1. A computer-implemented method, comprising: at a computer having memory, a display, and a processor, while a document displayed on the display is being browsed: displaying a first portion of the document on the display; receiving a user-specified text string that includes multiple search keywords; and upon receiving the user-specified text string that includes multiple search keywords: comparing the multiple search keywords with a plurality of candidate chunks within the document, wherein each candidate chunk corresponds to a predefined semantically-based unit of text in the document; identifying, among the plurality of candidate chunks, one or more chunks matching the multiple search keywords; and displaying, in addition to the first portion of the document, a list of the one or more chunks matching the multiple search keywords in the document on the display, wherein terms in a respective chunk that satisfy the search keywords are either ordered differently from the search keywords in the user-specified text string or separated from one another by at least one term that does not satisfy any of the search keywords.