Hi, Ahmed Towab,
I know that ( research) is generally used as an uncountable noun. However ,in some dictionaries, I find the plural ( researches ) which is rarely used nowadays. My question is :
Is it structurally right to say:
There are five researches available per person.
It is common to say:
There are five pieces of research available per person.
Try to avoid using 'researches'. 'Researches' is rarely used, as you have mentioned, and 'research' (U) is the one that is always used in academic writing. In American English, 'research' is always used as an uncountable noun. See Rachel's reply here:
Form 'Longman Dictionary of Common Errors', page 286:
'Research' is usually an uncountable noun: 'A team of American scientists is carrying out research into the effects of acid rain.'
'Researches' (plural) is also used, especially in formal styles of British English and usually refers to a series of related studies by a particular person or team: 'His researches go back to the 1950s.' 'Their more recent researches point to a decline in the morality rate.' The more usual word for this meaning, especially in American English, is studies.