991 resultados para Coccejo, Joanne, 1603-1669.


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As sea turtles migrate along the Atlantic coast of the USA, their incidental capture in fisheries is a significant source of mortality. Because distribution of marine cheloniid turtles appears to be related, in part, to sea surface temperature (SST), the ability to predict water temperature over the continental shelf could be useful in minimizing turtle–fishery interactions. We analyzed 10 yr of advanced very high resolution radiometer (AVHRR) SST imagery to estimate the proportion of 18 spatial zones, nearshore and offshore of Hatteras, North Carolina, USA (35° N), to north of Cape Sable, Nova Scotia (44° N), at temperatures >10 to 15°C, by week. Detailed examples for 11°C, the temperature employed by some management actions in the study area, and for 14°C, the lowest temperature at which turtles were sighted by some studies in the area, demonstrate a predictable pattern of rapid warming in March and April, followed by rapid cooling in October and November, with nearshore waters warming more rapidly than those offshore. Of those loggerhead turtles Caretta caretta that stranded, were sighted, or were incidentally captured between Cape Hatteras, North Carolina, and Cape Cod, Massachusetts, those at lower latitudes occurred when 25% or more of the area reached a water temperature of 11°C, while those in the northern zones did not occur until 50% or more of the area had reached a water temperature of 14°C. This analysis provides a means of predicting marine cheloniid turtle presence, which can be helpful in regulating fisheries that seasonally interact with turtles.

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Extensive plankton collections were taken during seven September cruises (1990–93) along the inner continental shelf of the northcentral Gulf of Mexico (GOM). Despite the high productivity and availability of food during these cruises, significant small-scale spatial variability was found in larval growth rates for both Atlantic bumper (Chloroscombrus chrysurus, Carangidae) and vermilion snapper (Rhomboplites aurorubens, Lutjanidae). The observed variability in larval growth rates was not correlated with changes in water temperature or associated with conspicuous hydrographic features and suggested the existence of less-recognizable regions where conditions for growth vary. Cruise estimates of mortality coefficients (Z) for larval Atlantic bumper (n=32,241 larvae from six cruises) and vermilion snapper (n= 2581 larvae from four cruises) ranged from 0.20 to 0.37 and 0.19 to 0.29, respectively. Even in a subtropical climate like the GOM, where larval-stage durations may be as short as two weeks, observed variability in growth rates, particularly when combined with small changes in mortality rates, can cause order-of-magnitude differences in cumulative larval survival. To what extent the observed differences in growth rates at small spatial scales are fine-scale “noise” that ultimately is smoothed by larger-scale processes is not known. Future research is needed to further characterize the small-scale variability in growth rates of larvae, particularly with regard to microzooplankton patchiness and the temporal and spatial pattern of potential predators. Small-scale spatial variability in larval growth rates may in fact be the norm, and understanding the implications of this subtle mosaic may help us to better evaluate our ability to partition the causes of recruitment variability.

