Note 14 - Stock Based Compensation - Stock-based Compensation Expense (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Total stock compensation expense	$ 1,053,496	$ 786,550
General and Administrative Expense [Member] \| Employee Stock Option [Member]
Total stock compensation expense	809,110	621,668
Research and Development Expense [Member] \| Employee Stock Option [Member]
Total stock compensation expense	$ 244,386	$ 164,882

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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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