检索结果-南通市图书馆

Transient species of fullerenes studied with pulse radiolysis and laser photolysis

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 1996年第6期39卷 561-567页

作者：姚思德连志睿林维真张加山林念芸 The Laboratory of Radiation Chemistry Shanghai Institute of Nudear Research Chinese Academy of Sciences

The excited triplet of C60 or C70 is generated via either direct excitation by laser light or energy transfer from excited states of solvent to C60 and C70. The cation radical of C60 is produced either via hole transfer from cation radical of CCl4 to C60 or via electron transfer from excited triplet of C60 to CCl4. C60 and C70 could be added to trichloromethyl radical to produce adduct radicals with different mechanisms.

关键词： fullerene pulse radiolysis laser photolysis triplet radical.

Antitumor mechanism of VP-16: A pulse radiolysis study

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2002年第4期45卷 394-397页

作者：汪世龙王玫倪亚明姚思德李文哲孙晓宇刘仕姮张超杰 Analysis and Research Centre of Tong Ji University Shanghai China Laboratory of Radiation Chemistry Shanghai Institute of Nuclear Research Chinese Academy of Sciences Shanghai China

The antitumor mechanism of etoposide (VP-16) is investigated using pulse radiolysis technology. The oxidizing mechanism of VP-16 is studied by sodium persulfate, and the reaction rate constant is 4.04× 109 L· mol-1 · s-1. The electron-transfer between VP-16 and tyrosine is observed and the reaction rate constant is 1.1 - 108 L · mol-1· s-1.

关键词： podophyllotoxin VP-16 pulse radiolysis antitumor activity.

Spectroscopic characterization of mechanisms of oxidation of Phe by SO_4^- radical: A pulse radiolysis study

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2002年第4期45卷 398-406页

作者：储高升韩镇辉都志文张淑娟姚思德张志成 Department of Applied Chemistry University of Science and Technology of China Hefei China Laboratory of Radiation Chemistry Shanghai Institute of Nuclear Research Chinese Academy of Sciences Shanghai China

By using time-resolved kinetic spectrophotometry and pulse radiolysis technique, the oxidation of Phe by SO4- radical has been investigated both in aqueous and water/acetonitrilemixed solutions. The results reveal that attack of the oxidizing SO4- radical on Phe leads directlyto the formation of Phe cation radical 3 with a strong absorption peak at 310 nm, then it proceeds in three competitive reactions via either hydroxylation, deprotonation or decarboxylation, which were found to be strongly dependent upon the ionization state of the substitutes -COOH and -NH2 and the nature of the solvents. Decarboxylation takes place only when the carboxyl group is deprotonated. At high pH deprotonation of Phe cation radical 3 is much easier to occur than that in neutral or acid solutions. Moreover, with addition of acetonitrile, deprotonation is more predominant than hydroxylation, whereas in aqueous solutions hydroxylation is much easier to occur.

关键词： Phe pulse radiolysis SO4- radical oxidation mechanism.

A Novel Achievement of Pulse radiolysis of Cytosine Aqueous Solution

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1993年第19期38卷 1612-1616页

作者：骆坚王文锋马先勇姚思德张加山林念芸 Laboratory of Radiation Chemistry Institute of Nuclear Research Academia Sinica P. O. Box 800-204 Shanghai 201800 PRC

1 Introduction Radiation-inducde direct damage of DNA originates primarily from the electron-gaining and losing sites. Determining the chemical nature and distribution of these sites is obviously a central problem in this field. At present, the most widely accepted model is T^-/G^+ dichotomy model, i. e. electrons are mainly trapped at thymine (T) and holes at guanine (G) through electron transfer along DNA chain. However, recent work showed another possible electron-gaining center: cytosine. In the mean time, the role of proton transfer in affecting the distribution of electron trapping among the DNA bases has received more

关键词： cytosine pulse radiolysis electron adduct protonation.

Repair effect of thymine radical anion by echinocoside using pulse radiolysis

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 1996年第5期39卷 544-550页

作者：李雯艳郑荣梁赵松岭姜岳林念芸 State Key Laboratory of Arid Agroecology. Lanzhou UNiversity. Lanzhou 730000 China Department of Biology Lanzhou UNiversity. Lanzhou 730000 China Laboratory of Radiation Chemistry Institute of Nuclear Research Chinese Academy of Science Shanghai 201800 China

Repair activities of thymine radical anion by echinocoside, isolated from Pedicularis plicata. were studied using pulse radiolysis technique. The thymine radical anion was produced by the reaction of hydrated electron with thymine. Echinocoside. one of the polyphenols of phenylpropanoid glycoside, was added to the thymine aqueous solution saturated with N2. Kinetic analysis by transient absorption spectrum showed that thymine radical anion was formed at first, and then after several decades of microseconds of pulse radiolysis. the spectrum of thymine radical anion was changed to that of echinocoside radical anion. The evidence indicated that thymine radical anion was repaired through one-electron-transfer between the DNA base radical anion and echinocoside. The rate constant of electron transfer by echinocoside was 1.45× 109 dm3 · mol1 · s 1.

关键词： echinocoside pulse radiolysis thymine radical anion.

