990 resultados para 554
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本工作合成了磺化的3,4-聚异戊二烯及其离子聚合体,IR和NMR谱图证明对3,4-聚异戊二烯的磺化反应是成功的,并且磺酸基团主要与3,4-链节的侧基双键发生反应。WAXD对磺化3,4-聚异戊二烯及其离聚体的研究表明,磺化度的增加使离聚体的结晶能力降低,SAXS结果表明,在离子含量为3.29mol%的离聚体中,未观察到离子簇聚集,只观察到多重离子对的散射。
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MSTN, also known as growth and differentiation factor 8 (GDF8), and GDF11 are members of the transforming growth factor-beta (TGF-beta) subfamily. They have been thought to be derived from one ancestral gene. In the present study, we report the isolation and characterization of an invertebrate GDF8/11 homolog from the amphioxus (Branchiostoma belcheri tsingtauense). The amphioxus GDF8/11 gene consists of five exons flanked by four introns, which have two more exons and introns than that of other species. In intron III, a possible transposable element was identified. This suggested that this intron might be derived from transposon. The amphioxus GDF8/11 cDNA encodes a polypeptide of 419 amino acid residues. Phologenetic analysis shows that the GDF8/11 is at the base of vertebrate MSTNs and GDF11s. This result might prove that the GDF8/11 derived from one ancestral gene and the amphioxus GDF8/11 may be the common ancestral gene, and also the gene duplication event generating MSTN and GDF11 occurred before the divergence of vertebrates and after or at the divergence of amphioxus from vertebrates. Reverse transcriptase polymerase chain reaction results showed that the GDF8/11 gene was expressed in new fertilized cell, early gastrulation, and knife-shaped embryo, which was different from that in mammals. It suggested that the GDF8/11 gene might possess additional functions other than regulating muscle growth in amphioxus.
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In this paper, the analytical representations of four wave source functions in high-frequency spectrum range are given on the basis of ocean wave theory and dimensional analysis, and the perturbation method is used to solve the governing equations of ocean wave high-frequency spectrum on the basis of the temporally stationary and locally homogeneous scale relations of microscale wave. The microscale ocean wavenumber spectrum correct to the second order has an explicit structure, its first order part represents the equilibrium between different source functions, and its second order part represents the contribution of microscale wave propagation.
