“无保护”的英语？

无保护左主干介入治疗可替代CABG 吗 ?Can PCI substitute CABG in treating unprotected left main disease?图 2-12a 是无保护的电路.Figure 2 - 12 a is the unguarded circuit.目的探讨鼓膜冲击场对内耳有无保护作用.Objective To explore the protect effects tympanic membran...