Dear Nitya

Go to https://scholar.google.co.za/scholar?as_q=health+policy+Impact+Evaluation&as_epq=+age+structure+transition&as_oq=&as_eq=&as_occt=any&as_sauthors=&as_publication=&as_ylo=&as_yhi=&btnG=&hl=en&as_sdt=0%2C5

I used the search:  health policy Impact Evaluation " age structure transition"

and found 80 papers. I have not looked at them.

Thanks Graham. I was not aware that " " can change search pattern. 

Thanks Gulzar. I will have a look

Dear Nitya

There is an advanced search panel on Google.Scholar..see attached screenshot.