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人类基因组全序列测定的完成,标志着一个崭新的时代-后基因组时代的来临。生命科学从大规模的基因组序列分析转向对基因功能的研究,蛋白质组学研究己成为21世纪生命科学的热点领域。蛋白质组学是以细胞、组织或体液内蛋白质的存在及其活动方式为研究对象,研究其结构、功能、相互作用和修饰。 血浆是血淋巴的重要的组成成分,具有重要的生理功能。当虾类发生病理损害时可引起血浆蛋白发生质和量的改变,分析这种特征性的变化对虾病防治具有十分重要的意义。血浆同时又是一个复杂和动态变化的系统,含有种类繁多、丰度各异的蛋白质,给研究工作带来了困难。蛋白质组学技术的不断丰富和发展,为全面而系统地认识健康和病害状态下血浆蛋白的性质提供了有利的平台。 本论文以中国明对虾为研究对象,以凝胶电泳/液质联用方法为技术平台,探索血浆蛋白质组学研究的方法。 本文首先综述了蛋白质组学的进展,包括蛋白质组学研究中的关键技术双向电泳、生物质谱以及生物信息学的进展和现状,概述了对虾类基因组、蛋白质组研究进展,提出了本课题工作的研究方向。 其次研究了中国明对虾血浆蛋白样品制备方法并获得理想的蛋白质表达图谱;确定了液质联用方法分离鉴定蛋白质的多肽洗脱条件;基于双向凝胶电泳/串联质谱策略,鉴定了中国明对虾20个血浆蛋白;验证了液相色谱/串联质谱分析复杂蛋白质混合物的鉴定技术,基于一维凝胶电泳预分离/串联质谱策略,分离鉴定了66个中国明对虾血浆蛋白质。 (1)优化了双向电泳的实验条件,分析了中国明对虾血浆蛋白双向电泳蛋白质表达图谱,进行了多次重复实验,取得良好的实验结果。 (2)确定了液质联用方法分离鉴定蛋白质组的多肽洗脱条件。利用血管紧张素,应用液相色谱和电喷雾离子阱质谱联用的方法,确定了适宜的多肽色谱洗脱条件,用牛血清白蛋白酶切后产生的多肽混合物对洗脱条件进行进一步验证,并确定了液质联用方法的灵敏度,应用液质联用方法鉴定牛血清白蛋白灵敏度可以达到50 fmol。 (3)利用双向电泳技术/串联质谱分析了中国明对虾血浆蛋白质,通过生物信息学分析,分离鉴定了20个中国明对虾血浆蛋白质,这些蛋白质可能通过不同途径参与了对虾生理过程并发挥着不同的功能。 (4)验证了液相色谱串联质谱联合的复杂蛋白质混合物鉴定技术。将几种蛋白质的混合物变性后直接在溶液中酶解,利用高效液相色谱-离子阱串级质谱进行序列分析,结合数据库搜索实现了混合蛋白质快速准确的鉴定。基于一维凝胶电泳预分离/串联质谱策略,分离鉴定了66个中国明对虾血浆蛋白质。运用生物信息学手段,对鉴定的蛋白进行功能分类,包括转录、细胞结构和骨架、信号转导、蛋白质合成与处理、蛋白质折叠分拣和降解、免疫功能、生长和发育、能量代谢、细胞周期、碳水化合物代谢、钙离子平衡、抗氧化剂、氨基酸和脂类代谢等。 最后利用Sephacryl S-100凝胶过滤柱层析技术对中国明对虾血蓝蛋白进行了纯化。实验结果表明所获得的血蓝蛋白纯化样品,在聚丙烯酰胺凝胶电泳中显示为两条带,双向电泳对纯化蛋白进一步分析表明中国明对虾血蓝蛋白有三种不同的亚基组成,利用质谱对该三种亚基分别进行了鉴定。通过质谱鉴定证明本文所得纯化样品确为血蓝蛋白。为进一步研究对虾血蓝蛋白的结构和功能奠定了基础。
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Rate of hydrogen permeation was measured under static as well as dynamic mechanical deformation conditions, Cylindrical tensile test specimens were used for the study and hydrogen permeation was measured electrochemically, It was observed that the hydrogen diffusivity decreased as plastic deformation increased for the static deformation experiments while elastic deformation had no significant effect on diffusivity but increased the steady state permeation flux, For the dynamic loading experiment, an elastic deformation increased the hydrogen permeation rate almost linearly. Onset of plastic deformation led a sudden decrease of permeation rate and the reduced rate was rapidly recovered when the plastic deformation ceased. These rapid changes in the permeation rates were explained that the absorbed hydrogen was trapped by dislocations and creation rate and density of dislocations changed drastically when plastic deformation started and stopped.
