When writing an email asking for PhD positions/projects

I've recently finished in Masters in Neuroscience in Germany ( & bachelors in pharmacy), and I'm trying to find a PhD position in European countries like Belgium, Sweden, Switzerland, etc. In most of them, I have to contact the professor I'm interested in working with myself. I've already emailed a lot of them ( app. 20, with 6 replying no positions available).

-The problem is, I'm afraid if my emails are too generic. Here's the part from my emails where I have some concerns:

"As you will see in my resume, I have steadily oriented my education and experience towards becoming an accomplished researcher of regenerative medicine/technologies for the nervous system. Being a pharmacy & neuroscience graduate gives me a unique perspective that is useful when exploring the regenerative capacity of the nervous system, whether through manipulating neurons directly, manipulating surrounding glia, or the use of stem cells."

For the rest, I clearly stated that I'm looking for a possible position in their group, what my previous accomplishments are, as well as who I am in a brief description. Naturally, I only emailed professors whose research I like and is linked to what I want & mentioned in this paragraph. So, is it inferred that I like their research/field, or is it still to generic?

Of course I read their about their projects on their group pages, but I'm not sure if I can go as far as reading their articles, since it would take too long, they may have no positions, and I don't know how many should I contact. So I wrote it in a more general manner, and if a professor/group leader expressed interest, then I would read in a lot more detail about their work (their articles & reviews). But is this truly the only way for them to consider someone?

-Another point is how many emails. One acquaintance mentioned that he had to send upwards of 300 emails to find a position. I simply can't believe he can send that many emails, without them being a single copy, but with each professor's name. I think it would be in the range of 20-50 emails, but that's pure conjecture on my part. I need to know from your experience, since if they're not so many, then I can read more about the professor's work in detail.