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爱美是人的天性。儿童对世界充满新奇感,他们喜欢看美丽的颜色,喜爱漂亮的衣服、造型优美的玩具和生动有趣的图画。他们什么都想了解,什么都想试一试,当他们拿起彩笔在一张白纸上画出各种颜色和图形时,于是就喜欢上画画了。而指导学生儿童画创作也就是我们美术教师的一个重要责任。那么,如何指导儿童画的创作呢?我认为:第一,必须了解儿童的生理特点和绘画心理。一般说,小学低年级学生作画大胆,富于想象,他们只满足于作画的过程,而不注意它的结果,因此作画 相似文献
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Preparation of bone-like apatite coating on surface of Ti-25Nb-2Zr alloy by biomimetic growth method
A bone-like apatite layer consisting of nano-crystals of apatite phase was prepared on the surface of Ti-25Nb-2Zr alloy by chemical biomimetic growth method. TiNbZr alloy specimens were first oxidized at 500℃ for 2 h in the air. Then, they were immersed in 40℃ saturated Na2HPO4 solution for 15 h and 25 ℃ saturated Ca(OH)2 solution for 8 h in turn for pre-calcification. The pre-calcified specimens were immersed in modified simulated body fluid up to 15 d for biomimetic growth. After common oxidization, amorphous titania and anatase were detected on the specimen surface. Except for the substantial amount of calcium and phosphorus, no new phase appeared on the pre-calcified specimens. After the coating process, it was found that the (002) orientation was the preferred orientation during the growing period of hydroxyapatite. The inorganic composition and structure of the coating are very similar to those of human thigh bone, which will be advantageous for its application as biomedical material. 相似文献
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