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圆锥曲线中非对称问题的处理策略
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作者 吕二动 《河北理科教学研究》 2023年第3期6-10,共5页
高中解题教学的首要任务是教会学生如何解题,进而提升学生的数学核心素养.实践表明,要使学生真正学会解题,需从数学本质出发,深究解题策略.常规的解题是按照由条件出发到思考目标问题进而解决问题.但由于学生认知的局限性,抓不住问题的... 高中解题教学的首要任务是教会学生如何解题,进而提升学生的数学核心素养.实践表明,要使学生真正学会解题,需从数学本质出发,深究解题策略.常规的解题是按照由条件出发到思考目标问题进而解决问题.但由于学生认知的局限性,抓不住问题的本质,往往不能直接根据已知条件,将要求的问题化归为已解决的本原问题,进而形成问题的解决策略.由于课堂教学时间紧、任务重,教师仅仅关注内容或方法有没有讲清楚或透彻,很少深挖问题的源与流,学生往往不能从问题的本原考虑,形成解题的基本思路,从而造成只要问题条件稍作变化,就不会解的困境.特别是在解析几何问题求解中多次遇到韦达定理用不上的问题,即在解题过程中出现非对称结构,本文通过一道模考试题的解法来说明非对称结构的处理策略,从而形成良好的解题思维习惯,实现高效解题. 展开更多
关键词 圆锥曲线 非对称结构 一题多解 命题拓展
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Synchrotron radiation photoemission study on growth of gadolinium film over Ni(110)surface 被引量:1
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作者 Faqiang Xu Junfa Zhu +5 位作者 Yuming Sun Xianfeng Wang erdong lu Pengshou Xu Xinyi Zhang Shuxian Zhuang 《Chinese Science Bulletin》 SCIE EI CAS 1999年第4期328-331,共4页
The growth of Gd film on Ni(110) surfaco was studied by synchrotron radiation photoemission spectroscopy and XPS techniques. It is revealed that in the coverage range of 0—0.22 nm Gd4f core level showed a single-peak... The growth of Gd film on Ni(110) surfaco was studied by synchrotron radiation photoemission spectroscopy and XPS techniques. It is revealed that in the coverage range of 0—0.22 nm Gd4f core level showed a single-peak structure, therefore Gd film grows over Ni(110) in the layer-by-layer mode. However, when Gd coverage was larger than 0.22, nm the Gd4f peak turned gradually into double-peak and a double-peak structure with 2.3 eV separation was formed at 1.51 nm, meanwhile similar phenomenon was observed in the Gd4d XPS spectra. It is suggested that the double-peak structure of Gd4f was derived from the growth of Gd film in cluster mode and the Gd atomic clusters may exhibit different electronic states from Gd metal owing to their special structures. The Gd4f double-peak evolved into a single-peak on annealing at 600 K, implying that Gd clusters are thermodynamically unstable. 展开更多
关键词 Gd FILM SYNCHROTRON radiation Ni(110) surface.
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