Question 1

Answer to Q1

Accepted Answer

A journal article, a thesis, and conference proceedings are primary literature sources because they present original research on the topic and include novel, never published in the past, experimental results. 
 
A journal review article and a book are secondary literature sources. And Wikipedia article is a tertiary source. They summarize and analyze primary literature. They are less current because they need a collection of published primary literature to build their study.

Question 2

Answer to Q1

Accepted Answer

“Dopamine receptors”and “D3 D2 receptors” are good keywords combinations to start with and then we can narrow down the results by using the keyword “drug addiction”. If we start from the keyword “drug addiction”, we may get results focused on this disease but our focus is receptors.  Keyword “dopamine” is too broadly defined and may lead us to an excessive number of articles. Dopamine receptors do bind dopamine but to answer the  above research question, we need to specifically focus on receptors.

Question 3

Answer to Q2

Accepted Answer

Did you suggest something like: substance abuse, drug abuse, substance-related disorder, substance addiction, dopamine-related disorder, dopaminergic disorder? Those would be good alternative combinations.

Question 4

Answer to Q2

Accepted Answer

A Wikipedia article is a popular (non-scholarly) source. Anyone can write/contribute to writing a Wikipedia article and we do not know if authors are necessarily scientists and experts in the field. Its structure is flexible. The bibliography section is limited and sometimes absent. 
A journal review article, a journal article, a book, a thesis, and conference proceedings are all written by experts in the field and thus are 
scholarly
 sources. Conference proceedings in the form of the poster presentations often include captivating images but they use scientific jargon and have a list of references to other scholarly sources.

Question 5

Answer to Q3

Accepted Answer

In 2020, SciFinder and Reaxys are the top two databases for chemistry research. They contain a set of specialized filters that allow sorting by CAS number, chemical and physical properties, and reactivity. They have a structure editor tool that allows one to draw a structure. But, they require university subscription and can only be accessed at the university library.
PubMed is a database for biomedical and health sciences research but it also has articles in chemistry. Importantly, it has specialized filters, prompts to protein structures data bank PDB, and is free. Try to use it at https://www.ncbi.nlm.nih.gov/pubmed/! ChemNetBase is for material science. Science of Synthesis (SOS) by Thieme is a very good database for organic chemistry but not as comprehensive for other fields of chemistry.

Question 6

Answer to Q3

Accepted Answer

In 2020, SciFinder and Reaxys are the top two databases for chemistry research. They contain a set of specialized filters that allow sorting by CAS number, chemical and physical properties, and reactivity. They have a structure editor tool that allows one to draw a structure. But, they require university subscription and can only be accessed at the university library.
PubMed is a database for biomedical and health sciences research, but it also covers chemistry. Importantly, it has specialized filters, prompts to protein structures data bank PDB, and is free. Try to use it at https://www.ncbi.nlm.nih.gov/pubmed/! ChemNetBase is for materials sciences. Science of Synthesis (SOS) by Thieme is a very good database of synthetic methods for organic and organometallic chemistry, specifcally.

Practice

On Search Strategy

Q. 1

Q. 2