Quertle is a semantic search engine for life and chemical science literature and information.[1][2][3] It covers a wide variety of information sources and, according to the company, is used by researchers in more than 150 countries.

Quertle uses semantic-based linguistics to automatically extract Subject Verb Object relationships asserted by the author(s) of each document. The identification of these assertions uses several methods including natural language processing.[4][5] For full-text documents, Quertle includes only the main content, not, for example, the references.

The Subject Verb Object relationships are stored in a metadatabase and the user's query is matched against that metadata. This identifies documents based on meaning and context and generally provides fewer, but more relevant, hits than a traditional keyword search. Thus, Quertle is fundamentally different from search sites such as PubMed. Nonetheless, Quertle does simultaneously search a keyword index to find documents based on inclusion of the search terms. These are presented on a separate tab in the results.

An ontology covering genes, proteins, chemicals, diseases, cell types, and other life, chemical, and biomedical science nomenclature is used to automatically search for all variants of a term in the user's query. For example, a search for "aspirin" will find asserted relationships that mention "acetylsalicylic acid". The ontology also is used to find members of a class of entities, such as "neurotransmitters".

Quertle indexes MEDLINE, full-text articles from BioMed Central[6] and PubMed Central (open access subset), NIH grants, the US National Library of Medicine TOXNET database, and biomedical news.[7]

If you search for two or more terms, you will find occurrences of a conceptual relationship, not just the terms scattered within the same document.

Since Quertle searches for Relationships, all the terms in your query must be found together in a meaningful way. Thus, Quertle immediately gives you results with more relevance.

Use Power Terms to search for categories of objects. For instance, you can use "$Protein" to search for any protein, rather than the occurrence of the term, "protein". View all Power Terms.

The Quertle search engine has been optimized to search full-text documents, including the Material and Methods section (but not the Bibliography).

Quertle recognizes capital "TWIST" as the transcription factor (not the verb), and capital "NO" as "nitrous oxide"(not a negative). So, use proper capitalization in your query, and you won't be lost in a sea of irrelevant results.

» More relevant results

» Easy filtering and breadcrumb tracking

» Automatic identification of key concepts

» Single-click access to PDFs of full-text documents