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991.
992.
Yi Ming LIU Feng Xin WANG Sui Ping DENG Jian Ming OUYANG 《中国化学快报》2006,17(5):687-690
Kidney stone disease, which occurs in about 10% of the U.S. population, causes substantial suffering and occasional renal failure, yet the disease mechanism is poorly understood1. Kidney stones mostly contain microcrystals of calcium oxalate monohydrate (… 相似文献
993.
Kaliyamoorthy Panneerselvam Masilamani E. Sobhia Kizakkekoikkal K. Chacko Edwin Weber Hans-Jürgen Köhler Rolf Pollex 《Journal of inclusion phenomena and macrocyclic chemistry》1992,13(1):29-36
Single crystal X-ray analysis of the hydrated KSCN complex of benzodinaphthopyridino-21-crown-7 (1) (1 : 1 : 1) is reported. Crystals of the complex are orthorhombic,Pnma, with = 16.946(4),b = 22.298(4),c = 10.390(8) Å andD
c = 1.184 g cm–1,Z = 4. The host macroring (1) has a mirror symmetry and exists in a so-called dentists chair conformation. The cation (K–) is coordinated to all the six ether oxygen atoms and also weakly to the pyridine N atom. The SCN– anion group has a statistical type of disorder with opposite orientations of S and N such that nitrogen and sulphur are coordinated to K+. Packing of the host molecules is in columns to form quasi channels with K+, SCN–, and H2O being located inside the stacks.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82132 (9 pages). 相似文献
994.
Francesco Malatesta Ambrogio Giacomelli Roberto Zamboni 《Journal of solution chemistry》1994,23(1):11-36
The activity coefficients of LaCl3, K3Fe(CN)6, and LaFe(CN)6 were measured down to about 1×10–4, 3×10–5, and 2×10–5 mol-kg–1 respectively, by means of cells with ion-exchange liquid membranes. In the diluted region, the trend of lanthanum chloride agrees with the Debye-Huckel theory and corroborates earlier findings in the literature relevant to more concentrated solutions, with minor systematic corrections of the ± values. K3Fe(CN)6 attains (rather than tends to attain) the Debye-Huckel limiting slope at1×10–3 mol-kg–1, and lanthanum ferricyanide in the diluted region shows negative deviations from the limiting law, similar to the ones predicted for large-sized, highly-charged ions in the diluted region by Bjerrum's, IPBE, and Mayer's theories. The behavior of LaCl3 in the concentrated solutions proves that lanthanum ion drags along with it into the membrane many molecules of water which were then found to be twelve. Pitzer's theory best-fit coefficients that meet the experimental curves to be reproduced satisfactorily are reported. 相似文献
995.
Isopiestic vapor pressure experiments are performed at 25°C with aqueous Mg(TcO4)2 solutions and with ternary mixtures containing various combinations of NaTcO4, Mg(TcO4)2, NaCl, MgCl2, Na2SO4, and MgSO4. The osmotic coefficients of the binary solutions are used to evaluate the binary Pitzer parameters (0), (1), and C for Mg(TcO4)2. We previously reported these parameters for NaTcO4. The binary parameters for KTcO4 and Ca(TcO4)2 are evaluated from solubilities of KTcO4 in KCl and CaCl2 solutions, respectively. The mixing parameters TcO
4
–
/Cl
–, M/TcO
4
–
/Cl
–, TcO
4
–
/SO
4
2–
, M/TcO
4
–
/SO
4
2–
, and Na
+
/Mg
2+
/TcO4
2– are calculated from either osmotic coefficients or solubilities in the corresponding ternary mixtures. The evaluated set of Pitzer parameters predicts well the activity coefficients and solubilities of KTcO4 in multicomponent systems. 相似文献
996.
