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Jaromir Dmytrzyk Andrzej Kotarba Hanna Grabowska Roman Klimkiewicz 《Research on Chemical Intermediates》2004,30(3):337-342
The influence of gas-phase methylation of phenol on the state of the Fe-Si-Cr-K oxide catalyst surface was investigated by thermodesorption of K atoms and ions. Changes in potassium desorption energies, as determined from Arrhenius-like plots, varied from 3.07 eV to 1.21 eV for the atoms and from 2.59 eV to 2.89 eV for ion desorption from the active and deactivated samples, respectively. The results were discussed in terms of transformation of the catalyst surface and formation of β-ferrite. 相似文献
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《Composite Interfaces》2013,20(6):547-566
Fast transient fluorescence technique (FTRF), which uses a Strobe Master System (SMS), is used to study swelling and drying of disc shape heterogels. Disc shape heterogels are prepared by free radical copolymerization (FCC) of methyl (methacrylate) (MMA) and styrene (S) with ethylene glycol dimethacrylate (EGDM). Pyrene (Py) is introduced as a fluorescence probe during polymerization and lifetimes, τ, of Py are measured during the in-situ swelling process. Chloroform was used as an organic vapor agent to induce gel swelling. It is observed that τ values decrease as swelling proceeds. The Li-Tanaka equation is used to determine the time constant, τc, and cooperative diffusion coefficients, D c, for the swelling processes. Lifetimes of pyrene increase during drying. An empirical equation is introduced to determine the desorption coefficient, D, for drying. Heterogels with high S content swell and dry much more slowly than heterogels with low S content. 相似文献
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无机离子交换剂以其选择性、耐热及抗辐照性很高一直受到重视.但由于它的交换过程缓慢,使其应用受到了限制,为了克服这一障碍,本文把十分之几微米的无机离子交换剂[Ti(HPO_4)_2·1/2H_2O]微晶粘结成球,以减低对流体阻力,同时大大增加交换表面.用这种交换剂研究了H~+-Li~+和Li~+-H~+互交换的动力学;同时,根据交换剂的几何模型,解出了相应界面条件的扩散方程.实验显示了在这种无机离子交换剂中的交换速度比在001×20的聚苯乙烯凝胶磺酸型阳离子交换树脂中的快3.5倍,它可能为提高无机离子交换剂的传质功能提供了新途径. 相似文献
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In this paper, nineteen FD mass spectra of cyclic nucletides are repoted. The results indicated that only (M+ + H) peak presents in the spectra of cy-AMP, cy-CMP and cy-UMP. The derivatives of cy-AMP (except 7) have M+, (M+ + H) peaks, and the main fragments corresponding to (B + 1), (T + 1) peaks as shown in Fig. 1 in the Chinese Text. The adenosine 3', 5'-cyclic phosphite and its derivatives with P(III) are somewhat different as compared with P(Ve. In some cases neither M+ nor (M+ + H) is present in their spectra, but there are some characteristic peaks. Their fragmentation process has been shown in Fig. 2 in the Chinese Text. 相似文献
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