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元素化学计量学指从化学计量学的角度出发,通过分析比较生命物质不同结构层次(分子、细胞、器官、机体、种群、群落等)或生态系统中元素的相对比值,来研究各层次相互之间以及生态学过程中元素之间的关系。生态化学计量学研究可以把生态实体的各个层次存元素水平上统一起来,足近年来新兴的一个生态学研究领域,广泛应用于生态学研究中。C,N,P是生物地球化学循环中的重要元素,在生态系统中占有重要地位,许多环境问题都与它们有关,由此这三种元素的化学计量学受到生态学家们的普遍关注。C:N:P化学计量学在水生生态系统中研究较为深入,目前已发展到染色体水平,而在陆地生态系统中的研究较为匮乏近年来由于人类活动的强烈影响,这三种元素的循环在速度和规模上都发生了前所未有的改变,导致一系列环境问题的出现,因此C:N:P化学计量学在陆地生态系统中的研究就显得尤为重要。作为地球生命存在基础的绿色植物,在地球上已有数亿年的演化历史,研究陆地植物的元素化学计量学不仅有助于深入了解植物存在于地球上的内在机制,而且可以为许多环境问题的解决提供理论依据。本文首先建立中国不同地区植物氮磷含量数据库,通过数据分析找出一般规律,并进一步揭示植物不同进化阶段N:P化学计量比的变化规律。在此基础上,通过在内蒙古羊草草原设立不同施肥样地来模拟自然界不同氮磷环境,从试验水平上研究不同施肥处理及施肥梯度下生态系统中氮、磷、有机质的变化规律,并从化学计量学角度研究其内在机制。 利州新建成的中国维管植物数据库(包含1603种植物)研究了不同进化水平以及不同功能群(生活型)间植物N:P比的变化规律,并沿胡焕庸线(胡线)把中团分为为东西两部分,从总体水平上对比了东、西部间叫植物氮磷含量以及N:P的异同。结果表明:l)从演化水平来看,尽管氮磷含量表现出极大的差异,除豆科植物外,植物N:P基本保持稳定水平;2)木本植物与草本植物的N:P比差异.显著,木本植物之间(常绿乔木,常绿灌木,落叶乔木,落叶灌木)N:P不具有显著差异;3)中国东西部植物养分含量和N:P比表现出极显著差异,东部的养分含量低于西部,而N:P显著高于西部。 在内蒙古羊草草原两块永久实验样地(样地A:1980年围封样地和样地B:1999年田封样地)进行了为期两年的N素和P素添加试验。氮素添加梯度为0,5,15,30,50,80 g NHN03.m.2.yr-1。P素添加梯度为0,2,4,8,16,and 32 g P2Osm-2 yr-1(仪分析了羊草器官的结果)。分别从植物器官、物种、功能群水平研究了N素添加对N:P化学计量学的影响,此外还研究了土壤和凋落物C:N:P化学计量学对N素添加的响应。结合生物量的变化趋势,探讨了元素化学计量学对养分状况的指示作用。 1.羊草器官对施肥的响应结果表明,添加N素可以显著提高羊草器官中的含N量,p素可以显著提高器官中的含P量:除2001年样地A中的根茎外,根茎中的含P量基本不受N素添加的影响;茎中的含P量同样表现出不受N素添加影响的趋势(2000年B区茎除外):N素添加可以显著增大羊草叶片中的含P量(B区2000年叶片除外)。P素添加对羊草器官的含N量没有影响;羊草器官中的氮磷含量施肥处理下表现出显著的正相关关系(N素添加下B区叶片除外)。N素添加对羊草器官的N:P比没有显著影响(A区茎2000年和B区叶片2000年除外):P素添加显著降低了羊草器官中的N:P比。 2.四种优势植物(羊草、羽茅、针茅和苔草)地上生物量和N:P化学计量学对氮肥的响应研究发现,四个物种的氮磷含量均具有极显著相关关系;氮肥可以显著提高样地A中的羽茅生物量,降低苔草的生物量,而使样地B中的羊草生物量增大;两块样地中,四个物种的氮磷含量及N:P比均随N素水平的增高而增大(样地A中的羽茅N:P比除外)。 3.基于生活型划分的功能群(多年生根茎禾草,多年生丛生禾草,豆科植物,多年生杂类草,一二年生植物,灌木和半灌木)对N素添加的响应研究表明:施N可以提高样地A中的多年生丛生禾草的生物量,而使样地B中的多年生根苇禾草增加;多年生杂类草的相对多度在两个样地中均随施氨水平的增加而显著 降低:在样地B中,施氮可以显著提高不同功能群的氮磷含量;在样地A中,功能群N、P含量对施肥的响应并没有一致的变化规律,添加N素可以显著提高不同功能群的含N量(豆科植物除外),多年生根茎禾草和多年生杂类草的P含量有显著增大的趋势(P < 0.005),而其它功能群(豆科植物、灌木和小半灌木、多年生杂类草和~二年生杂类草)的P含量基本恒定(P>0.05);在样地A中,多年生丛生禾草,多年生杂类草,一二年生植物,灌木和半灌木的N:P比随施氨水平的增加而显著增大,多年生根茎禾草和豆科植物的N:P比基本不变;在样地B中,多年生丛生禾草的N:P比随施氨水平的增加而显著增大,多年生根茎禾草、多年生杂类草和…二年生杂类草不受施氨水平的影响。 4.添加N素对根实验结果表明:两块样地中,上层根(0-10 cm)的生物量仅在施N后第一年显著增加,而下层根(10-20 cm)的地下生物量在两年的施N处理下均不受施肥梯度的影响i在样地A中,施肥后第一年对根的N、P含量影响不显著,施肥后第二年可以显著增大上层根的N、P含量;在样地B中,添加N素后第一年可以显著增大根的含P量; 在两个样地中,两年的N肥处理对根的N:P比没有显著影响:在施氨处理中,根的N、P含量及N:P比在施肥第一年的响应要高于第二年。 5.所有处理中,上层土壤(O-lO cm)养分含量(有机碳,全氮,全磷)均高于下层土壤(10-20 cm);在样地A中,氮素添加对r十壤有机碳没有显著性作用,在施肥第一年可以显著增加上层土壤的N、P含量,而在施肥后第二年对土壤N、P含量没有显著影响;在样地B中,添加N素对两年的土壤养分均没有显著影响:养分添加两个样地土壤中的元素比值(C:N比,C:P比,N:P比)没有显著影响;土壤养分对施N一年后的响应要高于第二年。 6.养分添加对凋落物化学特征及化学计量学特征的影响研究结果表明:凋落物现存量不受施肥的影响;2001年凋落物现存量与2000年和2001年的地上生物量相关关系不显著;添加N素可以显著提高凋落物的N含量,而对有机碳含量和P含量没有显著影响;凋落物C:N比随施肥梯度的增大而显著降低,N:P比显著增高,而C:P比没有明显变化。 以上研究结果表明,不同植物功能群的N:P比存在差异,人类活动强烈影响自然植被中的植物N:P比;但植物的N:P比不受植物进化的影响(豆科植物除外);由于植物已有数亿年的演化历史,同时N与P在植物的结构和功能上具有密切的联系,在生物地球化学循环中办存在耦合作用。因此植物N:P比值恒定可能是一普适性规律。 N素添加试验表明,在植物根、地上器官、物种和功能群水平上N与P均呈显著正相关关系,反映了植物体内的氮磷含量具有协同作用。共存种对N肥的响应不同,表明物种受不同元素的制约。因此除非把生态系统中所有物种对施肥的响应刻画清楚,笼统的认定生态系统缺乏某种元素是不适当的。 施肥试验表明,两种围封时间样地的主要限制性元素不同。极度退化(样地B)植物生长主要缺N,而在保护较好样地(样地A),P也逐步成为一种限制因素。反映了随着保护时间的增加,植物生长逐渐由N限制型向N、P共同限制型过渡。添加的养分要么被植物吸收,挥发到大气中,或以凋落物的形式返还到土壤表层。但是对养分的预算有待于进一步研究。土壤中的养分含量对N素添加有…个滞后效应,而植物响应较为迅速。功能群N:P比在施肥实验中不能保持恒定,可能是由于实验时间较短的缘故;化学计量学的研究表明羊草草原分解凋落物的微生物受P素的制约,可能是由于植物体内具有高的P素再转运机制。这一结论有待于进一步的验证。氮肥降低了凋落物的C:N比,因此凋落物的分解速率可能将要发生改变。这需要进一步开展C循环的研究。

