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采用基于超高效液相色谱-高分辨质谱联用的非靶标代谢组学方法来研究温度对黄曲霉菌生理代谢的影响,使用交互偏最小二乘判别分析(Ortho PLS-DA)等化学计量学方法对代谢组数据进行多元统计分析,使用二级质谱信息和谱库检索定性黄曲霉菌代谢特征信息。使用内标结合混合质控样品的方法对非靶标代谢组方法进行质量控制。将该方法应用于研究温度对黄曲霉菌代谢组的影响,发现不同温度下有3 593个(T检验p0.01)差异表达代谢特征,筛选出20个候选差异代谢物。研究结果表明,温度显著影响三羧酸循环、脂肪酸、苯丙氨酸、色氨酸、络氨酸等生物合成路径,并调控黄曲霉毒素、黄匹阿尼酸、曲酸等次生代谢物生物合成路径酶活性。研究发现曲酸和黄曲霉毒素前体化合物与黄曲霉毒素的累积变化规律相似,可作为候选靶标进行验证。该研究为开展我国黄曲霉毒素风险评估和分子预警研究提供了新的路径和方法。 相似文献
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DFT calculations have been performed to explore the aminotriazine adsorption on graphene surfaces.Relative energies,equilibrium geometries and electronic structures of monomer and dimer of aminotriazine molecules adsorbed at the surface were investigated and analyzed in details.It was found that the hydrogen atoms in the NH2 group of aminotriazine molecules are directed toward the graphene surface,and the adsorption energy increases as the NH2 group is added.The adsorbed aminotriazine molecules facilely form a dimer through the hydrogen bonding interactions,and the two aromatic rings of optimized structure of 2-amino-1,3,5-triazine(B) dimmer(denoted by B2) and melamine(D) dimmer(denoted by D2) are parallel to the graphene sheet.The large deviation of the averaged adsorption energy of B2 and D2 compared to monor adsorption may reflect the increase of π-π repulsion and the effect of hydrogen bond formation.The electronic structure analyses reveal that the formation of hydrogen bonds in melamine dimer has great influence on the adsorption mode at the graphene surface. 相似文献
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The mechanism of grafting of polystyrene on a polybutadiene (PB) backbone during the preparation of impact-resistant polystyrene was studied by withdrawing samples during propolym-erization from beginning of the reaction to about 25% conversion. Good separation of the “elastomer and graft” fraction of the polymer from the free polystyrene part could be achieved by using 0.24 volume fraction of methanol in (MEK + benzene) + methanol solvent-nonsolvent. IR analysis of the grafted fraction showed that the microstructure of the elastomer remained unaltered. The unsaturation of the samples studied through the bromine number as well as by the perbenzoic acid number was also found to remain unchanged. Formation of free polystyrene started with the onset of polymerization and was faster. During prepolymerization, 80% of styrene converted constantly to form free polystyrene and 20% went into the grafted polymer. The results indicate that grafting is initiated through proton abstraction at the α-carbon of butadiene, most probably by initiator radicals. The grafted polystyrene chains possibly are shorter than free polystyrene chains. 相似文献
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由于碳纳米管(CNT)具有优异的力学、电学、光学等性能,近年来,聚合物/碳纳米管(polymer/CNT)复合材料的研究已经成为研究者关注的热点。相关的研究主要集中在:一是将CNT作为填充材料制各复合材料,使复合材料的力学、电学等性能得到提高。二是将CNT作为主体,用聚合物对CNT进行修饰,使CNT在有机溶剂中能够获得良好的溶解度。而对于在聚合反应中,CNT的加入对聚合物分子量影响的研究,相关的报道较少。本文利用悬浮聚合法制备了聚苯乙烯/多壁碳纳米管(PS/MWNT)复合材料,采用透射电镜(TEM)和凝胶渗透色谱(GPC)对其进行了分析,详细研究了MWNT对于PS分子量的影响。 相似文献