A Case for “radiolysis” in Radiotherapy of Keloids

在线全文

学校读者我要写书评

暂无评论

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2014年第4期3卷 226-234页

作者： K. Malaker H. Weatherburn H. De Souza Department of Clinical Medicine Ross University School of Medicine Portsmouth Dominica Cancer Centre of London London UK

Successful treatment of keloids has eluded the medical community since their first description. Multitudes of therapeutic options are available, but none achieves satisfactory resolution of keloids. One major stumbling block is lack of understanding about their genesis. Assuming keloids are tumors, attempts have been made to treat this condition with standard radiotherapy, with dismal results. Keloidal masses are not an active biological entity. They are aggregations of cellular, hypovascular, hypoxic bundles of collagen, which are produced by atypical fibroblasts in the wounds and eventually cease production due to a hostile biological environment. Having no demonstrable inherent process of disposal of these collagen bundles, this excessive collagen tends to linger to form the bulk of keloids. The lesions eventually become symptomatic and aesthetically unacceptable, and therapeutic intervention is sought. Of all available treatments, such as post-resection radiotherapy, primary radiotherapy in selected cases and primary brachytherapy stand out above any other form of treatment. Be it brachytherapy or external beam treatment, one fundamental aspect of radiation action is the process of “radiolysis”, explaining why “radiobiological” approaches have been ineffective.

关键词： Radiotheraphy radiolysis Keloid Treatment

Reaction of hydroxyl radical with phenylpropanoid glycosides from Pedicularis species: a pulse radiolysis study

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Life Sciences) 1996年第2期39卷 154-158页

作者：王潘奋郑荣梁高建军贾忠建王文峰姚思德张加山林念芸 Department of Biology State Key Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 730000 China Department of Biology Lanzhou UniversityLanzhou 730000 China Laboratory of Radiation Chemistry Shanghai Institute of Nuclear Research Chinese Academy of Sciences Shanghai 201800 China

Using pulse radiolysis technique, the reaction between hydroxyl radical and 7 phenylpropanoidglycosides: echinacoside, verbascoside, leucosceptoside A, martynoside, pediculariosides A, M and N which were isolated from Pedicularis were examined. The rate constants of these reactions were determined by transient absorption spectra. All 7 phenylpropanoid glycosides react with hydroxyl radical at high rate constants within (0.97-1.91)×1010L · mol-1 · s-1. suggesting that they are effective hydroxyl radical scavengers. The results demonstrate that the numbers of phenolic hydroxyl groups of phenylpropanoid glycosides are directly related to their scavenging activities. The scavenging activities are likely related to o-dihydroxy group of phenylpropanoid glycosides as well.

关键词： phenylpropanoid glycosides Pedicularis hydroxyl radical pulse radiolysis rate constant scavenging effect.

固相微萃取-气相色谱-质谱联用鉴别荚醚N,N,N',N'-四丁基-3-氧-戊二酰胺辐射产物

在线全文

学校读者我要写书评

暂无评论

分析测试学报 2004年第Z1期23卷 171-172页

作者：张晓岚张东平杨燕琴金至清上海大学环境科学与工程系上海200072

　　N,N,N′,N′-四丁基-3-氧-戊二酰胺(TBOPDA)是一种新合成的萃取剂,它可以在高酸度情况下萃取铀等锕系元素[1],在高废液的萃取处理中具有良好的应用前景.曾有报道采用GC方法分析辐照后的气相产物[2],本文采用固相微萃取技术萃取TBOPD... 详细信息

　　N,N,N′,N′-四丁基-3-氧-戊二酰胺(TBOPDA)是一种新合成的萃取剂,它可以在高酸度情况下萃取铀等锕系元素[1],在高废液的萃取处理中具有良好的应用前景.曾有报道采用GC方法分析辐照后的气相产物[2],本文采用固相微萃取技术萃取TBOPDA部分挥发性和半挥发性液相辐照产物,结合GC-MS进行鉴定,确定了其液相辐照产物主要为二丁胺、二正丁基甲酰胺、二正丁基乙酰胺.……

关键词： Solid-phase micro-extraction GC - MS analysis radiolysis

Reactions of tea polyphenol four constituents with hydroxyl radical: A pulse radiolytic study

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 1998年第3期41卷 295-300页

作者：姜岳姚思德林维真林念芸朱大元 Laboratory of Radiation Chemistry Shanghai Institute of Nuclear Research Chinese Academy of Sciences Shanghai China Shanghai Institute of Materia Medica Chinese Academy of Sciences Shanghai China

Using the electron pulse radiolytic techniques, the reactions between hydroxyl radical and tea polyphenol four constituents epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC) have been investigated in detail, their corresponding rate constants for scavenging hydroxyl radicals have been determined to be 1.5 × 1010, 1.4 × 1010, 9.7 × 109and 9.2 x 109 dm3-mol?1-s?1, respectively. On the basis of their structures and transient absorption spectra, the OH adducts of EGCG and ECG undergo unimolecular elimination of gallate group.

关键词： electron pulse radiolysis hydroxyl radical transient absorption spectra tea polyphenol.