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数学的学习离不开做题,面对"题海",有的人感到的是"浩瀚无垠"与"沉重",有的人则能于"惊涛骇浪"之中,汲取其取之不尽、用之不竭的能量,同时准确把握隐藏在其厚重外表下的规律性的特征.因此,如何能在解题过程中,拓宽分析的视角,把握解题的规律,并于探究过程中体验学习的快乐,成为了每一个学习者十分关注的问题.下面不妨通过一道向量习题的解答,来剖析探究思维的脉络. 相似文献
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Copolymerization of ethylene/1-octene was carried out in toluene withvarious concentrations of comonomer in the feed using Et(Ind)_2ZrCl_2/MAO (methyl alu-minoxane) as catalyst. It was found that with the increase of 1-octene concentration in thefeed the content of 1-octene in the copolymer increases, while the density, melting point,crystallinity and intrinsic viscosity of copolymer decrease. A copolymer with very lowdensity, containing 11.5 mol% of 1-octene (VLLDPE) can be produced with this catalystsystem. The effect of temperature and zirconium aluminum mole ratio of the catalyst onthe copolymerization was also investigated. The results of ~(13)C NMR determination of thecopolymer showed that the 1-octene units in the copolymer are principally isolated. 相似文献
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锆茂均相催化剂对乙烯/丙烯和乙烯/1-丁烯共聚合研究 总被引:3,自引:0,他引:3
锆茂均相催化剂对乙烯/丙烯和乙烯/1-丁烯共聚合研究姚晖,肖士镜,陆宏兰(中国科学院化学研究所北京100080)关键词共聚合,乙烯,丙烯,丁烯,锆茂,甲基铝氧烷金属茂均相催化剂中过渡金属的性质,及其周围配位体的结构对催化剂性能有很大影响[1,2].金... 相似文献
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