PubMed Alerts (part of MyNCBI) let you save a structured PubMed search and get new matches by email. For pure biomedical queries, they're solid. But PubMed Alerts require you to write PubMed query syntax (MeSH terms, field tags, boolean operators), and they only search PubMed — you miss preprints, cross-disciplinary work, and papers in non-indexed journals.