Most of the tablets in the market do not accept charge from USB, except for the Apple’s first generation iPad and Galaxy Tab (P1000 only) but surprisingly Galaxy Note 10.1 does. 
Keep in mind that we still suggest charging with its charger as charging via USB is still very slow.
Interestingly, when you connect it to computer’s charging port, your Note 10.1 will put a X on the battery icon, but it is still charging. I installed Go Power Master app from App Store and it confirmed that it was infact, accepting the charge from USB.