阻碍DNA合成的药物（）
A.紫杉醇
B.顺铂
C.氟尿嘧啶
D.三尖杉酯碱
E.放线菌素D
参考答案：C
解析：氟尿嘧啶主要作用在体内经活化途径生成的5-氟尿嘧啶脱氧核苷酸与胸腺酸合成酶的活性中心共价结合，抑制此酶的活性，使脱氧核苷酸缺乏，DNA合成阻碍；顺铂的氯可被水取代，形成活泼的带正电的水化分子，然后与DNA反应，从而抑制DNA复制和转录；紫杉醇主要作用于聚合态微管，抑制微管解聚化而使之稳定，从而阻碍细胞有丝分裂；三尖杉酯碱抑制真核细胞蛋白质合成的起始阶段，使多聚核糖体分解，抑制有丝分裂。
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