MeV Si离子轰击SiO2溅射行为研究

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THERMODYNAMIC ENTROPY MODELS OF THE FROZEN-WALL SYSTEM (Ⅱ)

This paper is a further research of reference [1]. At first, the author analyzes the forceenergetics basis of the frozen-wall system. By quantitative discussion of Model (Ⅰ) in reference [1], we get a thermal stability entropy model of the frozen-wall system (called Model (Ⅱ)). At last, we check the models by the field observed data in Anhui Province. P.R.C. The result is greatly satisfactory.     

无水稀土氯化物催化丁二烯和顺丁烯二酸酐的Diels—Alder反应

稀土化合物在有机合成中特别是在Diels-Alder反应中的应用是近年来稀土化学中最引人注目的研究课题之一。对于某些难进行的Diels-Alder反应,使用Lewis酸作催化剂可缓和反应条件,提高产物收率,改善产物选择性。其中,含稀土离子的Lewis酸在某些反应中显示了比其它Lewis酸更高的催化活性和产物具有更高的选择性。本文报道以丁二烯和顺丁烯二酸酐为原料,用7种简便易得的稀土氯化物催化这一Dies-Alder反应的结果。