992 resultados para 171-1052A


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Strontium concentrations and 87Sr/86Sr values were measured on pore-water and sedimentary carbonate samples from sediments recovered at Sites 1049-1053 on the Blake Spur during Ocean Drilling Program Leg 171B. These sites form a 40-km-long depth transect extending along the crest of the Blake Spur from near the upper edge of the Blake Escarpment (a steep cliff composed of Mesozoic carbonates) westward toward the interior of the Blake-Bahama Platform. Although these sites were selected for paleoceanographic purposes, they also form a hydrologic transect across the upper eastern flank of the Blake-Bahama Platform. Here, we use pore-water strontium concentrations and isotopes as a proxy to define patterns of fluid movement through the flanks of this platform. Pore-water strontium concentration increases with depth at all sites implying that strontium has been added during sediment burial and diagenesis. The isotopic values decrease from seawater-like values in the shallow samples (~0.70913) to values as low as 0.707342 in one of the deepest samples (~625 meters below seafloor). The change in pore-water strontium isotopic values is independent of the strontium isotopic compositions predicted from the host sediment age and measured on bulk carbonate in some samples. In most cases the difference between predicted sediment strontium isotopic composition and measured value is less than ±2 about the mean of the measured strontium value. Both the increase in concentration and the decrease in the strontium isotope values with increasing depth indicate that strontium was expelled from older carbonates. The strontium concentration and isotope profiles vary between sites according to their proximity to the Blake-Bahama Platform edge. Profiles from Site 1049 (nearest the platform edge) show the greatest amount of mixing with modern seawater, whereas the site most distal to the platform edge (Site 1052) shows the most significant influence of older, deeper carbonates on the pore-water strontium isotopic composition.

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Contenido: Naturaleza del conocimiento humano : el significado de la abstracción en Santo Tomás (I) / Octavio Nicolás Derisi – El hombre, sujeto de la educación, en la perspectiva de Tomás de Aquino / Silvana Filippi – Premisas metafísicas de la bioética / Alberto Caturelli – Tecnociencia, eticidad y fecundación “in vitro” / Carlos I. Massini Correas – La causa eficiente en Descartes / Javier Fernández Aguado – Notas y comentarios -- Bibliografía

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Viruses, which are characterised by a relative simplicity of chemical composition, are involved with all the groups of the animal and plant world. The discovery of viruses of lower organisms has special interest. Along with the already known viruses lysing bacteria and actinomycetes, viruses have been discovered in recent years which lyse algae. During investigations of water from water-bloom patches and of mud taken from zones of massive accumulation of blue-green algae in the Dneprovsk reservoirs, the authors obtained viruses lysing algae. The revealing of viruses producing lysis of blue-green algae, which one could use in the control of water-blooms, has the greatest interest. With this aim, samples of water were collected from various zones of water-bloom patches in the Kremenchug, Dneprovsk and Kukhov reservoirs. For viruses lysing algae we propose the name 'algophages'. Along with the existence of viruses of algae of the phage type, one cannot deny the possibility of the existence of viruses of another type, multiplying in the cells of algae and causing their virus illnesses.

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在中国原子能科学研究院的HI 13串列加速器上通过157Gd(19F,5n)171Ta重离子熔合蒸发反应布居了171Ta的高自旋态,以多普勒移动衰减法的峰形分析法分析了171Tah9/2质子1/2[541]转动带的6条能级的寿命,得到了这6条能级的平均寿命值.

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Park Service Thwarts Cat Allies, by Marilyn Davis, Native Species Network, Bodega Bay, California Jim Miller Elected VP of Wildlife Society ADC Aerial Hunting Accident Kills 2 Obituary: Carl R. Gustavson HSUS Former Employee File Lawsuits Rats Shut Down Internet at Stanford Call for Papers: A Symposium on Mammal Trapping August 1997 in Edmonton, Alberta Fur in Cyberspace: The Fur Institute of Canada announces it has established a site on the World Wide Web, at the following address: http://www.fur.ca. Book Review: Beaver and Otter: Open Water Techniques, by Charles Dobbins 1992. Beaver Pond Publishing and Printing, P.O. Box 224, Greenville, Pennsyulvania, 16125. 114 pages. American Association of Wildlife Veterinarians: Resolution on Management of Feral Cats Use of Zinc Phosphide for Marmot Control, by Mark Collinge, NADCA Northern Rockies Region Director, USDA-APHIS-ADC Cat Colony Ordinance Adopted by Santa Clara County, California