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在青藏高原东北部连续两年观察了晚秋开花植物管花秦艽Gentiana siphonantha的传粉生态学特征,并在此基础上进一步比较分析了与该物种同域分布且亲缘关系较近、但开花较早的麻花艽G.straminea之间的传粉生态学特征。管花秦艽的花发育过程表现出雌雄异熟和雌雄异位的特点,不存在花内的自花传粉,套袋隔离的花不结实也支持这一结论;株内自交的高结实率表明该物种是自交亲和的。盛花期每植株平均有15朵开放的花,雄性和雌性阶段的花比例为1.2:1;自然条件下产生种子必须依赖传粉媒介;苏氏熊蜂是最有效的传粉昆虫,且访花过程中对雄性和雌性阶段花不具明显的偏向性;株内连续访花的频率高达87.8%,从而导致同株异花传粉自交的广泛存在。与同域分布的麻花艽相比,管花秦艽的单花花期、雄性和雌性期持续时间缩短。但盛花期开花数量明显增加。令人感兴趣的是尽管两个近缘种的花形态特征存在显著差异,但都是由同一种熊蜂传粉。这一特点与过去认为花颜色和花管长度是物种分化过程中与不同传粉昆虫协同进化导致生殖隔离的假说不相符合。管花秦艽单花的访花频率和同株异花连续访花的比例都明显高于麻花艽。两个物种不同花序设计导致访花昆虫行为的改变可能是造成这一差异的主要原因。两个物种具有不同的开花时间,但仍然存在一定的花期重叠,表现出不完全的传粉生殖隔离状态。
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了解三江源人工草地净生态系统CO_2交换(Net ecosystem CO_2 exchange, NEE)的季节变化规律和主要生物因子及环境因子对这些过程的影响将有助于认识青藏高原人工草地生态系统碳循环、生态价值、功能,以及对三江源区的生态安全的重要意义.该研究利用涡度相关技术,于2005年9月1日至2006年8月31日对位于青海腹地的垂穗披碱草(Elymus nutans)人工草地的NEE及生物和环境因子进行观测,阐明NEE及其组分的动态变化特征和影响因子.三江源区人工草地生态系统的日最大吸收量为2.38gC•m~(-2)•d~(-1),出现在7月30日.日间最大吸收率和最大排放率都出现在8月,分别为-6.82和2.95/μmol CO_2•m~(-2)•s~(-1).在生长季,白天的NEE主要受光合有效辐射(Photosynthetically active radiation, PAR)变化控制, 同时又与叶面积指数和群落多样性交互作用,共同调节光合速率和光合效率的强度.最大光合同化速率为2.46~10.39μmol CO_2•m~(-2)•s~(-1),表观初始光能利用率为0.013~0.070μmol CO_2•μmol~(-1)PAR.在碳交换日过程中,NEE并不完全随着PAR的增加而增大,当PAR超过某一值(>1200μmol•m~(-2)•s~(-1))时,NEE随PAR的增加而降低.受温度的影响,生长季的生态系统的呼吸商Q10(1.8)小于非生长季节的(2.6).生态系统呼吸主要受温度的控制,同时也受到叶面积指数的显著影响.生长季昼夜温差大并不利于生态系统的碳获取.三江源区人工草地生态系统是一个较强的碳汇,为-49.35gC•m~(-2)•a~(-1).
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依据祁连山海北高寒湿地植物生长期观测资料, 分析了区域辐射收支情况及其变化特征. 结果表明: 祁连山海北高寒湿地有较强的太阳总辐射(DR), 但地表反射辐射(UR)、地面有效辐射(ELR)较低;地表长波辐射(ULR)、大气逆辐射(DLR)、净辐射(Rn)均较高, 且具有明显的日、季节变化. 植物生长期5~9月的日变化振幅DR>Rn>UR>ULR>DLR>ELR, 其总量表现出ULR>DLR>DR>Rn>UR>ELR, 分别达4650.6、 4225.5、 3058.8、 2156.2、 477.6和425.1 MJ•m-2. 从月际分布来看, ULR、 DLR、 DR最高出现在7月, Rn出现在6月, UR出现在5月, ELR出现在8月, 分别为980.3、 913.1、 721.5、 554.9、 112.1和127.4 MJ•m-2.
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Five compounds were isolated from the EtOH extraction of the stem of Amoora dasyclada (How et T. Chen) C. Y. Wu (Meliaceae). On the basis of spectroscopic methods, their structures were elucidated as 24, 25-epoxy-tirucall-7-ene-3, 23-dione (1), 24, 25, 26, 27-tetranortirucall-7-ene-3-oxo-23(21)-lactone (2), taraxerone (3), taraxerol (4) and b-sitosterol (5). Among them, compound 1 was a new triterpenoid, compounds 3-5 were firstly obtained from this plant; compound 2, an tetranortriterpenoid, was firstly isolated from natural sources, and its NMR data were assigned for the first time. Moreover, the D7-bond and the Me-14 in compound 2 were never changed, which has never been found in other tetranortriterpenoids. And the biosynthetic pathway of tetranortriterpenoid was further discussed.
