什么是规模经济?它如何能成为国际贸易的基础?
胆甾醇可与哪个成分生成难溶性的分子复合物() ["A.强心苷苷元","B.甾体皂苷","C.黄酮","D.蒽醌苷","E.香豆素"]
筛选和诊断血色素沉着症的有效指标是() ["运铁蛋白","血红蛋白","铁蛋白","肌红蛋白","转铁蛋白受体"]
钙缺乏可能引起的疾病为()。 ["肾结石","贫血","脚气病","佝偻病","癞皮病"]
属于α-去氧糖颜色反应是() ["A.乙酐-浓硫酸反应","B.亚硝酰铁氰化钠反应","C.Keller-Kiliani反应","D.碘化铋钾反应","E.三氯化铁反应"]
国际贸易理论的研究对象是什么?