Unique Development in Hemichordates Suggests Some Unique Features of Chordates
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Unique Development in Hemichordates Suggests Some Unique Features of Chordates
-Three hundred and nineteen patients with primary adenocarcinoma of the ovary were studied to define those factors, many of them histopathological, which influence survival. The paper considers the stage of spread at the time of operation, the histological type of the tumour, its grade and in particular its mitotic activity, which proved a significant feature per se in assessing prognosis in ov...
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Four chordate characters — dorsal hollow nerve cord, notochord, gill slits, and endostyle — are compared morphologically, molecularly, and functionally with similar structures in hemichordates to assess their putative homologies. The dorsal hollow nerve cord and enteropneust neurocord are probably homoplasies. The neurocord (= collar cord) may be an autapomorphy of Enteropneusta that innervates...
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The simplest type of integral extension of a unique factorization domain B is obtained by adjoining to B an n-th root of one of its elements; that is, by forming the ring Bn = B[z]=(z n g), where n 2 Z and g 2 B. When n = 1, Bn = B. When n 2 it is natural to ask for what g 2 B will unique factorization be preserved? The case where B is a polynomial ring over an algebraically closed eld k immedi...
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ژورنال
عنوان ژورنال: PLoS Biology
سال: 2006
ISSN: 1545-7885
DOI: 10.1371/journal.pbio.0040288