936 resultados para 3-21


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A 68-day growth trial was conducted in a flow-through system to determine the effect of dietary manganese levels on growth and tissue manganese concentration of juvenile gibel carp (Carassius auratus gibelio). Seven purified diets containing 7.21, 8.46, 9.50, 10.50, 13.03, 19.72 and 22.17 mg manganese (as manganic sulfate) per kilogram diet were fed to triplicate groups of fish (initial weight 3.21 +/- 0.01 g). The results showed that dietary manganese levels did not significantly affect feed intake of the fish. Specific growth rate, feed efficiency, total hepatic superoxide dismutase activity, carcass and skeletal manganese concentration increased significantly with increased dietary manganese(P < 0.05) while condition factor decreased significantly(P < 0.05). It was concluded that dietary requirement of manganese was 13.77 mg Mn per kilogram diet. Carcass and skeletal manganese concentration could also be used to evaluate the manganese requirement. Total hepatic superoxide dismulase activity was not a sensitive indicator for dietary requirement.

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本书是《中国材料工程大典》中的卷目之一。 信息功能材料是信息科学技术和信息产业发展的基础和先导。21世纪将是以信息产业为核心的知识经济时代,对信息技术和信息资源的竞争将更加激烈。我国电子信息行业2004年完成产品销售收入达26500亿元,多年来已居外贸出口首位,并继续以高出工业发展速度10%的速度发展,已成为世界信息产业大国。加快由信息产业大国向信息产业强国迈进的步伐,是我们广大从事信息技术,特别是信息功能材料工作者义不容辞的责任。希望《中国材料工程大典》中《信息功能材料工程》卷的出版,将有力推动我国信息技术和信息产业的健康发展。 《信息功能材料工程》分上、中、下卷,共设20篇,约600万字。它涉及到信息的获取、传输、存储、显示和处理等主要技术用的材料与器件,是目前我国该领域比较完整的专业工具书。参加这部书编写的有中科院、高校和部分企业的专家教授近200名。参加编写的主要单位有中科院半导体研究所、中科院物理研究所、中科院微电子研究所、中科院上海精密光学机械研究所、中科院上海红外技术物理研究所、中科院长春应用化学研究所、中科院合肥固体物理所、南京大学、清华大学、西安理工大学、北京有色金属研究总院、武汉邮电科学研究院等。历时近3年完稿。由王占国、陈立泉、屠海令任主编并统稿。 本卷各篇不仅全面系统地反映了国外信息功能材料研究领域的现状、最新进展和发展趋势,而且也特别注重我国在该领域的研发和产业化方面取得的成果,力图使其具有实用性、先进性和权威性。本书适合于从事信息功能材料的科研工作者和工程技术人员查阅使用,也可供有关师生参考。

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黄土高原沟壑区王东沟流域从1986年至2006年的土地利用/覆被发生了较大变化,土地利用动态指数分别为:耕地3.21%,园地-36.11%,林地-4.05%,牧草地4.24%,居民点及独立工矿用地-0.62%,交通运输用地-12.27%,未利用地1.85%;变化趋势是:耕地逐年向园地流转,园地变化烈度较大,其他各类用地变化不太显著。引起这一变化的主要因素是自然、社会、经济、技术以及政策因素。结合这一变化,针对黄土高原沟壑区的实际情况,在黄土高原沟壑区土地利用经营与管理方面,应重视土地产出效益与粮食安全的关系,在保障区域粮食安全的基础上实现效益最大化。

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Background: Flying lemurs or Colugos (order Dermoptera) represent an ancient mammalian lineage that contains only two extant species. Although molecular evidence strongly supports that the orders Dermoptera, Scandentia, Lagomorpha, Rodentia and Primates form a superordinal clade called Supraprimates (or Euarchontoglires), the phylogenetic placement of Dermoptera within Supraprimates remains ambiguous. Results: To search for cytogenetic signatures that could help to clarify the evolutionary affinities within this superordinal group, we have established a genome-wide comparative map between human and the Malayan flying lemur (Galeopterus variegatus) by reciprocal chromosome painting using both human and G. variegatus chromosome-specific probes. The 22 human autosomal paints and the X chromosome paint defined 44 homologous segments in the G. variegatus genome. A putative inversion on GVA 11 was revealed by the hybridization patterns of human chromosome probes 16 and 19. Fifteen associations of human chromosome segments (HSA) were detected in the G. variegatus genome: HSA1/3, 1/10, 2/21, 3/ 21, 4/8, 4/18, 7/15, 7/16, 7/19, 10/16, 12/22 (twice), 14/15, 16/19 (twice). Reverse painting of G. variegatus chromosome-specific paints onto human chromosomes confirmed the above results, and defined the origin of the homologous human chromosomal segments in these associations. In total, G. variegatus paints revealed 49 homologous chromosomal segments in the HSA genome. Conclusion: Comparative analysis of our map with published maps from representative species of other placental orders, including Scandentia, Primates, Lagomorpha and Rodentia, suggests a signature rearrangement (HSA2q/21 association) that links Scandentia and Dermoptera to one sister clade. Our results thus provide new evidence for the hypothesis that Scandentia and Dermoptera have a closer phylogenetic relationship to each other than either of them has to Primates.

