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ExtensivestudiesofradiationorchemicalinjuryofbiologicaltargetmoleculesdemonstratethatOHradical,themostreactiveoxygenspecies,reactswithbiologicalmacromolecules,suchasDNA,inducingbasealterations,basicsites,andstrandbreaks,resultedinvariouspathogenesis,such… 相似文献
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A new idea is put forward to modify the Clarkson-Kruskal (CK) direct method. Using the usual CK direct method to a coupled KdV system, two types of usual similarity reductions can be obtained. However, the application of the modified CK direct method leads to three types of new similarity reductions different from the usual ones. 相似文献
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采用脉冲辐解技术, 研究了葛根素(puerarin, 一种异黄酮)对二氧化氮自由基(NO28226;)、一氧化氮自由基(NO8226;)和羟基自由基(OH8226;)的清除活性. 葛根素与NO28226;和NO8226;反应产生的瞬态吸收峰都在340 nm, 该吸收峰归结为瞬态产物puerarin-4-O8226;; 葛根素与OH8226;反应产生了较宽的瞬态吸收光谱(300~750 nm), 该谱图归结为puerarin-2-O8226;, puerarin-4-O8226;和[puerarin-OH]8226;瞬态吸收的叠加. 另外, 葛根素与NO28226;, NO8226;和OH8226;反应的速率常数分别为2.6 × 108, 1.7 × 108和3.9 × 109 L·mol-1·s-1. 相似文献
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Free radical theory of biology and medicine suggests that free radicals are involved in the happening of many chronic diseases including cancers and cardiovascular diseases, and natural antioxidants play positive effect in the prevention of such diseases[1]. This theory leads to much interest in the free radical scavenging activities of the pharmacologically active components in herbal medicines. Puerarin (fig. 1), a compound of isoflavone, is isolated from Chinese herbal medicine radix puera… 相似文献
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类胡萝卜素与二氧化氮自由基(NO2·)的反应 总被引:1,自引:0,他引:1
研究表明,类胡萝卜素可以降低肿瘤、某些心血管病及衰老退行性疾病的发生率[1].但流行病学干预研究也指出,吸烟者与石棉工人补充β胡萝卜素却能促进肺癌发生[2,3].吸烟对健康有害,香烟烟雾中有许多活性氧自由基,NO是一种主要成分,它可生成二氧化氮自由基(NO·2),引起不饱和脂肪 相似文献
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设 V、W是线性空间 ,本文用“VW”表示 V到 W的所有映射的集合 ,L( V)表示 V的所有线性变换的集合 ,L( VW)表示 V到 W的线性映射的集合。本文假定 V是实数域上的线性空间 ,W为欧氏空间。[1 ]证明了如下定理 :定理 1 [1] 设σ是欧氏空间 V的一个变换 ,φ∈ L ( V)且可逆 ,则对 α,β∈ V,均有 (σα,σβ) =( φα,φβ) ,当且仅当存在 V上正交变换 T,使 σ=Tφ。[2 ]推广 [1 ]的结果得 :定理 2 [2 ] 设 A,B∈ VV( 1 )若 B可逆 ,则有 α,β∈ V,( Aα,Aβ) =( Bα,Bβ) ,当且仅当存在 V的正交变换 T使 A=TB。( 2 )若 B… 相似文献
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通过脉冲辐解研究CCl3OO×与胭脂树橙(BIX), β-胡萝卜素(b-C)及番茄红素(LYC)在水/醇均相混液中反应. 在与CCl3OO×反应过程中, 类胡萝卜素本底吸收位置(BIX在500 nm左右, b-C在450 nm左右, LYC在500 nm左右)有明显的漂白, BIX与b-C在650 nm左右有反应产物生成过程的吸收峰出现. BIX和b-C与CCl3OO×反应的二级反应速率常数分别为1.78 ´ 108与7.8 ´ 107 mol-1·dm3·s-1 , LYC与CCl3OO ×反应只观察到漂白过程, 表明LYC与CCl3OO×反应产物在检测范围内没有特征吸收, 根据漂白过程求得二级反应速率常数为4 ´ 107 mol-1·dm3·s-1. 相似文献
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In this paper, Lie symmetry is investigated for a new integrable
coupled Korteweg--de Vries (KdV) equation system. Using some symmetry
subalgebra of the equation system, we obtain five types of the
significant similarity reductions. Abundant solutions of the coupled
KdV equation system, such as the solitary wave solution, exponential
solution, rational solution and polynomial solution, etc. are
obtained from the reduced equations. Especially, one type of
group-invariant solution of reduced equations can be acquired by
means of the Painlev\'e I transcendent function. 相似文献