核苷酸是组成核酸的单位,此外尚具有其他功能。与组成蛋白质的氨基酸不 同,无论是核糖核苷酸或脱氧核糖核苷酸主要都是在体内利用一些简单原料从头合 成的,所以本章的重点是介绍核苷酸的合成代谢。核苷酸不是营养必需物质。食物 中的核酸多以核蛋白的形式存在,核蛋白经胃酸作用,分解成蛋白质和核酸(RNA 和DNA)。核酸经核酸酶、核苷酸酶及核苷酶的作用,可逐级水解成核苷酸、核 苷、戊糖、磷酸和碱基

糖是一类化学本质为多羟醛或多羟酮及其衍生物的有机化合物。在人体内糖的主要形式 是葡萄糖(glucose,lc)及糖原(glycogen,n)葡萄糖是糖在血液中的运输形式,在机体 糖代谢中占据主要地位;糖原是葡萄糖的多聚体包括肝糖原、肌糖原和肾糖原等,是糖在 体内的储存形式。葡萄糖与糖原都能在体内氧化提供能量

ECENOMIC S Lorenz Curve shows Income Inequality T137 Figure 19-1 100 Curve of absolute equality Deviation fror absolute equality

ECENOMIC S Gross domestic product can be measured Either as(a) a Flow of Final Products or Equivalently, as(b) a Flow of Costs 1-153

ECENOMIC S Business fluctuations have been a Persistent Feature of Capitalism

ECENOMIC S We Now Turn to Money: Its Demand and the Role of Banks in Its Supply

ECNOMICS Economic Growth Is Key to Long- Term Living Standards

ECNOMICS Openness of Different Economies, 1997

Increases Affect Aggregate Supply?OSt How Do Growth in Potential Output and Ce

According to Say's Law, Supply Creates Its Own Demand as Prices move to balance Demand with Aggregate Supply