Of course.
I work in science. Between 2007-2013, the UK gave £78bn to the EU, of which £5.4 bn was earmarked for R&D. The EU funds science based on merit, so the UK does quite well out of the EU R&D budget - over that period we were awarding grants totalling £8.8bn.
Leave the EU and obviously that bonus goes, cutting our funding to ~60% of it's current figure. Funding tends to be awarded in blocks of around 5 years, so 5 years after we leave the EU, jobs are going to start drying up. You can make the argument that leaving the EU would free up funds to match the current investment from the EU, but that's unlikely to reflect reality. The EU's funding of science has doubled in that stated period, whilst the UK research councils have had to fight tooth-and-nail for their funding to stay the same. Over the last 15 years, successive governments have not seen scientific research as worthy of significant investment, despite the fact it has been shown that investing in fundamental science brings sizeable gains to the economy. I can't find the figures, but I've seen quoted that £1 of government investment equates to an economic benefit of £40. Rather than look at what this country achieves scientifically and imagine what could be achieved with more, I've seen government officials muse publicly that cutting UK science funding would spur scientists to achieve the same amount with less. There's no indication that whoever is in government would make any effort to support British science as well as the EU currently does, never mind match the EUs plans for increased funding.
So that's the financial argument, there's also the additional difficulties that Brexit would bring to international collaborations. When the EU funds projects, many grants cover multiple institutions in different countries. Brexit would mean that for the UK to maintain the same degree of collaborations, we would have to get funds for the UK end of the project awarded separately. Winning that grant is a second lottery the overall project has to win, and where possible you'd quite rightly expect EU countries to seek EU collaborators.
So those are the arguments on a large scale, on a personal scale the freedom to move and work around the EU will offer me many more opportunities than I will get within the UK. I'll stand a better chance of a decent career within the EU than out of it. There's other areas of our EU involvement where I have concerns, but they're of a secondary nature.
Given all that, it's highly unsurprising that Brexit is massive unpopular with scientists. I've seen polls showing anything from 80-95% of scientists backing a "remain" vote.