We measured electronic absorption spectra for all the
fractions (fraction 46 to 55) in the DNA-CNT band, and found a
remarkable difference in early fractions. Figure 3b compares the
spectrum for fraction 47 (f47) with that of fraction 49 (f49).
图中f47与f49指整个溶液体积的百分之47和49还是什么啊,谁有具体点的解释