The AND and OR buttons in MEDLINE allow you to combine the separate subject searches that you run. They have different functions.
AND is used to combine searches about different topics: e.g. Glioma AND Regression.
OR is used to combine similar searches or searches on subjects that you wish to compare.
OR is mainly used to combine searches for synonyms for terms or subjects.
Synonyms are alternative terms or names for a subject. They are worth including in your search to make it as rigorous as possible i.e. to increase your chances of finding all articles that mention your topic.
Spend some time thinking of as many alternative terms for your subject(s) as possible. These may include:
The more synonyms you can include, the more thorough your search will be.
For example, a glioma may occasionally be referred to as a glial cell tumour, so this is a synonym that is worth including in a glioma search.
Search for synonyms in MEDLINE in exactly the same way as your main term(s).
So, having already searched for Glioma, back on the MEDLINE Advanced Search page type in the synonym glial cell tumour and click Search.
MEDLINE will suggest possible subjects relevant to the term(s) you have searched for. If one of MEDLINE's suggestions is an exact match, tick it, tick Include All Subheadings, then click Continue >>. But if none of the suggestions match, tick the 'search as Keyword' option instead, then click Continue >>.
(For information on Advanced keyword searching, click the tab with that title above.)
You will be returned to the main search page, where your synonym search will be added to your Search History.
Search in the same way for any other synonyms that you think might be relevant to your subject (e.g. glial cell tumor instead of tumour).
Once you have searched for all your synonyms, tick the synonym searches in your Search History, then click the OR button.
Remember, OR combines searches that are similar. Your synonym searches are all similar (i.e. different ways of referring to the same subject), so they should be combined using OR.
MEDLINE will add a new line to your Search History, combining all your synonym searches. MEDLINE will automatically remove any duplicate references that appear in two or more of your synonym searches.
Repeat the above steps for your next term(s) and any synonyms you can think of for them (e.g. disease eradication as an alternative term for regression).
When you have searched for all your terms, tick the lines in your Search History that show your combined synonyms (i.e. that connect your synonym searches with OR), then click AND.
A new line will be added to your Search History, showing results that are about ALL of your subjects. Scroll down to view those results.
NOT enables you to exclude subjects or topics from your search.
For example, suppose you want to find articles about Diabetes Mellitus, but you want to exclude any article that is about Gestational Diabetes from your search.
First, search MEDLINE for Diabetes Mellitus. Then search for Gestational Diabetes. Both these subjects will appear in your Search History: Diabetes Mellitus is search number 1; Gestational Diabetes is search number 2.
To exclude articles about Gestational Diabetes from your Diabetes Mellitus search, type 1 NOT 2 into the Advanced Search box. Then click Search.
MEDLINE will add a new line to your Search History, showing how many results are about Diabetes Mellitus but not about Gestational Diabetes. Scroll down to view those results.
Exploding subject heading searches in MEDLINE is less violent, and more useful, than it sounds.
On the MEDLINE search page, you will notice a small box underneath the Advanced Search box, which is ticked by default.
As long as this Map Term to Subject Heading box is ticked, MEDLINE will suggest relevant subjects when you search for a subject or term. So, if you search for Glioma, MEDLINE suggests the following subjects that might be relevant.
These subjects are MeSH terms. MeSH stands for Medical Subject Heading. MeSH terms are labels that are attached, by database compilers working at the National Library of Medicine, to articles indexed in MEDLINE. MeSH terms indicate that articles are about particular subjects.
By ticking a MeSH term and clicking Continue >>, you are telling MEDLINE to display all articles that have been labelled with that MeSH term.
Some MeSH terms are, by their nature, broad, and have other, more specific MeSH terms linked to them. To check if there are more specific terms linked to a MeSH term, click on the MeSH term.
This will open up MEDLINE's 'MeSH Tree', which is a list of all MeSH terms that can be assigned to articles. Scroll down this tree until you find your selected MeSH term, highlighted in blue.
If there are any terms indented beneath it, these are more specific MeSH terms that are linked to it. (If there are no indented terms, then there are no more specific terms linked to your MeSH term.)
If you think these more specific MeSH terms indicate subjects that are relevant to your search, you can include them at this stage.
To include them all, tick the Explode box beside the top MeSH term: e.g. ticking Explode beside Glioma will include general glioma articles, but also articles about more specific types of glioma such as astrocytoma, ependymoma etc.
If only some of the more specific MeSH terms are relevant, tick them individually.
If you think none of the more specific terms are relevant, then just tick the top term i.e. the one highlighted in blue. For example, ticking Glioma and nothing else will get you only general articles about glioma.
When you have made your selection, scroll up and click Continue >>.
You will then be returned to the main search page, where your search will appear in your Search History.
Exploding a subject heading search can greatly increase the number of references you find. Below you can see a comparison between an unexploded search for Glioma and an exploded search (denoted by the prefix exp). The unexploded Glioma search finds over 33,600 results. The exploded search finds over 70,000.
If MEDLINE doesn't suggest any relevant MeSH terms for your subject, you have the option of ticking 'search as Keyword', which tells MEDLINE to search in the titles and abstracts of articles for the word(s) you have typed.
