Note 15 - Income Taxes (Tables)
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12 Months Ended |
Dec. 31, 2020 |
Notes Tables |
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Schedule of Deferred Tax Assets and Liabilities [Table Text Block] |
| | | | | | | | | | | Deferred tax assets: | | | | | | | | | Net operating loss carryforwards | | $ | 34,365,098 | | | $ | 31,966,658 | | R&D credit carryforwards | | | 9,301,709 | | | | 9,150,580 | | AMT credit carryforward | | | — | | | | 310,620 | | Stock compensation | | | 419,654 | | | | 382,016 | | Intangibles | | | 616,926 | | | | 610,783 | | Disallowed interest expense | | | 852,338 | | | | 857,648 | | Temporary differences | | | 267,312 | | | | 333,728 | | Deferred tax assets before valuation allowance | | | 45,823,037 | | | | 43,612,033 | | Valuation allowance | | | (45,823,037 | ) | | | (43,301,413 | ) | Net deferred tax assets | | $ | — | | | $ | 310,620 | |
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Summary of Tax Credit Carryforwards [Table Text Block] |
| | | | | | | | | | | | | | | | | 2001 | | | | | $ | — | | | $ | 39,128 | | 2002 | | | | | | — | | | | 5,350 | | 2003 | | | | | | — | | | | 2,905 | | 2004 | | | | | | — | | | | 22,861 | | 2005 | | | | | | — | | | | 218,332 | | 2006 | | | | | | — | | | | 365,541 | | 2007 | | | | | | — | | | | 342,898 | | 2008 | | | | | | — | | | | 531,539 | | 2009 | | | | | | — | | | | 596,843 | | 2010 | | | | | | — | | | | 1,094,449 | | 2011 | | | | | | — | | | | 1,950,744 | | 2012 | | | | | | 18,898,490 | | | | 468,008 | | 2013 | | | | | | 37,450,522 | | | | 681,772 | | 2014 | | | | | | 34,088,874 | | | | 816,116 | | 2015 | | | | | | 25,073,846 | | | | 492,732 | | 2016 | | | | | | 15,581,209 | | | | 262,257 | | 2017 | | | | | | — | | | | 387,892 | | 2018 | | | | | | — | | | | 197,547 | | 2019 | | N/A | | | | 11,245,808 | | | | 213,065 | | 2020 | | N/A | | | | 11,006,921 | | | | 222,842 | | | | | $ | 153,345,670 | | | $ | 8,912,821 | |
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Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] |
| | | | | | | | | | | | | | | | | | | | Benefit at statutory rate | | $ | (2,390,972 | ) | | | (21.0 | )% | | $ | (2,299,122 | ) | | | (21.0 | )% | Adjustments to valuation allowance | | | 2,521,625 | | | | 22.1 | % | | | 2,355,947 | | | | 15.3 | % | Adjustments to R&D credit carryforwards | | | (151,129 | ) | | | (1.3 | )% | | | (82,706 | ) | | | 6.1 | % | Permanent items and other | | | 20,476 | | | | 0.2 | % | | | 26,588 | | | | 0.3 | % | Provision (benefit) per financial statements | | $ | — | | | | | | | $ | 707 | | | | | |
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