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 本文用14 种识别6 碱基的限制性内切酶Apa Ⅰ、BamH Ⅰ、Bgl Ⅰ、Bgl Ⅱ、Dra Ⅰ、 EcoR Ⅰ、EcoR Ⅴ、Kpn Ⅰ、Pvu Ⅱ、Pst Ⅰ、Sac Ⅰ、Sal Ⅰ、Sma Ⅰ和Xho Ⅰ研究了来自我国12 个省 和自治区共计18 个地方山羊品种218 个个体mtDNA 的RFL P ,并运用Nei 氏公式计算了各限制 性类型间的遗传距离P 和群体遗传多态度π值。结果表明,在研究的所有个体中共检测到41 个 酶切位点,18 种限制性态型,其中BamH Ⅰ、Bgl Ⅱ、Dra Ⅰ、EcoR Ⅰ和Sal Ⅰ共5 种酶表现出多态。 18 种限制性态型可归结为6 种基因单倍型,单倍型Ⅰ(BamH Ⅰ2B、Bgl Ⅱ2A、Dra Ⅰ2A、EcoR Ⅰ2A 和Sal Ⅰ2A) 和单倍型Ⅱ(BamH Ⅰ2B、Bgl Ⅱ2A、Dra Ⅰ2A、EcoR Ⅰ2A 和Sal Ⅰ2B) 为两种基本单倍 型,研究结果提示我国地方山羊品种起源于两种不同的母系祖先。各限制性类型间的平均遗传距 离为0100436 ,整个群体的平均遗传多态度π值为010487 % ,表明我国地方山羊品种mtDNA 遗传 多样性比较贫乏,分化程度较低。

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比较了云南高黎贡山地区的贡山独龙江和腾冲大蒿坪白颌大角蟾(Megophryslateralis)两个地理种群的核型、C-带和Ag-NORs结果表明,两个地理种群在核型和带型上都有差异两个地理种群的核型均为2n=26,NF=52染色体形态差异不明显,而次缢痕的位置完全不同,贡山独龙江标本的次缢痕位于No.2的长臂上近着丝点处,腾冲标本的次缢痕位于No.5的短臂上近着丝点的部位在腾冲标本中发现一雄性个体中有一条额外的染色体,可能是B染色体两地标本的C-带差异不太显著,贡山独龙江标本的C-带相对较为显著.贡山独龙江标本的Ag-NORs位于No.2长臂近着丝点处,与次缢痕的部位对应,两条同源染色体上大小有显著差异.腾冲标本的Ag-NORs位于No.5短臂上近着丝点处,与次缢痕的部位对应依据核型和带型的比较,对白颌大角蟾的分类和进化问题进行了讨论。

