severe gradient

It is useful for preventing the occurrence of severe MR that using a stepwise dilatation technique and monitoring the changes of mitral valve gradient and cardiac murmur during PBMV procedure;

采用球囊直径递增法扩张并监测MVG、监听心杂音变化能有效预防严重MR的发生；

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For severe oligozoospermia, the recovery rate of motile sperm with density gradient was higher than that of improved swim-up ( P < ( 0.01)).

重度少精子症密度梯度离心法回吸收精子优于改良上游法（P<0.01）。

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