DECLARE @t TABLE(test varchar(8000))

INSERT @t
SELECT ' 1 iop 2?,.3e[]-4-@135.678;0--0;0...0'

 SELECT
        N,
        number = SUBSTRING(test,N,PATINDEX('%[-.0123456789][^.0123456789]%',SUBSTRING(test+',',N,LEN(test)-N+2)))
   FROM
        @t, Tally               
  WHERE
        N <= LEN(test)          -- Restrict rows to the number of cahracters in the string
    AND
        CHARINDEX(SUBSTRING(test,N,1),'-.0123456789') > 0            -- Only rows starting with a valid numeric start character
    AND
        (N=0 OR CHARINDEX(SUBSTRING(test,N-1,1),'-.0123456789') = 0) -- either at the start of the string or following an invalid character.