24 resultados para Uruguay Round (1987-1994)

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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额济纳天然绿洲位于我国西北干旱内流区黑河流域下游,近年来,随着黑河中、上游地区下泄地表径流量的减少,额济纳天然绿洲面临的生态环境问题日益突出。本文以额济纳天然绿洲景观为研究对象,以景观生态学及生态系统健康学原理为基础,综合运用35技术,基于研究区1987年、1994年和2001年的景观格局、动态变化特征及其演化机制的研究,发展并构建了额济纳天然绿洲景观健康评价指标体系及评价标准,对研究区景观健康问题进行了深入探讨与评价,从而为保护地区景观健康、维持区域生态安全提供科学依据。主要研究结果:①研究区景观属于典型的"基质一廊道一斑块"景观结构特征,景观破碎化程度较高,具有较低的景观多样性和较为粗糙的景观质地特征。②近巧年来研究区水域面积急剧萎缩、绿洲面积明显缩减、荒漠化程度较为严重;景观斑块形状复杂性及景观异质性程度下降,景观质地变得越发粗糙,景观多样性及景观稳定性降低。③上游入境水量的锐减是研究区景观发生退化的根本原因,绿洲人类活动强度的增加、绿洲关键区域的超载和过牧及蒸发度的升高、湿润系数的下降均加剧了研究区景观退化的程度。④基于35项景观变化、生物物理、生态环境及社会经济指标构建了研究区景观健康评价指标体系,运用模糊综合评判方法得出研究区景观健康指数LHI为0.1972,位于健康评价级别中"濒危的"级别偏下的位置。说明近十多年来研究区的景观健康状况较早时期相比趋于恶化,其发展态势表现出严重的不可持续性。

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基于研究区2001年Landsat7ETM+遥感影像资料,综合运用遥感与GIS技术手段,利用景观格局分析软件APACK分别从景观生态类型面积统计、景观水平指数、斑块类型水平指数及斑块类型间水平指数定量化分析了2001年额济纳天然绿洲景观空间格局特征,并结合研究区1987年和1994年的景观格局指数进一步探讨了关于格局指数间的相关性问题。研究结果表明:①研究区景观具有典型的“基质—廊道—斑块”结构特征;②研究区景观具有较高破碎化、较低多样性及粗糙质地特征,景观稳定性差;③各景观格局指数相互之间并不完全独立,有些指数之间具有明显的相关性。

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Re-examination of the syntypes of the capillariid nematode Neocapillaria phoxini Yu et Wang, 1994, the type species of Neocapillaria Yu et Wang, 1994, described from the intestine of the freshwater fish Phoxinus lagowskii variegatus Gunther (Cyprinidae) from China, confirmed its morphological similarity with species of Freitascapillaria Moravec, 1987, to which it is transferred as Freitascapillaria phoxini (Yu et Wang, 1994) comb. n. Consequently, Neocapillaria Yu et Wang, 1994 (a homonym to Neocapillaria Moravec, 1987) and Sinocapillaria Moravec et Spratt, 1998 become junior synonyms of Freitascapillaria. Skrjabinocapillaria gigantea is transferred to Freitascapillaria as F. gigantea (Wang, 1984) comb. n.

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In five groups of seasonally provisioned Tibetan macaques (Macaca thibetana) at Mt. Emei, males were sampled for wounds as an indicator of their competition for females during about 80 days in the 1987 mating season. Quantitative data on intergroup transfer were collected in a period between June 1986 and December 1987. The young adult (YA) males, the most active age-class in mating activity and intergroup transfer, received most of the wounds. Wounds tended to appear more in the front of body for YA and subadults (SA) than they did for middle-old aged (MO) males. This implies that some of the MO males were more active and aggressive in the fights. During the 1.5 year period, 5/6 of the YA and 5/17 of the MO males made intergroup shifts. Although YA males faced a high risk of receiving wounds at transfer, they usually rose in rank. On the other hand, the MO males transferred more smoothly but dropped in rank. The peripheral SA males, which rarely emigrated in the population, were an active component in determining the wounding rate, and the rate and direction of male migration. Three SA immigrants died of severe attacks made by resident males in 1988 and 1991. Adult sex ratios and their variations were considerably reduced with male nonrandom shifts and better conservation of the population.

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于1987-1989年对鱼腥藻7120质膜、类囊体膜和细胞壁进行分离纯化和基本的色素与蛋白质特性分析。采用机械性方法破碎细胞,以非连续蔗糖密度梯度离心分离纯化鱼腥藻7120营养细胞的质膜和类囊体膜,以TritonX-100处理方法获得细胞壁。色谱分析和电泳结果表明,其质膜、类囊体膜的色素和蛋白质特性与单细胞蓝藻相类似;Triton不溶细胞壁未发现可见光谱吸收,其两条主要蛋白带52KD和14KD均为精蛋白,并且14KD蛋白为肽聚糖层连结蛋白,细胞壁蛋白质全部对胰蛋白酶处理敏感,其上未发现“热修饰”蛋白。

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This paper studies the security of the block ciphers ARIA and Camellia against impossible differential cryptanalysis. Our work improves the best impossible differential cryptanalysis of ARIA and Camellia known so far. The designers of ARIA expected no impossible differentials exist for 4-round ARIA. However, we found some nontrivial 4-round impossible differentials, which may lead to a possible attack on 6-round ARIA. Moreover, we found some nontrivial 8-round impossible differentials for Camellia, whereas only 7-round impossible differentials were previously known. By using the 8-round impossible differentials, we presented an attack on 12-round Camellia without FL/FL 1 layers.

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IEEE Computer Society

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利用中国知识资源总库的中国引文数据库检索《水土保持研究》在1994-2006年所载论文的被引用情况,采用文献计量学方法对该刊1994-2006年载文被《中国期刊文献引证数据库》来源期刊引用的情况进行统计分析及评价。从文献引证的角度透视《水土保持研究》的学术水平。该刊1994-2006年共载文2098篇,被引用2018篇,占载文总数的96.62%。2001-2006年该刊影响因子、即年指标等文献计量指标逐年上升,分析表明:《水土保持研究》载文质量较高,在该学科有较大的学术影响力。

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