Limits

Limits vary by database. In Entrez Nucleotides, for example, you can limit by:

• search field
• source database (subset)
• molecule type
• gene location
• modification date
• exclude certain categories of records
  • Try this: starting with the search results for the serach: colon cancer[titl] AND human[orgn], use the Limits page to exclude patents.
  • How many patent sequences were in the original search results?
  • Note that sometimes users might want to exlude these from search results because the sequences are usually short and do not contain much, if any, biological annotation. Rather, a user would need to go to the patent application for more detail about the sequences. So for some users, patent sequence records are of limited use.
• and other types of limits, depending on database

Many Limits are drawn from the Properties [PROP] field.  More info about that field in the helpful search fields slide.

Now try this: Starting with the search results you just got (which exclude patent sequences), further refine the query to answer the user's question below:

I'd like to retrieve human nucleotide sequences associated with colon cancer, but only from mRNA, and only from the curated RefSeq database.