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71.
段雪 《高等学校化学学报》1990,11(7):765-767
对于一些气-固相反应,同样条件下的动力学行为随惰性载气不同有所差异[1,2]。为从实验上进一步揭示这一问题,并从理论上给出圆满的解释,我们对程序升温还原(TPR)[8]过程进行了系统的考察,同时研究了不同惰性载气条件下铜氧化物还原反应的动力学问题,结合有关反应机理和统计热力学的概念,讨论惰性载气对气-固相还原反应动力学的影响。 相似文献
72.
The enhancement effects of Y ( Ⅲ) ions on the fluorescence of Ce ( Ⅲ) in Ce ( Ⅲ)-Y ( Ⅲ)-PMMA (polymethylmethacrylate ) or Ce ( Ⅲ)-Y ( Ⅲ)-PVC (polyvinyl chloride ) complex systems were observed. The influence of Y ( Ⅲ) ions on the emission spectra of PMMA ligands in PMMA-Y ( Ⅲ) and the fluorescent enhance- ment of Y( Ⅲ) on Ce( Ⅲ) emission in PMMA-Ce-Y by Y( Ⅲ) ion were studied. It was also of interest to note that when Y ( Ⅲ) ions were added into PMMA and into bpy(bipyridine ), respectively, the emission spectrum of PMMA ligands was split into fine structure bands by Y ( Ⅲ), and the fluorescence intensities of bpy ligands in bpy-Y ( Ⅲ) complexes were considerably increased. 相似文献
73.
JIANG Ming WANG Mingxiang WANG Mu CHEN Kunji 《Chinese Journal of Lasers》1999,8(2):142-148
1IntroductionThetechniqueofpaterngeneration/formationonthinfilmsisabasicprocesinsemiconductorVLSItechnology.However,forthepat... 相似文献
74.
本文推引出热力学摩尔吸光系数定义,并且比较了它与表观摩尔吸光系数的特点。采用作图法测出硫氰酸钒热力学吸光系数对数lgε^0=1.58(20℃,I→0)。 相似文献
75.
载体对镍基催化剂CH4/CO2重整制合成气性能的影响 总被引:10,自引:3,他引:7
在Ni/MgO、Ni/CaO和Ni/CeO催化剂上,CH4/CO2重整制事成的活性测试表明MgO是一种较好的载体,TPR实验显示,Ni-MgO之间的相互作用比Ni-CaO和Ni-CeO2强,现场CO岐化和CH4解离实验表明, 经剂表面吸附的氢会促进CO歧化和CH4解离积炭。 相似文献
76.
金属钴对泡沫型镍电极及Ni/MH电池性能的影响 总被引:1,自引:0,他引:1
活 性物质 为化学共 沉积锌的 Ni( O H) 2 ,并 物理 掺杂 钴粉 的泡 沫镍 涂 膏式 镍电 极 表现出高的 放电比 容量和循 环稳定性 ,其中 钴 可以 显著 提 高镍 电 极活 性物 质 利用 率, 这是 由于 第 一次活化充 电时由 Co 形 成导电 性能良好 的 Co O O H 提高了放 电深度, 循环过程 中的容量 稳定 性是 锌和钴协同 作用的 结果,特别 是共沉 积锌,它可 以抑制 γ_ Ni O O H 的形成 从而缓 解镍电极 的膨胀 . 相似文献
77.
The reaction of 2,4,6-tribromophenol with dibromomethane in an alkaline solution of KOH/dibromomethane two-phase medium, catalyzed by tetrabutylammonium bromide (TBAB or QBr), was carried out. Both mono-substituted as well as bi-substituted products were found to have formed during or after the reaction, when dibromomethane was used both as organic solvent as well as organic-phase reactant. The active catalyst tetrabutylammonium 2,4,6-tribromophenoxide (ArOQ) was identified during the reaction, from which the organic-phase reaction was inferred to be the rate controlling step. The mass transfer of both the catalysts viz. QBr and ArOQ between the two phases was found to be fast. A peculiar phenomenon was observed while investigating the effect of KOH on the reaction rate, viz. the reaction rate does not monotonously increase or decrease with increase in the amount of KOH. This phenomenon is attributed to the activity of ArOQ, the distribution of active catalyst (ArOQ) between the two phases and the hydration of active catalyst in the organic phase, both of which are affected by the amount of KOH. An effective method is proposed to determine the two intrinsic rate constants of the organic-phase reaction, based on the reaction carried out at high KOH concentration. 相似文献
78.
Summary Several mobile phase parameters were investigated for controlling enantioselective retention and resolution on a chiral stationary
phase made in-house. The chiral selector was the enzyme amyloglucosidase, which was immobilized onto a silica support via
reductive amination. The influences of the mobile phase pH, concentration and type of uncharged organic modifier, ionic strength
and column temperature on enantios-electivity were studied. The analysis time for resolving enantiomers could be adjusted
with only a minor decrease in enantioselectivity by using a high ionic strength mobile phase buffer. This indicated a retention
mechanism involving ion-exchange interactions. It was further confirmed by the decreasing enantioselectivity of amines when
using a mobile phase pH below the isoelectric point of the native protein. Interesting effects were observed when the organic
modifier concentration was increased and also when the column temperature was raised. Both retention and enantioselectivity
increased with increasing concentration of 2-propanol in the mobile phase. Examples are given where both enantioselectivity
and retention increased with increasing column temperature. Thermodynamic studies were performed to calculate the entropy
and enthalpy constants. The results showed that, depending on mobile phase composition, the enantioselective retention may
be caused by differences in entropy or enthalpy. 相似文献
79.
用紫外分光光度法对几种物质分别作了经前后的吸收光谱,发现物质受磁化后其吸收峰的位置不变,但吸收强度发生了不同程度的变化,而且不同的磁化时间有不同的磁化效果。 相似文献
80.
The effect of Ti and C additions on the corrosion behavior of Nd9.4Pr0.6Febal.Co6B6Ga0.5TixCx (x=0, 1.5, 3, 6) isotropic nanocomposite melt-spun ribbons in 3.5 wt% sodium chloride solution was studied. The melt-spun ribbons were annealed at 750 °C for 10 min in argon-filled quartz capsules. The microstructure of multiphase nanocrystalline samples and corrosion products was characterized using the X-ray diffraction and electron microscopy techniques. The electrochemical behavior was assessed using potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the addition of Ti and C increases the corrosion resistance of NdFeB ribbons; the best corrosion resistance was obtained for 1.5 wt% Ti and C content. 相似文献