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t***m
发帖数: 114 | 1 The first polymers used were all obtained from natural products. Natural ru
bber from the Hevea trees was being used by the American Indians when Columb
us arrived in 1492. Cellulose in different forms, starch and collagen in lea
ther are other examples of native polymers. Modification of native polymers
started in the mid-nineteenth century and the first wholly synthetic polymer
was made in the beginning of the 20th century. The science of polymers bega
n in the 1920s.
The development of polyme | y****u
发帖数: 50 | 2 who pays?
【在 t***m 的大作中提到】
: The first polymers used were all obtained from natural products. Natural ru
: bber from the Hevea trees was being used by the American Indians when Columb
: us arrived in 1492. Cellulose in different forms, starch and collagen in lea
: ther are other examples of native polymers. Modification of native polymers
: started in the mid-nineteenth century and the first wholly synthetic polymer
: was made in the beginning of the 20th century. The science of polymers bega
: n in the 1920s.
: The development of polyme
| t***m
发帖数: 114 | 3 财迷啊 *_^
只是FYI的
但是俺E文太差
【在 y****u 的大作中提到】
: who pays?
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