You can answer this question by using the UNT Library Catalog. Let's say you want to find this article at the UNT Libraries:
Russell, W., Gratz, S., Duncan, S., Holtrop, G., Ince, J., Scobbie, L., & ... Flint, H. (2011). High-protein, reduced-carbohydrate weight-loss diets promote metabolite profiles likely to be detrimental to colonic health. The American Journal Of Clinical Nutrition, 93(5), 1062-1072.
Go to the Libraries homepage
Select the Books & Media tab in the central search box, and then select Journal Title from the left drop-down menu
Type in the title of the journal, and Search
Look to see whether the journal is available online, in print, or both. Newer issues are usually in the online version and older issues in the print version.
For online, pick the link that includes the year you need, in this case, 2011. The online journal will open and you can browse to the individual article. Look to the right for the rest of the steps.
For print, look at Library Has: for the year you need, and then select View All Copies to see where the volume is located.