Note 14 - Stock Based Compensation - Stock-based Compensation Expense (Details) - USD ($)	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Stock compensation expense	$ 639,751	$ 687,752
General and Administrative Expense [Member]
Stock compensation expense	449,944	483,000
Research and Development Expense [Member]
Stock compensation expense	$ 189,807	$ 204,752

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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