I want ask a question, which textbook of quantum mechanics is appropriate for a beginner? thanks.

The easiest to read, IMO, is Morrison's Understanding Quantum Theory.

Interesting, clear, starts from the basics: The Principles of Quantum Mechanics / Dirac.
(Some people consider this book old-fashioned or difficult, but I don't think so.)

The Dirac's book has too many mathmatics, and the physical description is profound, If read it, May be I need some basic knowledge of general physics more.
by the way, I want to do rearch in superstrings(M-theory), What do I need about quantum mechnics?

thank you for JohnDubYa , salsero.

:rofl: The math, I´d say (and a lot more math) :rofl: