How to convert pdf to tiff as if it is done in Acrobat?

Hi,

For example, I have
https://rapidshare.com/files/4005872511/number_of_sites_nofilter.pdf

Acrobat can convert it to the following tiff file
(File->Export->Image->TIFF and then selection resolution 300).

https://rapidshare.com/files/3958086688/number_of_sites_nofilter1.tiff

I use the following IM command to convert the pdf to a tiff file with
the same resolution. But the resulted file is too big and the
characters are shown differently when you look at it at a magnified
scale.

convert -monochrome -density 300x300 -resize 300%
number_of_sites_nofilter.pdf  number_of_sites_nofilter.tiff

Does anybody know what I options of convert I should use to get the
same conversion as Acrobat?

-- 
Regards,
Peng