I use the amsmath package and when I put fractions (especially partial derivatives) into a matrix, the entries are very tightly packed and sometimes even overlap. Does anyone know a way to fix the spacing to make it look nicer?

Also, the fractions are always small, is there a way to make them larger (aka, display size)? I've tried \dfrac, and that does make them bigger, but then the spacing problem above becomes even worse as it doesn't seem like the matrix knows it's entries are larger.

Thanks!