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121.
Empirical solvent parameters of silica surfaces are determined by means of solvatochromic dyes, e.g., Cu(tmen) (acac)+ ClO
4
–
/B(C6H5)
4
–
, Fe(phen)2(CN)2, and Michlers Ketone dissolved in 1,2-dichloroethane or cyclohexane. The values obtained by UV/VIS-measurements are compared with both the polarity scales of Kamlet and Taft and with Gutmann's donor and acceptor numbers. Kamlet and Taft's -parameter (the hydrogen-bond donation capacity of a solvent) is determined independently by means of salicylideneaniline. The * of silica is determined using 5-N,N-dimethylamino-5-nitro-2,2-bithiophene and the complex of tetracyanoethylene with Michlers Ketone, respectively. Further on the reliabilities of the obtained Kamlet-Taft parameters , , and * are checked by comparism with experimental and calculated values of theE
T(30)-parameter of silica by means of multi-parameter regression analysis. The surface properties of silica are influenced mainly by HBD-properties (75%) and dipolarity/polarizability * (20%), but hardly by the HBA-properties (<5%). UV/VIS-measurements were carried out in a special equipment with glass fiber optics, A drawing of the apparatus is given. 相似文献
122.
本文介绍FAB质谱的原理、功能和优点。综述了FAB机理,讨论了影响FAB谱的因素。归纳了FAB法在金属有机配合物研究中的应用。 相似文献
123.
本文以纯Y_2O_3中杂质元素的ICP-AES测定为例,研究用数值微分技术解决光谱干扰同题。结果表明,导数光谱法不仅可以有效地消除来自基体的光谱干扰,还能减小谱线干扰对检测能力的影响。当分析物浓度较低时,导数光谱法的加入回收率明显优于离峰分析法,多数情况下也优于在峰法校正光谱干扰时的回收率。 相似文献
124.
Ganglin Xue Bin Liu Huaiming Hu Jianhui Yang Jiwu Wang Feng Fu 《Journal of Molecular Structure》2004,690(1-3):95-103
A new family of heteropolytungstate complexes (NH4)21[Ln(H2O)5{Ni(H2O)}2As4W40O140]·xH2O(Ln=Y, Ce, Pr, Nd, Sm, Eu, Gd) were prepared by the reaction of Na27[NaAs4W40O140]·60H2O with NiCl2·6H2O and Ln(NO3)3·xH2O at pH≈4.5. The crystal structures of (NH4)21[Gd(H2O)5{Ni(H2O)}2As4W40O140]·51H2O was determined by X-ray diffraction analysis and element analysis. The compound crystallizes in the monoclinic space group P21/n with a=19.754(3), b=24.298(4), c=39.350(6) Å, β=100.612(3)°, V=18564(5) Å3, Z=2, R1(wR2)=0.0544(0.0691). The central site S1 and two opposite sites S2 of the big cyclic ligand [As4W40O140]28− are occupied by one Ln3+and two Ni2+, respectively, each site supply four Od coordinating to metal ion, another one water molecule and other five water molecules coordinate, respectively, to Ni2+and Ln3+. Polyanion [Ln(H2O)5{Ni(H2O)}2As4W40O140]21− has C2v symmetry. IR and UV–vis spectra of [NaAs4W40O140]27− of the title compounds are discussed. 相似文献
125.
稀土氨基酸固体络合物的合成及结构分析进展 总被引:16,自引:2,他引:16
本文综述了稀土氨基酸络合物的合成,以及应用红外、核磁、X-射线衍射、热分析等方法进行结构分析研究的进展情况。 相似文献
126.
