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991.
Hydrogen species in both SiO2 and Rh/SiO2 catalysts pretreated in different atmospheres (H2, O2, helium or air) at different temperatures (773 or 973 K) were investigated by means of 1H MAS NMR. In SiO2 and O2-pretreated catalysts, a series of downfield signals at -7.0, 3.8-4.0, 2.0 and 1.5-1.0 were detected. The first two signals can be attributed to strongly adsorbed and physisorbed water and the others to terminal silanol (SiOH) and SiOH under the screening of oxygen vacancies in SiO2 lattice, respectively. Besides the above signals, both upfield signal at -110 and downfield signals at 3.0 and 0.0 were also detected in H2-pretreated catalyst, respectively. The upfield signal at -110 originated from the dissociative adsorption of H2 over rhodium and was found to consist of both the contributions of reversible and irreversible hydrogen. There also probably existed another dissociatively adsorbed hydrogen over rhodium, which was known to be p hydrogen and in a unique form of "delocalized hydrogen". It wa 相似文献
992.
993.
Iodide ion-selective electrode were studied, prepared and applied for the complex formations and solubility product determination. The thermodynamic formation constant of PbI+ and the solubility product of PbI3 were found to be 54 and 9.2 × 10?9, respectively. The formation constant of PbNO3+ was calculated to be 4.6 from the different formation constant of PbI+ in perchlorate and nitrate media. 相似文献
994.
L. J. Ning Y. P. Wu L. Z. Wang S. B. Fang R. Holze 《Journal of Solid State Electrochemistry》2005,9(7):520-523
Three kinds of silicon-containing disordered carbons have been prepared by pyrolysis of polysiloxanes with different amounts of phenyl side groups. X-ray powder diffraction, X-ray photoelectron spectroscopy and electrochemical capacity measurements were performed to study their behaviors. Graphite crystallites, micropores, and silicon species affect their electrochemical performances. All of them present high reversible capacities, >372 mAh/g. Since the graphite crystallites are very small, they contribute very little to reversible capacity. The number of micropores produced by gas emission during the heat-treatment process decides whether they exhibit reversible capacity. Si mainly exists in the form C–Si–O and influences the irreversible capacity. There is no evident capacity fading in the first ten cycles, indicating promising properties for these disordered carbons. 相似文献
995.
Jiunn-Der?LiaoEmail author Chonyu?Chen Yi-Te?Wu Chih-Chiang?Weng 《Plasma Chemistry and Plasma Processing》2005,25(3):255-273
High density and well surface-distributed oxygen microwave plasma with an extensible antenna-coupling design was utilized to modify a densely weaved and large-surface-area Nylon-6 fabric within a short treatment time. Plasma pretreatment and subsequent acrylic acid (AAc) or 2-hydroxyethyl methacrylate (HEMA) grafting process were studied and optimized at the stage after dyed and finished procedure. The monomer-grafted dyed Nylon-6 fabrics evolved lasting hydrophilic properties and thereafter created or improved surface properties such as water diffusion, drainage, moisture regain and water absorbency, in different degrees. The pHEMA-grafted sample exhibited minor effect in color perception, which was also much hydrophilic than the pAAc-grafted one. Based upon surface analyses and wetting assessment, the penetration of HEMA monomer into the plasma-treated fabric matrix contributed to the facilitation of wetting properties. This work accordingly ensures such plasma-induced system to incorporate with the pattern of hydrophilic properties on the analogous textiles without interrupting their finishing process. 相似文献
996.
铈、镨二乙基磷酸盐的晶体结构 总被引:1,自引:0,他引:1
合成了Ce[PO_2(OC_2H_5)_2]_3和Pr[PO_2(OC_2H_5)_2]_3(简称Ce(DEP)_3和Pr(Pr(DEP)_3)。用四圆衍射仪测定了其晶体结构。它们均属三斜晶系,空间群P1。晶胞参数,对Ce(DEP)_3:α=10.324(4)A,b=12.861(4)A,c=13.998(5)A,x=106.49(3)°,β=112.83(4)° γ=115.61(3)°,V=1296(1)A~3,Z=2;对Pr(DEP)_3:α=10.27(1)A,b=11.81(1)A,c=12.51(1)A,x=109.93(9)°,β=111.9(9)°,γ=93.0(1)°,V=1293(3)A~3,Z=2。用Patterson法并经分块全矩阵最小二乘法修正,最后的R值,Ce的为0.1071,Pr的为0.1066。结构分析指出,两种配合物结构类似,Ce和Pr原子均由二乙基磷酸根的六个氧原子配位形成八面体构型。 相似文献
997.
某些生物分子在C60—γ—环糊精/Nafion化学修饰电极上的电催化行为 总被引:4,自引:0,他引:4
研究了C60-γ-环糊精(C60-γ-CD)(1:1)/Nafion和C60-γ-CD(1: 2)/Nafion化学修饰电极在水溶液中的电化学行为,发现它们都有一对一电子转移的可逆表面波,而且它们对某些生物分子有电催化作用。 相似文献
998.
999.
偶合反应化学发光法测定痕量银的研究 总被引:6,自引:0,他引:6
本将Ag(Ⅰ)催化S2O^2-8氧化Mn(Ⅱ)生成MnO^-4的催化反应与LuminolMnO^-4-OH^-的化学发光反应相偶合,建立起一种新的灵敏测定痕量银的化学发光分析法,在所研究的优化条件下,该法测定银的选择性较好,检测限达到3.2×10^-12g/mLAg线性浓度范围为1.0×10^-11-1.0×10^-5g/mLAg,用于水样分析,结果较为满意。 相似文献
1000.
The electrocatalytic properties of the SiC particle‐modified glassy carbon electrode (MGC) for adrenaline oxidation were studied by cyclic voltammetry (CV), double‐potential step chronocoulometry (DPSCC), and electrochemical impedance spectroscopy (EIS) techniques in McIlvaine buffer solution. It was shown that the electrode modified with SiC particles markedly displayed an electrocatalytic effect on the process of the electrochemical reaction of adrenaline, i.e., the activity and the reversibility of the MGC electrode has been significantly improved. This was attributed to the adsorption effect of the electroactive adrenaline molecules on the MGC electrode surface. 相似文献