The feasibility of the use of potassium nitrate and potassium perchlorate as temperature standards in Differential scanning calorimetry has been studied. The solid-state phase transition temperatures of KNO3 and KClO4 were determined by means of DSC. The metrological properties of these salts as calibration materials were examined. The reliability of KNO3 and KClO4 calibrations was investigated by twofold determination of the bismuth melting temperature after the apparatus had been calibrated with indium and lead, and with KNO3 and KClO4. Conclusions were drawn concerning the suitability of these salts for use as DSC temperature calibrants.
Zusammenfassung Es wurde die Möglichkeit der Verwendung von Kaliumnitrat und Kaliumperchlorat als Temperaturstandard für DSC untersucht. Die Bestimmung der Temperaturen für Feststoff-Phasenumwandlungen von Kaliumnitrat und Kaliumperchlorat wurde mittels DSC erreicht. Weiterhin wurden die meßtechnischen Eigenschaften der untersuchten Salze (KNO3 und KClO4) als Bezugssubstanzen geprüft. Die Zuverlässigkeit der Kalibrierung mittels KNO3 und KClO4 wurde durch eine zweifache Bestimmung der Schmelztemperatur von Wismut überprüft: einmal nach der Kalibrierung des Gerätes mit Indium und Blei und andererseits nach der Kalibrierung mit Kaliumnitrat und Kaliumperchlorat. Angesichts der Resultate kann man feststellen, daß die untersuchten Salze zur Temperaturkalibrierung in der DSC geeignet sind.相似文献
997.
998.
Sakamoto Wataru Kosugi Kana Arimoto Tadashi Yogo Toshinobu Hirano Shin-ichi 《Journal of Sol-Gel Science and Technology》1999,16(1-2):65-75
Highly oriented tungsten bronze K0.4(Pb0.6Ba0.4)0.8Nb2O6 ferroelectric thin films have been prepared from metal alkoxides and metal acetate by chemical process. The formation of solid solution with potassium was found to be very effective to form the tungsten bronze phase at lower temperatures compared with (Pb0.6Ba0.4)Nb2O6. The amount of potassium in the composition of Kx(Pb0.6Ba0.4)1 – x/2Nb2O6 [0 x 0.4] is also important to crystallize in the tungsten bronze phase. K0.4(Pb0.6Ba0.4)0.8Nb2O6 films with c-axis preferred orientation were successfully synthesized on MgO(1 0 0) and Pt(1 0 0)/MgO(1 0 0) substrates above 700°C. KPBN60 thin film on Pt(1 0 0)/MgO(1 0 0) showed a remnant polarization of 20 C/cm2 and a coercive field of 140 kV/cm at –150°C. 相似文献
999.
研究了高锰酸钾-Ⅰ--甲醛体系化学发光,从而建立了一种测定微量Ⅰ-的新方法.讨论了各种反应物浓度、酸度、干扰离子等因素对测定结果的影响.Ⅰ-浓度在1.0×10-6~4.0×10-5g/mL范围内与化学发光强度有较好的线性关系.对1.0×10-5g/mL的Ⅰ-进行了11次平行测定,相对标准偏差为2.8%,方法的检出限为2.4×10-8g/mL.结果令人满意. 相似文献
1000.
以有机盐山梨酸钾(PS)作为模板,在氮气氛围下进行一步热解处理,制备出一种衍生的三维互连的多孔碳材料(PSIPC)。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、热重分析(TGA)及N_2吸附-脱附测试对该多孔碳材料进行表征。于不同热解温度下制备电极材料PSIPC-X(X=700、800、900℃),并采用滴涂法制备了山梨酸钾衍生多孔碳修饰电极(PSIPC-700/GCE、PSIPC-800/GCE及PSIPC-900/GCE),使用循环伏安法(CV)和差示脉冲伏安法(DPV)考察了橙皮素(HSP)在PSIPC-900/GCE上的电化学行为。结果表明,在最优条件下,HSP在该电极上的检测范围为0.05~15.0μmol/L,检出限为0.021μmol/L。该方法灵敏度高、检测范围广,可用于实际样品的检测。 相似文献