1000 resultados para 77-535


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The elastic constants of NaBrO3 and NaClO3 are evaluated from ultrasonic velocity measurements using pulse superposition techniques. The values of C11, C12 and C44 for NaBrO3 at 298°K are 5.578, 1.705, 1.510 (x 1010 N/m2) and for NaClO3 the values are 4.897, 1.389, 1.174. The values at 77°K are respectively 6.35, 1.98 and 1.65 for NaBrO3 and 6.15, 2.16 and 1.32 for NaClO3.

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The elastic constantsC 11,C 12 and C 44 of sodium chlorate single crystal have been evaluated using 10 MHz ultrasonic pulse echo superposition technique. The values are C 11=4.90,C 12=1.39,C 44=1.17 (× 1010 N/m 2) at 298 K and 6.15, 2.16, 1.32 (×1010 N/m 2) at 77 K. The data agree well with the values measured earlier up to 223 K. Brief mention is also made of the low temperature bonding problems in these soft crystals.

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In Czechoslovakia, the occupation of 1968 denoted the beginning of normalization , a political and societal stagnation that lasted two decades. Dissident initiative Charter 77 emerged in 1977, demanding that the leaders of the country respect human rights. The Helsinki process provided a macro-level framework that influenced opposition and dissident activities throughout Eastern Europe. The study contributes a focused empirical analysis of the period of normalization and the dissident movement Charter 77. Dissent in general is seen as an existential attitude; it can be encapsulated as a morally rationalized critical stance as derived from shared experience or interpretation of injustice, which serves as a basis for a shared collective identity comprising oppositional consciousness as one unifying factor. The study suggests that normalization can be understood as a fundamentally violent process and discusses the structural and cultural manifestations of violence with relation to Charter 77. In general, the aim of the system was to passivize the society to such an extent that it would not constitute a potential threat to the hegemonic rule of the regime. Normalization caused societal stagnation and apoliticization, but it also benefited those who accepted the new political reality. The study, however, questions the image of Czechoslovakia s allegedly highly repressive rule by showing that there was also quite considerable tolerance of Charter 77 and consideration before severe repression was brought to bear against dissidents. Furthermore, the study provides understanding of the motives and impetuses behind dissent, the strategic shifts in Charter 77 activities, and the changes in the regime s policies toward Charter 77. The study also adds new perspective on the common image of Charter 77 as a non political initiative and suggests that Charter 77 was, in fact, a political entity, an actively political one in the latter half of the 1980s. Charter 77 was a de facto hybrid of a traditional dissident initiative and an oppositional actor. Charter 77 adopted a two-dimension approach: firstly, it still emphasized its role as a citizens initiative supporting human rights, but, secondly, at the same time, it was a directly political actor supporting and furthering the development of political opposition against the ruling power.

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A compact clamp-type high pressure cell for carrying out electrical conductivity measurements on small solid samples of size 1 mm or less at pressures upto 8 GPa (i.e., 80 kbar) and for use down to 77 K has been designed and fabricated. The pressure generated in the sample region has been calibrated at room temperature against the polymorphic phase transitions of Bismuth and Ytterbium. The pressure relaxation of the clamp at low temperatures has been estimated by monitoring the electrical conductivity behavior of lead. Review of Scientific Instruments is copyrighted by The American Institute of Physics.

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Contenido: El trabajo humano / Octavio N. Derisi – El valor moral / Joseph de Finance – La historicidad del arte / Vicente O. Ciliberto – Meditación sobre la calumnia / Alberto Caturelli – Notas y comentarios -- Bibliografía

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Torna público as inscrições para concurso público destinado ao preenchimento de cargos em comissão de Assessor Legislativo da Câmara dos Deputados.