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国家自然科学基金

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A series of Nd3+-doped LaF3 nanoparticles with Nd3+ concentrations from 0.5 to 10 mol% were synthesized. The fluorescence intensity and lifetime of the nanoparticles at various Nd3+ doping concentration were investigated. The nanoparticles displayed strongest fluorescence intensity at 3 mol% Nd3+ concentration. Eighty-eight percentage quantum efficiency was obtained when the Nd3+ concentration was 0.5 mol%. Optical properties of nanoparticles were studied according to Judd-Ofelt theory. A larger emission cross-section, sigma(em), for F-4(3/2) -> I-4(11/2) transition of the Nd3+ ion was obtained as 3.21 x 10(-20) cm(2), which was two times of the currently reported value. The larger emission cross-section and strong fluorescence intensity demonstrate that these nanoparticles are promising materials for laser applications. (C) 2010 Published by Elsevier B. V.

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目的:探讨胃肠道癌术后预防腹腔转移及肝转移的有效方法。方法:对157例胃肠道癌切除术后病人,随机分成术中腹腔温热灌洗及术后静脉微泵和置泵持续动脉灌注化疗组72例(简称治疗组),单纯静脉化疗组85例(简称对照组),并对其腹腔转移率、肝转移率及3年生存率进行对照研究。结果:治疗组腹腔转移率21.5%、肝脏转移率13.4%、3年生存率71.6%,对照组腹腔转移率41.2%、肝脏转移率22.6%、3年生存率47.5%。两组之间比较有显著性差异(P<0.05)。结论:术中腹腔温热灌洗及术后静脉微泵和置泵持续动脉灌注化疗,对胃肠道癌病人术后腹腔转移及肝转移有良好的防治作用。

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耗散反应产物激发函数中涨落结构的研究,是分析重离子反应中间双核系统时间演化和耗散过程的一个有效手段。本论文论述102一108MeV19F+93Nb反应和110.25一118.75MevlgF+2勺反应耗散产物激发函数的实验结果,通过关联函数分析、误差分析并结合有关统计模型探讨耗散反应产物截面特征涨落的物理根源。实验采用△E一E方法对反应产物进行电荷鉴别。各个出射道的激发函数中都观测到了涨落结构。通过统计理论方法的分析,揭示出耗散反应产物截面涨落区别于复合核截面涨落的一系列特征性质,如长程的能量关联、反应系统和宏观条件相同的多次独立测量的截面及其涨落不重复。对19F+93Nb反应耗散产物截面进行误差分析的结果表明:能量自关联函数的离散程度大约相当于随机计数率引起的离散程度的3倍;激发函数曲线相对于能量平均本底的几率分布,有大约21%超出了标准高斯分布宽度的3倍;两次测量得到的截面之差的几率分布,大约有18%也超出了标准高斯分布宽度的3倍。可见,两次测量的产物激发函数中截面的不重复性具有明确的统计意义,其来源不是有限计数率的随机涨落。另外,为了进一步验证耗散产物截面不重复的结果,还测量了入射能量固定的19F+27AI反应产物截面随靶点的分布,截面相对于平均值的偏差有巧%超出标准高斯分布宽度的3倍。通过测量19F+27AI反应耗散产物角分布并提取角分散参数,讨论角分散参数的物理意义及其与产物电荷数z之间的依赖关系:产物中转移的核子数越多,动力学角分散越大。新近发展的核反应统计理论指出:在高激发的、强相互作用的有限多体系统中,考虑微观的道与道之间的关联,认为相位的无地化过程进行得非常缓慢,中间系统的演化过程具有对初始条妙的极端敏感性。能够解释耗散反应产物激发函数中不平滑的能量结构,解释多次救立钡吐量的截面不重复性具有统计意义。