However, this method of keyword searching has its limitations.
In the example above, ticking 'search as Keyword' beside 'regression' tells MEDLINE to look for the word regression in the titles and abstracts of articles, but only the word regression. Variations on regression (e.g. regress, regressed, regresses, regressing) will be ignored so, potentially, your keyword search might not detect key articles that are nevertheless relevant to your topic.
If you are concerned about missing key articles, and if you wish to perform a more effective keyword search, don't tick the 'search as Keyword' option at all. Instead, click Search to go back to the main search page.
Untick the Map Term to Subject Heading box underneath the Advanced Search box. This means that MEDLINE will no longer suggest MeSH terms when you run your search. Instead, MEDLINE will run a keyword search, looking for what you type into the search box in the titles and abstracts of articles.
Type your search term(s) into the search box, but this time you can type various symbols (known as operators and wildcards) to maximise the effectiveness, and thoroughness, of your keyword search. These symbols are listed below.
Typing * at the end of a word finds different word endings. For example, regress* will look in the titles and abstracts of articles for the words regress, regressed, regresses, regressing, regression, regression's, regressive etc.
The ? symbol can be used to look for extra letters within a word. It is particularly useful for finding US and UK English spellings. For example, p?ediatrics will search for pediatrics or paediatrics, and tumo?r will search for tumor or tumour.
The # symbol can be used to look for different letters within a word. For example, wom#n looks for woman or women, and (if you are so inclined) g##se looks for goose or geese.
Putting "..." around a set of words tells MEDLINE to treat the words as a phrase: i.e. it looks for them in article titles and abstracts beside each other and in the order of typing.
"..." also enables you to run keyword searches for phrases containing the words AND or OR. For example, if you wish to run a keyword search for accident and emergency, you need to type "accident and emergency" for it to work.
Typing adj between words tells MEDLINE to look for those words beside each other (adj is short for 'adjacent'). Typing a number after adj tells MEDLINE to look for the words within that number of words of each other, in any order. Using adj allows you to run more flexible keyword searches for phrases. Some examples are below:
You can use multiple symbols in a single keyword search.
For example, searching for cognitive adj2 therap* will find articles mentioning, among other variations:
You can run a keyword search for multiple synonyms for a term by typing them all into the search box, typing 'or' between them and enclosing them in brackets (...).
For example, "glial cell*" adj3 (cancer* or neoplas* or malignan* or tumo?r* or carcinoma*) finds the following word combinations:
Not sure if a subject heading (MeSH term) suggested by MEDLINE is relevant to your search? Click the Scope (or 'i') icon to the right of the subject heading.
This will open a Scope Note - a summary of what is covered by the subject heading. This will hopefully help you decide whether or not the subject heading is useful to you. Once you've read the Scope Note, click << Previous Page to return to the subject heading screen.
A Focus tick box appears beside subject headings suggested by MEDLINE. Tick Focus if you only want articles whose major focus is the subject you have chosen.
Use Focus with caution, as often it will reduce the number of results you get drastically and potentially exclude many relevant references.
(There is also an Explode box beside every subject heading. Instead of ticking this box to explode your searches, it is better to use the method described earlier - click the Exploding subject headings tab above for details.)
You can save your MEDLINE search as an AutoAlert. This means that MEDLINE will re-run your search automatically and email you new results of potential relevance to your topic.
To save a search as an Autoalert, click Save All under your Search History.
Log in to your personal Ovid account if you haven't already done so. Give your search a name, and change the Type from Permanent to AutoAlert (SDI).
Use Scheduling Options to tell MEDLINE how frequently you wish your search to be re-run (e.g. weekly).
Change other AutoAlert Options as appropriate. Then click Save.
Your AutoAlert will be created, and you will start to receive email updates about new articles.
To cancel an AutoAlert at any time, open MEDLINE, click View Saved, log in to your personal Ovid Account. Scroll down until you see your AutoAlert. Tick it, and click Delete.
Click Delete again to confirm.
Your AutoAlert will be deleted and you will no longer receive email updates.
Every MEDLINE result has a tick box. You can use this to mark useful references.
You can then output these references in various ways using the Print, Email or Export menu at the top of the results display.
Click this option to print a list of ticked references. Tick Search History to include a list of your search terms.
Click this option to email a list of results to yourself, or to another email address (e.g. your supervisor, fellow researcher)
Click this option to send a list of references into Word, or to any reference management tool you might use (there is a direct export link for RefWorks; if you use Mendeley, choose the Export To: RIS option).
The MEDLINE database, from the National Library of Medicine, is a good place to look if you want quality, peer-reviewed medicine and life science research. It indexes over 20 million references from approximately 5,500 journals.
HONNI allows Medical & HSC Library members to search MEDLINE via the Ovid platform.
Log in with your Library number and password when prompted, and MEDLINE will open in Ovid.
By default, your MEDLINE Search History will only show the 4 most recent searches that you have run, so earlier searches may seem to 'disappear.'
To view all lines of your search, make sure you click Expand in your Search History.