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981.
982.
An all-atom dimethyl sulfoxide (DMSO) model and a TIP5P water model have been adopted for molecular dynamics simulation. Two new qualities ηrelE and ηrel are introduced to describe the anomalous nonideal behaviors of DMSO–water mixtures. The simulation is compared with chemical shift and excess enthalpy of mixing, which shows good concentration dependences. In addition, our all-atom simulation also indicates that the C–H groups of DMSO may interact with the oxygen atoms of water and DMSO. The weak C–HO contacts and the strong O–HO hydrogen bonds represent the consistent concentration dependences, which exhibits the cooperation effect. 相似文献
983.
离子注入修饰电极检测硝基苯 总被引:9,自引:0,他引:9
离子注入是一种新技术,可按人们的意愿和需要,将不同的离子注入不同的基本电极表面,制成具有催化活性强,稳定性高,重现性好等特点的修饰电极。作者研究了离子注入钴和注入镍的玻碳电极在0.1mol/LHAc-NaAc缓冲溶液中硝基苯的行为及测定。 相似文献
984.
Xiao Jie He Qun Qiu Shengchao Li Haoquan Wang Binghua Zhang Bin Bu Weifeng 《中国科学:化学(英文版)》2020,63(6):792-801
It is well-known that amphiphilic star-shaped copolymers can self-assemble in selective solvents to form complicated micellar constructs as a synergistic result of both the topological constraints and relative volume fractions of the arms. Although the association phenomena of amphiphilic stars have been observed in nonselective solvents, both the structural detail and formation mechanism of these associates are not clear yet. Moreover, these experimental observations are controversial with respect to molecularly dispersed starlike copolymers in nonselective solvents as is popularly believed. To clarify these issues, we have synthesized a series of polyoxometalate-based polystyrene-poly(ethylene glycol)(PS-PEG) miktoarm star supramolecular copolymers(SEW-1–5) by coupling a Keggin-type polyoxometalate of K_4[α-SiW_(12)O_(40)] with 1,2,3-triazolium bridged block copolymers of-PS_n-b~+-PEG_mI~-(n=17, 26, 39, 57, 81; m=45) through ionic exchange reactions, respectively. TEM imaging,contact angle and ~1H NMR studies reveal that SEW-2–5 self-assemble in chloroform, THF, and toluene to create micellelike aggregates ranging from cylinder to sphere with a PS corona and a PEG core, while for SEW-1, reverse bilayers are captured with a PEG corona and a PS core. Among these aggregates, the Keggin clusters of [α-SiW_(12)O_(40)]~(4-) localize at the core-corona interfaces between PS and PEG. In terms of solvent quality, chloroform, THF, and toluene are only slightly poorer for PEG than that for PS with a relative order of chloroformTHFtoluene. These unexpected aggregates originate from the topological constraints of the chemically different arms of PS and PEG in the miktoarm stars, where the weak incompatibility between the PS and PEG arms is intensified appropriately. The presence of the reverse bilayered structures of SEW-1 is due to the magnified steric hindrance of the PEG45 arm with decreasing the molecular weight of the PS17 arm. However, to the best of our knowledge,these are the first examples clearly indicating that miktoarm star copolymers can self-assemble in common good solvents or slightly selective solvents to generate micellelike aggregates. This scenario is not only in sharp contrast to the intuitively considered behavior of unimolecular miktoarm stars in nonselective solvents, but also rather different from the conventional selfassembly behavior of amphiphilic star copolymers in selective solvents. 相似文献
985.
986.
A piezoelectric nucleic acid sensor was constructed ofr detection of tumor necrosis factor gene.Two methods were employed for immobilization of nucleic acid probe on gold electrode of piezoelectric crystal.The results show that polyethyleneimine adbesion and glutaraldehyde cross-linking method has higher sensitivity,stability and selectivity than protein A method.The solid-phase nucleic acid hybridization of oligo unclecotides and tumor necrosis factor target gene sequence were monitorde using this sensor.Tumor necrosis factor gene sequence(580bp) was detected by this nucleic acid sensor for the first time. 相似文献
987.
高分子催化剂由于同时具有多相催化剂和均相催化剂的优点,已引起了广泛的重视.然而表面活性组份贵金属的流失直接影响了此类高活性催化剂的推广应用.作者合成了不同载体的几类负载钯催化剂,探讨其在1,5,9-环十二碳三烯的选择加氢反应过程中钯的流失规律.从改变高分子配位体入手,通过调整聚合物载体的物理性能、配位原 相似文献
988.
利用Foster-Boys定域化程序和STO-3G ab initio方法,对含有C、H、O、N原子的100多个有机链状分子进行了研究,得到定域分子轨道能量及其相互作用参数。应用这些参数和定域分子轨道模型,对于众多的含有C、H、O、N原子的有机链状分子,可得到相应的正则分子轨道能量及其与定域分子轨道的关系。以此预测它们的电离能,结果与实验值符合较好。 相似文献
989.
Peng Li Assem Abolmaaty Christine D’Amore Stefanie Demming Constantine Anagnostopoulos et al. 《Applied biochemistry and biotechnology》1992,36(2):88-96
Materials and Methods
Synthesis of thionyl chloride-activated succinamidopropyl-glass beads 相似文献
990.
A Pt microelectrode modified with nickel(II) polytetramethyldibenzo[b,i]tetraaza[14]annulene was prepared by electropolymerization of nickel(II) tetramethyldibenzo[b,i]tetraaza[14]annulene monomers and applied to determine sulfur dioxide in vitriol plant wastewater. For determination of SO2 with this electrochemically modified Pt microelectrode, the linear range was from 9.6 x 10(-6) to 2.4 x 10(-4) mol L-1, the sensitivity was 1.8 x 10(-4) A L mol-1, the detection limit was calculated to be 4.8 x 10(-6) mol L-1 (S/N = 3), the response time was less than 20 s and the relative standard deviation was found to be 2.1% on analyzing 4.8 x 10(-5) mol L-1 SO2 solution repeatedly (n = 7). These results demonstrated good accuracy compared with those obtained by the conventional iodimetric method. 相似文献