100% jpeg quality is probably overkill, and resolution is meaningless here. Quality can be affected by several other parameters. Can you post a screenshot of the export dialog? What are the dimensions of the exported jpeg in terms of pixels?
Do you have Resize to fit checked? If so, what pixel dimensions are you exporting to?
And how are you comparing the two images? To do a valid comparison, and to evalute sharpening properly, you need do view the images at 100%.
Jpg uses lossy compression, and even at 100 quality there may be some visible image degradation.
It would be good if we could see your export settings. I can compare JPEG images exported at quality setting 100 or 80 And can see no difference in image quality, at least on my monitor. Is there any chance you are exporting as original?
Your indications are not giving the information we need to advice on your problkem. A screen shot and the final image would however be welcome.