Cost-benefit ratio criterion----No activity where the present value of net benefits is less than zero should be taken.
成本效益分比率准则——净利润现值低于零的无活力地区应该被承揽。
At present, the V_P/V_S ratio keeps in high value anomaly, we should be alert the occurrence of felt earthquakes when the mean value drop.
目前九江—瑞昌地震序列的波速比持续处于高值异常，应当警惕回落到平均值以下后发生显著有感地震。
Objective To assess whether regional magnetization transfer ratio (MTR) changes are present in Alzheimer's disease (AD) patients and to evaluate their clinical value.
目的评价阿尔海默病（AD）患者与正常老年人脑结构磁化转移率的差异，并探讨其临床实用性。
应用推荐