I want to extract the words that are mentioned in PubMed abstracts only. I used the code below. But my programs extracts the words that are outside the abstract too. For example: i need to extract NOV if it is in the abstract but some PubMed ids contain NOV as date and outside the abstract and even that is extracted. How can i solve this?

my $args = "db=pubmed&id=$id[$i]&retmode=text&rettype=abstract";
    my $req = new HTTP::Request POST => 'https://eutils.ncbi.nlm.nih.g
+ov/entrez/eutils/efetch.fcgi';
    $req->content_type('application/x-www-form-urlencoded');
    $req->content($args);
    

    my $response = $ua->request($req);
    my $content = $response->content;
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