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根据分支系统学的原理和方法,对禾本科鹅观草属进行了系统发育分析。鹅观草属传统分类上的18 个系被确定为终端类群,来自形态学、解剖学、细胞学和孢粉学的23 个性状被选作建立矩阵的依据;雀麦族中的短柄草属作为外类群被用于外部性状的极性识别,过去分析过的性状资料被用于微观特征的极性判断;采用PAUP 程序对矩阵进行运算,共获得6 个同等简约的谱系分支图,其中具最低f - 比值的图被选作分支分析的基础。结果表明,分支图上显示的组、系划分与传统分类的基本一致,各类群间的演化关系与过去凭借单一证据所作的零散推断也基本吻合。所不同的是半颖组各支类群不是共祖起源,可能具有复杂的内部组成;在个别系间,分支图展现的类群位置与宏观分析的存在差异。
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To characterize evapotranspiration (ET) over grasslands on the Qinghai-Tibetan Plateau, we examined ET and its relevant environmental variables in a Kobresia meadow from 2002 to 2004 using the eddy covariance method. The annual precipitation changed greatly, with 554, 706, and 666 mm a(-1) for the three consecutive calendar years. The annual ET varied correspondingly to the annual precipitation with 341, 407, and 426 mm a(-1). The annual ET was, however, constant at about 60% of the annual precipitation. About 85% annual ET occurred during the growing season from May to September, and the averaged ET for this period was 1.90, 2.23, and 2.22 mm/d, respectively for the three consecutive years. The averaged ET was, however, very low (< 0.40 mm/d) during the nongrowing season from October to April. The annual canopy conductance (gc) and the Priestley-Taylor coefficient (a) showed the lowest values in the year with the lowest precipitation. This study first demonstrates that the alpine meadow ecosystem is characterized by a low ratio of annual ET to precipitation and that the interannual variation of ET is determined by annual precipitation.
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Multitracer technique was used to study the uptake and distribution of some relatively long half-life radionuclides Be, Na, Mn, Co, Sc to growing cucumber (Cucumis Sativus L.) with two different treatments. In Hoagland solution, only Mn-54 and Co-60 accumulated in the every part of plants. Mn-54, Co-60 and other radionuclides were absorbed in distilled water. The results indicate that there were major differences in the accumulation of trace elements between the two different treatments.
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轮腿复合移动机器人是具有高机动高通过能力、感知能力和自主行为能力的地面移动系统,它能搭载多种载荷,进行快速机动部署,可遥控、半自主、甚至全自主地完成使命。研究轮腿复合移动机器人的根本意义在于其可以在超出人类承受极限的复杂和危险环境中代替人类完成目标作业任务。 本文针对移动机器人的运动控制进行了详细的论述,主要内容包括(1)机器人机构尺寸综合;(2)轮腿复合移动机器人的运动特性分析;(3)远程监控系统的设计;(4)机器人控制系统的设计。 通过分析轮腿复合移动机构运动机理,给出了移动机器人的机构尺寸综合。在移动机器人的运动特性方面,提出了构型在线优化、轮腿运动协调控制算法,并在实验样机对上述优化算法和控制算法进行了实验验证,实验结果表明,构型优化算法和轮腿协调算法在机器人通过典型地形障碍物时是有效的。在远程监控系统分析设计中,对控制系统的远程遥控端硬件搭建及软件设计过程进行了详细的阐述。在机器人控制系统的研究方面,首先介绍了系统的硬件组成;其次依据机器人系统的功能要求,提出选用QNX实时多任务操作系统作为控制系统的操作系统,并对其特性进行了详细的论述;最后在实时多任务操作系统下完成了控制系统的软件设计。 本论文的研究为多轮腿移动机器人的系统设计和研发提供了理论依据和技术支持。
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土地退化是导致土地生产力下降的过程之一,也是造成土地资源日益减少的主要原因.在气候变化的大背景下,人类对土地资源的过度利用正使得土地退化成为世界性难题.
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澜沧银铅锌矿床是滇西南发现的规模最大的多金属硫化物矿床,大地构造位置位于晚古生代大陆边缘裂谷系的澜沧裂谷北段,矿产资源储量达到大型,但因数十年来的开采,资源日趋枯竭.现今,在铅逐渐萎缩,锌稳步发展和银前景看好的市场趋势下,地表高品位炉碴和砂泥铅生产殆尽而转入深部开采.然而,矿山后备资源基地眉目不清,资源问题已成为严重制约矿山企业发展,甚至威胁企业生存的根本问题.同时,2万吨/年的"高压浸取电积锌"工艺即将投入工业生产,急待扩大生产规模.因此,当务之急是加强矿山深部和外围找矿,以期扩大后备资源储量.