现金循环周期（cash conversion cycle）
现金循环周期=存货转换期间 应收账款转换期间－应付账款递延期间=生产经营周期－应付账款平均付款期
cash conversion cycle= operating cycle- accounts payable deferral period
operating cycle= inventory conversion cycle average collection period
其中，平均应付账款期=365/ (销售成本/应付账款)
accounts payable deferral period= 365/ (cost of goods sold/ accounts payable)
