Doctors call this protection the " blood-brain barrier."

医生将这种保护称为“血脑屏障”。

There isn't a separate category called protection credits -- yet.

目前还没有一个单独的类别称为保护信用。

There are also some books that are so old that they no longer have what's called copyright protection.

还有一些书太老了，已经没有所谓的版权保护了。