目录 中英文对照缩略词对照表 ······················································1 摘要 ··············································································2 ABSTRACT ·······································································4 一、前 言 ········································································6 二、资料与方法 ··································································7 1.研究对象 ·········································································7 2.内容与方法 ······································································8 三、结 果 ········································································9 四、讨 论 ·······································································11 五、小 结 ······································································16