Yes, you can register for the UGC NET Exam even if your post-graduation degree is not complete yet but you have the mark sheets of previous semesters. Here are the details:

Eligibility Criteria for UGC NET Exam:
To be eligible for the UGC NET Exam, candidates must meet certain criteria set by the National Testing Agency (NTA). The eligibility criteria include educational qualifications, age limit, and other requirements.

Educational Qualifications:
According to the NTA guidelines, candidates must have a master's degree or equivalent from a recognized university or institution. The degree should be in a subject that falls under the UGC NET exam's list of subjects. Candidates must have obtained at least 55% aggregate marks (50% for reserved categories) in their master's degree.

Explanation:
In your case, if you have completed the required number of semesters of your post-graduation degree and have the mark sheets for those semesters, you can still apply for the UGC NET Exam. The NTA considers the completion of semesters as equivalent to a completed degree for the purpose of eligibility.

Procedure to Register:
To register for the UGC NET Exam, follow these steps:

1. Visit the official website of NTA.
2. Look for the UGC NET Exam registration link and click on it.
3. Fill in the required details such as personal information, educational qualifications, etc.
4. Upload the scanned copies of your mark sheets for the completed semesters.
5. Pay the registration fee online through the available payment methods.
6. Submit the application form and take a printout of the confirmation page for future reference.

Important Points to Note:
- It is essential to carefully read and understand the eligibility criteria mentioned on the official website before applying for the exam.
- Make sure to keep all the necessary documents, including mark sheets, ready while filling out the application form.
- Contact the NTA helpline or email support if you have any doubts or queries regarding your eligibility or the registration process.

By following these guidelines, you can successfully register for the UGC NET Exam even if your post-graduation degree is not complete yet but you have the mark sheets of previous semesters. Good luck with your exam preparations!