Genera obscura
نویسندگان
چکیده
منابع مشابه
Leonardo and the Camera Obscura
If Leonardo's studies of the camera obscura stand in a well established tradition, they remain important for at least three reasons. One is their sheer quantity: there are no less than 270 diagrams of camera obscuras in Leonardo's notebooks. Second, he uses it to demonstrate a wide range of optical principles: inversion of images, non-interference, images all in all, intensity of light and shad...
متن کاملX-Ray Effects on Drosophila Pseudo-Obscura.
In order to procure new material for the study of problems connected with the non-disjunction of the sex chromosomes in Drosophila pseudoobscura, a series of X-ray experiments was carried out. Among the species of Drosophila,pseudo-obscura is distinguished by the length of itsxchromosome, whose genetic map is the longest recorded in any species (LANCEFIELD 1922). The work of LANCEFIELD has made...
متن کاملAnomalous Chromosome Pairing in the Male Drosophila Pseudo-Obscura.
The chromosome complement The Diptera have not proved to be the most favorable material for the study of chromosome behavior, but the extensive work of STEVENS, METZ, KEUNEKE, and others has shown two exceptional properties in most sections of the order, namely, the pronounced somatic pairing of homologous chromosomes at mitosis, and the apparent lack in the male of the characteristic stages of...
متن کاملMorphometrical evolution in a Drosophila clade: the Drosophila obscura group
Five morphometrical traits (wing and thorax length, ovariole number, and thoracic and female abdomen pigmentation) were investigated in laboratory stocks of 20 species belonging to the Drosophila obscura group (subgenus Sophophora). These species originated from four biogeographical regions and represent all five of the presently recognized, taxonomic subgroups. Size-related traits (wing and th...
متن کاملObscurine: a new cyclostachine acid derivative from Beilschmiedia obscura.
From the methylene chloride extract of the stem bark of Beilschmiedia obscura, a new cyclostachine derivative, obscurine (1), has been isolated, together with six known compounds. The structure of compound 1 was established by spectroscopic methods, including 1- and 2-dimensional NMR techniques.
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ژورنال
عنوان ژورنال: Nature
سال: 1998
ISSN: 0028-0836,1476-4687
DOI: 10.1038/30892