Once you have submitted your thesis, you may want to publish the results of your research in various ways. Before making your thesis available online, you should consider whether it is appropriate to publish/ deposit your thesis online and/or whether a period of embargo or restricted access would be best. Publishers are aware that students must generally publish their theses online so if you have a publication in the works or an intended outlet for a proposed publication, you should check that publisher's and/or that specific journal's guidance on this. When submitting your article, you should make sure that the publisher is aware that some material will be from / based on your thesis. It is up to the journal to make a call as what they feel is acceptable.
An interesting article from the UCL Library in their series on 'E-theses Best Practice Summaries' refers to the 'Impact on Future Publication': Brown, J.; Sadler, K.; (2010) Impact on future publication. (E-theses Best Practice Summaries ). UCL (University College London)