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1.
M. Aguilar 《Solid State Communications》1984,50(9):837-840
A study by means of the Electron-Paramagnetic-Resonance (EPR) technique of the valence states of the cobalt ion in oxidized and reduced BaTiO3 is presented. As a result, the identification of high-spin Co+ in reduced crystals was possible. The Co2+ centre is also discussed. 相似文献
2.
贺文婷 《广东微量元素科学》2017,24(4)
目的应用电感耦合等离体子质谱(ICP-MS)检测法测定西班牙Quinton海洋水中的生命元素(该文特指人体所需的宏量元素和微量元素)。方法建立电感耦合等离子体质谱(ICPMS)法同时测定Quinton海洋水中21种生命元素含量的分析方法。结果方法检出限为0.01~0.10μg/mL,元素加标回收率为94.12%~104.35%,相对标准偏差为0.3%~12.2%。结论方法简单、快速、准确,适用于海洋水中多元素含量同时测定。并用元素含量评价Quinton海洋水的特性和功能。 相似文献
3.
A method is described for leaching of nanogram amounts of mono-, di and tri-butyltin compounds and mono-, di- and tri-phenyltin compounds from sediments. The procedure is based on soaking the sediments in a water–hydrogen bromide mixture (2:3) with magnetic stirring for 1 h followed by extraction with 0.02% (w/v) tropolone solution in pentane for 2 h. Organotins are determined by GF FPD after clean-up through a Florisil column and derivatization by Grignard pentylation. The method has been applied to the study of water and sediments in different areas of south-west Spain. Predominant species are butyltins, especially tributyltin (TBT), which has high values in waters and sediments of Puerto de Santa Maria and Cadiz Bay, as well as in sediments of the Sancti Petri Channel, which suggests a harmful action on biota. A direct relation has been found beween organotin levels and distance of potential focus determined by boating activities. In addition, the relative occurrence of dibutyltin (DBT) and monobutyltin (MBT) together with TBT has been noted, possibly as a result of a degractation process, and the influence of grain size of sediment and presence of organic matter on organotin accumulation has been studied. 相似文献
4.
ELS has been used to characterize the initial steps in the oxidation of polycrystalline Ta and Nb in an oxygen atmosphere at low pressures (~1.3 × 10?6 Pa) and room temperature. The results are interpreted in terms of transitions to unoccupied states above EF and plasmon losses, and are discussed in the light of previous studies. The results show important changes in the valence band. The O 2s and O 2p bands increase in intensity during oxidation. 相似文献
5.
In the present study, we treat the stochastic homogeneous Gompertz diffusion process (SHGDP) by the approach of the Kolmogorov equation. Firstly, using a transformation in diffusion processes, we show that the probability transition density function of this process has a lognormal time‐dependent distribution, from which the trend and conditional trend functions and the stationary distribution are obtained. Second, the maximum likelihood approach is adapted to the problem of parameters estimation in the drift and the diffusion coefficient using discrete sampling of the process, then the approximated asymptotic confidence intervals of the parameter are obtained. Later, we obtain the corresponding inference of the stochastic homogeneous lognormal diffusion process as limit from the inference of SHGDP when the deceleration factor tends to zero. A statistical methodology, based on the above results, is proposed for trend analysis. Such a methodology is applied to modelling and forecasting vehicle stocks. Finally, an application is given to illustrate the methodology presented using real data, concretely the total vehicle stocks in Spain. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
6.
The geometrical arrangement of sites favourable for formic acid oxidation and the poison formation reaction is determined using low index platinum single crystal planes. For this determination, the least number of sites required for the reactions to occur, which was obtained in the study of electrocatalysis by adatoms, was used, that is three adjacent sites are required for formic acid oxidation and four adjacent sites are required for poison formation.The triplet of sites on a unit lattice of Pt (111) and that on a unit lattice of Pt (100) plane are equally very favourable for the main oxidation reaction, but that on a unit lattice of Pt (110) is not so favourable as those on the former two planes. The oxidation rate is more than one order of magnitude lower on the latter than on the former triplets.The poison formation reaction proceeds at a very high rate on the (100) and the (110) planes. The geometrical arrangement of four sites on a square unit lattice of the (100) plane and on a rectangular unit lattice of the (110) plane are favourable for the poison formation reaction, but that on a hexagonal unit lattice of the (111) plane is not so favourable as the former two. 相似文献
7.
The transformation of the organopalladium compound (3) into the corresponding deuteriated, chlorinated, or oxidized derivatives (7), (8), or (9), (11), and (12) respectively. is described. The palladation of compound (9) takes place regioselectively leading to the palladated system (13), which is transformed into the difunctionalised oximes (15) and (16). The palladation of -2,2-dimethyl and 2,2,6,6-tetramethyl-cyclohexanone oxime leads to the corresponding organopalladium compounds (17) and (27), which through deuteriation or oxidation affords the expected products (21) and (31), or (22), (23), (24), and (32), respectively. The second palladation of the compound (22) takes place on the remaining methyl group yielding the organopalladium derivative (26). Finally, -lupanone oxime is palladated selectively in the 23-position leading to the organopalladium compound (38); the transformation of this compound into its 23-deuterio and 23-acetoxy- derivatives (41) and (42), respectively is also described. The stereochemistry in the palladatlon of lupanone oxime is deduced from NOE studies at 500 MHz. 相似文献
8.
The behaviour of the calorimetric response in continuous injection devices, which are well suited for measurement of excess partial molar enthalpies at different concentrations, is analysed by means of heat transport models. Signal analysis of the thermal response gives the enthalpy values at very low concentrations. We establish an operating routine for the identification of the time-varying device, and a generalized deconvolution procedure to obtain, with high accuracy, the power released in the calorimeter as a function of time. The main features considered are the changes in sensitivity and dynamic properties of the experimental system due to the injection of one component in the mixture. A formal decomposition of the heat transport equations shows that typically time-invariant methods are able to deal with deconvolution in non-invariant systems. 相似文献
9.
The phosphorescence spectra of naphthopyrene 7 and dinaphthopyrene 8, measured at 77 K in organic glasses and at 4.2 K in Shpolskii matrices, are reported. Contrary to expectation, the extension of the π-electron system in 8 relative to 7 produces a small violet rather than a big red shift of the phosphorescence bands. This finding is shown to be fully consistent with the sextet formalism and indicates an interruption of electronic conjugation in 8. 相似文献
10.