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The adsorption of cholesterol and several bile salts on the surface of modified hydrophobic silica adsorbent from individual and mixed solutions is studied at constant solution pH as a function of the concentration of bile salts. It is shown that, despite the solubilization of cholesterol by bile salts, cholesterol is adsorbed on the adsorbent as an individual compound, i.e. not as a complex with bile salts. The stronger the cholesterol is bound with bile salts, the smaller the value of adsorption. For the quantitative interpretation of adsorption data, a nonelectrostatic model of complexation on the surface is used. 相似文献
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用AM1方法对红菌素(包插甲素和乙素)与它们的溴代物进行了量子化学对比计算,得到了生成热,前线轨道能级及偶极矩等,讨论了溴代作用对竹红菌素分子性质的影响。 相似文献
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Pt在SAPO-11分子筛上的分散性研究 总被引:3,自引:3,他引:0
采用H2-TPR、NH3-TPD、H2脉冲化学吸附和H2-O2化学滴定等方法对Pt/SAPO-11催化剂上金属分散进行了表征,并与该催化剂制备因子及其正构烷烃骨架异构化反应性能进行关联。实验表明,以与NH3配位的阳离子形式制备的催化剂,Pt的分散效果最好;用低浓度浸渍液、多次浸渍的方式制备的催化剂,Pt的分散度高;Mn2+、Sm3+、Zn2+等作助剂和Pd-Pt复合浸渍可提高Pt的分散度。调整分子筛的酸量使之与金属含量达到平衡时,催化剂活性和选择性最佳。 相似文献
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Xiao Yu ZHANG Feng Hua CHEN Ping Hui WEI Jia Zuan NI 《中国化学快报》2006,17(8):1105-1108
Epimedium, one of representatives of traditional Chinese herb, is mainly composed of flavones and polysaccharide. It is famous for its antioxidant, antineoplastic and antiaging activities and has been widely used in the field of invigorating kidney and st… 相似文献
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With vinyl monomers, viz., styrene, butyl methacrylate, dimethylaminoethyl methacrylate, and ethyl acrylate, it was noted that higher per cent grafting was obtained with “recrystallized” cellulose than with “amorphous” cellulose. The possibility of the production of a porous structure in cellulose as a result of γ-irradiation followed by the dissolution of the reactive regions is suggested. DTA and DTG data of irradiated cellulose triacetate (CTA) reveal lowering of the melting point on irradiation, indicating a decrease in crystallinity. Decrease in density of cellulose on irradiation by γ-rays also indicates loosening of the structure of cellulose. It is postulated that grafting occurs in those regions of cellulose which were crystalline before irradiation, as well as in less crystallinie regions. 相似文献
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酞菁金属配合物是光动力治疗的新一代光敏剂,其治疗作用的机理以及引起的生物效应一直是人们研究的热点.本文选用色氨酸作为与喹啉氧基酞菁金属配合物作用的靶分子,讨论了配合物的组成结构与其光敏化氧化色氨酸能力的相关性.结果表明,酞菁环内中心金属离子和环周边取代基的组成结构以及取代位置与数目都影响其光敏化氧化色氨酸能力,中心金属离子为闭壳层电子结构、取代基位于α位以及提高取代基数目均有利于提高光敏化氧化活性,同时显示,取代基的组成结构对靶分子有一定选择性,研究结果可为研发该类光敏剂提供依据. 相似文献
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Z. Grauer S. Yariv L. Heller-Kallai D. Avnir 《Journal of Thermal Analysis and Calorimetry》1983,26(1):49-64
