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101.
This "emerging engineering education (3E)" project "Upgrade and Practice of Chemistry-related Majors of Local and/or Specialized University Responding to the Industry Changes" was supported by the Ministry of Education. To aim at the issue of how to upgrade the chemistry-related majors of a local and/or specialized university responding to industry changes, an investigation on local regional economy and industry changes was carried out, the capability requirements of 3E for talents were analyzed, and the training objectives, graduation requirements as well as the new teaching models were also studied for the major to meet the future requirements. The practical experience for 3E construction of chemistry-related majors by selected universities was suggested.  相似文献   
102.
采用温和条件下的溶胶-凝胶技术,成功制备了阴离子交换-反相混合模式硅胶基质毛细管电色谱整体柱.通过调整反应液中不同前体的比例,优化了整体柱的制备条件.通过扫瞄电镜,对柱床进行了表征和分析.实验发现,所制备的整体柱电渗流的方向和大小可随流动相pH值的改变而改变,在酸性和中性条件下,具有从阴极流向阳极的电渗流;当流动相pH值升至约7.5时,电渗流方向发生了反转(由阳极流向阴极).在优化的实验条件下,用所制备的整体柱对所考察的酸性(中性)化合物实现了快速分离,并获得了高达160,000 N/m的柱效.  相似文献   
103.
范小振  丁天惠   《色谱》1994,12(1)
研究开发的一种新型的元素光度检测器主要用于锗、砷、锡和锑的氢化物气相色谱检测,具有高灵敏,高选择性。它是在普通火焰光度检测器的基础上加装了特制的滤光片改制而成的。对锗、砷、锡和锑的检测限分别为3.0×10 ̄(-11)g、7.0×10 ̄(-11)g、7.0×10 ̄(-10)g和1.1×10 ̄(-8)g,相对标准偏差分别为1.8%、2.4%、2.6%和3.0%。  相似文献   
104.
A dual resistance model with distribution of either barrier or pore diffusional activation energy is proposed in this work for gas transport in carbon molecular sieve (CMS) micropores. This is a novel approach in which the equilibrium is homogeneous, but the kinetics is heterogeneous. The model seems to provide a possible explanation for the concentration dependence of the thermodynamically corrected barrier and pore diffusion coefficients observed in previous studies from this laboratory on gas diffusion in CMS. The energy distribution is assumed to follow the gamma distribution function. It is shown that the energy distribution model can fully capture the behavior described by the empirical model established in earlier studies to account for the concentration dependence of thermodynamically corrected barrier and pore diffusion coefficients. A methodology is proposed for extracting energy distribution parameters, and it is further shown that the extracted energy distribution parameters can effectively predict integral uptake and column breakthrough profiles over a wide range of operating pressures.  相似文献   
105.
Human glutathione (GSH) transferase (hGSTP1-1) processes with similar kinetic efficiencies the antitumor agents 2-crotonyloxymethyl-2-cyclohexenone (COMC-6), 2-crotonyloxymethyl-2-cycloheptenone (COMC-7), and 2-crotonyloxymethyl-2-cyclopentenone (COMC-5) to 2-glutathionylmethyl-2-cyclohexenone, 2-glutathionylmethyl-3-glutathionyl-2-cycloheptenone, and 2-glutathionylmethyl-2-cyclopentenone, respectively. This process likely involves initial enzyme-catalyzed Michael addition of GSH to the COMC derivative to give a glutathionylated enol(ate), which undergoes nonstereospecific ketonization, either while bound to the active site or free in solution, to a glutathionylated exocyclic enone. Free in solution, GSH reacts at the exomethylene carbon of the exocyclic enone, displacing the first GSH to give the final product. This mechanism is supported by the observation of multiphasic kinetics in the presence of high concentrations of hGSTP1-1 and the ability to trap kinetically competent exocyclic enones in aqueous acid using COMC-6 and COMC-7 as substrates. That the exocyclic enone is formed by nonstereospecific ketonization of an enol(ate) species is indicated by the observation that COMC-6 (chirally labeled with deuterium at the exomethylene carbon) gives stereorandomly labeled exocyclic enone. The isozymes hGSTP1-1, hGSTA1-1, hGSTA4-4, and hGSTM2-2 catalyze the conversion of COMC-6 to final product with similar efficiencies (K(m) = 0.08-0.34 mM, k(cat) = 1.5-6.1 s(-)(1)); no activity was detected with the rat rGSTT2-2 isozyme. Molecular docking studies indicate that in hGSTP1-1, the hydroxyl group of Tyr108 might serve as a general acid catalyst during substrate turnover. The possible significance of these observations with respect to the metabolism of COMC derivatives in multidrug resistant tumors is discussed.  相似文献   
106.
王洪  顾峻岭 《分析化学》1998,26(11):1293-1297
通过流动相中电解质浓度对毛细管电色谱柱效能的流动相平均线速度的影响,研究了CEC中双电层叠加现象。提出选择合适电解质组成的浓度及在制备色谱柱过程中避免细小和破碎的固定相颗粒进入柱中,以有效地减小双电层叠加作用。  相似文献   
107.
A new type of dendritic 2-amino-2'-hydroxy-1,1'-binaphthyl (NOBIN)-derived Schiff-base ligands have been synthesized and applied to the titanium-catalyzed hetero-Diels-Alder reaction of Danishefsky's diene with aldehydes. These reactions afforded the corresponding 2-substituted 2,3-dihydro-4H-pyran-4-ones in quantitative yields and with excellent enantioselectivities (up to 97.2 % ee). The disposition of the dendritic wedges and the dendron size in the ligands were found to have significant impact on the enantioselectivity of the reaction. The recovered dendritic catalyst could be reused without further addition of the Ti source or a carboxylic acid additive for at least three cycles, retaining similar activity and enantioselectivity. The high stability of this type of assembled dendritic titanium catalyst may be attributed to the stabilization effect of large-sized dendron units in the catalyst molecule. The other important phenomenon observed with this catalyst system is that a higher degree of asymmetric amplification has been achieved by attachment of the dendron unit to the chiral ligand, which represents a new advantage of dendrimer catalysts for asymmetric reactions using chiral ligands of lower optical purity.  相似文献   
108.
壳聚糖季铵盐的合成及结构表征   总被引:39,自引:4,他引:39  
用异相法合成了水溶性壳聚糖季铵盐衍生物,并用红外光谱及核磁共振谱进行结构表征。结果表明:在中性反应条件下,壳聚糖分子的季铵盐衍生化反应主要发生于亲该中心C2位的氨基上,所合成的壳聚糖季铵盐衍生物可直接溶解于水。其水溶液可以任意比例与乙醇、丙二醇、甘油等混溶。  相似文献   
109.
The properties of the triplet excited state of [60] fullerene-containing cyclic sulphoxide have been investigated by time-resolved absorption spectroscopy. Transient absorption bands of [60] fullerene-containing cyclic sulphoxide showed two decay-components, which wrer attributed to triplet excited states of different spin multiplicity. The properties of photoexcited states of [60] fullerene-containing cyclic sulphoxide are also reported.  相似文献   
110.
We extend our method of systematic removal of secular terms in a singular perturbation treatment of the Boltzmann equation with small Knudsen numbers to the initial layer. The requirement that the solution through the initial layer should connect smoothly to the normal solution removes an ambiguity noted in our previous paper. We show that removal of secular terms improves Grad's solution for the initial layer and reintroduces soundlike modes associated with higher moments, first found by Wang Chang and Uhlenbeck.  相似文献   
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