共查询到17条相似文献,搜索用时 62 毫秒
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用自由基本体聚合方法合成了一种新型的X光显影含糖三元共聚物P(2-IEMA-AcGEMA-MMA). 探讨了单体配比和链转移剂用量对聚合物分子量及其分布的影响, 并用FTIR, 1H NMR和GPC对其结构进行了表征. 研究结果表明, 改变单体配比对聚合物的分子量几乎不产生影响, 但减少链转移剂用量时, 可明显增加三元共聚物的分子量. 聚合物分子量分布一般在2~3之间, 符合自由基聚合产物分子量分布的一般规律. 聚合物具有良好的显影性, 显影效果随着样品厚度的增加而增强. 相似文献
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酚类聚合物在水相胶束中的酶促合成 总被引:3,自引:1,他引:3
本文报道辣根过氧化物酶在水相胶束中催化聚合取代酚类的研究。水相胶束中酶催化活力高,产物分子量均一;通过调节表面活笥剂和单体的浓度,可以有效地控制产物的分子量,从而建立了不同聚合度有机纳米材料酶促合成的新方法。产物具有较强的蓝紫色荧光及较好的耐热性能,是一种很有应用前景的蓝光材料。 相似文献
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以两端溴化的聚9,9-二己基芴作为大分子引发剂, 6-O-甲基丙烯酰基-1,2∶3,4-二-O-异亚丙基-D-吡喃型半乳糖(6-O-Methacryloyl-1,2∶3,4-di-O-isopropylidene-D-galactopyranose, MaIpGa)为单体, 氯化亚铜/1,1,4,7,10,10-六甲基三乙基四胺为催化剂, 通过原子转移自由基聚合(ATRP), 合成了一种新型的具有良好光学性能的三嵌段共聚物聚甲基丙烯酸羟基保护半乳糖酯-聚芴-聚甲基丙烯酸羟基保护半乳糖酯(PMaIpGa-PF-PMaIpGa). 在酸性条件下进一步水解, 得到水溶性的聚甲基丙烯酸半乳糖酯-聚芴-聚甲基丙烯酸半乳糖酯(PMaGa-PF-PMaGa)三嵌段聚合物, 其结构和分子量(分布)通过核磁共振、红外光谱和凝胶渗透色谱(GPC)确证, 并研究了其紫外-可见和荧光光谱特性. 相似文献
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用磷酸三酯法在溶液中合成了两个带有3′-(S)-胸腺嘧啶基-4′-(R)-羟基-5′-(S)-羟甲基四氢呋喃的三脱氧核苷酸3和4。与三脱氧核苷酸(2)相比,化合物3和4对核酸酶S1具有更大的稳定性。 相似文献
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Li Cai 《Journal of carbohydrate chemistry》2013,32(7):535-552
Glycosylation is one of the most important reactions in nature as it results in the formation of glycoconjugates with diverse biological functions. Sugar nucleotides serve as the natural donor molecules for the biosynthesis of such glycoconjugates and other carbohydrates. Furthermore, these donor molecules are also indispensable building blocks for the enzymatic synthesis of carbohydrates in vitro using Leloir-type glycosyltransferases. Given such importance, the biosynthetic pathways of sugar nucleotides have been exploited, enabling the development of both chemical and enzymatic approaches to produce these molecules. A survey of recent progress in enzymatic synthesis of common mammalian sugar nucleotides as well as their derivatives is thus presented. As a popular strategy, conjugation of sugar nucleotide synthesis with glycosyltransfer reactions and in vivo production of sugar nucleotides are also included. 相似文献
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巯基-乙烯基加成反应具有清洁、高效、条件温和的特点,广泛应用于有机合成、聚合物科学和材料化学等诸多领域。国内外关于这一反应的研究已有大量文献报道,但该反应在含硅聚合物的合成与应用研究中还少有触及。本文综述了巯基一乙烯基加成反应在聚硅氮烷、聚硅碳烷、聚硅氧烷三种含硅聚合物合成中的应用,介绍了国内外的研究现状及发展趋势,并... 相似文献
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聚肽是由人工合成的氨基酸聚合物,具有良好的生物相容性和生物可降解性。本文以菠萝蛋白酶为催化剂,在温和条件下于非水体系中从L-苯丙氨酸甲酯聚合得到齐聚L-苯丙氨酸。通过FT-IR、~1HNMR、MS和MALDI-TOF确定了齐聚L-苯丙氨酸的结构和聚合度。通过单因素考察了菠萝蛋白酶催化聚合反应的最优条件。结果表明,在40℃下用2.44U菠萝蛋白酶于15%DMSO的磷酸缓冲液(pH=8.0)中催化0.43g L-苯丙氨酸甲酯盐酸盐聚合,反应3h后齐聚L-苯丙氨酸得率达到最大值,为35.67%。 相似文献
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《中国化学会会志》2018,65(4):452-458
Lipase‐catalyzed synthesis of lauroyl glucose ester was continuously performed in a biphasic system consisting of supercritical CO2 and an ionic liquid (IL). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy are employed to identify the product lauroyl glucose ester. The effects of reaction pressure, temperature, substrate flow rate, the amount of enzyme, and the amount of IL on the glucose conversion rate are investigated. The highest glucose conversion of up to 95.5% could be achieved at the optimal condition, which is higher than that in the pure IL. The enzyme activity in the biphasic system was 18.19 μmol/g/min, which is much higher than that in the pure IL. The continuous reaction in the binary system could last for 10 h at high enzyme activity. The combination of supercritical CO2 and ILs could not only improve the reaction rate and yield, which are attributed to the fast mass transfer rate and enhanced enzyme activity and lifespan, but also make the product separation and enzyme/ILs recycling easier. 相似文献
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The enzymatic synthesis of CCK-8 tripeptide derivative Phae-Met-Asp(OMe)-Phe-NH2 is reported.Starting with Phac-Met-OCam,we have successfully synthesized the target tripeptide with three free or immobilized enzymes, α-chymotrypsin,papain and thermolysin in reasonable yields.The key steps in this synthesis were the coupling of Phac-Met-OCam and H-Asp(OMe)2 to from Met-Asp peptide bond catalyzed by α-chymotrypsin and the selective hydrolysis of α-ester of Phac-met-Asp(OMe)2 catalyzed by papain. 相似文献