You are looking for exam papers for PG exams with solutions. For solutions, it is easier to buy books online.
A. JIPMER PG entrance exam papers
You want JIPMER PG papers with explanations. You can try Target Jipmer Pgmee set Paperback – 2017
by Arun Babu (Author). This has questions and the answeres with explanations.
B. FOR AIIMS
You need to register in this site to get 5 years PG entrance exam papers (https://www.educationobserver.com/forum/showthread.php?tid=17508).
This is the link for PDF AIIMS 2016 PG paper(https://drive.google.com/file/d/1l7Qu6J0TXsgF_s2ltMGaI1rzbotNYbM5/view). Some papers from 2001 to 2017 can be checked on this site (https://www.examtime.co/aiims-pg-question-paper/).
This site (https://www.aim4aiims.in/pg/download.php) has many free downloads. we get PDF files like this one from 2010 (https://www.aim4aiims.in/download/9159faca9ed9233.pdf).
C. DNB CET old PG questions papers
This site (http://www.oldquestionpapers.net/dnb-cet-question-paper-answer-previous-year-old-papers) has some subject wise that you can browse.
This site needs a registration (https://www.jbigdeal.in/dnb-cet/#DNB_CET_Previous_Year_Question_Papers) for old papers.
D. NEET PG question papers and practice papers can be downloaded from here.
E. Some books with explanations can be found in
1.Review of PGI Chandigarh Paperback – 2018 by Mukhmohit Singh (Author), Shveta Saini (Author)
2.PGI Chandigarh – (Volume - 1: 2016-2012) (Postgraduate Medical Entrance Exam) (SEVENTH EDITION) by Manoj Chaudhary
3. AIIMS PGMEE November 2017 Perfect Paperback – 2017 by Dr. Sandhya Gaur Dr. Apoorv singh (Author).
4. AIIMS PGMEE SOLUTIONS VOL-1A VOL-1B (2016-2013) Paperback – 2017
by Amit Tripathi Ashish Gupta (Author)
5. Self Assessment & Review of DNB-PDCET, DNB-CET, JULY 2013 : for DNB-PDCET, DNB-CET AIPGMEE (New Pattern), AIIMS and Regional PGMEEs (DNB - PDCET AND DNB - CET) Paperback – 2013
by Alok Aggarwal (AA) (Author), D. K. Taneja (Foreword)
6. A Complete Guide To Dnb–Cet (2011 – 2000): Fully Explanatory With References From Latest Edition Of Standard Textbooks Paperback – 2013