请参考百度文库http://wenku.baidu.com/link?url=oL-fA3XkcCmaVcMIj8uJtnALW5a_7hR3p-tYJnU4QTEG8EQV5zpxKh5pFKidh2lyqSlw8dJlcfd31DSMxAhws9DrLClBDc36hLoxsxnM9mm