Shares in China’s leading memory chipmaker soared about 470 percent on its first day of trading on Monday, quickly making it the most valuable company on the Shanghai stock exchange. 周一，中国存储芯片制造龙头企业的股价在上市首日交易中飙升约470%，迅速成为上海证券交易所市值最高的公司。 ChangXin Memory Technologies…