Objective: 4-hydroxycoumarin is a pivotal intermediate in synthesis of other 4-hydroxycoumarin derivatives. This article aims to investigate the optimal condition in synthesis of 4-hydroxycoumarin.

前言：目的：4 -羟基香豆素是合成其他4 -羟基香豆素衍生物的关键中间体，本研究摸索出了合成4 -羟基香豆素的最有效条件。

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While the Digital Intermediate Frequency technology is one of the pivotal technology in the wireless base station system.

而数字中频技术是无线基站传输系统中的关键技术之一。

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