would someone please check over my paragraphs for any grammatical errors, and more importantly, correct sentence structure? I was told I was bad at both...

thank you so much in advance!

The case of scientific fraud I would like to discuss extensively is the case of John Darsee, a medical researcher who deliberately fabricated data for over half of his 100 abstracts and publications. (source here) Dr. John Darsee has been a renowned researcher for over fourteen years, working at two different medical research centers, as well, he has conducted studies and research at Harvard University, where he was caught faking data in a heart study. (source data). More specifically, during his study of testing heart drugs on dogs at the National Institute of Health, the abstract he was preparing did not have an accurate data supporting it. (source here) Three fellow colleagues spotted Darsee falsely recording the time period with his experiment. (source here) He would record the data at various of time intervals such as one hour, 24 hours, two weeks, but in reality, only minutes have passed in the actual experiment. (source) When confronted, Darsee admitted to fabrication and assured his director of the lab that it was an isolated incident.

However, that was not the only incident in which Darsee had deliberately published results in which he knew to be false. In the next months, the results Darsee has provided from four different labs in the National Heart Lung and Blood Institute (NHLBI) seemed too good to be true, and the sincerity of his work was once again questioned. (source) The follow-up investigation and the evidence proved that he indeed, once again has fabricated his data. Consequently, Darsee lost his research position, lost his funding, and lost his reputation. (source)

Your worst problem seems to be consistency in verb tenses. Be sure that if you are speaking in the past, you use the past tense.

Before this sentence you need a general sentence about the pervasiveness of scientific fraud....

An outstanding case of scientific fraud involved John Darsee, a medical researcher who deliberately fabricated data for over half of his 100 abstracts and publications. (source here) Dr. John Darsee had been a renowned researcher for over fourteen years, working at two different medical research centers; as well, he hadconducted studies and research at Harvard University, where he was caught faking data in a heart study. (source data). More specifically, during his study of testing heart drugs on dogs at the National Institute of Health, the abstract he was preparing did not have an accurate supporting data . (source here) Three fellow colleagues spotted Darsee falsely recording the time period involved in his experiment. (source here) He would record the data at various of time intervals such as one hour, 24 hours, two weeks, but in reality, only minutes had passed in the actual experiment. (source) When confronted, Darsee admitted to fabrication and assured his director of the lab that it was an isolated incident.

However, that was not the only incident in which Darsee had - delete deliberately published false results delete (he knew to be false). In the following months, the results Darsee provides from four different labs in the National Heart Lung and Blood Institute (NHLBI) seems too good to be true, and the sincerity of his work is once again questioned. (source) The follow-up investigation and the evidence prove that he indeed, once again has fabricated his data. Consequently, Darsee lost his research position, lost his funding, and lost his reputation. (source)

Were it I, I would put in a final comment about the dangers in scientific fraud....

Repost if you have further questions.

thank you!

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Sure, I'd be happy to help you check your paragraphs for any grammatical errors and sentence structure. Here is the revised version of your paragraphs:

The case of scientific fraud I would like to discuss extensively is the case of John Darsee, a medical researcher who deliberately fabricated data for over half of his 100 abstracts and publications (source here). Dr. John Darsee has been a renowned researcher for over fourteen years, working at two different medical research centers. He has also conducted studies and research at Harvard University, where he was caught faking data in a heart study (source data). More specifically, during his study of testing heart drugs on dogs at the National Institute of Health, the abstract he was preparing did not have accurate data to support it (source here). Three fellow colleagues spotted Darsee falsely recording the time period for his experiment (source here). He would record the data at various time intervals such as one hour, 24 hours, and two weeks, but in reality, only minutes had passed in the actual experiment (source). When confronted, Darsee admitted to fabrication and assured his lab director that it was an isolated incident.

However, that was not the only incident in which Darsee had deliberately published results that he knew to be false. In the following months, the results Darsee provided from four different labs in the National Heart Lung and Blood Institute (NHLBI) seemed too good to be true, raising doubts about the sincerity of his work (source). The subsequent investigation and evidence proved that he had once again fabricated his data. As a consequence, Darsee lost his research position, funding, and reputation (source).