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91.
反向流动注射化学发光法测定痕量铁 总被引:10,自引:1,他引:10
基于邻菲别名林对高碘酸钾-碱性鲁米诺-铁体系发光强度的增敏作用建立了水体中总铁的反向流动性化学发光检测方法。该法线性范围在1×10^-4-10mg/L,检测限为3×10^-6mg/L,对于5×10^-3mg/L Fe测定9次的相对标准偏差为0.9%。此方法已用在水处理中总铁的监测。 相似文献
92.
W. Kunz J. Barthel L. Klein T. Cartailler P. Turq B. Reindl 《Journal of solution chemistry》1991,20(9):875-891
A variety of methods has been used for the study of lithium bromide solutions in acetonitrile yielding by their combination reliable information on different levels of approximation. Osmotic coefficients based on precise vapor pressure measurements are reproduced by CM (chemical model) and HNC (hypernetted chain) calculations and by BD (brownian dynamics) simulations. The results of neutron scattering experiments are treated with the help of HNC and BD methods. Hartree-Fock calculations on isolated LiBr pairs and solvated lithium ions yield reliable particle distances and reveal the geometry of the lithium solvation sphere. 相似文献
93.
荧光光谱法研究磷酰化5,7-二羟基黄酮与ctDNA的相互作用 总被引:1,自引:0,他引:1
以溴化乙锭(EB)为荧光探针,研究了磷酰化5,7-二羟基黄酮与ctDNA的相互作用。实验结果表明,磷酰化5,7-二羟基黄酮与ctDNA间存在相互作用。随着温度的升高,磷酰化5,7-二羟基黄酮对ctDNA-EB体系的荧光猝灭常数降低,磷酰化5,7-二羟基黄酮可与ctDNA形成复合物,此猝灭过程为静态猝灭。根据Stern-Volmer方程,算出25℃及37℃下磷酰化5,7-二羟基黄酮对ctDNA-EB体系的荧光猝灭常数分别为Kq1=30 860 L/mol及Kq2=27 760 L/mol,并且算出它与ctDNA结合的平衡常数为KM=2.39×107L/mol。 相似文献
94.
考察了茂环上不同取代基及钛上阴离子配体对茂基钛配合物/正丁基锂催化体系加氢活性和稳定性的影响。在充分发挥该体系催化活性的条件下,由配合物Cp2TiCl2、Cp2TiF2和Cp2Ti[OC6H3(CH3-2)Cl-4]2组成的催化体系对辛烯-1加氢的最高活性(或初活性)达到46 ̄58s^-1。 相似文献
95.
The enthalpies of crystallization of LiNO3 and LiNO3–3H2O from aqueous solutions at 25°C, measured by a calorimetric method and determined from the previously published data on the concentration dependence of the enthalpy of solution, are reported. The results are compared with the values obtained from the concentration dependences of the activity coefficients and from the temperature dependences of the solubilities. The enthalpy of solution at infinite dilution and the enthalpy of hydration are given. 相似文献
96.
Mark Salomon 《Journal of solution chemistry》1990,19(12):1225-1236
Conductivity data are used to determine thermodynamic complex formation constants for cases in which both the initial electrolyte and the complexed electrolyte form ion pairs. Using the method described in the text, the complex formation constants of Li+, Na+ and K+ with the crown ether 18-crown-6 and of Li+ with the ligand triphenylphosphine oxide in propylene carbonate have been evaluated from conductance data. The complexation of AgBr in propylene carbonate solutions of n-etrabutylammonium bromide has also been studied by the measurement of molar conductivities. The results of these studies indicate that ion pairing should not be neglected, even in high permittivity solvents such as propylene carbonate, and that the ion pair association constants correlate well with structural studies on cation-crown ether molecular conformations. 相似文献
97.
以SiO2和Li2CO3为反应原料,采用高温固相法于不同温度下合成了一系列可在高温500~750 ℃之间直接吸收CO2的硅酸锂(Li4SiO4)材料。采用扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)分别观察和评价了合成材料的表面形貌与结构特征,用热重分析仪(TG)研究了硅酸锂材料吸收CO2的性能。实验结果表明,在750 ℃下煅烧6 h即可合成出吸收CO2性能良好的硅酸锂材料,在CO2气氛下,于700 ℃保持约15 min即可达到吸收平衡,其吸收量约达43%(wt)左右。与文献报道相比,材料的合成条件有所改善,材料吸收CO2的容量也有较大提高。 相似文献
98.
Yu. L. Frolov I. V. Guchik V. A. Shagun A. V. Vashchenko 《Journal of Structural Chemistry》2005,46(6):979-984
Models of alkali metal hydroxide-water-dimethylsulfoxide superbasic media have been constructed using Hartree Fock and DFT (B3LYP) quantum chemical methods; the structure and energies of anion complexes are considered. The hydroxide anion in the models is stabilized as complexes of OH?·H2O and OH?· 2H2O types. 相似文献
99.
Bassan A Blomberg MR Siegbahn PE Que L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(2):692-705
The reactivity of [HO-(tpa)Fe(V)=O] (TPA=tris(2-pyridylmethyl)amine), derived from O-O bond heterolysis of its [H(2)O-(tpa)Fe(III)-OOH] precursor, was explored by means of hybrid density functional theory. The mechanism for alkane hydroxylation by the high-valent iron-oxo species invoked as an intermediate in Fe(tpa)/H(2)O(2) catalysis was investigated. Hydroxylation of methane and propane by HO-Fe(V)=O was studied by following the rebound mechanism associated with the heme center of cytochrome P450, and it is demonstrated that this species is capable of stereospecific alkane hydroxylation. The mechanism proposed for alkane hydroxylation by HO-Fe(V)=O accounts for the experimentally observed incorporation of solvent water into the products. An investigation of the possible hydroxylation of acetonitrile (i.e., the solvent used in the experiments) shows that the activation energy for hydrogen-atom abstraction by HO-Fe(V)=O is rather high and, in fact, rather similar to that of methane, despite the similarity of the H-CH(2)CN bond strength to that of the secondary C-H bond in propane. This result indicates that the kinetics of hydrogen-atom abstraction are strongly affected by the cyano group and rationalizes the lack of experimental evidence for solvent hydroxylation in competition with that of substrates such as cyclohexane. 相似文献
100.