jQuery selector to a specific string

I have a string variable which contains HTML tags. Is it possible to the jQuery selector to pick a certain HTML element?

To be more specific,
I have a javascript variable which contains a row of a table
<TR><TD>value1</TD> <TD>value2</TD> <TD>value3</TD> <TD>value4</TD> <TD>value5</TD></TR>
How can I the value of third TD's value, i.e., value3

Thanks,
Madhu