use XML::XPath
                                                                                
$/ = undef;
                                                                                
my $foo = <DATA>;
my $xp = XML::XPath->new(xml => $foo);
                                                                                
my $nodes = $xp->find('/RESEARCH/LINK/@PUBID');
                                                                                
foreach my $node ($nodes->get_nodelist())
{
   print $node->getData(),"\n";
}
__END__
<RESEARCH>
  <xslobject name="research.xsl" />
  <PGFROM>12/30/04</PGFROM>
  <PGOFFSET>0</PGOFFSET>
  <PGCOUNT>1</PGCOUNT>
<LINK PUBID="584557" DOCID="100386419" CLIENT="0" HIDDEN="1" DELETED="0">
  <SCORE>1.00</SCORE>
  <PUBDATE>01/06/05</PUBDATE>
  <DOCDATE>01/06/05</DOCDATE>
  <EXPDATE>NEVER</EXPDATE>
  <TITLE>SC 4 DOC AND IMAGE</TITLE>
  <URI>/DDL/servlets/dv.search?docID=100386419&amp;searchType=INTRANET</URI>
   <FILETYPE>doc</FILETYPE>
  </LINK>
</RESEARCH>