本文介绍了一种同步测周期计数器的设计，并基于该计数器设计了一个高精度的数字频率计。

The design of a counter measuring synchronous period is introduced in this paper. And based on it, a high precision digital cymometer is designed.

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通过对甘薯叶、茎中的总黄酮含量进行了提取，以芦丁为对照品，用紫外分光光度计对其含量进行了初步测定。

This paper reported the extraction and the preliminary determination of flavonoids in sweet potato leaves and stems by UV-spectrophotometry using rutin as comparison sample.

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