Note 8 - Loss Per Share - Shares Used in Basic and Diluted Loss Per Common Share Computations (Details) - USD ($)		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Net loss attributable to common shareholders per common share: basic and diluted calculation		$ (4,529,317)	$ (3,293,184)
Weighted average common shares outstanding-basic (in shares)	[1]	4,886,328	1,573,152
Effect of diluted stock options, warrants and preferred stock (in shares)	[2]
Weighted average common shares outstanding-diluted (in shares)		4,886,328	1,573,152
Loss per common share-basic and diluted (in dollars per share)		$ (0.93)	$ (2.09)

[1] Includes 1,390,166 contingently issuable shares related to prefunded warrants for the three months ended March 31, 2020.

[2] (2) The following is a summary of the number of underlying shares outstanding at the end of the respective periods that have been excluded from the diluted calculations because the effect on loss per common share would have been anti-dilutive: Three Months Ended March 31, 2020 2019 Options 794,038 407,158 Warrants 5,663,594 595,113 Convertible debt 378,000 504,770 Preferred stock: series B 7,925 7,925 Preferred stock: series D 350,000 - Preferred stock: series E 691,159 -