It's true that - sadly - the modern office environment has become a minefield of distractions! You simply can't shut yourself away from it completely. However, there are a few techniques to help you. Here are some:
1. Be an early riser: If you're able to get to work early, this could be your best time to get quality work done and get ahead of the game before distractions start pouring in and derail you from your work. Of course, you have to be disciplined with yourself and not waste these early hours checking e-mails or surfing the net; make them truly productive hours.
2. Stop ALL *optional* notifications: There are some notifications that you can't turn off (e.g., your office ringing, or your boss calling you!). However, there are a lot of optional notifications that you can turn off, e.g., alerts from your mobile phone, notifications on your desktop computer, etc. Turn these off! They'll reduce the urge for you to stop your work and go check the latest e-mail. Which reminds me...
3. Don't check e-mail ALL the time: The world won't stop if you don't check your e-mails. Trust me. I tried it. Things will move on. So don't be obsessed about checking your latest e-mails every 5 minutes. Check e-mails at certain reasonable intervals (e.g., every hour or 2 hours, etc.).
4. Ask your colleagues/boss for some quiet time: Sometimes simply asking your colleagues/boss to leave you alone a bit to focus on an important piece of work can work. You'll never know till you ask. Make it a regular habit (every morning from 8am - 10am, you'll be working on a particular project and need your colleagues/boss to understand to give you some quiet time to get the work done).
5. Work in Pomodoro sessions: I've spoken about Pomodoro technique before, the technique where you work on a single task for 25 minutes then take 5 minutes break. You can use this at work as well. During those 25 minutes, you can close your door (if you have an office) or put up a sign saying you're busy for 25 minutes, close all notifications, unplug the phone if you have to and simply sit down and get work done.
A lot of times we tend to invite the distractions in our lives without us knowing, then we blame everyone when we're not focused or when we're distracted. It's time that you take ownership of your focus and career and not let the distractions around you stop you from being productive.