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8—氮鸟嘌呤的极谱伏安行为 总被引:4,自引:0,他引:4
用循环伏安法(CV)、电流采样极诸法(SCP,即TAST)、常规脉冲极谱法(NPP)、微分脉冲极谱法(DPP)、线性扫描伏安法(LSV)、Osteryoung方波伏安法(OSWV)和计时库仑法(CC)等电化学技术研究了抗癌药物8-氮鸟嘌呤(8-azaguanine,guanazolo,简称8-AG)的极谱伏安行为.在 0. 1mol/L H2SO4底液中,8-AG有一良好的还原峰,峰电位(Ep)在-0. 95V(vs.Ag/AgCl,下同)附近,8-AG浓度在4×10-6~8×10-4mol/L范围内.峰高与浓度有良好的线性关系,线性相关系数r=0.9999~0.9910,检出限为1× 10-6mol/L.实验证明了该峰具有吸附性.本文提出了电极反应机理,它包括:酸性介质中8-AG的质子化、质子化的8-AG在汞电极上吸附以及完全不可逆的两电子还原过程.同时用量子化学计算方法(全略微分重叠法即CNDO/2)对8-AG和鸟嘌呤的各原子的净电荷以及Wiberg键级进行了计算,从理论上解释了8-AG的电化学还原机理。 相似文献
95.
1—酰基—4—氯环己烷与取代芳烃的区域与立体选择性反应 总被引:2,自引:0,他引:2
从环己烯合成了1-酰基-4-氯环己烷,发现在其在AlCl3催化与苯,氯苯,溴苯等优先生成反式1-芳基-4-酰基环己烷,与联苯反应时选择性较差。 相似文献
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ELECTROCHEMICAL POLYMERIZATION OF ANILINE IN PHOSPHORIC ACID AND THE PROPERTIES OF POLYANILINE 总被引:1,自引:0,他引:1
The behavior of the electrochemical polymerization of aniline in a weak acid, phosphoric acid, is very similar to that in strong acids, i.e. its polymerization rate increases quickly with the electrolysis time. The FTIR spectra of polyaniline samples synthesized in phosphoric acid indicate that the counter ion H2PO4^- is present in both the oxidized form and the reduced form of polyaniline. The counter ion plays an important role in adjusting the pH value at the electrode surface of polyaniline during the oxidation and reduction processes. As a result, a pair of redox peaks still appear in cyclic voltammograms of polyaniline in a solution of sodium sulfate of pH 5.5 and in a solution of NaH2PO4 of pH 7.0,respectively, at low potential scan rate; and the color of polyaniline film also changes with applied potential at pH 7.0. Thus,the pH region for the electrochemical activity and the electrochromism of polyaniline is extended to pH 5.5 for a solution of sodium sulfate and to pH 7.0 for a solution of NaH2PO4. The conductivity of polyaniline is 3.3 S cm^-1, depending on the concentration of phosphoric acid used in the stage of polymerization of aniline. The result of elemental analysis of polyaniline is presented here. 相似文献
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Jianjun ZhangFanzuo Kong 《Tetrahedron letters》2003,44(9):1839-1842
A general method for the synthesis of 2-xylose or glucuronic acid branched (1→3)-linked mannose oligosaccharides has been developed. As a typical example, the synthesis of the methyl glycoside of β-d-GlcpA-(1→2)-α-d-Manp-(1→3)-[β-d-Xylp-(1→2)-]α-d-Manp-(1→3)-[β-d-Xylp-(1→2)-]α-d-Manp, the repeating unit of the exopolysaccharide from Cryptococcus neoformans serovar A, was achieved in a regio- and stereoselective manner. 相似文献
100.
Lianghui Gao Mengjie Gong Fanbo Kong Ting Yuan Xiaohong Li Lili Zu Yunchao Li Louzhen Fan 《大学化学》2020,35(5):81-87
During the fight against the new coronavirus epidemic, the "Physical Chemistry" team of Beijing Normal University used various network platforms and tools, such as MOOC of China University, Rain Classroom and WeChat Group in the teaching process. The exploration and practice of online learning of "Physical Chemistry" is carried out based on MOOC teaching, with student learning as the center and teacher guidance as the support. Taking the most difficult chapter of "fundamentals for statistical thermodynamic" as an example, we designed a complex teaching program that includes previews, watching MOOC videos in class, real-time online exercises, teachers' answers, and after-class reflection and questioning. The students were encouraged to learn independently through the reserved information, designed activities and assignments. Practice shows that the online course has cultivated the students' self-management ability, trained their critical thinking skills, and achieved good teaching results. 相似文献