三用电表内部使用1 mA 5Ω之永久动圈式(PMMC)表头时，使50V电压档时，其输入阻抗为 (1)50KΩ (2)100KΩ (3)500KΩ (4)1MΩ。 （4）16.
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Conclusions PMMC is an efficient, safe and economic method to theraphy the mitral stenosis with bad valvular condition.
结论PMMC是治疗瓣膜条件差的二尖瓣狭窄的一种安全、经济及有效的手术方式。
Although has the good specific stiffness and specific strength. However, low plasticity and low toughness of PMMC, has been an obstacle to hinder its further application.
虽然具有良好的比刚度、比强度，然而PMMC的低塑性和低韧性一直是阻碍其进一步应用的障碍。
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