(here B, C and D are some names, and 'stone theorem' and 'the cake process' also represent something else, but it is not important for the structure) Question: is it ok to use a past tense in the first sentence which refers to 1978, but use a present tense in the second sentence which describes something that happened relatively recently, in 2014?
It's perfectly fine to use the present tense for all research, even going back to ancient times; see here for another question about this.
When you are writing a paper, try to get your ideas across in such a way that the audience will understand them effortlessly, unambiguously, and rapidly.
To this end, strive to write in a straightforward way.
However, there is a way that you can usefully shift tense in a literature review in a scientific paper.
You can use the present tense for recent research that is still a topic of current conversation—especially if your paper extends or contradicts that research.This trick will probably have no effect on non-native speakers, who are usually oblivious to the difference between the simple past and the present perfect.And most native speakers do not consciously understand how they exploit these differences in tenses.However, if you are citing articles in the paper, as you probably should, then you should check with your professor to see if he or she would prefer that you use the literary present or the past tense when referring to these articles..pass_color_to_child_links a.u-inline.u-margin-left--xs.u-margin-right--sm.u-padding-left--xs.u-padding-right--xs.u-relative.u-absolute.u-absolute--center.u-width--100.u-flex-inline.u-flex-align-self--center.u-flex-justify--between.u-serif-font-main--regular.js-wf-loaded .u-serif-font-main--regular.amp-page .u-serif-font-main--regular.u-border-radius--ellipse.u-hover-bg--black-transparent.web_page .u-hover-bg--black-transparent:hover. The cut-off point for "recent"—that is, the present—is "present conversation".The present perfect is a convenient way to suggest that the matter is still "open" and that your paper is going to make a contribution to it.In the present paper, we prove that stones in non-random cakes are indigestible.Switching to the various forms of the present tense suggests that the research in those tenses is more directly relevant to the "present" paper—that is, yours.There is no need to write about science in unusual, complicated, or overly formal ways in an effort to "sound scientific" or to impress your audience.If you can tell a friend about your work, you are off to a good start.