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131.
The stereoselective synthesis of (2R,4R)-2-N-tert-butyloxycarbonyl amino-4,5-epoxido-valeric acid methyl ester 8,which is the key intermediate for the synthesis of (2′S,2R)-3-trans-nitrocyclopropyl-alanine,was first accomplished. 相似文献
132.
以取代的3-羧酸活化色酮、靛红与消旋脯氨酸为原料,乙腈为溶剂,依次经1,3-偶极子[3+2]环加成和脱羧反应,合成了8个新型的二氢色原酮拼接多环吡咯螺环氧化吲哚类化合物 (3a~3h),产率68%~87%, dr值15/1~20/1,其结构经1H NMR, 13C NMR和HR-MS(ESI-TOF)表征。采用MTT法研究了3a~3h对人白血病细胞(K562)的体外抑制活性。结果表明:化合物3d,3f, 3g对K562具有一定的抑制活性(IC50=46.3~69.4 μmol·L-1)。 相似文献
133.
Tan B Dozier A Lehmler HJ Knutson BL Rankin SE 《Langmuir : the ACS journal of surfaces and colloids》2004,20(17):6981-6984
Mesoporous silica materials with pore structures such as 2D hexagonal close packed, bicontinuous cubic, lamellar, sponge, wormhole-like, and rectangular have been made by using surfactant templating sol-gel processes. However, there are still some "intermediate" phases, in particular mesh phases, that are formed by surfactants but which have not been made into analogous silica pore structures. Here, we describe the one-step synthesis of mesoporous silica with a mesh phase pore structure. The cationic fluorinated surfactant 1,1,2,2-tetrahydroperfluorodecylpyridinium chloride (HFDePC) is used as the template. Like many fluorinated surfactants, HFDePC forms intermediate phases in water (including a mesh phase) over a wider range of compositions than do hydrocarbon surfactants. The materials produced by this technique are novel elongated particles in which the layers of the mesh phase are oriented orthogonal to the main axis of the particles. 相似文献
134.
A rapid and simple method using capillary electrophoresis (CE) with chemiluminescence (CL) detection was developed for the determination of levodopa. This method was based on enhance effect of levodopa on the CL reaction between luminol and potassium hexacyanoferrate(III) (K3[Fe(CN)6]) in alkaline aqueous solution. CL detection employed a lab-built reaction flow cell and a photon counter. The optimized conditions for the CL detection were 1.0 × 10−5 M luminol added to the CE running buffer and 5.0 × 10−5 M K3[Fe(CN)6] in 0.6 M NaOH solution introduced postcolumn. Under the optimal conditions, a linear range from 5.0 × 10−8 to 2.5 × 10−6 M (r = 9991), and a detection limit of 2.0 × 10−8 M (signal/noise = 3) for levodopa were achieved. The precision (R.S.D.) on peak area (at 5.0 × 10−7 M of levodopa, n = 11) was 4.1%. The applicability of the method for the analysis of pharmaceutical and human plasma samples was examined. 相似文献
135.
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
136.
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
137.
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
138.
139.
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
140.
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