什么是活性混合材料和非活性混合材料?掺入硅酸盐水泥中各能起到什么作用? 发布时间:2017-07-22 22:01 │ 来源:www.tikuol.com 题型:问答题 简答题 问题: 什么是活性混合材料和非活性混合材料?掺入硅酸盐水泥中各能起到什么作用?
题型:问答题 简答题 患者,女,11岁。替牙,上牙前突,有间隙,前牙深覆,下颌明显后缩,面下1/3短。诊断:安氏Ⅱ类 1分类。矫治器设计为功能性(FR-1)矫治器,导下倾向前FR-Ⅱ型矫治器是在FR-Ⅰ型基础上做了部分修改而成的,FR-Ⅱ型矫治器被修改的部位是()A.上颌前腭弓B.下颌支持丝C.下颌舌侧丝D.上尖牙唇侧卡E.唇挡连接丝 查看答案
题型:问答题 简答题 下列两个实验都是为了演示“碘的升华”而设计的.并参阅表中几个温度的数据,你认为哪个实验能更好的反映“碘的升华”现象,并说明理由.实验1实验2在试管内装入碘的固体颗粒,用酒精灯直接加热装了固态碘的试管,发现试管内出现了碘的蒸气.在试管内放少量碘的固体颗粒,塞紧盖子后把试管放入沸水中,发现试管内出现了碘的蒸气.碘的熔点:114℃碘的沸点:184.3℃水的沸点:100℃酒精灯火焰:500℃左右你认为实验哪个方案更好些,说出你的理由. 查看答案
题型:问答题 简答题 Artificial flowers are used for scientific as Well as for decorative purposes. They are made from (51) of materials, such as wax and glass, so skillfully that they can scarcely be (52) from natural flowers. In making such models, painstaking skill and artistry are called for, (53) thorough knowledge of plant structure. The (54) of glass flowers in the Botanical Museum of Harvard University is the most famous in North America and is widely known (55) the scientific world. (56) , there are several thousand models in colored glass, the work of two artist naturalists, Leopold Blalschka and his son Rudolph. The intention was to have the collection (57) at least one member of each flower family native to the United States. (58) it was never completed, it contains more than seven hundred species representing 164 families of flowering plants. (59) detail of these is accurately reproduced in color and structure. The models are (60) n locked cases as they are too valuable and fragile for classroom use.A.throughB.throughoutC.overD.on 查看答案