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41.
The association constant K of mono-acetato complex of Tb3+ has been determined at normal p and T conditions by measurement of its luminescence lifetime in aqueous solution containing increasing concentrations of acetate. Two experimental arrangements used for the measurement are described. 相似文献
42.
W 7-agarose是常用的细胞外CaM功能的拮抗剂,本实验采用荧光光谱法研究了水溶液中钙调素拮抗剂W 7-agarose与植物胞外钙调素的相互结合反应。W 7-agarose是一种将W 7-共价连接到颗粒型agarose(琼脂糖)的粒子。W 7-agarose颗粒较大且容易沉淀,静置5m in后,溶液中的荧光强度完全由游离的CaM产生。在溶液中加入W 7-agarose后,溶液中一部分CaM与其结合后沉降至荧光比色皿底部,导致溶液中CaM的荧光强度下降。由此可以确定溶液中游离CaM的浓度。根据公式lg{[Q]t(F0-F)/F0}=nlg{[Q]tF/F0} lgnK[B]t,从而计算出配位体系的结合常数和配比。研究表明:二者以摩尔比1∶1结合,其平衡常数为4.9×105。由此进一步计算了W 7-agarose对胞外钙调素的拮抗率,在拮抗剂W 7-agarose浓度达到15~20μmol/L时,拮抗率可达到90%以上,与文献报道的生物学体内实验结果一致,从分子水平上解释了W 7-agarose与CaM的结合作用。 相似文献
43.
Using flow microcalorimetry, the ion association reaction M2+(aq)+Fe(CN)
6
4–
(aq)=MFe(CN)
6
2–
(aq) (M=Ca, Mg) has been studied at 25°C over the ionic strength range 0.02 to 0.08 mol-dm–3. Analyses of the data to obtain Ho, the enthalpy change at infinite dilution, are described. The value obtained for Ho is sensitive to the kind of functions used to correct for non-ideal behavior. 相似文献
44.
In this review paper, the NBS scale and its limitations are briefly discussed. The magnitude of liquid junction potentials and some calculated values are presented. The use of a molality scale for hydrogen electrode concentration cells at high temperatures is described, and results from measurements on ionization equilibria are summarized. Use of this scale is also recommended for certain circumstances with cells without liquid junction. As an alternative activity scale, use of the Pitzer ion-interaction treatment for ions is recommended for special cases. Finally, reference data are presented for ±HCl in HCl(aq) to 350°C and (HCl+NaCl)(aq) to 200°C that were derived by use of the Pitzer ion-interaction treatment.Presented at the Second International Symposium on Chemistry in High Temperature Water, Provo, UT, August 1991. 相似文献
45.
46.
Alessandro D' Aprano Dorina Ines Donato Antonio Carrubba Doctor in Chemistry thesis of A. Carrubba 《Journal of solution chemistry》1983,12(3):209-220
Conductance measurements are reported for LiPi, NaPi, KPi, RbPi, CsPi, Bu4NPi, Bu4NBr, Bu4NClO4, Bu4NNO3, and Bu4NBBu4 at 25°C in -butyrolactone-sulfolane mixtures. In these mixtures of solvents that are practically homomorphous, isodielectic and with comparable dipole moments, the ion pair association and ionic mobilities of large ions conform to the expectations of the primitive model. Electrolytes containing lithium or sodium ions show anomalies indicating that other factors besides shape, dipole moment, and polarizability of the solvent molecules are involved in the association and transport processes of these ions. 相似文献
47.
48.
49.
Thermodynamics of the dissociation of 2-aminopyridinium ion in synthetic seawater and a standard for pH in marine systems 总被引:1,自引:0,他引:1
Buffer solutions composed of 2-aminopyridinium chloride and 2-aminopyridine in synthetic seawater are useful as a supplement to buffers of Tris (pH 8.2) and Bis (pH 8.8) in standardizing measurements of hydrogen ion concentration (pm
H
or pH(SWS)) in oceanography. The dissociation constant of 2-amino-pyridinium ion over the range of salinities (S) from 30 to 40 has now been determined from the emf of cells without liquid junction at eight temperatures (T) from 278.15 to 313.15 K. The results fit the equation pK=2498.31/T–15.3274+2.4050 lnT+S(0.012928–2.9417×10–5T) with a standard deviation of 0.0023. Thermodynamic constants for the dissociation process and standard reference values of pm
H
and pH(SWS) were derived from the data. The pm
H
of the buffer consisting of 2-aminopyridinium chloride and 2-aminopyridine (each 0.04 molal) in synthetic seawater of salinity 35 varies from 7.356 at 278.15 K to 6.601 at 313.15 K. 相似文献
50.
仲胺型双冠醚与四苯硼酸碱金属盐在丙酮溶液中。25℃下的电导说明它们与Na~+可能形成1∶1络合物(冠醚单元∶金属离子),而与K~+、Rb~+、Cs~+离子则形成2∶1络合物。用Schlff碱型和仲胺型双-(苯并15-冠-5)在水-氯仿体系中进行萃取,测量了分配比D和萃取平衡常数K,发现后者的K值均大于前者。双冠醚F_2对K~+的萃取能力最强,选择性最佳。 相似文献