共查询到20条相似文献,搜索用时 46 毫秒
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本文为戴安邦教授及其学生们关于多碱化学的研究的回顾和总结 ,叙述了他的早期工作 ,Cr3 的水解聚合 ,富马酸和马来酸存在下Cr3 的水解聚合 ,及稀土离子的水解聚合。这项研究对实用领域是有益的 ,诸如核化学 ,鞣革及塑料与金属的粘接 相似文献
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量热法研究Cr3+水解聚合作用的热力学性质 总被引:1,自引:0,他引:1
水合多价金属离子在水溶液中发生水解聚合是一种普遍现象,铬(Ⅲ)离子就是这样的金属离子,具有水解聚合特征,铬(Ⅲ)的许多应用常与其水解特性有关[1],虽然早在1907年Bjerrum[2]已经指出,但迄今为止,有关它的水解聚合的研究报道仍然较少[3],而用微量热法研究Cr3十水解聚合作用的热力学还未见报道.Cr3+水解聚合状态与其浓度有关,在低浓度和较高浓度下发现水解聚合产物不同.在较高浓度下形成单羟联的聚合质点,此观点曾相继由Hall[4]、戴安邦[5]等人提出并得到了验证.之后,戴安邦等人对Cr3+的水解聚合作用进行了… 相似文献
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用密度泛函方法在B3LYP/6-31G(d,p)基组水平上对反应系统中的所有物种进行全优化,用CPCM溶剂模型在同一基组水平上进行了单点计算,系统研究了硅醇盐前驱体Si(OCH3)4在酸性条件下的水解、聚合机理,阐明了二者的相互竞争关系.研究发现,H2O以氢键或配位键与前驱体结合,然后通过氢转移完成水解;水分子从质子化烷氧基的对面键合并发生水解;第4级水解是H2O从对位驱逐质子化烷氧基,但不能水解完全;水解产物通过"环状模式",由氢键结合成多元环,然后发生氢转移并完成聚合;水解过程的能垒明显低于聚合过程;H+阻止水解产物聚合成环;硅正离子可引发无垒聚合反应,但在能量上并不可行. 相似文献
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Abstract— In dimethylsulfoxide the emission spectrum of luminol chemiluminescence is red-shifted by 300 cm-1 from the photoexcited fluorescence of the product 3-aminophthalate dianion, while in aqueous solvent the two spectra are identical. The spectral properties of the product dianion have been measured in aqueous solvent and in a number of aprotic solvents, both at room temperature and at 77°K. The ground states and the excited states from which emissions are observed are characterized. Two alternatives are presented to explain the aprotic emission spectra. 相似文献
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WielA. G. BrulsJoop A. J. Faber†Jan C. van der Leun 《Photochemistry and photobiology》1982,36(5):531-535
The minimal erythema dose (MED) is often used as a quantity by which the influence of certain treatments of the skin can be measured. Differential measurements are performed by assessing the difference of the MED on the skin treated in some way and the untreated skin.
As the MED-measuring scale is discrete, the question is sometimes raised whether it is possible to measure differences smaller than one scale unit. In the present paper it is shown that this is indeed possible; in principle the discreteness of the scale does not impose any restriction on the smallest value of the difference that can be measured. The discreteness of the scale introduces an extra random variation into the measurement. This variation is estimated theoretically. It is automatically included in the usual error analysis.
The discreteness variance is small when compared to other variance components, which are computed from an analysis of variance of actual experiments. Reducing the discreteness variance, by reducing the dose decrement of the MED-measuring scale, therefore, does not enhance the overall accuracy considerably. Finally, it is found that the assessments of the MED by the various observers do not differ significantly from each other, and that multiple assessments do increase the accuracy, especially for small effects. 相似文献
As the MED-measuring scale is discrete, the question is sometimes raised whether it is possible to measure differences smaller than one scale unit. In the present paper it is shown that this is indeed possible; in principle the discreteness of the scale does not impose any restriction on the smallest value of the difference that can be measured. The discreteness of the scale introduces an extra random variation into the measurement. This variation is estimated theoretically. It is automatically included in the usual error analysis.
The discreteness variance is small when compared to other variance components, which are computed from an analysis of variance of actual experiments. Reducing the discreteness variance, by reducing the dose decrement of the MED-measuring scale, therefore, does not enhance the overall accuracy considerably. Finally, it is found that the assessments of the MED by the various observers do not differ significantly from each other, and that multiple assessments do increase the accuracy, especially for small effects. 相似文献
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分光光度法低浓度区不成线性关系的探讨 总被引:3,自引:0,他引:3
本文研究分光光度法低浓度区不成线性的有关因素及其克服方法,以铝-二甲酚橙体系为例,通过对体系不同条件下吸收光谱及其等色点的研究,发现当体系pH渐变时(铝,二甲酚橙浓度固定不变),曲线簇现两个等色点.从对等色点的分析,证明体系形成络合物须按一个反应式进行才能出现等色点,而与反应式是否涉及到两个或三个有色化合物无关.若同时按两个反应式进行,则不能得到等色点,测定时也无线性关系.所以用这个体系进行铝的测定,铝浓度的变化范围只能限于存在等色点的区间才有线性关系. 为了克服常法测定铝时不符线性的现象,本文采用的方法是在二甲酚橙中预先加适量的铝作为显色剂,使反应严格按一个反应式进行,所得结果为一直线. 相似文献
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对苯二胺衍生物的光催化氧化 总被引:1,自引:0,他引:1
以TiO2作为催化剂,利用波长>330nm的光辐照研究了N-取代的对苯-二胺衍生物的光催化氧化。研究表明,氧分子与光生电子 反应生成羟基自由基,羟基自由基氧化PPDs,生成醌二亚胺,后者在羟基的进攻下脱氨生成苯醌,苯醌继续光解无机化。PPDs光催化氧化近似遵循一级反应动力学,醇类和硫酸根离子可抑制PPDs的光催化氧化。催化剂表面荷影响电子转移速率,从而控制光催化氧化的反应速率。 相似文献
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The kinetics of the decomposition of cyclohexyl hydroperoxide(CHHP) in benzene catalyzed by vanadyl dibenzoylmethane[V0(DBM).,] has been studied.It was found that the products of decomposition of CHHP were cyclohexanol and cyclohexanone,which are produced in about equimolar amount,and the product cyclohexanol obviously inhibited the decomposition of CHHP.The kinetics data can be satisfactorily described by the following equation (with [CHHP]0>>[VO(DBM)2]0)R0=kK[CHHP]0[VO(DBM)2]0/(1+k[CHHP]0)This is the kinetic evidence for the formation of a catalyst-hydro-peroxide intermediate.In the equation K is the stability constant of the catalyst-hydroperoxide intermediate complex;k is the rate constant for the decomposition of the complex.The rate constant K at 500℃ may be expressed as follows:k=1.9×108exp(-53.7×103/RT)S-1 with the activation energy Ea=53.7kJ mol-1 相似文献