987 resultados para ESR DOSIMETRY


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Water-soluble polyhydroxylated fullerene derivatives (fullerenol) were synthesized, and their scavenging ability for (OH)-O-.-radical was studied by the combination of ESR spectroscopy and spin-trapping technique with phenyl-t-butyl-nitrone. It was found that fullerenols showed an excellent efficiency in eliminating (OH)-O-. free radicals generated by UV photolysis of H2O2. At an applied fullerenol concentration of 0, 3 mg/mL in the final solution, a radical scavenging efficiency of approximate 95% was achieved, revealing the potential use of these compounds as novel potent free radical scavengers in biological systems.

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The synthesis for lanthanofullerenes was studied by activating the La2O3 containing graphite rod in situ and back-burning the carbide-rich cathode deposite, La@C-2n are efficiently extracted in high temperature toluene, among them, La@C-74 as a new species is added into the soluble lanthanofullerenes, The toluene extraction is first characterized by desorption electron impact (DEI) mass spectrometry, The ESR spectrum of the extraction at room temperature is also discussed.

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采用对掺入La_2O_3的石墨棒原位活化并结合交换电极回放方法制备了产率较高的金属富勒烯,并用甲苯高温热提取的方法有效地提取出La@C_(2n),其中La@C_(74)为可溶性金属富勒烯增加了新成员.同时,首次采用解吸电子轰击质谱对提取物进行了表征,讨论了提取物的ESR谱.

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富勒醇清除·OH自由基的ESR研究祝严师,孙大勇,刘桂珍,刘子阳,詹瑞云,刘淑莹(中国科学院长春应用化学研究所应用谱学开放实验室,长春,130022)关键词C_(60),富勒醇,OH自由基,自旋捕捉,ESR生物体内的许多现象均涉及到自由基反应,现已发?..

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本文通过对不同条件下的Co(W_2O_7)_6~(10-)和CuW_(12)O_(40)~(6-)掺杂聚吡膜ESR谱线的分析并以相同条件下NO_3~-掺杂聚吡咯膜作为参照,表明杂聚阴离子不仅起着中和电性的作用,而且与聚吡咯分子链相作用形成某种加合物,它影响聚吡咯的电结构,这种加合物在过正或过负的电位下均不稳定.首次发现在CuW_(12)O_(40)~(6-)掺杂的干态聚吡咯膜具有Dysonian线型,表明膜中其它电结构的存在.

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ESR和自旅捕捉技术用于研究活体动物犬心肌缺血再灌产生的自由基,PBN从冠状静脉血液中捕捉到了OH自由基,直接地证实了缺血再灌细胞膜损伤的活性氧自由基作用机制;实验还看到一种甾体皂甙药物具有保护心肌细胞.防止自由基损伤的功能.

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本文通过WAXD,DSC方法讨论成核剂(Nd2O3)对PA1010的聚集态结构的影响。用ESR研究辐照不同聚集态结构PA1010体系的俘陷自由基行为。结果表明:俘陷自由基—CH2CONHCHCH2—主要存在于结晶表面,结晶的表面积越大,俘陷自由基—CH2CONHCHCH2—的含量越高,在一定条件下,如升温,常温放置一段时间,转化为俘陷自由基—CH2C=O的量也越大;俘陷自由基-CH2C=O主要存在于非晶区

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ESR method has been used to study superhyperfine. interaction of I-127 in [Cu (IO5OH)(2)](5-) ion for Na4KCu(IO5OH)(2) . 12H(2)O single crystal. The main purpose of this paper is to confirm the existence of unpaired electron spin on iodine atom and to find a reasonable explanation for the spin delocalization of CU2+ ions. Based on the ESR parameters of paramagnetic [Cu(IO5OH)(2)](5-) ions, the calculated results show that about 0.77% of the unpaired eletron spin is located on each iodine atom.

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Nonstiochiometric SnO2-x nanocrystalline material were successfully prepared through Sol-Gel process using anhydrous stannic chloride and iso-propyl alcohol. TEM observation shows that the mean diameter of the powder sintered at 700 degrees C for 2 hours is about 20 nm. By the investigation of XRD and ESR, we can conclude that the sample sintered at 300 degrees C for 2 hours was amorphous and it grew into nanocrystalline with the oxygen vacancies and defects when sintered at 700 degrees C for 2 hours. Using these conclusion, the ESR signals and the difference between the two SnO2-x samples are explained.

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采用溶胶凝胶法,以无水四氯化锡及异丙醇为原料,制得非化学计量比的SnO_(2-x)纳米微晶材料.透射电镜图片显示700℃焙烧2h得到的粉体的粒度为20nm,由X射线衍射及X射线光电子能谱的分析可知,300℃焙烧2h得到颗粒边界部分原子无规排布的纳米粉体,而700℃焙烧2h得到的是晶格趋于完整的纳米微晶,它们都存在氧空位及晶格缺陷,利用这些结论可以解释SnO_(2-x)纳米微晶材料中出现的顺磁信号.

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用ESR定量法研究了聚乙烯醇胺肟螯合纤维吸附铜(Ⅱ)离子的吸附反应动力学.为研究吸附反应动力学提供了新方法.并证实该螯合纤维的吸附性能较好.

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用电子自旋共振(ESR)和固体 ̄(13)CNMR研究了聚丙烯腈(PAN)在不同裂解温度(T_P)下的结构变化,当T_P从250℃增加到600℃,ESR信号线形没有变化,g值与T_P无关,ΔH_(PP)减小,自旋浓度(N_S)开始增加,T_P进一步升高,N_S又减少. ̄(13)CNMR谱指出在不同T_P下谱峰发生很大变化,与另文报道的红外及X-射经衍射结果一致,随T_P升高,PAN逐渐脱去小分子形成具有环化共轭结构的产物.

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亚硝基特丁烷(2—methyl—2—ntirosopropane,简称MNR)为捕集剂,利用自旋捕集技术,对γ射线辐照嘧啶核苷水溶液进行了ESR研究,确定了胸苷、尿苷和胞苷可产生的自旋捕集自由基的类别,并讨论了自由基形成的机制。

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尼龙1010(以下简称PA1010)是半结晶聚合物。我们采用不同浓度的成核剂,通过淬火和退火的方法制备了不同微晶尺寸的试样,用~(60)Coγ—射线进行辐照,利用ESR方法研究其交联和裂解反应的机理。

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PVDF是传感器和换能器领域里非常有吸引力的组成元件,由于它的特殊的压电性能和热电性能,薄膜PVDF成功地应用于高加速度测量,集成红外传感器等领域。在民用和军事及医学等方面有广泛的应用前景。PVDF的结构、结晶和形态与压电性能和热电