《Journal of voice》2002,16(2):244-250
The objective of this study was to determine the incidence of vocal problems in young choir singers and to correlate vocal problems with demographic and behavioral information. A questionnaire addressing vocal habits and hygiene was offered to 571 young choir singers, up to 25 years of age, who sing at least weekly; 129 (22.6%) responded. More than one-half of the respondents had experienced vocal difficulty, particularly older adolescents. Detrimental behaviors and circumstances surveyed were not reflective of the incidence of vocal difficulty, except for morning hoarseness, chronic fatigue, insomnia, and female gender after puberty. Voice care professionals should be aware that self-reported voice difficulties are common among young choral singers, especially postpubescent girls, and children with symptoms consistent with reflux (morning hoarseness) and emotional stress (insomnia). Laryngologists should communicate with choral conductors and singing teachers to enhance early identification and treatment of children with voice complaints, and to develop choral educational strategies that help decrease their incidence. 相似文献
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O. E. Nasakin A. N. Lyshchikov P. M. Lukin A. Kh. Bulai 《Chemistry of Heterocyclic Compounds》1995,31(1):35-39
It was shown that briefly boiling solutions of 2,5-diaryl-3,3,4,4-tetracyanopyrrolidines in DMF caused rearrangement into 5-aryl-2-(N-arylidenamino)-3,4-dicyanopyrroles, which are methylated with diazomethane both at the NH bond and at the carbon atom of the azomethine fragment.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 42–46, January, 1995. 相似文献
7.
Alexei Yu. Lukin Sergei V. Shevyakov Alexei V. Laptev Olga I. Davydova Vitali I. Shvets Olga V. Demina Yury P. Strokach Valery A. Barachevsky Michail V. Alfimov Sergei P. Gromov Artem I. Vedernikov Johan Lugtenburg Andrey A. Khodonov 《Journal of inclusion phenomena and macrocyclic chemistry》2004,49(1-2):153-161
An effective synthetic approach to the preparation of a new crown-ether vinylogs involving the Horner–Emmons olefination of carbonyl precursors with the use of C2- and C5-phosphonates was proposed. The effects of the conjugation chain length and the nature of the terminal polar functions in the phosphonate reagent on the yield and process stereoselectivity were discussed. 相似文献
8.
L. O. Atovmyan A. B. Zolotoi N. M. Sergeev A. V. Buevich P. M. Lukin O. E. Nasakin S. V. Konovalikhin V. P. Sheverdov 《Russian Chemical Bulletin》1989,38(5):972-976
Conclusions 1-(N,N-Dimethylhydrazino)-4-methyl-2,2,3,3-tetracyanocyclopentane is isomerized reverslbly in solution, with inversion of the configuration of the tetrahedral carbon atom in position 1.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1075–1079, May, 1989. 相似文献
9.
I. V. Moiseeva P. M. Lukin O. E. Nasakin V. N. Romanov V. A. Tafeenko A. Kh. Bulai P. A. Sharbatyan 《Chemistry of Heterocyclic Compounds》1992,28(2):237-237
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, p. 282, February, 1992. 相似文献
10.
V. G. Pimenov D. V. Lukin A. V. Bondarenko V. S. Mikheev 《Journal of Analytical Chemistry》2002,57(2):138-141
A procedure for analyzing high-purity arsenic by atomic emission spectrometry (AES) was proposed that provides the preconcentration of silicon and other nonvolatile impurities in a crater of a graphite electrode using matrix distillation from 2-g sample portions as As2O3. The procedure is characterized by a low correction for the blank experiment. The detection limit for silicon was 4 × 10–7 wt %. 相似文献