Sodium carbonate deposits may be classified into three major types, Quaternarysalt lake, Quaternarysand-covered playa and Tertiary continental detrital rock, all three having been found in China.
碳酸钠矿床有三大类型：第四纪盐湖型、第四纪砂下湖型及第三纪陆相碎屑岩型，在中国均有发现。
2
The preparation methods of quaternary ammonium salt of chitosan at home and abroad, meanwhile were introduced, and heir advantages and shortcomings were compared.
对目前国内外壳聚糖季铵盐的制备方法加以介绍，并比较了它们的优缺点。
3
The rate of reaction is first order with icspect to epoxy group, zero order with respect to methylacrylic acid, and 0.71 order with lespect to quaternary ammonium salt catalyst respectively.