基金The research was supported by NNSF of China(19971027, 10271048) Shanghai Priority Academic Discipline. The research was done while the author was visiting LRI.
基金The research was partially supported by NNSF of china(19971027,10271048)Shanghai Priority Academic Discipline.The research was done while the first author was visiting LRI.
基金Research supported by NNSF of China(No. 10271048)the Science and Technology Commission of Shanghai Municipality (No.04JC14031)NSF of Shanghai(05ZR14046)