The second phase, usually lasting a year, involves studies of the drug's effectiveness in limited clinical trials.

None of the games are entirely free but all offers a limited trial for testing purposes.

So, he said: "A number of centers did limited trials with living unrelated donors.

"These limited trials can't be the mechanism to bring about justice," she said.

As of late 2012, only staff and a small number of customers on a single exchange had participated in limited trials.

Under a special humanitarian rule for rare diseases, only limited clinical trials were required.

The new stock was considered to be a limited trial.

Instead of starting with this large scale project, we ought to begin with a more limited trial.

But because fibrillation is so dangerous, scientists can conduct only limited human trials.

As of 2011, only limited human trials had been performed.