Whether you are a member of the scientific community or a student looking for help with a dissertation, scientific journals are an excellent way to find information that is both reliable and reputable. These journals have to go through a rigorous review of others from that particular field, known as a peer review, meaning that the information you get to read is always of the highest quality and up to date.
Journals can be published weekly, monthly or even annually; depending on the popularity of the subject, as well as whether there have been any important discoveries or results that have arisen. The journals themselves comprise of a number of useful articles that are written by prominent academics, focussing on the subject that the journal concerns itself with, which makes it extremely useful for those interesting in a particular field.
There are many online resources for accessing these journals, and many require a fee to be paid in order to read them. Alternatively, new open access journals are available from some places, offering a free way to read up on the latest peer reviewed journals. As you would expect, a service that you pay for is superior to one that you do not, and so there are sometimes stipulations attached to the free journals, such as only being able to view the abstracts or those that have been published for more than 6 months.
One matter to consider when utilising the information found in scientific journals is that all such information must be probably attributed to the original author or authors. Without proper references, any information used in such a way would be plagiarism, and if you were a student who was writing up a paper it would be looked upon in the direst of manners. In order to avoid such a situation, it is imperative that the proper care be taken to ensure all relevant parties are recognised.