USA has access to all volumes of the ACS journals, but not to the books. To find only fulltext articles, follow directions on this page for limiting to journals.
If you choose not to limit to journals, when you get your results lists you will see book chapters and other non-fulltext material. Look for the green page with gold key icon and the note "Subscriber Access" for items that are fulltext.
On a page with mixed results, look for the green page with gold key icon to identify subscribed fulltext. To limit to journals only, look at the column on the left of your results page and click on "Journal Article."