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61.
Microwave-assisted extraction coupled to headspace solid-phase microextraction with on-fiber derivatization with gas chromatography ion trap mass spectrometry analysis is reported for the determination of aldehydes in environmental water. Hexanal, (E)-2-hexenal, heptanal, octanal, nonanal, E-2-decanal, and E, E-2,4-decadienal were employed to develop and validate this method. The effects of relevant parameters on the quantitative extraction of these analytes in this one-step procedure were systematically investigated. The aldehydes were extracted from environmental water by a poly(dimethylsiloxane)/divinylbenzene fiber using o-(2, 3, 4, 5, 6-pentafluoro)-benzylhydroxylamine as the derivatization reagent. Under microwave-assisted heating, the aldehydes were transferred from water by headspace solid phase microextraction. Thus, efficient extraction and derivatization were simultaneously achieved. The recovery values ranged from 72.2–96.9%, and the relative standard deviation was between 4.1–14% for the aldehydes. The detection limits were from 0.001–0.005 µg L?1. The method was validated illustrating its potential for the analysis of environmental water while offering simplicity and rapid analysis. 相似文献
62.
唐孝明 《武汉化工学院学报》2012,(1):19-25
综述了近几十年来国内外对双核二茂铁及其衍生物的研究进展.按照化学结构将这些衍生物进行分类,系统介绍了烷基化双核二茂铁、酰基化双核二茂铁、含活性基团双核二茂铁、双金属双核二茂铁和其它类型双核二茂铁等衍生物的合成及其燃速催化应用,并指出了今后的研究方向. 相似文献
63.
王建成 《装备指挥技术学院学报》1998,9(3):28-33
在建立手征单球平面波电磁散射几何模型的基础上,通过对小球内外各区场量的广义复球矢量波函数表示,利用边值技术和有关数值方法,详细推导了该模型的归一化双静截面的计算公式,从而为实验测量提供了必要的理论依据。 相似文献
64.
赵启松 《北京邮电大学学报》1994,17(1):85-90
利用傅氏变换的广义微分定理,导出了当信号f(t)分区满足n阶常系数线性齐次微分方程时,求连续频谱的一般代数表示式,最后又给出了寻求连续频谱反演的一个定理,从而可以避免复杂的,有时不易求解的积分方法,对于一类广泛的常用信号使求其傅氏正反主为换的运算得到简化。 相似文献
65.
用电位滴定法,在(25.0 ±0.1)℃, I= 0.10 m ol·dm 3(NMe4NO3) 条件下测定了N,N′—二羧甲基大环醚双内酯(Ⅰ,Ⅱ,Ⅲ) 的质子化平衡常数,及其与Mg2+ ,Ca2+ ,Sr2+ ,Ba2+ ,Cu2+ ,Zn2+ ,Cd2+ ,Pb2+ 金属离子配合的平衡常数,讨论了醚环大小对平衡常数、配位方式以及配体稳定性的影响. 配体Ⅰ与上述金属离子形成配合物的稳定常数,对于同一种金属与配体Ⅱ,Ⅲ相比为最小. 配体Ⅰ与较大的金属离子如Sr2+ ,Ba2+ ,Cd2+ 生成配合物时,这种差异更加显著. 配体Ⅰ与Pb2+ 配合的稳定常数,比预料的高出很多. 与碱土金属离子Ca2+ ,Sr2+ ,Ba2+ 形成配合物的稳定常数,随金属离子半径增大而减小. 与过渡金属离子Cu2+ ,Zn2+ ,Cd2+ 形成配合物的稳定常数,呈相似的规律. 配体Ⅱ与Mg2+ 形成的配合物,其稳定性最差.而与Ca2+ ,Sr2+ ,Ba2+ 形成配合物的稳定常数比与Mg2+ 形成的配合物的稳定常数高出很多且相互间很相近,故配体Ⅱ可用于从碱土金属离子中分离出Mg2+ 离子. 用NMR 研究了配体Ⅰ的水解产物的结构 相似文献
66.
