CHEM 481-482: Literature & Seminar

Before diving deeper into using Boolean operators, make sure that you have read the section on Boolean Searching on the "Search Strategies" page. Boolean searchers vary in their complexity, so having a foundational knowledge of how Boolean operators work is important before moving on to more challenging searches. 

This guide will outline how to run Boolean searches in the three databases used throughout CHEM 481: SciFinder-N, Scopus, and PubMed. 

SciFinder-n used the three Boolean operators (AND, OR, NOT), and two wildcard symbols (* , ?) to conduct advanced searches. SciFinder also uses double quotes ( " " ) to search for exact phrases. Parenthesis ( ) should be used around OR terms to ensure that these keywords are specifically compared, similar to how parenthesis function in a mathematical expression. 

When searching, use Boolean operators and other symbols to join your keywords together to create logical expressions. For example: 

(removal OR purification) AND desalination AND "sea water" NOT "drinking water"

This search would yield results that discuss either removal or purification, uranium, and sea water, but exclude all resources that discuss drinking water. 

When starting your searches begin by using a few Boolean terms and symbols, such as (removal OR purification) AND desalination, and then gradually build your search's complexity. 

The asterisk (*) is is used to truncate a search or to replace an internal character. This is especially helpful when there are multiple endings for a root word, or if there are variations in the spelling of a word. For example: polymorph* would retrieve words such as polymorphic or polymorphism.

The question mark (?) symbol does the same function when conducting a substance search, specifically. For example, if you searched for alk?ne, you would receive the words alkane, alkene, and alkyne. 

Additional SciFinder-n Boolean searching resources are here (p. 4) and here. 

Scopus employs a wide range of search tools, some of which drastically vary from other databases, so please read with care. 

Scopus uses the Boolean operators (AND, OR, AND NOT), the asterisk (*), question mark (?), double quotes (" "), and curly que brackets ({ }) to annotate advanced searches. Note that Scopus does not use parenthesis ( ) to delineate around OR terms. 

The Boolean operators retain their ordinary functions, but Scopus lists NOT as AND NOT. Meaning that if you want to search using NOT, you must enter AND NOT into the search.

desalination AND "sea water" AND salt OR purification AND NOT "drinking water"

In Scopus, Boolean terms must be entered in a specific order. Enter all AND terms first, followed by OR, and lastly, AND NOT must always be the final Boolean term entered, unless you want to exclude more than one term. Example: mice AND NOT cat OR dog. 

Scopus inserts the Boolean term AND between all search terms, unless otherwise specified. For example, if you search for drinking water, Scopus will interpret your search as drinking AND water-- two separate keywords. 

Loose Phrases: To search for a loose phrase, wrap your phrase in double quotes (" "). When searching using double quotes, Scopus will retrieve results where the words in the phrase are adjacent to one another. For example: searching for "water purification" will ensure that this is search for as a phrase, not to separate words. 

Exact Phrases: If you need to search for an exact phrase, wrap your phrase in curly que brackets { }. When using curly que brackets, Scopus will search for your terms exactly as entered. For example, searching for {high-density polyethylene} will yield keywords that exactly match wat is within the { }. Ordinarily, hyphens are omitted in Scopus, but not when included in { }. 

Asterisk: Use an asterisk to replace any number of characters anywhere in a word. For example, searching for hydro* will provide hydrogen, hydroxide, hydrocarbon, etc. 

Question Mark: Use a question mark to replace a single character anywhere in a word. Use one question mark for each character that you'd like to replace. This is especially helpful for differences in spelling (American English vs. British English, for example). For example, searching for alumin?um will retrieve both aluminum and aluminium. 

Proximity Searching: If you'd like a word to appear within a certain number of other words, you can use proximity searching. Note that in Scopus, AND and AND NOT are not compatible with proximity searches. Example: salt w/5 water OR "sea water" In this search, uranium would need to appear within five words of either water or sea water. 

Additional resources on searching in Scopus are here and here. 

PubMed uses the three Boolean operators (AND, OR, NOT), an asterisk (*) for wild card searches, parenthesis to "nest" OR terms, and double quotes (" ") to search for specific phrases. 

Two important features to note:

1. PubMed employs automatic term mapping (ATM). The ATM function works by matching your entered keywords with the MeSH (Medical Subject Headings) dictionary, and ATM also accommodates for other variations, such as British and American Spellings, drug brand names compared to generic formulations, and more. You can turn off ATM by either employing double quotes or an asterisk when wildcard searching. ATM has advantages and disadvantages; on average, ATM will provide more search results, but results can sometimes be too broad. Vary your search strategy accordingly. 
2. PubMed automatically places an AND between all keywords, unless otherwise specified. 

Boolean Searching: PubMed uses Boolean searching to logically order search queries. The order of preference for PubMed is AND, OR, NOT, meaning that AND terms should be placed first, OR terms can be nested accordingly, but NOT must always be the last entry. For example: 

desalination AND treatment (salt OR "carbon dioxide") NOT "water treatment"

Using Parenthesis: To "nest" OR terms together, wrap the terms in a set of parenthesis. This allows the terms to be directly compared. 

Phrase Searching using Double Quotes: ATM does recognize many phrases, but if you'd like to run a highly specific phrase search, you can do so by wrapping the phrase in a set of double quotation marks. For example, searching for heavy metal toxicity yields ~98,983 results, because ATM is applied to this phrase. Searching for "heavy metal toxicity" only yields ~1,092 results, because PubMed searches for this exact phrase alone.

Truncation Searching Using an Asterisk: The asterisk (*) can be used to replace a character or characters within a term or phrase. For example, toxi* will yield toxic, toxicity, toxicology, toxicant, etc. 

This FAQ from the National Library of Medicine provides an extensive database of search strategies.