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Plenário vota benefícios para empresas de capital nacional. Constituintes entraram em acordo para votar a Ordem Econômica. A fórmula saiu na última hora e foi aprovada pelo Plenário. O artigo ficou assim: "será considerada empresa nacional aquela constituída sob as leis brasileiras e que tenha no país sua sede e administração". Também foi estabelecido que a empresa brasileira de capital nacional poderá gozar de benefícios e incentivos. Alguns constituintes tentaram derrubar este dispositivo que propicia reserva de mercado, mas a proposta foi rejeitada. Depois foi aprovado um destaque que garante a empresa brasileira de capital nacional uma preferência nas compras de produtos e serviços pelo Estado, mas houve críticas. Logo na abertura do texto, fica estabelecido que a Ordem Econômica deverá assegurar a todos uma existência digna, fundada na valorização humana e na iniciativa privada. Para os constituintes esse texto foi uma vitória. Para muitos constituintes o acordo na Ordem Econômica levou a um entendimento que beneficiará o país.

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The UNDP/FAO supported Federal Fisheries Project for the Development of Artisanal and Inshore Fisheries in Nigeria has the specific objective of increasing fish production through an integrated approach aimed at upgrading the rural coastal fishermen and improving their living conditions. The project has an operating life-span of three years and envisages a total outlay of nearly N3 million in terms of personnel and services. This paper attempts to review the activities of the project during the first two years of the operational phase and highlight some of its specific achievements.

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The Siberian Dace (Leuciscus leuciscus baicalensis (Dyb)is an important trade fish in Siberian waters. In the Ob basin more than 30,000 centners are produced annually. Catches of dace fluctuate significantly both between different rivers and between years in the Tomsk region. Defining the stocks of dace in the waters of the Tomsk region and explaining the fluctuations over time seems to be a very important and relevant question for the workers of the fishing industry. An answer, however, requires an accurate knowledge of the biology of dace; its reproductive, feeding and migration habits and the conditions of wintering etc. In the following we examine one of the above questions i.e. the biology of the reproduction of dace. The study was carried out in the Middle Ob in May 1951. This tranlations provides the introduction, summary and table captions only of the original article.

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This fisheries report summarises developments of the years 1974-77 in the region of the North West Water Authority. This report provides catch statistics, rod and line and commercial for salmon and sea trout, fish culture and hatchery operations, restocking with trout and freshwater fish, upstream fish movement recorded at Authority fish counters, counts of salmon and sea trout spawning redds, fish mortalities, licences issued, and prosecutions.

