Dimethyl carbonate （DMC） and poly（ethylene terephthalate） was simultaneously synthesized by the transesterification of ethylene carbonate （EC） with dimethyl terephthalate （DMT） in this paper. This reaction is ...Dimethyl carbonate （DMC） and poly（ethylene terephthalate） was simultaneously synthesized by the transesterification of ethylene carbonate （EC） with dimethyl terephthalate （DMT） in this paper. This reaction is an excellent green chemical process without poisonous substance. Various alkali metals were used as the catalysts. The results showed alkali metals had catalytic activity in a certain extent. The effect of reaction condition was also studied. When the reaction was carded out under the following conditions： the reaction temperature 250℃, molar ratio of EC to DMT 3 ： 1, reaction time 3h, and catalyst amount 0.004 （molar ratio to DMT）, the yield of DMC was 68.9%.展开更多
The X-ray phantom material (PM) is a kind of substitute materials of the tissues ofhuman or biological beings in radiology and application of atomic energy to investigatethe dosage effect. It is necessary for the PM t...The X-ray phantom material (PM) is a kind of substitute materials of the tissues ofhuman or biological beings in radiology and application of atomic energy to investigatethe dosage effect. It is necessary for the PM to have nearly the same interaction results asthe tissue it simulated with X- or γ-ray. Since the 1960s, because of the wide use ofradiology and atomic science. this field has received much attention and become a brisk as-pect in biomedical engineering.展开更多
基金the National High Technology Research and Development Program of China(No.2003AA321010).
文摘Dimethyl carbonate （DMC） and poly（ethylene terephthalate） was simultaneously synthesized by the transesterification of ethylene carbonate （EC） with dimethyl terephthalate （DMT） in this paper. This reaction is an excellent green chemical process without poisonous substance. Various alkali metals were used as the catalysts. The results showed alkali metals had catalytic activity in a certain extent. The effect of reaction condition was also studied. When the reaction was carded out under the following conditions： the reaction temperature 250℃, molar ratio of EC to DMT 3 ： 1, reaction time 3h, and catalyst amount 0.004 （molar ratio to DMT）, the yield of DMC was 68.9%.
文摘The X-ray phantom material (PM) is a kind of substitute materials of the tissues ofhuman or biological beings in radiology and application of atomic energy to investigatethe dosage effect. It is necessary for the PM to have nearly the same interaction results asthe tissue it simulated with X- or γ-ray. Since the 1960s, because of the wide use ofradiology and atomic science. this field has received much attention and become a brisk as-pect in biomedical engineering.
