The search terms or keywords you use to search are what determine the results you get. Here's a good exercise to help you generate keywords:

1. Express your topic in a topic sentence:  "What research is there on modeling drug interactions with target molecules to identify new uses for the drug?"

2. Generate keyword search terms by identifying the main ideas or concepts within the topic sentence:  "What research is there on modeling drug interactions with target molecules to identify new uses for the drug?"  --> modeling, drug, interactions, target molecules, new 

3. Expand your search terms by brainstorming related terms or synonyms that describe your main ideas:

• Modeling; modelling, simulation, computational, predicting
• Drug; ligand
• Interactions; binding, docking 
• Target molecules; receptors, proteins
• New; novel

You can create complex search strategies by combining keywords using the linking words AND, OR and NOT. For example, if your search terms are transcription and regulation:

• AND - Narrows and focuses the search results. The search transcription and regulation finds only results containing both the terms transcription and regulation.
• OR - Broadens the search results. Searching transcription or regulation will find results containing the term transcription or the term regulation or both terms in the same result.
• NOT - Excludes any result containing the term listed after the not.  The search transcription not regulation will find results containing the term transcription but not containing the term regulation. Use not cautiously since it excludes all mentions of the term in every context.

Searching for exact phrases instead of individual words can focus your search so that more results are directly relevant to your topic. Different databases and search engines accomplish this in different ways. Two common ones are:

• Quotation marks - Some databases treat words enclosed within quotation marks as phrases. Searching "protein folding patterns" will find only results containing those three words next to each other in that order.
• Default setting - In some databases, words typed next to each other are automatically searched as an exact phrase. Searching protein folding patterns will only find results containing that exact phrase

Remember: Exact phrase searches can focus your results, but they can also miss some relevant results. Searching the phrase "protein folding patterns" will not find folding patterns in proteins or keratin folding patterns, both of which are relevant.

Searching the root of a word without specifying a particular ending is a way to find variations on a word that relate to the same core concept without searching each word separately.

Some databases automatically search terms for singular, plural, and various other endings.

Some databases use a truncation symbol to indicate that any ending is acceptable after exactly matching the letters entered.

• gene*       will find     gene, genes, genetic, genetics, genetically            but not           genome or genomics
• sequenc*    will find    sequence, sequences, sequencer, sequencing      but not           sequential

The actual symbol used will vary among databases. The asterisk (*) is most common, but some use a ? or other symbol, so check your database.

In some databases you can restrict searching your terms to specific sections or fields in a database record, for example the article title or author name.

You can tailor your search by combining information from different parts of the record, like combining an author name with a subject term, or focus your search by restricting terms to an article title or abstract.

This is frequently done by using a pull-down menu to select the appropriate field for each search term.