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基础教育英语语法教学价值分析 被引量:20
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作者 陈力 《课程.教材.教法》 CSSCI 北大核心 2011年第3期75-80,共6页
结合西方应用语言学和语言习得研究的进展,分析中国英语语法教学的现状,我们可以发现国内对语法教学价值判断的失当源于极性思维、盲从心理和实践精神的缺位;语法教学的必要性受多种复杂变量影响而处于一种分层次的连续状态,因此不... 结合西方应用语言学和语言习得研究的进展,分析中国英语语法教学的现状,我们可以发现国内对语法教学价值判断的失当源于极性思维、盲从心理和实践精神的缺位;语法教学的必要性受多种复杂变量影响而处于一种分层次的连续状态,因此不是“教与不教”的问题而是“更适合谁”的问题;立足实践第一的原则才能客观看待语法教学的价值。 展开更多
关键词 外语教学 语法教学 特定性分析
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Stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling 被引量:2
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作者 孔令飞 李言 +3 位作者 吕延军 李德信 李淑娟 汤奥斐 《Journal of Central South University》 SCIE EI CAS 2009年第3期451-457,共7页
The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic f... The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent. 展开更多
关键词 copper stave deep hole drilling drilling shaft NONLINEARITY BIFURCATION
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