You can use lookbehind to do this:
split(/(?<=.)/, $string)
The regex matches an empty string that follows a period.
If you want to remove the whitespace between the sentences at the same time, you can change it to:
split(/(?<=.)s*/, $string)
Positive and negative lookbehind is explained here
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…