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泡沙参复合体属沙参属组,原有6个种,从东北连续分布到西南,本研究从辽宁、内蒙古、河北、河南、山西、陕西、甘肃和四川等9个省、市、自治区,采集了22个居群(包括复合体原有的6个种)及筒花组的对照种(A.stcnanthina)一个居群.通过野外和移栽后的对比观测,播种栽培,染色体观察,杂交试验和子代测定,同工酶电泳,并结合多变量统计分析,对复合体从不同水平和角度进行了研究. 1.本复合体多年生,实生苗当年只长基生叶,第二年才抽茎开花,个体花朵很多,因而花期很长(可达2个月).野生个体的结实量很大,种子萌发率接近100%.雌雄异熟,以异花授粉为主.自交(同株异花授粉)亲和,但结实量和萌发率均有所下降.等位酶估测的平均异交率(t)为0.77.末发现无融合生殖现象.全部居群的染色体均为2n= 34.末发现倍性和基数的变化. 2.同一个体的野生及栽培观测表明,根、茎、花序分枝等都是环境可塑性很高的性状,而叶片形态、花萼裂片长则有明显的发育可塑性,茎叶被毛、花部、果实和种子性状的可塑性较小. 3.针对在以往复合体类群划分中起鉴别作用的叶型、叶缘锯齿、茎叶被毛等几个性状,进行了大量的子代测定、杂交试验和天然居群的分析,结果表明,叶型、叶缘锯齿数目和大小、茎叶被毛等都是相关性很强的一组性状,但它们在天然居群中连续变化,是受多基因决定的数量性状.根据这些性状所划分的几个“种”,不过是连续变异的极端个体,极端个体(“种”)的自由授粉子代会分离出各种性状状态的个体,包括变异另一极端(另一个“种”)的个体,极端个体间的杂交进一步证实了这些数量性状的变异.据此,并结合地理分布,将A.bockiana和A.polydentata归并在A.potaninii之中:将A.biformifolia归并在A.wawreana之中.并证明A.wawreanavar. lanceifolia并不存在. 4.对20个居群34个形态性状的统计学和主成分分析表明,不同性状的系统学意义不一样,具有较大分类价值的性状是那些可塑性低、群内变异小的花部、果实、种子和部分营养性状.根据性状变异式样的分析和20个居群二套性状的聚类结果,可将复合体分为两个区别明显的类群.其中A.lobophylla形态十分独特,仅分布在四川西北部.另一个广布类群,在一些性状上体现出由西南(原A.potaninii)至东北(原A.wawreana)的地理变异式样,但性状在山西、陕西一带有过渡,是两个分化不充分的类群. 5.对复合体内8个居群及对照种居群的杂交试验表明,根据形态性状分析所归并的三个“种”与复合体其它类群间没有任何育性障碍,证实了归并的合理性。与此同时,发现根据形态变异式样所划分出的两个分化明显的类群(A.lobophylla与A.wawrcana和A.potaninii)间有很大的生殖隔离,不仅杂交结实量很低,杂交种子萌发率均小于10%.说明它们之间的亲缘关系较远,而A.lobophylla与筒花组的A.stenauthina间却有很高的杂交亲和性,平均结实量为53,与同种居群内的结实量相当;杂交种子萌发率达65%左右.只稍低于两个种各自居群内杂交的种子萌发率.因此,根据形态学,生境特点和杂交试验,建议将A.lobophylla放在远离本复合体的筒花组内. 6.采用控制杂交等方法确定了8个酶系统共10个等位酶位点的遗传基础.采用等位酶分析技术对复合体14个居群及一个对照种居群进行了测定.结果表明,本复合体植物的遗传变异水平很高,多态位点百分率(P)为79.2.等位基因平均数(A)为2.35,平均期望杂合度(He)为0.284.居群处于中等分化程度.总的等位酶变异中,有31%来自于居群间(FST=0.311).而其余69%左右存在于居群内.相比之下,四川西北的特有种A.lobophylla遗传变异水平稍低(P=70.0,A=2.0,He=0.211),尤其是居群中的杂合体比例明显偏离理论期望比例,异交率估计值(t)为0.535. 7.本复合体丰富的遗传变异和高度的环境可塑性使其适应性强,分布范围广.物种形成的方式基本上是地理式的,南部居群和北部居群是两个分化不完全的地理宗,并仍处在强烈的分化之中.对本复合体、A.lobophylla和对照种A.stenanthina形态学、杂交及等位酶分析表明,沙参属起源较晚、进化速度较快.推测在其起源早期,历了一段快速的适应性辐射阶段,随后则以地理式物种形成过程为主,逐渐发展为当今这样一个中等大小的属. 8.通过上述各方面的研究,最后将本复合体原有的6种l变种归并为两个种,即A.potaninii Korsh.和A.lobophylla Hong.后者实际上不属于本复合体,而是另一个组--筒花组的成员;而前者包含两个亚种:ssp.potaninii和ssp.wawreana Ge et Hong.

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介绍了一种可用于低温装置内的补偿式光纤位移传感器(CFODS),讨论了该传感器在低温下的输出特性并在液氮温度(77 K)和液氦温度(4.2 K)下进行了实验研究.结果表明,该传感器在液氮温度下的灵敏度0.311 mm~(-1),高于液氦温度下的灵敏度0.278 mm~(-1).

