What is PubMed?
PubMed is a system that allows you to search more than 15 million biomedical article citations from the 1950's to the present. These citations come from MEDLINE and other life sciences literature. PubMed is a service of the National Library of Medicine.
Accessing
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi
Go to the PubMed site now and refer back to it as you go through this tutorial.
Finding Information
Basic searching of PubMed is a lot like using any Internet search engine (like Google) or even searching your favorite store - you have an idea of what you are looking for, you just need to find where the item you want is located and then narrow down your choices.
More advanced PubMed searching requires a few more steps and a little more experience. The more you use the tool, the more you will learn about it.
Basic Search Strategies
To do a basic keyword search in PubMed, just type keywords or phrases about your topic into the query box at the top of the PubMed search page.
The fewer terms you use, the "wider" your search will be; the more terms you use, the "narrower" your search will become. Start out wide, and then narrow if you get too many results.
If you don't find citations that meet your needs, start experimenting. You may just be typing in one phrase when another phrase is more appropriate.
AND
Use the word and when you need to find a relationship between terms.
vitamin b12 and supplement
By using the word and, you are telling the database to only give you citations that deal with both vitamin B12 and supplement.
Think of it like a peanut butter and jelly sandwich. If you want a sandwich containing peanut butter and containing jelly, you make a peanut butter and jelly sandwich.
OR
Use the word or when more than one term may provide an answer to your question.
vitamin B12 or folic acid
By using the word or, you are instructing the database to give you citations that deal with either vitamin B12 or folic acid. You will receive citations on both if such citations are available. Using or is valuable when you have multiple topics you want to address in a single search.
For instance, you are hungry and you know that you have a taste for pizza or pasta. Either dish would satisfy you.
Limits
PubMed's limiting functions help you to further narrow down your search. By clicking on the word Limits beneath the PubMed query box, you have access to settings which allow you to limit your search in many ways (publication date and type, age of group studied, language, etc.).
Just remember that limits can sometimes be hard to remove once you put them in place. When you begin a new search, make sure that the small box beside Limits is not checked, or your old limits will apply to your new search!
More Advanced Search Strategies
History
Along with and and or, you can also combine keywords you have searched with by clicking on the word "History" beneath the PubMed query box. This function allows you to go back to searches you have just run and combine them with newer searches. Remember to read the short instructions listed on the History page so that you will know how to set up your search strategy.
History can also save you from re-doing older searches. Just click on the number of results beside your older search and you return to that search.
PubMed Tutorial from the National Library of Medicine
National Library of Medicine's PubMed Tutorial
(http://www.nlm.nih.gov/bsd/pubmed_tutorial/m1001.html)