However, often I do not hear from them even after two weeks
If what you are asking needs a response, talk to them. Many people won't read an email in depth to see there is something they need to do, or will have "conveniently" missed that part of the mail.
In consultancy people are usually taught to discuss with the person they are asking, then if necessary send an email to document the ask, and this is a good way to work. Just requesting and sitting back is not a good way of proceeding (if the person is remote from you you may need to email, but try and have the conversation by phone/skype etc).
If the matter isn't urgent, wait until your next standup/progress/status meeting and ask the person if they can give you a couple of minutes at the end to cover something, so as not to interupt their work.
Would the above be appropriate?
This is a passive-aggressive way of saying you expect them to jump at your request, just ask them. If they are too busy, agree when would be appropriate to discuss.
As a developer of 20+ years (and a bit of an introvert myself) I understand, but as someone who primarily coaches teams on improving development (usually Agile), I can say it's a major mistake, and the reason why so many projects fail to deliver. It's always the hardest thing for teams, but face to face is by far the best way to communicate. With Agile teams I push whiteboards and stickys rather than Jira etc for the same reason, we get teams to collaborate, and that's 90% of the issues with teams, always.