56 research outputs found

    菲律宾花鳗鲡种类鉴别与形态差异分析

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    根据脊椎骨数及量度性状,用形态学分析方法鉴别了菲律宾花鳗鲡鳗苗的种类,并应用方差、主成分和判别等分析方法比较研究了引进鳗苗种类间形态差异。结果表明,引进的菲律宾花鳗鲡鳗苗实为2种鳗鲡,即花鳗鲡和太平洋双色鳗。其中花鳗鲡数量绝多,个体较小;太平洋双色鳗数量少,但个体显著大于花鳗鲡。花鳗鲡总脊椎骨数、臀鳍起点前和起点后脊椎骨数均显著小于太平洋双色鳗。花鳗鲡与太平洋双色鳗的多个形态性状差异显著,包括体型、头部、口裂及鳍,散布全身。建议在鳗苗培育后期分级选别时,可根据花鳗鲡与太平洋双色鳗体型的差异和鳍型不同将其分开。花鳗鲡体型较小,背鳍前端和臀鳍前端距离较远;太平洋双色鳗体型较大,背鳍前端和臀鳍前端几乎平齐

    七种捕食性鱼类对中华绒螯蟹幼蟹捕食风险的评估

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    分别以鲤、鳜、斑点叉尾、黄颡鱼、瓦氏黄颡鱼、大口鲇和乌鳢作为捕食者,以中华绒螯蟹幼蟹作为猎物,在室内水泥池(2.4 m3)进行捕食试验。以日捕获率和日摄食率为指标,评估这些鱼类对幼蟹的捕食作用和危害程度,为提高湖泊幼蟹放流效果、建立蟹—鱼复合的优质高效养殖模式提供科学依据。在幼蟹完全暴露的条件下,经过多次(至少9次)重复的试验(短期1d和长期7d),鳜对不同大小的硬壳和软壳(刚蜕壳的)幼蟹没有任何捕食作用;黄颡鱼对硬壳和软壳幼蟹也没有捕食作用,但还需做进一步观察;虽然鲤、瓦氏黄颡鱼对硬壳蟹的捕获率低,但对软壳的幼蟹有较大的危害性,对幼蟹的日摄食率分别为0.070%、0.012%;大口鲇、斑点叉尾、乌鳢对幼蟹具有较强的捕食能力,对幼蟹的日摄食率分别为0.122%、0.188%和0.284%。根据这些研究结果,可以建议:(1)在池塘和湖泊河蟹养殖中,完全可以将鳜作为套养或混养对象,以期提高养殖效益;(2)在河蟹放养的湖泊,需要抑制乌鳢和大口鲇种群,适当减少鲤和瓦氏黄颡鱼丰度,以期减少这些鱼类的捕食作用,提高幼蟹存活率;(3)在河蟹养殖池塘,不能放养乌鳢、大口鲇、斑点叉尾、瓦氏黄颡鱼和鲤

    Effects of Low Energy Carbon Ion and Nitrogen Ion Implantation on Germinant Rate, Growth Weight and Peroxidase of Stevia rebaudiana Bertoni

