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Report On The Nest Record Scheme, 1958, by J. F. Burton  相似文献   

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The small size of insects, correlated with high food-consumption,growth, and metabolic rates, makes possible their high efficiencyof food-utilization, short life cycles, high biotic potential,and rapid genetic adaptation and speciation. Most of the qualitativenutritional requirements are known for many insect species;many essential nutrients are provided by microbial symbiotes.Recent studies in quantitative nutrition make possible moredetailed analysis of the utilization of food, of the kineticsof growth and metabolism in intact animals, and of the controllingmechanisms in the animal-food interaction.  相似文献   

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J. S. Henry 《CMAJ》1943,49(3):167-173
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Terrestrial immigrants from the sea have to cope with two importantnutritional problems: a shift in pathways of absorption, andthe altered availability of nutrients. The more terrestrialspecies of littoral crustaceans switch to food as the main sourceof water and salts. No serious difficulties accompany the oraluptake of mobile ions, but the vegetarians amongst the immigrantsare required to assume a new attitude with regard to the assimilationor heavier metals. Some important heavy elements, notably Cuand Zn, are soluble in sea water but form rather intractableorganic complexes in plant tissues. Herbivorous amphipods andisopods on land are incapable of extracting copper directlyfrom their primary food sources. To compensate for this shortcoming,help is enlisted from microorganisms, which render the copperpresent in ill-digested fecal material available to the crustaceans.Moreover, in terrestrial and intertidal herbivorous crustaceans—ascompared with their marine relatives—the storage capacityof the hepatopancreas, as well as the efficiency of Cu-assimilation,is augmented; compartmentalization of Cu-storage is more rigorouslycarried through; the movements of Cu and Zn within the bodyare more strictly regulated, copper, for example, being exchangedbetween different compartments in the course of endogenouslyor exogenously induced phases of the animal's life cycle.  相似文献   

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Abstract

New routes to the preparations of 2′-deoxy-3′-C-methyl uridine (2c) and 1-(5′-0-trityl-3′-deoxy-β-D-glycero-pentofuran-2-ulosyl)uracil (4) from 5′-0-trityl-2′-0-tosyl uridine (1) and 5′-0-trityl-3′-0-tosyl uridine (3) respectively are described.  相似文献   

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SYNOPSIS. Three hundred and fifty-seven reptiles belonging to 15 species (11 genera, 7 families) from the Pacific Northwest were examined for haematozoa. Twenty-six (7.3%) had parasites. Eleven (3.1%) were infected with haemogregarines, 6 (1.7%) with microfilariae and 9 (2.5%) with unidentified organisms. Four species of snakes and 4 of lizards were positive. Several forms of haemogregarine from the Pacific gopher snake ( Pituophis melanoleucus catenifer ) are described.  相似文献   

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