position：absolute生成绝对定位的元素，相对于 static 定位以外的第一个父元素进行定位。;position：relative生成相对定位的元素，相对于其正常位置进行定位。;position：fixed生成绝对定位的元素，相对于浏览器窗口进行定位。
aAbsolute stereo chemistry of each residue was determined by a combination of Marfey analysis and NMR data. The acid hydrolysate of 1 was separated by ODS HPLC to afford Leu, Sta, Aba, and hydroxy aspartic acid (hAsp). The S-configuration for both Leu and Aba was determined by Marfey ...