排序方式: 共有16条查询结果,搜索用时 809 毫秒
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制备了甘氨酸-壳聚糖复合膜修饰玻碳电极(Gly-CTS/GCE),研究了抗坏血酸(AA)和尿酸(UA)在该修饰电极上的电化学行为。结果表明在pH=5.59的磷酸盐缓冲溶液中,AA、UA在Gly-CTS/GCE上均产生灵敏的不可逆氧化峰,其峰电流与浓度在一定范围内呈良好的线性关系。对AA和UA混合溶液平行测定7次,相对标准偏差分别为4.6%、2.9%,表明该电极重现性和稳定性良好。AA、UA在Gly-CTS/GCE电极上的氧化峰峰电位相差340mV,据此可实现对二者的同时检测,并可应用于实际样品测定。 相似文献
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C70X2(X=H,F, Cl)的稳定性和电子光谱 总被引:1,自引:0,他引:1
用INDO方法研究C70H2四种异构体的稳定性, 表明其最稳定异构体为1, 9-C70H2和7, 8-C70H2, 两者能量差为16.3KJ.mol^-^1, 与实验值及ab initio计算值接近; 光谱计算表明, 其特征吸收峰与实验值一致。在此基础上预测C70F2和C70Cl2的稳定性和电子光谱, 表明C70F2四种异构体的稳定性顺序与C70H2一致, 而C70Cl2则以21, 42-异构体最为稳定。二者的电子光谱与C70H2极其相似只是在500nm以上有细微差别。 相似文献
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Maljaars CE Halkes KM de Oude WL Haseley SR Upton PJ McDonnell MB Kamerling JP 《Journal of combinatorial chemistry》2006,8(6):812-819
Two combinatorial glycopeptide libraries were synthesized on solid support via the "split-and-mix" method combined with the ladder synthesis strategy. The O-glycopeptide library contained Gal(beta1-O)Thr, whereas the S-,N-glycopeptide library contained both Gal(beta1-S)Cys and Gal(beta1-N)Asn. In this model study, the two libraries were screened against the fluorescently labeled lectin Ricinus communis agglutinin (RCA120). The screening results showed that both O- and S- or S-,N-glycopeptides were recognized by the lectin with similar amino acid recognition patterns. Surface plasmon resonance interaction studies demonstrated that both the selected S- or S-,N-glycopeptide hits and the O-glycopeptides bound to the lectin with a similar affinity. Structure 19, containing two glycosylated cysteine residues, bound to the receptor with the highest affinity (KA = 3.81 x 10(4) M(-1)), which is comparable to N-acetyllactosamine. Competition assays, in which some selected glycopeptides and methyl beta-d-galactopyranoside competed for the binding site of immobilized RCA120, showed that the glycopeptide-lectin interaction was carbohydrate-specific. Incubation of the O- and S-,N-glycopeptides with beta-galactosidase demonstrated the complete stability of S-,N-glycopeptides toward enzymatic degradation, whereas O-glycopeptides were not completely stable. 相似文献
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Carvalho de Souza A Kuil J Maljaars CE Halkes KM Vliegenthart JF Kamerling JP 《Organic & biomolecular chemistry》2004,2(20):2972-2987
The gut-associated circulating anodic antigen (CAA) is one of the major excretory antigens produced by the parasite Schistosoma mansoni. The immunoreactive part of CAA is a threonine-linked polysaccharide composed of long stretches of the unique repeating disaccharide-->6)-[beta-D-GlcpA-(1-->3)]-beta-D-GalpNAc-(1-->. Previously, using surface plasmon resonance and ELISA techniques, it has been shown that some anti-CAA IgM monoclonal antibodies (MAbs) also recognize members of a series of bovine serum albumin (BSA)-coupled synthetic di- to penta-saccharide fragments of the CAA glycan. To generate information on the molecular level about the glycan specificity of the relevant IgM MAbs, two series of oligosaccharides related to the CAA disaccharide epitope were synthesized, and coupled to BSA. The first three analogues, beta-D-GlcpA-(1-->3)-[small beta]-D-GlcpNAc-(1-->O), beta-D-GlcpNAc-(1-->6)-[beta-D-GlcpA-(1-->3)]-beta-D-GlcpNAc-(1-->O), and beta-D-GlcpA-(1-->3)-beta-D-GlcpNAc-(1-->6)-[beta-D-GlcpA-(1-->3)]-beta-D-GlcpNAc-(1-->O), wherein the native beta-D-GalpNAc moiety was replaced by beta-D-GlcpNAc, were synthesized to investigate the specificity of the selected MAbs to the carbohydrate backbone of CAA. The second series of analogues, beta-D-Glcp6S-(1-->3)-beta-D-GalpNAc-(1-->O), beta-D-GalpNAc-(1-->6)-[beta-D-Glcp6S-(1-->3)]-beta-D-GalpNAc-(1-->O), and beta-D-Glcp6S-(1-->3)-beta-D-GalpNAc-(1-->6)-[beta-D-Glcp6S-(1-->3)]-beta-D-GalpNAc-(1-->O), wherein the native beta-D-GlcpA moiety was replaced by beta-D-Glcp6S, was synthesized to evaluate the importance of the type/nature of the charge of CAA for the MAb recognition. 相似文献
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The fracture of thick laminated graphite/epoxy composites has been the subject of an extensive research program. The program
was divided into three major areas of investigation which included laminate thickness, laminate stacking sequence, and part-through
surface flaws. The results from this program are reviewed with emphasis placed on their applicability to the design of thick
laminated composite structures.
Paper was presented at 1985 SEM Spring Conference on Experimental Mechanics held in Las Vegas on June 9–14, 1985. 相似文献
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二氧化硅悬浮体和水解聚丙烯酰胺体系的流变性 总被引:6,自引:0,他引:6
研究了二氧化硅悬浮体的流变性。在固体含量较少的情况下, 体系呈Newton型;固体含量达到一定程度以后, 产生三维结构, 为假塑性体系。三维结构的固体含量与pH值有关。实验证实, 在等电点(i,e, p)附近三维结构最为疏松。还研究了水解聚丙烯酰胺(HPAM)对悬浮体流变性能的影响。HPAM破坏了二氧化硅粒子聚集体结构, 呈絮凝体结构, 并出现触变性。当高聚物在固体表面覆盖一半时, 具有最大触变性和动剪切力。HPAM的水解度达到一定程度, 由于对固体粒子由“强”吸附转变为“弱”吸附, 固体粒子“屏蔽”了高分子间的相互作用, 出现了负触变性现象。在流动时粒子会脱附, 静止以后又产生吸附, 这种吸附与脱附是产生负触变性的主要原因。HPAM水解过度或用量过多, 均会减弱负触变性现象。 相似文献