Dear Hailu Kendie Addis Is this what your are looking for?https://www.elsevier.com/connect/reviewers-update/introducing-reviewer-hub#:~:text=Complimentary%20access%20to%20ScienceDirect%20and,have%20accepted%20your%20review%20invitation.
It looks like an incentive for reviewers (of an Elsevier journal).
The information provided by Rob Keller seems to be for more than one day. Thank heavens for that! I think of something one day and by the time I read it and think of more related questions or note articles to look for, it is usually more than one day later!
It is usually a 30 day, but my question is that can I get free access to those journal articles which had been published by Scopus in the specified period?
Dear Hailu Kendie Addis If you refer to the link I provided in my previous reply then it means you have 30-days of full access to the papers included in ScienceDirect. This means all journals published by Elsevier (I presume all papers published in the past until now).
Access to Scopus means that you can access all the info (citations and other metric info) provided by Scopus. Scopus includes all journals, but the access to the full text is 'limited' to the ones you can access in ScienceDirect (so all papers published by Elsevier and not to those published by others).