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151.
The present paper employed density function theory to investigate two reaction pathways for isomerization of enol ester proposed by Yang(path a) and the present authors(path a), respectively. The base catalytic effects of solvent triethylamine on these two reactions were also evaluated. It is demonstrated that path B is more preferable than path a due to low barrier height for the rate-determining step. 相似文献
152.
基于卟啉对癌细胞的特殊亲和作用和哌嗪化合物的抗肿瘤、抗病毒作用,设计并合成了具有哌嗪结构的新型卟啉化合物5,10,15,20-四[4-(4'-乙基哌嗪基)苯基]卟啉(TEPPPH2),其结构经UV-Vis, 元素分析,1H NMR等手段证明。采用UV-Vis光谱和荧光光谱研究了TEPPPH2和小牛胸腺DNA 的相互作用模式和结合机理。实验发现,TEPPPH2能嵌入到DNA的碱基对中,1个小牛胸腺DNA分子对TEPPPH2分子的最大结合数n约为88,结合常数为8.4×106mol•L-1 。TEPPPH2与DNA的结合数和结合常数大于已知的四(4-N-甲基吡啶基)卟啉和Ca/sal-his、Ni/sal–aln型席夫碱抗癌药物。 相似文献
153.
Two natural products databases, the marine natural products database (MNPD) and the traditional Chinese medicines database (TCMD), were used to find novel structures of potent SARS-CoV protease inhibitors through virtual screening. Before the procedure, the databases were filtered by Lipinski's ROF and Xu's extension rules. The results were analyzed by statistic methods to eliminate the bias in target-based database screening toward higher molecular weight compounds for enhancing the hit rate. Eighteen lead compounds were recommended by the screening procedure. They were useful for experimental scientists in prioritizing drug candidates and studying the interaction mechanism. The binding mechanism was also analyzed between the best screening compound and the SARS protein. 相似文献
154.
155.
离聚体水基微乳液化的研究——聚苯乙烯离聚体微乳化过程相反转的表征 总被引:7,自引:0,他引:7
以乙酰磺酸为磺化剂制备磺化度为3~15mol%的磺化聚苯乙烯(SPS)并中和成盐.在一定的温度和搅拌速率下,加水将SPS乳化成水包油的稳定水基微乳液.用乳化过程中体系电导率和粘度的变化表征了乳化相反转过程.研究了溶剂的极性和离子含量对聚苯乙烯离聚体溶液可乳化性和乳化过程及乳液稳定性的影响. 相似文献
156.
The fabrication and electrochemical characteristics of a penicillamine (PCA) self-assembled monolayer modified gold electrode were investigated. The self-assembled electrode shows obvious electrocatalytic activity for the oxidation of epinephrine (EP). In phosphate buffer (pH 7.73), a sensitive oxidation peak was observed at 0.190V with the PCA modified Au electrode. The peak current is proportional to the concentration of EP in the range of 2.0×10–56.0×10–4molL–1 and 5.0×10–6 2.0×10–4molL–1 for cyclic voltammetry (CV) and differential pulse voltammetry (DPV) with the detection limits of 1.8×10–7 and 1.3×10–7molL–1, respectively. The possible reaction mechanism is also discussed. The PCA self-assembled monolayer modified gold electrode is highly stable and can be applied to the determination of EP in practical injection samples. Application is simple, rapid and produces accurate results. 相似文献
157.
Tetragonal tungsten bronze K0.71Nd0.028WO3 was synthesized by rare earth co-permeation method using Keggin type POMs of α-K10[SiCu3(OH2)W9O37]·6H2O (abbreviated as SiW9Cu3) as precursor. XRD, XPS, XRF, TG-DTA were used to characterize the resulting material. The XPS results indicate that Nd has permeated and diffused into the body of the sample and exists in tungsten bronze in the form of K0.71Nd0.028WO3. The results of TG-DTA show that K0.71Nd0.028WO3 begins to decompose at 320 ℃. The consequence of DC four-probe shows that the conductivity of the sample permeated by rare earth is 103 times higher than that of the sample only permeated by methanol at room temperature. The conductivity of the sample only permeated by methanol is only 10-3 S·cm-1 but the conductivity of the sample permeated by rare earth is 1.65 S·cm-1. 相似文献
158.
159.
Neural growth inhibitory factor (GIF), a member of metallothionein family (metallothionein-3, MT3), was well known by its distinct neural growth inhibitory activity, which is not shown by other MT isoforms. However, till now, people still did not know clearly how GIF exerts its biological functions. Since it has been reported that GIF might serve as NO scavenger and was related to the release of zinc, our study was focused on the interaction of GIF and NO. By studying the reactions of human GIF and human MTlg with SNOC-a type of NO donor, it was found that GIF was more reactive than MT-lg toward SNOC. In order to further figure out if the high reactivity of GIF in this reaction resulted from the acid-base catalysis, several mutants were constructed: E23K, E41G/E43A, E23K/E41G/E43A. By studying their basic properties and the reactions toward SNOC, it was found that the S-nitrosylation of GIF was not only related to the acid-base catalysis, but also to the accessibility of metal-thiolate clusters. 相似文献
160.
用CoMFA和HQSAR两种QSAR方法研究了50个乙内酰脲类分子的定量构效关系.本研究从构象搜索所得的低能结构出发构建化合物分子的构象, 建立CoMFA模型,并进行了全空间搜索. HQSAR本质上是一种二维的QSAR方法,与CoMFA方法相比,该方法在数据处理方面,比CoMFA方法快捷,并且可重复性好.两种方法均得到了较好分析结果, CoMFA的交叉验证相关系数q2 值为0.815, HQSAR的q2值为0.893.这些方程有力地说明了该类分子在(R,R)-N-3,5-dinitrobenzoyl-1,2-diamine型手性固定相上拆分过程中的影响因素,对今后类似拆分的实验研究提供了理论支持. 相似文献