中文摘要：

研究了零售企业在商业信用条件下的两阶段易腐商品库存决策问题。第一阶段产品连续腐败且腐败率是已知的常数；在过了确定的货架时间后，剩余产品必须采用技术手段改变状态从而进入第二阶段，而且此时商品没有腐败。供应商允许零售商延期支付贷款，而零售商的决策是订货周期长度，并使得自身总成本最小化。通过建立该问题的数学模型，结合解析分析证明了一些理论结果，从而确定每种情况下的最优解，并给出了求解步骤以解得零售商的最优决策。最后结合数值算例说明了所得结论及两阶段策略对于企业的贡献。

英文摘要：

A retailer＇s two phase inventory system with changing deterioration rate under permissible delay in payments is studied. In the first phase, the product deteriorates continuously and has a constant deterioration rate, after a deterministic period of shelf life, all the remaining items should turn into another status by technical means, and in the second phase the instantaneous rate of deterioration drops down to zero. The supplier offers a trade credit policy and the decision variable of the retailer is the replenishment cycle time to minimize the total relevant cost. The proper mathematical model is established, through analysis several theoretical results are derived to determine the optimal solution under various situations, and a solution procedure is developed to solve this problem. Finally, a numerical example is shown to illustrate the theoretical results and the income achieved by the two phase inventory policy of the retailer.