Cystopteris tennesseensis Confirmed Extant in Maryland
نویسندگان
چکیده
منابع مشابه
Sperm removal during copulation confirmed in the oldest extant damselfly, Hemiphlebia mirabilis
Postcopulatory sexual selection may favour mechanisms to reduce sperm competition, like physical sperm removal by males. To investigate the origin of sperm removal, I studied the reproductive behaviour and mechanisms of sperm competition in the only living member of the oldest damselfly family, Hemiphlebia mirabilis, one species that was considered extinct in the 1980s. This species displays sc...
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Question 2 (25 points) Consider the problem of minimizing the cost of producing some output level Y . The firm uses two inputs, labor (L) and capital (K), which can be combined to produce goods according to the production function f (L,K) = LαK1−α, α ∈ (0, 1). The effective amount of labor that is used in production is determined as L = l× t, where l is the number of workers hired, and t is the...
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Pharmacological activity (e.g. antipsychotic ac tion [1]) and chemotaxonomic interest of xanthones may explain the increasing interest in these substances in recent years. It has been suggested [2] that Cystopteris fragilis complex is the most inter esting biosystematic problem in ferns. Xanthone analysis may be of interest in the study of relation ships of the taxa of this complex since pre...
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ژورنال
عنوان ژورنال: American Fern Journal
سال: 1989
ISSN: 0002-8444
DOI: 10.2307/1547295