DECLARE @name VARCHAR(50) -- database name 
DECLARE @path VARCHAR(256) -- path for backup files 
DECLARE @fileName VARCHAR(256) -- filename for backup 
DECLARE @fileDate VARCHAR(20) -- used for file name

-- specify database backup directory
SET @path = 'D:\Backup\SQL\' 

-- specify filename format
SELECT @fileDate = CONVERT(VARCHAR(20),GETDATE(),112) + REPLACE(CONVERT(VARCHAR(20),GETDATE(),108),':','')

DECLARE db_cursor CURSOR READ_ONLY FOR 
SELECT name
FROM master.dbo.sysdatabases
WHERE name NOT IN ('master','model','msdb','tempdb')  -- exclude these databases

OPEN db_cursor   
FETCH NEXT FROM db_cursor INTO @name   

WHILE @@FETCH_STATUS = 0   
BEGIN   
   SET @fileName = @path + @name + '_' + @fileDate + '.BAK' 
   BACKUP DATABASE @name TO DISK = @fileName 

   FETCH NEXT FROM db_cursor INTO @name   
END   


CLOSE db_cursor   
DEALLOCATE db_cursor