多取代5,6二氢-4-噻喃并咪唑酮类化合物的合成

在α-肉桂酰基二硫缩烯酮类化合物(1)的基础上,由2,3-二氢-4-噻喃酮化合物(2)与水合肼在温和条件下合成了多取代5,6-二氢-4-噻喃并咪唑酮类化合物(3),通过核磁共振、红外光谱、质谱及元素分析对所得化合物进行了表征,并对该反应机理进行了探讨.     

路由查找技术的分析及研究

从数据结构的角度分析各种路由查找技术的原理.并针对IPv6可聚类的全局单播地址,提出面向IPV6的路由查找算法.通过研究对比各种路由查找技术及其优化策略,为实际工作提供理论依据.     

碳酸酯胺解合成氨基甲酸酯反应动力学研究

通过监测反应体系的胺值变化,对Zn(OAc)2催化剂作用下,碳酸二甲酯胺解合成六亚甲基二氨基甲酸甲酯反应动力学进行了研究.结果表明:反应级数对1,6-己二胺(HDA)为准一级;反应活化能为18.58 kJ/mol;反应速率常数在温度343 K,353 K,363 K,373 K时分别为1.995×10-1h-1,2.513×10-1h-1,3.044×10-1h-1,3.334×10-1h-1,并与催化剂浓度成正比.提出了可能的催化反应机理,导出的速率方程圆满地解释了实验现象.     

基于IPv6的分布式实时网络测量系统设计

针对当前许多网络测量系统无法进行实时网络流量监测以及无法支持下一代互联网协议IPv6等不足,提出了一种基于IPv6的比特模式流定义方法和数据结构实时网络测量系统.系统通过在IPv6扩展首部中承载测量信息实现精确流测量,减少了测量开销,提高了测量效率.比特模式流定义方法提供了一种灵活的按需流定义方式,使系统能在IPv4/IPv6环境下实现流测量工作.实验证明,整个系统运行正常、效果良好.     

p38丝裂原活化蛋白激酶在小鼠T细胞增殖中的作用

目的:了解p38丝裂原活化蛋白激酶(MAPK)在ConA刺激下小鼠T细胞增殖中的作用。方法:以活体染料羧基荧光素乙酰乙酸琥珀酰亚胺酯染色,建立了在多克隆刺激剂刀豆蛋白A(ConA)刺激下评价小鼠T细胞增殖的模型,通过流式细胞术分析p38丝裂原活化蛋白激酶的特异性抑制剂SB203580在不同剂量、不同时间对T细胞增殖的作用,并应用CellQuest和SPSS10.0 forW indows软件分析增殖细胞各代所占比例和增殖指数(PI)。结果:羧基荧光素乙酰乙酸琥珀酰亚胺酯染色分析显示,随着SB203580浓度从0.5μmol/L逐渐增至15.0μmol/L,T细胞增殖逐渐减弱,以15.0μmol/L SB203580的抑制作用最为明显,呈剂量依赖关系(r=-0.97,P<0.01);SB203580浓度增加至20.0μmol/L时,细胞大量死亡。选用SB203580最佳浓度(15.0μmol/L),随时间从24 h至72 h递增,SB203580对T细胞增殖的抑制作用逐渐增强,以72 h抑制作用最为明显,84~96 h后,抑制作用逐渐减弱。结论:p38 MAPK在ConA刺激的T细胞增殖中起着重要的作用。     

柴油超深度脱硫技术进展

降低柴油中硫含量对于提高汽车尾气排放质量从而保护环境具有十分重要的意义。生产超低硫柴油的技术主要有加氢脱硫(HDS)和非加氢脱硫两大方法。概述了深度加氢脱硫的机理和需要解决的关键问题。柴油的深度加氢脱硫需要有效分解馏分油中的4,6-二苯并噻吩(4,6-DMDBT)等难脱除的化合物。提出了研制高活性深度HDS催化剂的思路和途径并介绍了近年国内外柴油深度加氢脱硫研究的成果。此外对非加氢脱硫技术中的吸附法、氧化法和生物技术深度脱硫的研究近况也做了介绍。加氢方法和非加氢方法的有机结合是十分有前途的生产超低硫柴油的手段。     

罗丹明6G荧光猝灭法测定Hg2+离子

在PVA-124存在下,Hg2 与KI和罗丹明6G形成稳定的多元离子缔合物,并使罗丹明6G发生荧光猝灭,据此建立了测定Hg2 的荧光猝灭分析方法.方法的线性范围为4~60μg/L,检出限为2.5μg/L,用于水中Hg2 的测定,结果令人满意.     

m6A修饰在骨肉瘤中分子机制的研究进展

N6-甲基腺苷(m6A)是真核生物mRNA中最丰富的表观遗传修饰之一,在多种疾病尤其是肿瘤中发挥重要作用。m6A修饰受到甲基转移酶、去甲基化酶和RNA结合蛋白的动态调控。骨肉瘤是一种好发于儿童和青少年的恶性骨肿瘤之一,近年来骨肉瘤发生率呈上升趋势,m6A修饰的调控表达与骨肉瘤的发生发展及预后相关。本文就m6A修饰在骨肉瘤发生发展、化疗耐药、靶向治疗、预后转归的分子机制方面的研究进行综述,旨在为骨肉瘤的早期诊断和靶向治疗提供新思路。     

N-acetylmuramic acid 6-phosphate lyases (MurNAc etherases): role in cell wall metabolism, distribution, structure, and mechanism

MurNAc etherases cleave the uniqued-lactyl ether bond of the bacterial cell wall sugar N-acetylmuramic acid (MurNAc). Members of this newly discovered family of enzymes are widely distributed among bacteria and are required to utilize peptidoglycan fragments obtained either from the environment or from the endogenous cell wall (i.e., recycling). MurNAc etherases are strictly dependent on the substrate MurNAc possessing a free reducing end and a phosphoryl group at C6. They carry a single conserved sugar phosphate isomerase/sugar phosphate- binding (SIS) domain to which MurNAc 6-phosphate is bound. Two subunits form an enzymatically active homodimer that structurally resembles the isomerase module of the double-SIS domain protein GlmS, the glucosamine 6-phosphate synthase. Structural comparison provides insights into the two-step lyase-type reaction mechanism of MurNAc etherases: β-elimination of the D-lactic acid substituent proceeds through a 2,3-unsaturated sugar intermediate to which water is subsequently added. Received 31 August 2007; received after revision 12 October 2007; accepted 1 November 2007     

The three-fingered protein domain of the human genome

Extracellular domains of some cellular receptors expressed in the organisms at different levels of development belong to three-fingered protein (TFP) fold. The Homo sapiens genome encodes at least 45 genes containing from one to three TFP domains (TFPDs), namely diverse paralogues of the Ly6 gene, CD59 and the receptors of activins, bone morphogenetic proteins, Mullerian inhibiting substance and transforming growth factor-β. C4.4a and urokinase/plasminogen activatory receptor contain two and three TFPD repeats, respectively. These diverse proteins have a low overall sequence similarity with each other and their hydrophobicity levels vary to a considerable degree. It is suggested that sequence differentiation within the TFPD led to distinct groups of proteins whose attributes were optimized to fit both the physicochemical properties specific to their functional microenvironment and selective targeting of their highly diversified extracellular cofactors. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 7 August 2008; accepted 29 August 2008