The adapter you listed is made for doing the opposite of what you wish to do: It is made for using C-mount cameras with DSLR lenses.

There are a couple of issue with doing what you want that make it problematic:

• The C-mount registration distance (a/k/a flange focal distance a/k/a distance from the film/sensor to the lens mounting flange) is 17.526mm. The registration distance for most DSLRs is around 42-47mm. That means an adapter would need to have a negative thickness to use a DSLR on a C-mount lens or microscope. Since that is physically impossible, any such adapter would need additional optical elements to correct for the disparity in registration distance and a correction for that large of a difference would be severely detrimental to image quality.
• The image circle projected by a C-mount lens is anywhere from 5mm to 22mm wide, depending on the particular format for which it is intended. Systems that use C-mount connectors range from 8mm and 16mm movie cameras to 1/3", 1/2", 2/3", 1", and 4/3" video formats. (For more on the ramifications of this, please see this wikipedia article for C mount.) Even at the largest, 22mm is only about half the length of a 35mm film frame diagonal. That means that at best you can only use the center one-fourth or so of your FF DSLR's pixels when connected to a C-mount coupler without introducing additional optical elements to expand the image circle. Just like using a teleconverter with a DSLR, this would introduce additional optical aberrations and spread the light thinner. A 2X teleconverter makes a lens two stops slower, or one-fourth as bright, than the same lens without the TC.