The different brokerage firms will produce their own in-house research reports on selected SGX-listed companies.
You can access the various research reports if you have a trading account with the respective brokerage firms.
Another way is to visit The Society of Remisiers website, which holds the research reports of all the brokerage firms.
However, it seems that they only store the reports for the last thirty days. Well, at least it is still quite useful to be able to find all the reports at one central location.
The website lists the research reports by the dates on which they are released, so it will be easier to find what you want using the search function.