Yes, and a lot of people do this with 220/240 and their electric close dryer outlet. Couple things to keep in mind.
1. Always have everything turned off when working with a cord with two male plug ends. Otherwise, when one end is plugged and the other isn't, you have a nice arc welder. A few extra minutes of running up and down your stairs may save your life.
2. Let the generator warm up first (see #4), then shut down and g to #1. Otherwise, when the furnace blower surges and your generator dies, you get to undo/redo #1 a few more times.
3. Typical master switch on your breaker panel is not really designed to prevent electricity inside your house from going back out onto the grid. This means, you might actually injure the people trying to fix your electricity. Lawsuits? might just want to wire in a outlet for your furnace and run only the furnace and fridge etc. directly from generator bypassing house wiring.
4. Most generators in the 3500 W range are really alternators, not generators. This means as long as your generator is perfectly tuned and running at the correct RPM the frequency of your electricity is good. Otherwise, not so much. So, I generally recommend run your furnace and your fridge/freezer, and not your expensive electronics that prefer clean electricity.