ora-01578 system01.dbf有坏块，无法打开数据库

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ora-01578 system01.dbf有坏块，无法打开数据库。startup mount成功,alter database open;失败。mount状态下执行exp导出表空间提示EXP-00056:3127。system表空间没有备份。现在有何办法能够修复并打开数据库（然后手工备份一些数据出来）。万一数据库无法修复，那么有什么办法能把data file中原库的数据导入新建的数据库吗？谢谢！

上面更正下，是system3.dbf的坏块。用dbv检测了一下，发现是file_id=18中的block_id=2279和2709两个块坏了。但是SELECT tablespace_name, segment_type, owner, segment_name FROM dba_extents where file_id=18 and block_id in(2279,2709);没有找到对应的对象。现在
SQL>startup mount;
SQL>alter database open;
成功执行，但是打开的是oem的库。自己的数据库还是打开不了。客户端连接时提示：
ORA-01034:ORACLE not available.
ORA-27101:shared memory realm does not exist.


startup mount是可以的，打开时就强行关闭连接了。alert日志如下：
***
Corrupt block relative dba: 0x048008e7 (file 18, block 2279)
Bad header found during buffer read
Data in bad block -
type: 2 format: 2 rdba: 0x048008e3
last change scn: 0x0bb0.84a2de40 seq: 0x1 flg: 0x06
consistency value in tail: 0xde400601
check value in block header: 0x58e2, computed block checksum: 0x0
spare1: 0x0, spare2: 0x0, spare3: 0x0
***
Reread of rdba: 0x048008e7 (file 18, block 2279) found same corrupted data
Sat Jun 16 14:48:53 2012
Errors in file d:\oracle\admin\yxptt\udump\yxptt_ora_228.trc:
ORA-01578: ORACLE 数据块损坏（文件号18，块号2279）
ORA-01110: 数据文件 18: 'E:\ORACLE\ORADATA\YXPTT\SYSTEM3.DBF'

Error 1578 happened during db open, shutting down database
USER: terminating instance due to error 1578
Sat Jun 16 14:48:53 2012
Errors in file d:\oracle\admin\yxptt\bdump\yxptt_smon_3964.trc:
ORA-00604: error occurred at recursive SQL level 1
ORA-01578: ORACLE data block corrupted (file # 18, block # 2279)
ORA-01110: data file 18: 'E:\ORACLE\ORADATA\YXPTT\SYSTEM3.DBF'

Sat Jun 16 14:48:54 2012
Errors in file d:\oracle\admin\yxptt\bdump\yxptt_pmon_500.trc:
ORA-01578: ORACLE data block corrupted (file # , block # )

Instance terminated by USER, pid = 228
ORA-1092 signalled during: /* OracleOEM */ ALTER DATABASE OPEN ...


没备份可以恢复吗