oracle 字符集的问题

SQL> select dump(convert('中','ZHT32TRISFIXED','ZHS16GBK')) from dual;

DUMP(CONVERT('中','ZHT32TRIS
----------------------------
Typ=1 Len=4: 142,161,196,227





SQL> select * from v$nls_parameters where parameter like '%CHARACTERSET%';

PARAMETER                                                        VALUE
---------------------------------------------------------------- ----------------------------------------------------------------
NLS_CHARACTERSET                                                 ZHS16GBK
NLS_NCHAR_CHARACTERSET                                           AL16UTF16