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Nursing - Dallas

Search Skills

As TWU students in the health sciences, your work will need to be based upon solid research: Evidence-based practice (EBP) is an approach to medical practice intended to optimize decision making by emphasizing the use of evidence from well-designed and well-conducted research.

As future nurses, you will be required to continue your professional development and continually find new research throughout your career. Learning how to search databases as a student will prepare you for finding evidence-based research as you work in your chosen field.

How Do I...?

Keyword searches will look through the text of an article for whatever word(s) you have specified. 


  • A keyword search will bring back up to the minute articles as they are uploaded to databases.
  • A keyword search will invariably bring back more results than a subject heading search.
  • A keyword search allows for the use of Boolean operators, field searches, phrases, et cetera, giving the searcher far more control over the search than an automated subject heading search.


  • More results to sift through.
  • Many of these results can be less relevant than a subject heading search.

A subject heading search, also known as a controlled vocabulary search, will search for articles on a given subject or topic rather than by looking for keywords within the text, i.e., an article will be tagged and indexed in a database as being about certain subjects. It is these subjects that are searched with this type of query.

Not all databases use the same subject heading catalog.


  • Subject heading searches are easy to run.
  • All articles produced should all be about the subject you have selected.
  • In theory, you should receive more pertinent, albeit fewer, results than a keyword search. 


  • Subject heading searches  will not always produce the most recent literature a database has to offer*.
  • Only the bigger databases offer the utility of a subject heading search. All other databases will need to be keyword searched.

*Note: Due to the high volume of medical literature coming out every week, most databases, if not all, are several months behind at indexing articles. Until articles have been properly indexed by the database, they will not show up on a subject heading search. However, a keyword search will pick up articles as soon as they are uploaded to the database regardless of if they have been indexed yet or not

Putting phrases in quotation marks can make a huge difference to your search! Anything over one word is technically a phrase and should be placed inside "quotation marks." The reason for this is that databases are very literal; without the quotation marks, they will search for the terms quotation and marks separately. They do not understand that multiple words are part of the same phrase unless you tell them. 

For example, if you typed peanut butter and jelly day without quotation marks, the database would bring back every article with the word "peanut" in it, every article with the word "butter" in it, and so on...

In the example below, you can see that the phrase "peanut butter and jelly day" was not placed in quotations and Google Scholar brought back 27,100 results of which most were not pertinent. 

peanut butter google 1

In the second picture the phrase was placed in quotations and only 23 results came back, but all were pertinent.

peanut butter google 2

Note: When you put a phrase into quotation marks, the database will search for what's inside the quotations and ONLY what is inside the quotations. For example, a search for "aspirin vs. Tylenol" will fail to bring back articles where the author phrased this differently, e.g., "Tylenol vs. aspirin," or "aspirin versus Tylenol."

Phrases are highly specific. Be sure to consider all the different variations and make sure you include them in your search too.

Note: Some databases will not accept quotation marks and will assume that everything placed between two Boolean OR statements is a phrase, e.g., OR Tylenol vs Ibuprofen OR Ibuprofen vs Tylenol.

There are three Boolean operators: AND, OR, and NOT.


The AND Boolean operator will reduce the amount of results a search yields as it forces the database to be more specific. For example, here the database will only return results that feature both the terms "peanut butter" AND jelly.

Tip: If you have too many results to wade through, try using an additional search concept with AND to get a smaller, more specific, batch of results.

Venn diagram of search for peanut butter AND jelly.


OR is used to add synonyms or alternate words to your search. By adding more synonyms to each concept you should get more results. A good rule of thumb is that OR is always more.

Here you can see that the database will bring back all articles that have either the phrase "peanut butter." or the word jelly, or both.

Venn diagram of search for peanut butter OR jelly.


The NOT  Boolean operator will purposefully exclude articles containing the specified search term(s.) 

NOT can be used to narrow down the desired meaning of a term that has different connotative meanings. 

Venn diagram of search for peanut butter NOT jelly.

Here you can see that the database will bring back articles about "peanut butter" — but if that article mentions jelly anywhere in the text, even randomly, the database will exclude that article from the results.

Tip: Use the NOT Boolean operator with care. You might lose the perfect article because it randomly mentioned the term you excluded. If you need to reduce the amount of results your search yields first try thinking of another search term and adding it to your search with an AND.

A Note on Capitalization

In our examples, you'll see that the Boolean operators are in all caps. Some databases require them to be in all caps, others do not. It's better to get into the habit of always capitalizing them so that it's easier to copy and paste your search terms from one database to another.