Tetrafluoroaurates(III) of Lanthanoides M2F[AuF4]5 (M = Tb, Dy, Ho, Er) Tetrafluoroaurates(III) M2F[AuF4]5 with M = Tb, Dy, Ho, Er, all yellow, have been obtained. From single crystal data they crystallize triclinic, space group P1 -C1i (No. 2) with Tb: a = 1 194,34(7) pm, b = 798,46(6) pm, c = 902,02(7) pm, α = 89,033(7)°, β = 88,990(6)°, γ = 89,006(7)°; Dy: a = 1 191,66(9) pm, b = 796,33(8) pm, c = 899,65(9) pm, α = 88,956(8)°, β = 89,056(8)°, γ = 88,972(8)°; Ho: a = 1 189,06(10) pm, b = 795,46(6) pm, c = 896,81(7) pm, α = 88,912(8)°, β = 89,101(7)°, γ = 88,873(8)°; Er: a = 1 185,20(40), b = 793,98(14), c = 893,83(20), α = 88,751(23)°, β = 89,187(26)°, γ = 88,884(9)° 相似文献
127.
γ-[SiW10O36]8-夹心型稀土元素单取代多酸化合物的合成与表征 总被引:2,自引:0,他引:2
利用缺位填充法合成了12个γ-[SiW10O36]8-夹心型稀土元素单取代多酸化合物K13[Ln(SiW10O36)2]·nH2O(Ln=La3+,Ce3+,Pr3+,Nd3+,Sm3+,Eu3+,Gd3+,Tb3+,Dy3+,Ho3+,Er3+,Yb3+).通过元素分析确定其组成,由红外光谱、紫外-可见吸收光谱、循环伏安及室温磁化率测定结果确认稀土离子与γ-[SiW10O36]8-相配位;183WNMR及荧光光谱结果则表明,稀土离子处于2个γ-[SiW10O36]8-构成的八配位环境中,标题化合物具有夹心型D2d对称性结构. 相似文献
128.
M. Yu. Gorshkov A. D. Neuimin N. M. Bogdanovich Yu. V. Danilov L. A. Dunyushkina 《Russian Journal of Electrochemistry》2007,43(6):721-728
Oxygen-ion conduction in apatite-like compounds based on silicates and germanates of lanthanum La x A6O12 + 1.5x (A = Si, Ge; x = 9.11–10.22) is studied. The compounds are shown to be purely ionic conductors at 600–900°C and partial oxygen pressures 10?16 to 105 Pa. The electroconductivity of the best conducting specimens of La x A6O12 + 1.5x (A = Si, Ge; x = 9.77–10) exceeds that of electrolyte YSZ at moderate temperatures. The electroconductivity of lanthanum germanate is substantially greater than that of lanthanum silicate, specifically, 7.85 × 10?2 and 2.35 × 10?2 S cm?1, respectively, at 800°C. An inflection is discovered at ~750°C in the temperature dependences of electroconductivity of La x Ge6O12 + 1.5x (x = 9.77–10.22). A dilatometric examination points to a second-kind phase transition that may be due to the oxygen sublattice disordering. The behavior of apatite-like electrolytes La x A6O12 + 1.5x (A = Si, Ge) during long exploitation periods in the interval of working temperatures of electrochemical devices is studied for the first time ever. The electrolytes’ aging at 800°C in air for 1000 h was investigated by the electroconductivity method. The electroconductivity of lanthanum germanates decayed with time by 5% and that of lanthanum silicates, by 9.5%. The steady-state values of electroconductivity of all compounds studied is reached after 600–700 h. The compounds studied form a class of materials that hold some promise as solid electrolytes for medium-temperature fuel cells and other electrochemical devices. 相似文献
129.
白光电致发光二极管(LED)是固体照明的重要光源.荧光体转换是获取白光LED的主要途径之一.当前,转换用荧光体的研究在发光材料领域中最活跃.本文对近年来白光LED用发光材料新体系的研究进展作了评述. 相似文献
130.
群体决策随机偏爱数映射的若干性质 总被引:1,自引:0,他引:1
杨万铨 《高等学校计算数学学报》2008,30(1):8-13
1引言近年来,群体决策在社会选择、福利、经济和军事等领域得到广泛应用,从而其理论研究越来越被人们所重视.20世纪中叶,K.J,Arrow提出了偏爱公理系和不可能性定理,并 相似文献