1000 resultados para 81-552A
Resumo:
Auf der 81. Reise des FFS "Walther Herwig" im März 1987 in die Gewässer östlich Schottlands, Irlands und Nordfrankreichs wurden auf dem Nord-Süd-Schnitt "Westbritische Gewässer-östlicher Kanalausgang nördliche Biskaya" zahlreiche Einzelfischproben für die spätere spurenanalytische Bestimmung der toxischen Schwermetalle Blei und Cadmium gezogen. Bei den Proben handelt es sich um den verzehrbaren Anteil (Muskel, Filet) von kommerziell genutzten Meeresfischen, die den Hols lebend entnommen wurden.
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In freshwater environments of modest size and without notable ecological structure, there is usually present only one diaptomid species. When two or more diaptomid species are present in the same habitat, generally their body dimensions are distinctly different. There are only four examples of co-existence of Arctodiaptomus bacillifer (Koelb.) and Acanthodiaptomus denticornis (Wierz.) situated at higher altitudes alpine lakes. The article discusses the results of sampling in the summer of 1953 and the problem of the co-existence of Arctodiaptomus bacillifer, Acanthodiaptomus denticornis and Heterocope saliens.
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The angling census carried out in the Sanyati Gorge, August 1980 - March 1981, is reported. The results are compared to those obtained in the 1973 census. The objectives of the census were: 1) to determine the extent of angling mortality on tigerfish (Hydrocynus vittatus) thereby quantifying this previously neglected component of total mortality; and 2) to assess the economic importance of tigerfish to the recreational fishery on Lake Kariba.
Resumo:
本论文首先介绍了原子核高自旋态研究的一般概况以及其物理解释的基本理论,然后介绍了在束Y谱学及其实验技术。在此基础上分析和讨论了141Nd和142Pm核的高自旋态实验研究。利用能量为75-95 Mevl0F束流,通过反应128Te(19F,5ny)142Pm研究了双奇核142Pm的高自旋态能级结构。实验中进行了丫射线激发函数和Y-Y符合测量。建立了限Pm核高自旋态能级纲图,位于前人建议的一个2毫秒、8-同质异能态之上。由测量的丫射线激发函数和Y一Y符合关系,澄清了一个67微秒同质异能态及其衰变混乱的指定,本论文把67微秒同质异能态及其衰变指定给了142Pm,建议此同质异能态的激发能为2828.5 keV,推断此同质异能态的自旋宇称为13-。在本实验研究的同时,有人利用133Cs(13C,4n)142Pm反应报道了一个建立在2毫秒、8-同质异能态之上的142P亩高自旋态能级纲图;除了相应Y跃迁的多极性有较大差别外,他们报道的瞬Pm高自旋态能级纲图与我们建立在67微秒同质异能态上的基本一致。根据能级结构的系统性,识别了四个两准粒子态,一个为g7/2质子空穴耦合h11/2中子空穴激发,另外三个是h11/2质子藕合h11/2中子空穴多重态成员。根据经验壳模型计算建议了几个新建的关键能级的组态。67微秒同质异能态的组态被建议为一个四空穴态(πg_(7/2)~(-1)d_(5/2)~(-2)vh_(11/2)~(-1))_(13)-。通过130Te(16O,5nγ)141Nd反应布居了14tNd的高自旋态能级。对反应产生的在束丫射线进行了γ射线单谱和γ-γ符合测量。基于γ-γ符合关系,对原来的141Nd的高自旋态能级纲图做了很大修改,建立了14lNd核高自旋态能级纲图。新观察到了一个由八条γ射线组成的长E2级联跃迁,并指定给了141Nd。基于实验测量的γ跃迁各向异性,建议了141Nd部分能级的自旋值。根据经验壳模型和粒子震动祸合理论,用一个h11/2价中子空穴祸合142Nd核芯晕态激发定性地解释141Nd的能级结构,新发现的长E2级联跃迁很可能涉及两个hu/2质子激发。
Resumo:
Foram estudados os solos de uma area com 390.000 ha, situada a margem esquerda da Rodovia Santarem-Cuiaba, num trecho compreendido entre a cidade de Santarem e a Ruropolis Presidente Medici, no Estado do Para, com o objetivo de fornecer elementos basicos ao planejamento para ocupacao da area, atraves projetos de colonizacao. O trabalho constou do levantamento pedologico e posterior determinacao da aptidao agricola dos diferentes solos identificados e mapeados. Predominam na area os Latossolos e os podzolicos, ocorrendo em pequenas proporcoes as areias Quartzosas. As principais limitacoes se referem a fertilidade e a deficiencia de agua, enquanto que nos podzolicos, porquanto existam as limitacoes supracitadas, e o relevo que exerce em sua maioria, o principal papel de limitacoes das terras para o aproveitamento agropastoril. De acordo com o sistema de aptidao agricola adotado, os Latossolos, apesar de apresentarem baixa fertilidade e alta saturacao de aluminio, dada as suas propriedades fisicas, podem ser utilizados em empreendimentos agropecuarios com bons resultados, assim como os Podzolicos de relevo forte ondulado, recomenda-se a sua utilizacao para pastagem plantada ou silvicultura, e, para as Areais Quartzosas a melhor indicacao e a silvicultura.
Resumo:
In our continuing study of triterpene derivatives as potent anti-HIV agents, different C-3 conformationally restricted betulinic acid (BA, 1) derivatives were designed and synthesized in order to explore the conformational space of the C-3 pharmacophore. 3-O-Monomethylsuccinyl-betulinic acid (MSB) analogues were also designed to better understand the contribution of the C-3' dimethyl group of bevirimat (2), the first-in-class HIV maturation inhibitor, which is currently in phase IIb clinical trials. In addition, another triterpene skeleton, moronic acid (MA, 3), was also employed to study the influence of the backbone and the C-3 modification toward the anti-HIV activity of this compound class. This study enabled us to better understand the structure-activity relationships (SAR) of triterpene-derived anti-HIV agents and led to the design and synthesis of compound 12 (EC(50): 0.0006 microM), which displayed slightly better activity than 2 as a HIV-1 maturation inhibitor.
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p.45-64
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p.65-84