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作者根据近年在长江中下游对江豚进行考察的资料和收集到的标本,系统分析评价了长江中下游江豚的种群现状,主要结果如下:1.长江江豚上至宜昌(距河口1669公里),下至长江口,以及洞庭湖、鄱阳湖均有分布。分布型式是沿长江纵向呈集群性分布,横向呈趋岸性分布;2.长江中下游江豚种群数量估计为2700头。其数量冬季最高,夏季最低。夏季的SPUE值仅为冬季的48.7%—58.6%;3.长江中下游江豚群体以1—5头最为常见,占88%;4.理论推算长江中下游每年新产生个体为539头,年出生率为20%;5.通过分析比较长江中

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This paper reports on seasonal changes in stable carbon and nitrogen isotope ratios of seston and muscle tissue of silver carp and bighead carp during 2004 and 2005, focusing primarily on the carbon sources and trophic relationships among phytoplankton, zooplankton and silver carp and bighead carp in a large fish pen of Meiliang Bay (Lake Taihu, China). delta C-13 showed a minimal value in March 2005 and a maximal value in August 2005 in seston both inside and outside the pen, whereas delta N-15 of seston showed the minimum in winter and the maximum during algal blooms. A positive correlation between delta C-13 of silver carp and that of seston suggested that temporal variation Of delta C-13 in seston was preserved in fish via the food chain. The differences of delta C-13 among seston, zooplankton and muscle tissue of silver carp and bighead carp ranged only 0.2-1.7%, indicating that plankton production was the primary food source of filter-feeding fishes. According to a mass balance model, we estimated that the contributions of zooplankton to the diets of silver carp and bighead carp were 45.7% and 54.3%, respectively, based on the delta N-15 values of zooplankton and planktivorous fishes. (C) 2007 Elsevier B.V. All rights reserved

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Silicon-on-insulating multi-layer (SOIM) materials were fabricated by co-implantation of oxygen and nitrogen ions with different energies and doses. The multilayer microstructure was investigated by cross-sectional transmission electron microscopy. P-channel metal-oxide-semiconductor (PMOS) transistors and metal-semiconductor-insulator-semiconductor (MSIS) capacitors were produced by these materials. After the irradiated total dose reaches 3 x 10(5) rad (Si), the threshold voltage of the SOIM-based PMOS transistor only shifts 0.07 V, while thin silicon-on-insulating buried-oxide SIMOX-based PMOS transistors have a shift of 1.2V, where SIMOX represents the separated by implanted oxygen. The difference of capacitance of the SOIM-based MSIS capacitors before and after irradiation is less than that of the thin-box SIMOX-based MSIS capacitor. The results suggest that the SOIM materials have a more remarkable irradiation tolerance of total dose effect, compared to the thin-buried-oxide SIMOX materials.

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Electron irradiation induced defects in InP material which has been formed by high temperature annealing undoped InP in different atmosphere have been studied in this paper. In addition to Fe acceptor, there is no obvious defect peak in the sample before irradiation, whereas five defect peaks with activation energies of 0.23 eV, 0.26 eV, 0.31 eV, 0.37 eV and 0.46 eV have been detected after irradiation. InP annealed in P ambient has more thermally induced defects, and the defects induced by electron irradiation have characteristics of complex defect. After irradiation, carrier concentration and mobility of the samples have suffered obvious changes. Under the same condition, electron irradiation induced defects have fast recovery behavior in the FeP2 ambient annealed InP. The nature of defects, as well as their recovery mechanism and influence on material property have been discussed from the results.

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Ta is often used as a buffer layer in magnetic multilayers. In this study, Ta/Ni81Fe19/Ta multilayers were deposited by magnetron sputtering on sing-crystal Si with a 300-nm-thick SiO2 film. The composition and chemical states at the interface region of SiO2/Ta were studied using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that there is an 'inter-mixing layer" at the SiO2/Ta interface due to a thermodynamically favorable reaction: 15 SiO2 + 37 Ta = 6 Ta2O5 + 5 Ta5Si3. Therefore, the Ta buffer layer thickness used to induce NiFe (111) texture increases.

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CMM/CMMI(capabilitymaturitymodel/CMMintegration)自1999年开始为中国软件企业所接受并逐步得以推广,但目前中国实施CMM/CMMI的企业还不多,有些企业实施效果并不理想.通过调查软件企业在实施CMM/CMMI过程中存在的问题,并对发现的问题及其负面影响进行分析,提出了基于PDCA(plan-do-check-action)的软件过程控制与改进模型,开发了SoftPM软件质量管理平台.该平台的广泛应用表明,该模型对提高CMM/CMMI的企业软件过程的效率和改善实施效果很有帮助.