> For the complete documentation index, see [llms.txt](https://docs.nested-knowledge.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nested-knowledge.com/guides/write-a-search-query/embase.md). # Embase Learn how to write an Embase search query. Embase is Elsevier's biomedical literature database, distinguished from PubMed by two things: Emtree, its own controlled vocabulary, and deeper coverage of conference abstracts. Many regulatory, HTA, and publication protocols require searching Embase alongside PubMed. This page covers Embase's query syntax. See [Embase Integration](/integrations/embase-integration.md) to connect your organization's Embase credentials. Embase access requires an active Elsevier subscription and API access billed separately by Elsevier. ### Write A Boolean Query Use `AND`, `OR`, and `NOT` to combine terms — always capitalized. Embase treats an unquoted multi-word entry as a phrase by default, in the exact order typed: ``` life quality ``` searches for the phrase "life quality," not "life" and "quality" separately. Use quotation marks only when a term itself contains a phrase you want to keep intact within a larger expression: ``` 'acetylsalicylic acid' AND headache ``` ### Search Emtree, Embase's Controlled Vocabulary Emtree is Embase's equivalent to PubMed's MeSH — a hierarchical controlled vocabulary that Embase can search with or without exploding to narrower terms. Add one of these after a term, as a slash-suffix: * `/exp` — explosion: searches the term plus every narrower term beneath it in the Emtree hierarchy * `/de` — no explosion: searches only the exact term entered * `/mj` — major focus: limits to records where indexers identified the term as a main focus of the study * `/syn` — synonyms: adds the term's listed synonyms to an exploded search, broader than either `/exp` or `/de` alone ``` 'hypertension'/exp ``` returns records tagged with hypertension or any narrower term beneath it in Emtree. PubMed's MeSH explodes automatically; Embase doesn't, which makes `/exp` the single most common gap when translating a PubMed MeSH search into Embase — leaving it off silently narrows the search. ### Search Specific Fields Restrict a term to a field by adding a colon and a two-letter code. Combine multiple fields with commas: ``` 'vaccine':ab,ti ``` searches for "vaccine" in title or abstract. Commonly used field codes: * `:ti` — title * `:ab` — abstract * `:ti,ab` — title or abstract * `:kw` — author keywords * `:ti,ab,kw` — title, abstract, or author keywords See Elsevier's [full field code list](https://www.elsevier.support/embase/answer/what-field-codes-can-i-use-in-embase) for fields beyond these. ### Wildcards * `*` — matches any number of characters, for example `cat*` matches cat, catalog, and category. Use at least three characters before truncating for a workable result set. * `?` — matches zero or one character within or at the end of a word, for example `wom?n` matches woman and women, and `tumo?r` matches tumor and tumour. ### Proximity Operators * `NEAR/n` — the two terms appear within *n* words of each other, in either order: `therapy NEAR/5 sleep` * `NEXT/n` — the two terms appear within *n* words of each other, in the order typed: `therapy NEXT/5 sleep` matches "therapy for improved sleep" but not "sleep therapy" Combine proximity with field limits and truncation: `(symptom* NEAR/5 (headache* OR 'head ache')):ti,ab` ### Filter By Study Traits Combine a term with `AND` and one of Embase's built-in options — for example, restricting to conference abstracts, clinical trials, or a publication date range. ### Build A Strong Search PICO and expanding-or-narrowing guidance apply here the same way they do on PubMed — see [PubMed](/guides/write-a-search-query/pubmed.md) for the full explanation, and Best Search Practices for more depth. Because Embase's Emtree doesn't explode automatically, converting an existing PubMed search is usually the fastest starting point rather than building an Embase search from scratch — Emtree also carries more synonyms per concept than MeSH does, so a direct search will often need fewer manually added synonyms. ### FAQs
Can I paste a PubMed query directly into Embase? No — beyond the different field syntax, Embase's Emtree doesn't explode automatically the way PubMed's MeSH does. A PubMed MeSH term needs `/exp` added explicitly, or the Embase version of that search will be narrower than intended.
Does Embase searching cost anything beyond my Nested Knowledge subscription? Yes — Embase access requires an active Elsevier subscription, and commercial organizations need a separate API subscription arranged through Elsevier. See [Embase Integration](/integrations/embase-integration.md) for how that's set up and billed.
Why did my `/exp` search return more results than I expected? `/exp` searches the term plus everything narrower than it in the Emtree hierarchy, which can be broad for a high-level concept. Use `/de` instead to search only the exact term, or `/mj` to limit to records where it's a major focus.
--- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.nested-knowledge.com/guides/write-a-search-query/embase.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.