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本文以南黄海1997~2006年10年表层海水和沉积物中重金属为主要研究对象,同时结合对生态环境信息的综合分析,系统探讨了海水和沉积物中重金属的生物地球化学特征、影响控制因素、演变趋势,并对海域生态风险进行了评估,获得了以下一系列新的结果和认识: 1.系统获得了南黄海海水和沉积物中重金属的地球化学分布模式,揭示了影响和控制其生物地球化学特征的因素 南黄海表层海水中重金属As、Cd、Cu、Hg、Pb、Zn的平均浓度分别为2.33、0.078、1.41、0.0036、0.37、6.21 μg/L,低于其它中国近海海水,而高于水交换较好的深海;表层海水重金属的分布模式(除Pb外)表现为在离岸较远的南黄海中部地区其含量较低,而近岸海区则普遍含量较高,区域分布呈现“高Cd-Cu-Hg-Zn区”,“高Pb-Cu-Zn区”以及“高Pb区”三个地球化学分区。 南黄海表层沉积物中重金属比邻近海域沉积物中的浓度低,南黄海重金属主要受沉积物粒度控制,即在细粒度高的南黄海中部区域重金属(除As外)的含量较高,粗粒度的近岸区则较低,区域分布呈现“高Cd-Cu-Pb-Zn区”,“高Hg低As-Cu-Zn区”以及“高As低Cd-Hg-Zn区”三个地球化学分区。 人类活动已经显著影响了南黄海海水中重金属的含量水平,重金属分布是径流、大气沉降、pH、盐度和重金属自身性质等各种影响因子耦合的结果。沉积物重金属的富集因子Pb>As>Hg>Cd>Zn>Cr>Cu,其中Pb和As主要来自人为污染排放,污染状况相对较重,Cr和Cu几乎没有受到人为污染的影响。沉积物的粒度是控制表层沉积物重金属分布的最主要因素,次要的因素包括沉积物有机质的含量、沉积速率以及重金属存在形态等。 2.首次获得了南黄海海水和沉积物中重金属的演变趋势 近10年来南黄海表层海水中,Zn呈上升趋势,As、Cd、Cu、Pb基本稳定变化不大,而Hg则呈略下降趋势。Zn的线性上升趋势明显,在近岸水域和中央水域中其浓度和公元年的统计关系分别为y=0.9524x+0.0034(R=0.97)和y=0.8622x+0.0299(R=0.95)(其中y为Zn的浓度,x为年度,取1997~2004)。近10年沉积物中重金属年际变化较小,浓度变化在多年均值的±(10%~30%)之间变动。As、Cd、Cu、Hg、Pb、Zn的均值变化范围分别为7.17±1.70、0.108±0.024、17.61±1.65、0.024±0.008、18.44±4.26、70.53±5.73 mg/kg,除了Hg随公元年呈较好的线性增加(y=0.0033x-6.50,R=0.75)外,其它重金属未显现出有明显的演变趋势。 近百年来,南黄海重金属的变化可分为3个阶段,20世纪60年代以前,20世纪60年代至90年代,及20世纪90年代至今。第一个阶段的60年可以看作是南黄海未明显受人类活动影响的一个时期,该段时期内明显的特征是重金属含量的变化受径流输入不均等多种因素影响,变化规律性不强;第二阶段是南黄海近岸工农业迅猛发展的阶段,由近岸传输到这一海域的重金属量增加,南黄海沉积物重金属浓度增加,沉积物质量有下降的趋势,这一阶段是人类活动影响南黄海最为明显的一个阶段;第三个阶段是20世纪90年代至今,南黄海沉积物重金属浓度呈降低趋势,与中韩两国减排及治污措施有关。近几年,南黄海沉积物的环境质量较20世纪末期有了较明显的改善。 3. 初步阐明了南黄海重金属的环境污染危害和潜在生态风险 采用潜在生态危害指数法和地积累指数等方法对南黄海沉积环境进行分析,结果表明,中等重金属污染程度海区占研究海区面积的38.7%,中等生态风险的区域则占了研究海区面积77.8%,但均未发现沉积物中的重金属与生物量的分布有明显的关系,总体表明,南黄海沉积物中的重金的污染状况及生态风险较低,南黄海沉积物质量良好。