If you are building a search string with multiple concepts, added parentheses to your string helps to tell the database how to link the terms. So if you're building a search based on your PICO research question, and you have terms related to your population and your intervention, the parentheses group the terms to tell the database what to look for.


Population terms
  • Alzheimer's disease
  • dementia
  • cognitive impairment
Intervention terms
  • hydration
Search string

("Alzheimer's disease" OR dementia OR "cognitive impairment") AND hydration

Larger databases allow users to limit their search by certain criteria, hence the name limiters.  Limiters are incredibly helpful and are usually found under the main search box or on the left hand side of the screen.


  • Allows users to narrow down search results by various criteria. Useful limiters include:
    • Date range: Usually expressed by publication year or range, like the last ten years.
    • English language: Exclude articles in languages you may not understand.
    • Peer reviewed: Make sure the articles you are reading are from a peer-reviewed publication.
    • Study type: Specify if you want only systematic reviews, randomized controlled trials, etc.


  • Limiters vary from database to database.
  • Using too many limiters or poorly chosen limiters may bring back few results or poor quality results.

Note: Be aware of the full text limiter. It prevents you from seeing citations that might prove to be the perfect article for you. You can always request articles from other libraries via our free interlibrary loan service.

Fields are allocated spaces within a electronic article that are set up to store a specific type of information, e.g., the author field will be where author names are stored, and the title field is where the title of the article will be stored.

Field searching allows you to tell a database exactly where you want to look for your keywords. By default, the field search will be set to "All fields," meaning that your keyword search will check everywhere within an article's text for your specified keywords.

Here are some ways that field searching may be helpful:

  • If you need more pertinent articles, limit your search to the title or abstract fields.
  • If you're looking for a specific author, limit to the author field.
  • If you're looking for a specific article, even if you only remember a few words of the title, limit to the title field.
  • If you're searching on a specific topic, search the subject field. (Check out the subject searches tab above to learn the best ways to do this.)
  • If you have an ISBN number, limit to that field.

Example of PubMed's fields:

Screen grab of search fields in PubMed, showing options like All fields, Author, Date, ISBN, and more.

Narrowing Results

To find fewer results:

  • Add another concept using the AND Boolean operator. This will exponentially reduce the number of results you get back while making those results far more pertinent.
  • Reduce the number of synonyms you are using. 
  • Try a field search. For example, run a title field search.
  • Use the NOT Boolean operator to select words that you do not wish to appear anywhere in the article.
  • Use your limiters to:
    • Set a date range or reduce your date range.
    • Limit your results to a specific language.
    • Limit your results by article type, e.g., randomized controlled trials or systematic reviews

Broadening Results

To find more results:

  • Add synonyms to your search string with the Boolean operator OR (remember, OR is more).
  • Reduce the number of concepts in your search string by eliminating AND Boolean operators.
  • Phrases are very specific; reduce or replace phrases with single keywords if possible.
  • Use your limiters to:
    • Extend your date range.
    • Search more types of articles.

Saving your search can be useful if you ever want to run the search again at a future point in time or set up alerts so that you will be automatically emailed should new results populate within that search.


  1. Create a personal account by clicking "Log in" at the top right of the page.
  2. Click on "Sign up" where it asks "New here?" You can use their Google option to use your TWU email to sign up for a free account.
  3. Once you're logged in, use the link at the top right to go to PubMed and enter your search.
  4. Click the "Create alert" link located under the search box.
  5. Confirm how you want to name the search and its search terms, then determine whether you'd like email updates and how frequenly. Once you've finalized your selections, click "Save."
  6. To access your saved searches in future, click on your username at the right top of the page and select "Dashboard."
  7. You'll see your saved searches listed in the right column.
  8.  The retrieved search or alert can either be rerun, edited, or deleted.


  1. Create a personal account by clicking "Sign in" at the top of the page.
  2. Click on "Sign up" where it asks if you have an account. Fill out the form and click on "Create account."
  3. Enter your search.
  4. Click the "Search History" link located below the search boxes and above the search results.
  5. Select the search you wish to save. Click on "Save Searches/Alerts," fill out the form to name and describe your search and designate this as a saved search or an alert.
    1. If you select "Alert," you'll get a list of options to select for frequency, how to get updates, etc.
    2. Make all necessary selections, then click on "Save."
  6. To access your saved searches in future, click on the Folder icon located next to the "Sign in" or "Sign out" link at the top right of the page, then click on the "Saved Searches" link located on the left hand side of the page.
  7.  The retrieved search or alert can either be rerun, edited, or deleted.