近年来，在核医学领域中短寿命放射性同位素

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C（半衰期20.4分钟）引起了人们的重视。碳是人体内重要的生理元素之一，也是构成药物分子所必需的元素，所以用

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C标记化合物，可不改变其分子结构，又能直接利用其放出的正电子或正电子湮灭产生的二个光子（0.511MeV）来检测。若能与

γ

闪烁照相机或正电子断层计算机扫描仪组合使用，则在生物医学研究和临床疾病诊断中可以显示出

11

C所具有的独特的优点。

Three

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C-carboxyl-labelled Amino acids——Valine

Leucine and Amino cyclopentane carboxylic acid were prepared by modified Bücherer-Strecker method. With

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C-sodium cyanide as starting material

the reaction was accelerated under high temperature and high pressure. The synthesis and purification was completed in fifty minutes. The influence of reaction temperature on yield of Amino acids was investigated. The purity of Amino acids were determined by paper chromatography. Both chemical purity and radiochemical purity were over 95%.