Inclusion behavior of oxybutynin (OBN) with hydroxypropyl-β-cyclodextrin (HP-β-CD) was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex
stoichiometry was provided by the continuous variation technique. Alcohol was added to further investigate the mechanism of
the inclusion behavior. Thermodynamic constants ΔG, ΔH and ΔS for inclusion interaction of OBN and HP-β-CD were determined. The results show that host-guest complex with molar ratio of 1:1 is formed, and inclusion stability constant
between OBN and HP-β-CD is 54.9 L/mol determined by ultraviolet spectrum and 11.1 L/mol determined by fluorescence spectrum. OBN has weak binding
ability with HP-β-CD in aqueous solution (stability constant <102 L/mol) and addition of alcohol leads to a decrease of stability constant, which indicates that the hydrophobic force contributes
to the inclusion process. ΔG, ΔH and ΔS are all less than zero, which indicates that the inclusion process is a spontaneous and exothermic process. 相似文献
67.
给出了三种含有吡咯基团的芳香内酰胺型单体的合成方法,并对上述三种单体的电聚合能力和电化学性质,以及形成聚合物后电化学性质的变化采用循环伏安法和其他电化学方法进行了研究。 相似文献
68.
Returning to an earlier frequency-domain analysis of the problem of long-span bridge response to ambient winds, the paper emphasizes the indispensable experimental information necessary to bring results into conformity with full-scale prototype action. Focus is placed upon the use of a sectional wind tunnel model under simulated turbulent flow as the prime source of this information, which consists principally of the flutter derivatives and the spectra of the wind forces, both obtained under turbulent flow. The effect of three-dimensional turbulence upon the flutter derivatives is observed to influence structural stability in a manner consistent with that observed in full-bridge wind tunnel models. 相似文献
69.
Haiyuan Ren Jinrui Li Ai Peng Ting Liu Mengjun Chen Hongguang Li Xiaojing Wang 《International journal of molecular sciences》2022,23(10)
As carbon-based nanomaterials, water-soluble C60 derivatives have potential applications in various fields of biomedicine. In this study, a water-soluble fullerene C60 derivative bearing alanine residues (Ala-C60) was synthesized. The effects of Ala-C60 on neural stem cells (NSCs) as seed cells were explored. Ala-C60 can promote the proliferation of NSCs, induce NSCs to differentiate into neurons, and inhibit the migration of NSCs. Most importantly, the Ala-C60 can significantly increase the cell viability of NSCs treated with hydrogen peroxide (H2O2). The glutathioneperoxidase (GSH-Px) and superoxide dismutase (SOD) activities and glutathione (GSH) content increased significantly in NSCs treated even by 20 μM Ala-C60. These findings strongly indicate that Ala-C60 has high potential to be applied as a scaffold with NSCs for regeneration in nerve tissue engineering for diseases related to the nervous system. 相似文献
70.
Yanhe Li Xiaoming Li Xin Li Suiqun Yang Bingui Wang Honglei Li 《International journal of molecular sciences》2022,23(10)
Six novel verrucosidin derivatives, namely, poloncosidins A–F (1–6), together with one known analogue (7), were isolated and identified from the deep-sea-derived fungus Penicillium polonicum CS-252, which was obtained from cold-seep sediments collected in the South China Sea at a depth of 1183 m. Their structures were mainly established on the basis of a detailed interpretation of NMR spectroscopic and mass spectrometric data. The relative and absolute configurations of compounds 1–6 were determined by ECD calculations and a DP4+ probability analysis. Compounds 1–5 represent the first examples of verrucosidins with a 2,5-dihydrofuran ring which is uncommon among the known analogues. These compounds exhibited inhibitory activities against several human and aquatic pathogens with MIC values ranging from 4 to 32 μg/mL. 相似文献