问题 问答题 简答题

简要分析4种电子显微衬度像的衬度来源。

答案

参考答案:

1)质厚衬度:是由于材料的质量厚度差异造成的透射束强度的差异而产生的衬度(主要用于非晶材料)。

2)衍射衬度:由于试样各部分满足布拉格条件的程度不同以及结构振幅不同而产生的(主要用于晶体材料)。

3)相位衬度:试样内部各点对入射电子作用不同,导致它们在试样出口表面上相位不一,经放大让它们重新组合,使相位差转换成强度差而形成的。

4)原子序数衬度:是SEM/TEM中由于试样表面物质原子序数(或化学成分)差别而形成的衬度。

阅读理解

任务型阅读

       In cold weather, 45 Japanese war orphans(孤儿) visited China to thank their Chinese foster(抚养)

families.    

       The Japanese orphans were those who had been left behind by their parents after the eight-year

Japanese-Aggression War against China. Most of them are more than seventy years old. Chinese Premier Wen Jiabao met them in the Zhongnanhai compound tJll Nov. 11 and invited them to visit the former

residence (故居) and office of the late Premier Zhou Enlai. The thariksgiving gathering was organized to

express the war orphans' thanks to their foster families, but the visit was an emotional(激起感情的) one

because many of their foster narents had l)een deacl.    

       "We care about the living conditions(生活状况)of the orphans after they returned to Japan, and

Ibelieve that everybody will live a happy life through their own efforts and by support from the Japanese

government," said Wen.

       Wen said the war orphans would feel again the love given by their foster parents and the deep

friendship between the Chinese and Japanese people during their visit in China.

                                                           

1. The Japanese war orphans visited China to____their foster families.

2. Chinese Premier Wen Jiabao____  them in the Zhongnanhai compound on Nov. 11.

3. 'l'hese orphans were left by their____after the eight-year Japanese-Aggression War against China.

4. Premier Wen wished them to live d____ife in Japan.

5. rl'he war orphans felt again the love and the deep____ becween China and Japan.

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