共查询到20条相似文献,搜索用时 15 毫秒
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F. Dudley Hart 《BMJ (Clinical research ed.)》1951,2(4734):795-796
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M M Mossoba I Rosenthal P Riesz 《International journal of radiation biology and related studies in physics, chemistry, and medicine》1981,40(5):541-552
gamma-Radiolysis in the polycrystalline state and U.V. photolysis in aqueous solution at 220 nm of several dihydropyrimidines and their derivatives have been investigated by spin-trapping and electron spin resonance. 2-Methyl-2-nitrosopropane was used as the spin-trap. The spin-adducts of the 6-yl radicals obtained fall into two categories. Those from dihydro-1-methyluracil, dihydro-6-methyluracil, dihydro-1-ethyluracil and dihydro-1-methylcytosine exhibit a beta-nitrogen hyperfine coupling constant (alpha beta N) equal to or less than 2.0 G while the ones fom dihydro-orotic acid, dihydrouracil and dihydrothymine showed much larger alpha beta N values (greater than 3.3 G). Dihydrouridine gives radicals characteristic of both the dihydropyrimidine ring and the sugar moiety. The same radicals were obtained by gamma-radiolysis or U.V. photolysis. For all the 5-yl radicals obtained by U.V. photolysis, a direct photoexcitation mechanism is proposed. 相似文献
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《BMJ (Clinical research ed.)》1940,1(4134):541-544
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