The color reaction conditions of Cu 2+ and 1-(2-pyridylazo)-2-naphthol(PAN)were researched, and a new method was developed for the determination of copper in sulfuric acid anodizing liquor.

研究了铜与1-（2-吡啶偶氮）-2-萘酚（PAN）的显色反应，建立了测定硫酸阳极氧化液中铜的新方法。

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PAN on the samples has symmetrical color, high substance, exquisite particles and good thermal stability.

所得样品上的聚苯胺颜色均匀，牢度高，粒度细腻，热稳定性好。

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Each of the color is packed with a little plastic pan at the size of the nail of my thumb.

剥开包装纸，就像剥开糖纸，每个颜色都有一个塑料格子，都只有拇指盖大小。

youdao

When the caramel is the color you want, remove the pan from the heat and cool the mixture.

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For the first 15 minutes or so, you want the onions at the bottom of the pan to be slowly but steadily taking on color as they sweat out their liquid.

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