First go HERE to the PubMed website.
In the empty "search box" at the top, middle of the page, type your search term.
For example, type cellular injury. Then hit enter or click on "go".
You will see that there are 105635 articles that refer to cellular injury. Of these 105635 articles, 15099 are review articles (these numbers change as new articles are added to the database).
Clicking on article #2 will bring up the title, authors, abstract and tell you which journal published the article. To the left of the abstract, you will see links to a series of related journal articles.
Go to the top of the page and click on the History tab. On this page you will see #1 Search cellular injury. To the far left you will see the number of journal articles.
Now type ischemic in the empty search box at the top of the page and click on "go".
You see that there are 114951 articles referring to the term "ischemic". [Note: this number can change daily with the addition of new journal articles into the library.]
Click on the History tab again.
Now you see a list of both your search terms - cellular injury and ischemic.
Type this exactly in the empty search box: #1 AND #3 ("AND must be captalized), then click on "go".
Now you see that there are 8856 journal articles that contain both terms. If you had typed #1 OR #3 you would have obtained 211730 articles that contain one term or the other. If you had typed #1 NOT #3, you would have obtained 96779 articles containing the term "cellular injury" but not containing the term ischemic
Go to the upper left hand part of the page where the 'tabs' are located and click on "Limits".
This page allows you to greatly refine your search of cellular injury AND/OR/NOT ischemic. Let's say you only want to see articles printed in english. Under "Language" click the box marked english.
Let's say you only want to see articles referencing female humans. Just click on the "Human" and "Female" boxes. Click the box that says "links to free full text" to find the entire article for free.
Go to the bottom of the page and click on "Go". Up pops the 1216 articles in english about "cellular injury" but without the word "ischemia" specifically concerning "human" "females".
Click on article #1 and the abstract pops up. Notice that on the right hand side of the page containing the abstract, there is a box that says Journal of Invasive Cardiology. If you click on that box the entire article will pop up. More often there will be a free text box in that location and you can download a pdf file of the article.
If you start a search with new terms, remember to unclick the 'Limits' box or you will only get articles in english that reference humans and females.
There are many, many other databases (accessible on the library computers) and search engines (Google) that can be used to find information. But how do you know which information or articles to trust?
Here are a few general rules:
Expertise: Most of the papers you find in PubMed have been written by experts and then peer reviewed by experts. Websites that end in .gov, .org, .edu are surely more likely to provide valid information than what you find in many .com websites. Resources like Quackwatch are useful in determining the value of many medical information websites.
Experience: People tend to trust the advice of "experienced" individuals. This is because they are expected to have accumulated knowledge over time. One has to be careful here because in rapidly changing situations (like science), you need to be sure the "experienced" person has kept up with the changes and new discoveries.
Verifiability: Claims of medicine and science need to be verified or scientifically repeatible. That is why we can typically be assured that FDA approved drugs will do what the drug company claims they will do. Remember Ronald Reagans advice to trust, but verify.
Disinterest: A car salesman tells you that the car that he is about to sell you is the best in the world and will be trouble free for 15 yrs. Maybe it will, but do you believe the car salesman? No, because he is about to make money upon selling you the car. That is why most journals require full disclosure of whether scientists are funded by companies that have an interest in the publication.
A simple Google search is also well worth doing. A Google search will bring up the names of many government and non-government websites that contain a lot of useful information. The advantage of these sites are that they present information in layman terms.