A big part of life boils down to one word: priorities. Any parent, male or female, has to realize that as much as he or she wants to sink into his or her job, some time and energy has to be set aside for the family. You'll even find that your coworkers respect people who have their priorities straight, just as people respect those who take care of themselves and don't slave away like martyrs. Of course, you're a responsible, honest worker, but once you get home, you set boundaries and you tell yourself, "Now it's family time."
Before you leave work, write down a list of what you need to do the next day, so you won't be tempted to check in after you get home. On the ride home, continue your transition from doctor/CEO/lawyer/hairdresser to Mommy, particularly trying to relax and put any work-related unpleasantness out of your mind so any bad mood or tension doesn't spill over onto your family.
Unless you're being paid to be available 24 hours a day (you're a midwife or you offer computer technical support around the clock), turn off your cell phone and Blackberry when you come home. During dinner time and bedtime, you can even unplug your regular phone, too. Usually, whatever comes up at work during off-hours can be dealt with the next morning, but your children's feeling that they're not as important as your clients or work are not so easily fixed.
If you feel that you just can't keep up with your workload unless you steal time from your family, you might try implementing time-management techniques at work to maximize your time there, or speak to your boss about reviewing your workload to see if it's excessive.