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991.
大面积高质量石墨烯的制备对石墨烯电子特性及石墨烯基纳器件相关研究有重要意义。本文综述了近几年来衬底上制备石墨烯的相关实验以及衬底与石墨烯相互作用研究的重要进展。目前,采用化学气相沉积、外延生长等方法可在衬底表面上制备出较大面积、高质量的石墨烯材料。衬底与石墨烯相互作用和界面间晶格匹配、原子成键及电荷转移等密切相关,其对吸附石墨烯的几何结构、能带结构及电子特性等产生明显影响。实验与理论计算的结合可望加深衬底与石墨烯作用机理的理解,指导衬底上石墨烯制备及改性的进一步研究。 相似文献
992.
993.
为了寻找新的含噻唑杂环的先导化合物,利用¨(2-氰基亚胺基-1,3-噻唑烷-3-基)甲基]-2-氨基噻唑与取代苯甲酰氯(或乙酰氯)在吡啶存在下发生缩合反应,合成了19个新型含2-取代-1,3-噻唑烷环的噻唑酰胺类化合物4.经1HNMR和元素分析对目标化合物的结构进行了表征,经MS进一步证实了化合物4s的结构,并通过X射线单晶衍射分析测定了化合物4a的晶体结构.对所合成的目标化合物进行了生物活性测试,部分化合物表现出一定的杀菌和植物生长调节活性. 相似文献
994.
995.
结合阴离子开环聚合方法合成了内壳为聚(乙氧基乙基缩水甘油醚),外层为聚环氧乙烷的两亲性类树枝状嵌段共聚物PEEGE-G2-b-PEO(OH)12. 使用核磁共振氢谱以及凝胶渗透色谱等表征了中间产物和目标产物. 选择阿霉素作为实验药物,研究了该聚合物的载药和控释行为. 聚合物的载药率和包覆效率分别为13.07%和45.75%,体外释放试验表现为持续性的释放,并受到释放介质pH影响. 相似文献
996.
997.
998.
A new analytical method for the determination of ascorbic acid by the perturbation caused by different amounts of ascorbic acid on the BZ oscillating chemical system involving the Ce(IV)-catalyzed reaction between potassium bromate and malonic acid in a acidic medium is proposed. The method relies on the linear relationship between the change in the oscillation amplitude of the chemical system and the concentration of ascorbic acid, which is in this work exposed for the first time. The calibration curve is linearly proportional to the concentration of ascorbic acid over the range 3.5x10(-6)-4.7x10(-4) M, with the regression coefficient is 0.9975. Two different methodologies were used to address the determination. Some aspects of the potential mechanism of action of ascorbic acid on the BZ oscillating chemical system are discussed in detail. 相似文献
999.
Chitosan, a naturally abundant biopolymer, has widely been studied for metal adsorption from various aqueous solutions, but the extension of chitosan as an adsorbent to remove humic substances from water has seldom been explored. In this study, chitosan was coated on the surface of polyethyleneterephthalate (PET) granules through a dip and phase inversion process and was examined for humic acid removal in a series of batch adsorption experiments. Scanning electron microscopic (SEM) images showed that the PET granules were uniformly covered with a layer of chitosan and the chitosan layer possessed numerous open pores on the surface. Zeta potential study indicated that the chitosan-coated granules had positive zeta potentials at pH < 6.6 and negative zeta potentials at pH > 6.6. Adsorption of humic acid onto the chitosan-coated granules was found to be strongly pH-dependent. Significant amounts of humic acid were adsorbed under acidic and neutral pH conditions, but the adsorption capacity was reduced remarkably with increasing solution pH values. The adsorption isothermal data under various initial humic acid concentrations (at the same solution pH value) can be adequately modeled by the Langmuir and Freundlich models. X-ray photoelectron spectroscopy (XPS) revealed that the amino groups of the chitosan layer were protonated due to humic acid adsorption, suggesting the formation of organic complex between the protonated amino groups and humic acid. Kinetic study indicated that the adsorption process was transport-limited at low solution pH values, but became both transport- and attachment-limited at high solution pH values. 相似文献
1000.
Li JS Li XW Yuan JX Wang X Li JS Li XW Yuan JX Wang X 《Journal of AOAC International》2000,83(4):830-836
A procedure was developed for the preparation of anti-sulfonamide (SA) group-specific antibodies and immunosorbents. Sulfonamide haptens and conjugates were synthesized by building spacer arms on an N1 group of 4-aminobenzensulfonamide. The anti-SA group-specific antibodies and immunosorbents were prepared successfully. After extraction with methanol-water (8 + 2), sulfamonomethoxine, sulfadimethoxine, and sulfaquinoxaline were cleaned up on immunoaffinity columns and determined by reversed-phase liquid chromatography with UV detection at 270 nm. The recoveries from fortified swine meat (10-100 microg/kg) ranged from 70.8 to 94.1%, with coefficients of variation of 3.4-12.9%. Limits of detection were 1-2 microg/kg. 相似文献