There is probably no other section in a scientific manuscript that is more overlooked than the Keywords section. After all of your work to do the research, analyze the results, and put together the paper, little thought and attention is paid to this seemingly trivial portion of your paper. However, this section is far from trivial and selecting good keywords is essential for getting your work noticed and cited. Here are some tips on selecting good keywords:
1) Techniques/methods - This can be a good place to start, but you need to be careful that your technique is not something that is extremely widely used (e.g., western blot or PCR).
2) Words Related to Your Main Research Topic - This is where most of your keywords will come from. If you are talking about Alzheimer's then some keywords could be neurodegenerative disease, dementia, memory loss, etc.
Note: Some journals request that the keywords not match any words in the title, so please be cognizant of that. If this is not the case, you may benefit from using a keyword(s) that are present in both your title and/or Abstract, as some search algorithms will show a preference for these papers.
Note: As mentioned above, make sure that your keywords are not too broad. All too often people select terms like 'protein' or 'DNA' or 'growth', which will not help readers find your work.
In the end, you want to think about what your potential readers will search for if they were looking for a paper like yours. Good luck!
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