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131.
Abdelfetah Mounir Mohamed El Guendouzi Abderrahim Dinane 《Journal of solution chemistry》2002,31(10):793-799
Ternary aqueous solutions of MgSO4 and K2SO4 have been studied by the hygrometric method at 25°C. The relative humidity of this system is measured at total molalities from 0.35 mol-kg–1 to about saturation for three ionic-strength fractions (y = 0.25, 0.50, and 0.80 of MgSO4. The data allow calculation of water activities and osmotic coefficients. From these measurements, the Pitzer ionic mixing parameters are determined and used to predict the solute activity coefficients in the mixture. The results are used to calculate the excess Gibbs energy at total molalities for ionic-strength fraction y. 相似文献
132.
133.
E. V. Alekseev E. V. Suleimanov E. V. Chuprunov G. K. Fukin L. G. Alekseeva 《Journal of Structural Chemistry》2005,46(5):936-940
The crystal structure of KAsUO6·3H2O was solved at 100 K and 293 K. KAsUO6·3H2O at T = 100 K: tetragonal, P4/ncc, a = 7.2037(6) Å, c = 17.811(2) Å; Z = 4, R1 = 0.0263, wR2 = 0.0546, for 618 independent reflections; at T = 293 K: tetragonal, P4/ncc, a = 7.1600(4) Å, c = 17.746(1) Å; Z = 4, R1 = 0.0263, wR2 = 0.0433 for 427 independent reflections. The results of X-ray analysis are compared with our previous data on heat capacity of this compound, and changes that take place in the structure at elevated temperature are considered. 相似文献
134.
V. M. Zainullina V. L. Volkov N. V. Podvalnaya A. L. Ivanovskii 《Journal of Structural Chemistry》2005,46(2):340-342
The calculations of the electronic structure of layered polyvanadate K2V3O8 were made employing the spin-polarized tight-binding LMTO method. Calculated magnetic moment for K4V6O16 compound phase equals 1.97 μB. V-O interactions were established to be dominating in the chemical bonding generation in this polyvanadate according to the estimated crystal orbital overlap population. The covalent bonds V(2)-V(2) in V(2)2O7 groups and electron density localization on vanadium atoms in isolated pyramids V(1)O5 were found. 相似文献
135.
HU Rong TIAN Jinping & YIN Yingwu . College of Chemistry & Environment Protection Engineering Southwest University for Nationalities Chengdu China . TH-UNIS Insight Co. Ltd. Beijing China . Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology Ministry of Education Department of Chemistry Tsinghua University Beijing China 《中国科学B辑(英文版)》2006,49(4):351-356
The formation of peptides and then protein by small abiological molecules clusters such as amino acid is a key stage in the origin of life[1]. More and more ex- perimental results showed that phosphate plays an important role in the formation of biomolecules in prebiotic chemical evolution. The principal reservoirs of biochemical energy are phosphates (such as ATP). The peculiar role of phosphates in contemporary life might suggest its essential role in prebiotic energy conversion, syntheses … 相似文献
136.
氟钽酸钾中碳存在形式的探讨 总被引:2,自引:0,他引:2
本文从氟钽酸钾(K2TaF6)的生产工艺论述了有机物存在于D2TaF6的可能性。通过K2TaF6低温通氧燃烧前后测定碳的结果比较,以及X射线能谱仪表面分析结果,证实了碳的来源是残留的有机萃取剂。 相似文献
137.
138.
Alexei A. Belik Shinya Uji Eiji Takayama-Muromachi 《Journal of solid state chemistry》2005,178(11):3461-3463
Magnetic properties of quasi-one-dimensional S=1/2 Heisenberg antiferromagnet Sr2Cu(PO4)2 were investigated by temperature and field dependence of AC susceptibility down to 0.03 K. A sharp peak was observed at on the temperature dependence of AC susceptibility indicating long-range magnetic ordering. Taking into account the exchange constant, (Hamiltonian =J∑SiSi+1), the ratio kBTN/J is 0.06%. Sr2Cu(PO4)2 is, therefore, one of the best one-dimensional Heisenberg antiferromagnet known so far. 相似文献
139.
《Arabian Journal of Chemistry》2022,15(4):103712
Although recent decades have witnessed the synthesis of 1,3,4-thiadiazoles via phosphorus POCl3-promoted cyclization reaction, simultaneous access to 2-amino-1,3,4-thiadiazole and 2-amino-1,3,4-oxadiazole analogs remains unexpected and elusive. Herein, a detailed regiocontrolled synthesis of 2-amino-1,3,4-thiadiazoles in good to high yields with good regioselectivities from readily available thiosemicarbazides using POCl3 was disclosed. Meantime, to establish a comprehensive structure–activity relationship, 2-amino-1,3,4-oxadiazole derivatives as single regioisomers were prepared via EDCI·HCl-triggered cyclization of the thiosemicarbazide intermediates. The in vitro anti-influenza assays proved that the selected compounds with the pyrazine/pyridine ring exhibited certain inhibitory activities against influenza A virus strains A/HK/68 (H3N2) and A/PR/8/34 (H1N1) in MDCK cells. Among them, N-(adamantan-1-yl)-5-(5-(azepan-1-yl)pyrazin-2-yl)-1,3,4-thiadiazol-2-amine (4j) was the most active compound, and exhibited favorable activity with EC50 values of 3.5 μM and 7.5 μM, respectively. In addition, the molecular docking results explained the reason why compound 4j had dual inhibitory activity and revealed the reasonable binding mode of this compound with the M2-S31N and M2-WT ion channels. This compound had the potential to be further developed as an anti-influenza drug. 相似文献
140.
A simple, rapid and specific chemiluminescence (CL) method for the determination of glutathione has been developed. The method
is based on the enhanced CL of the reaction between Ru(phen)3
2+ (phen = 1,10-phenanthroline) and KMnO4 by glutathione in HCl medium. Under the optimum conditions, the response is linearly proportional to the concentration of
glutathione between 1.5 × 10−7 and 1.0 × 10−5 mol L−1. The dection limit for glutathione (5.8 × 10−8 mol L−1) is about 10 and 200 times better than those of the spectrophotometric method using Ellman regent and the Lucigenin – CL
method, respectively. The final procedure allows the determination of glutathione in human serum with recoveries of 92%–108%.
A satisfactory agreement was obtained with a mean relative difference of 2.5% compared to the HPLC method. 相似文献