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    以经过碳、氮 (75× 1 0 14 ke V/ cm2 )离子注入处理后的甜叶菊 (Stevia rebaudianaBertoni)种子为材料 ,研究低能离子注入对甜叶菊萌发率、生长量及过氧化物同工酶的影响。结果表明 :(1 )萌发期处理组的萌发率低于对照 ,萌发延迟 ,幼苗成活率不及对照组 ;萌发后期处理组的相对生长量、过氧化物酶活性高于对照组。 (2 )幼苗移至实验地种植后 ,处理组幼苗长势明显优于未处理组 ,处理组 60 d蕾株比明显高于对照组。 (3)过氧化物酶同工酶谱分析发现 ,对照组具有完整 6条基本带的植株数为 1 2 ,具有完整 B1、B2基本带的植株数为 2 0 ;C+处理组分别为 5和 1 1 ,N+处理组分别为 5和 6。统计发现低能离子的注入影响最大的是同工酶谱 B1、B2带。 N+处理组生物学负效应大于 C+处理组The paper reports the effects of low energy Carbon and Nitrogen ion (75×10 14 keV/cm 2 )implantation into S. rebaudiana seeds.on germinant rate, relative growth weight and peroxidase of S. rebaudiana. The results showed: (1)The seed germinant rates were lower and seeding servival rates and deve lopment speeds were slower in the treated groups than those in the control in the initial period of seed germinating;but in the late period of seed germinating the relative growth weight and peroxidase activity were higher in treated groups than those in the control.(2)When seedings were transplanted into experimental field the growth and development were speeded up in treated groups than that in the control.The rate of flower bud plants were higher in treated groups than that in the control. (3)The isozymogram of peroxidase by PAGE showed that there were 12 plants which had 1~6 basic bands and 20 plants which had B1,B2 bands in the control,but only there were 5 plants and 11 plants, respectively, in C + treated groups,and there were 5 plants and 6 plants, respectively, in N + treated groups. The result also showed there were more negative effects by ion implantation into S. rebaudiana in N + treated groups than those in C + treated groups in the periods of seed germinating and plant growth.国家基金委重大项目资助课题!( 1 9890 30 0

    Expression Analysis of a Stress Repressed Gene OsDSR4 from DUF966 Family and Generation of OsDSR4- overexpressing Transgenic Rice(Oryza sativa L. ssp. japonica)

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    OSdSr4基因是duf966基因家族中的一个未知功能基因,目前其生物学功能尚不清楚。本研究生物信息学分析显示,OSdSr4基因CdnA全长2 167 bP,包含一个1 149 bP的开放阅读框(Orf),编码382个氨基酸,推测的蛋白中包含一个高度保守的duf966结构域;表达模式分析表明,OSdSr4主要在水稻(OryzA SATIVA l.SSP.JAPOnICA)的茎节间和叶片中表达,干旱、高盐和低温等非生物胁迫明显抑制了OSd Sr4的表达,而脱落酸(AbSCISIC ACId,AbA)则显著诱导了它的表达;利用重叠延伸PCr方法成功克隆了OSdSr4,并将其转化进水稻中,获得了32株超表达转基因植株。分子鉴定结果表明,该基因已被整合进水稻基因组中,并在部分转基因植株中实现了超量表达。本实验为进一步开展OSdSr4基因的生物学功能研究提供了基础资料。OsDSR4 is a gene of unkown function in DUF966 gene family,and the function of DUF966 family genes have not been reported until now.In this study,the bioinformatic analysis showed that the cDNA of OsDSR4 had 2 167 bp containing an open reading frame(ORF) of 1 149 bp,and it encoded a putative protein of 372 amino acids with a highly conserved DUF966 domain.The gene expression profile analysis indicated that OsDSR4 was expressed mainly in internode and leaf blade of rice(Oryza sativa L.),and it was repressed markedly by drought,salt and cold stresses,and induced significantly by abscisic acid(ABA).OsDSR4 was cloned using overlap extension PCR,and the fusion construct containing OsDSR4 was introduced into rice(Oryza sativa L.ssp.japonica) by Agrobacterium- mediated transformation method.Thirty- two OsDSR4- overexpressing transgenic plants were obtained and identified by PCR and qRT-PCR,which was demonstated that OsDSR4 had been integrated into rice genome and was overexpressed in some positive transgenic plants.These results establish the foundation for further study of the precise function of OsDSR4.国家重点基础研究发展计划(973)前期研究专项(No.2012CB126312

    The lineal Polarization Method for Corrosion Rate Measurement of Reinforcing Bar of Concrete in Situ