The nature of the adsorption complex formed between dibenzotropone (DBT) and montmorillonite at elevated temperatures is strongly dependent on the interlayer cations. This was shown by electronic and IR spectra, by X-ray diffraction, and by study of the effects of gradual heating of the samples on these analyses. All samples exhibited significant red shifts of the electronic spectra of DBT into the visible range. These red shifts are attributed to two factors, both contributing to the enhancement of the tropylium planar character of DBT: hydrogen-bonding of acidic interlayer water to the carbonyl group, imparting positive charge to the tropone ring; and π interactions between the aromatic moiety and the oxygen planes. The position of the maximum was temperature-dependent for Cu-, Ni-, Al- and Fe-montmorillonites, for which heating (100°) under vacuum increased the red shift. The organic molecule assumes a planar conformation and is oriented parallel to the clay layers. IR spectra confirming this conformational orientation of DBT are discussed. The basal spacings of the DBT montmorillonite associations depend on the number of water and DBT sheets present in the interlayers. Layers with one or two sheets of DBT and with up to two sheets of water could be distinguished, leading to a maximum spacing of 20.4 Å. 相似文献
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聚(β-羟基丁酸酯-β-羟基戊酸酯)(PHBV)是一种拥有生物可降解性、生物相容性、压电性、光学活性等诸多优良特性的热塑性树脂,具有广阔的应用前景。但是PHBV脆性大,韧性差,导致其应用受到限制。本文综述了近年来国内外纳米材料增韧改性PHBV的进展。当纳米材料添加到PHBV时,可以起到异相成核剂的作用,改善结晶性能,从而降低PHBV的脆性。在众多的纳米材料中,纳米纤维素质量轻、强度高、模量大并可生物降解,有希望在不影响PHBV自身降解性的基础上提高其韧性。文章最后概括了目前纳米纤维素增韧PHBV存在的几点问题,同时对用纳米纤维素增韧PHBV的发展前景提出展望。 相似文献
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镍激活EB病毒的研究 总被引:2,自引:0,他引:2
应用间接免疫荧光法和抗补体免疫荧光技术研究,证实在试管内1~40mg/L NiSO4.6H2O(Ni)显著增强携带Epstein-Barr Virus(EBV)基因组的三株类淋巴母细胞株的VCA、MA、EA、EBNA-2抗原表达.此外还发现1~20mg/L Ni能明显促进EBV转化人脐血B淋巴细胞的作用,当多次加Ni时促进效应更强,前者转化促进率为13.31%~46.6 1%,后者达22.70%~57.04%.以上结果表明,Ni具有激活 EBV的作用.EBV与鼻咽癌(NPC) 密切相关,广东 NPC高发区大米和饮水中 Ni的含量偏高,NPC患者血和头发中 Ni 的水平明显高于健康人.研究结果提示,EBV与 Ni相互作用可能是 NPC发生、发展过程中的一个协同因素. 相似文献
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磷素营养对植物抗旱性的影响 总被引:13,自引:0,他引:13
综述了近年来磷素营养与植物抗旱性关系的研究进展,指出磷素营养主要通过水分调节、渗透调节、光合调节和根冠生长等一系列生理生长机制来增强植物的代谢活性,提高植物抗旱性,植物对磷的利用效率与抗旱性也有着密切的关系。 相似文献
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对调查区和对照区共203名 ̄6岁幼儿进行了血铅汪洋的调查。结果显示,生活在不同环境下的幼儿,已受到程度不同的铅污染。工业相对集中的城镇(调查区)幼儿血铅含量为5.15μg/dL,大于郊区(对照区)幼儿的血铅含量3.54μg/dL,交通和工矿企业对周围环境的污染是幼儿体内铅的主要来源。 相似文献
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Summary Trace amounts of Co, Ni, and Mn have been enriched from aqueous solutions by retention of their ions on polyacrylonitrile (PAN). The recovery has been determined as a function of the amount of PAN, pH, the concentration of eluent (HCl) and the volume of sample solution. The elements were removed with 100% efficiency by means of conc. HCl. Recoveries were up to 95% depending on the elements. The resin has been used in combination with atomic absorption spectrophotometry for the determination. 相似文献