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    本文尝试用线性极化的方法对埋置于混凝土内部的钢筋的腐蚀速度进行测量 .自行设计了一组特殊结构的辅助电极 ,制备了不同尺寸和保护层厚度的混凝土试样 .通过改变辅助电极 ,调整电位的分布 ,使线性极化方法的测量误差降低到腐蚀速度测量允许的误差范围内 .确定了两种适用于混凝土中钢筋腐蚀速度测量的辅助电极 .A linear polarization method was applied to measure corrosion rate of reinforcing bar of concrete in situ. Generally in the experiment, the area and shape of the reinforcing bar as a working electrode can be changed and adjusted according to our needs. But polarization area cannot be defined when reinforcing bar is polarized in situ, so that a real R p can't be obtained. Thus the purpose of present work is to improve the measurement system. We used the double_ring auxiliary electrodes made by ourselves. The size of the double_ring auxiliary electrodes was adjusted repeatedly until the real polarization area was equivalent to one of the auxiliary electrodes. Using such an auxiliary electrode to measure R p, we obtained the result that the measurement error of R p is about 2.5%. This result can meet the need of measurement in situ.作者联系地址:山东工业大学化学工程系!山东济南250061,山东工业大学化学工程系!山东济南250061,山东工业大学化学工程系!山东济南250061,山东工业大学化学工程系!山东济南250061Author's Address: Department of Chemical Engineering, Shangdong University of Technology, Jinan 250061 Chin

    AIDA通过内质网相关的蛋白质降解途径选择性下调脂肪合成途径的代谢酶从而减缓肠道脂肪吸收并防止肥胖发生

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    文章简介肠道对膳食脂肪吸收的效率是个人是否易患肥胖的主要决定因素之一。然而,目前人们还不清楚脂肪吸收是如何受调控并导致肥胖的。本研究表明,抑制内质网相关的蛋白质降解途径会提高甘油三酯合成途径的数个代谢酶的水平,并促进小肠对脂肪的吸收。包含C2结构域的蛋白AIDA作为一个重要国家重点基础研发计划;;\n国家自然科学基金;;\n厦门大学校长基金等支

    The Research on Local World Network with Deleting Mechanism

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    20世纪90年代以来,随着信息科学技术的发展,尤其是以TCP/IP为基础的互联网取得了巨大成就后,人类活动开始步入了网络时代。从Internet到WWW,从大型电力网络到全球交通网络,从社会合作网到政治、经济网络,可以说人们已经离不开网络,因此对复杂网络的研究,备受科学家们的热切关注。 目前学术界研究主要集中于无标度网络,在已有的研究中,有的学者提出了无标度网络的扩展模型,讨论加边和重连等对网络拓扑结构的影响;有的学者提出适应度模型来讨论现实社会中的“适者越富”的竞争现象;有的学者为了扑捉现实网络中的高集聚现象,提出了“三角形”演化机制,构建聚类系数可调的无标度网络模型。而现实网络中存在着两...Since 1990s, with the development of information science technology, especially the Internet based on TCP/IP having gotten great achievements, the human beings enter into the network era. From the Internet to WWW, large power grid networks to global transportation networks, the social cooperation networks to political and economic networks, the human has been inseparable from networks. The study o...学位:工学硕士院系专业:信息科学与技术学院自动化系_控制理论与控制工程学号:2322008115336

    复合材料力学进展

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    本书内容包括:复合材料的力学特点、研究方法以及在设计、制造、应用时所遇到的一系列力学问题

    DPPM在相干光通信中的应用研究

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    针对空间激光通信系统高能效高灵敏度的调制问题,对差分脉冲位置调制(DPPM)格式进行研究,并将其运用在相干光通信系统中,通过仿真及实验在系统功耗、误码(BER)性能和占用带宽中找到平衡点。实验结果表明,在直调直检和相干光通信传输系统中,在相同的传输信道,相同的传输速率为1.25 Gbit/s的DPPM信号时,两者达到硬判线所需的信号路光功率分别为-36.5和-60.0 dBm。相干传输系统对比直调直检传输系统提升了约24 dB的光功率裕度。对于实现硬判线的传输目标,传输3、6、12和24 Gbit/s速率的DPPM信号需要接收端光功率分别约为-49、-47、-42和-36 dBm。论证了采用DPPM格式/相干探测能够得到更高的灵敏度及更低的误码率
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