455 resultados para 5S


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Collections of phytoplankton were made by Mr. Durairatnamat various stations between latitude 5°S and 25°S and longitude 78° E and 101° E (Fig. 1) from December 1962 to January 1963 during a cruise of the research vessel "Umitaka Maru" belonging to the Tokyo University of Fisheries. This vessel was engaged in work in connection with the International Indian Ocean Expedition (I.I.O.E.). The collections made from these stations (T.G.) were examined at the Fisheries Research Station, Colombo, for the various diatoms present and the findings are reported in this paper.

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在简略介绍非线性空间及场方程的基础上, 以非线性科学中的孤子概念为例, 结合分子进化和生物大分子结构与功能研究中存在的一些问题, 着重讨论了生物系统在分子层次上的非线性问题, 并运用分形理论对80余种5S rRNA序列的分维进行了计算。参17

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Rapid thermal annealing of arsenic and boron difluoride implants, such as those used for source/drain regions in CMOS, has been carried out using a scanning electron beam annealer, as part of a study of transient diffusion effects. Three types of e-beam anneal have been performed, with peak temperatures in the range 900 -1200 degree C; the normal isothermal e-beam anneals, together with sub-second fast anneals and 'dual-pulse' anneals, in which the sample undergoes an isothermal pre-anneal followed by rapid heating to the required anneal temperature is less than 0. 5s. The diffusion occuring during these anneal cycles has been modelled using SPS-1D, an implant and diffusion modelling program developed by one of the authors. This has been modified to incorporate simulated temperature vs. time cycles for the anneals. Results are presented applying the usual equilibrium clustering model, a transient point-defect enhancement to the diffusivity proposed recently by Fair and a new dynamic clustering model for arsenic. Good agreement with SIMS measurements is obtained using the dynamic clustering model, without recourse to a transient defect model.

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A new freshwater phototrophic species of the dinoflagellate genus Peridiniopsis, P. niei sp. nov., is described based on morphology. The new species appeared during spring with densities up to 1.48 x 10(7) cells L-1 in some tributaries and gullies of Three Gorge Reservoir and Lake Donghu, China, forming red tides. Peridiniopsis niei is a cyst-producing freshwater dinoflagellate that belongs to the group Penardii. The plate tabulation is po+x+4 '+0a+6 ''+5c+5s+5 '''+2 '''' and the plate pattern is symmetric. The cells of P. niei are pentagonal in ventral view, the epitheca is larger than the hypotheca, making up about 2/3 the length of the cell. Plate 3 ' is hexangular. The closest species to P. niei is P. penardii (Lemmermann) Bourrelly, but cells of the former are pentagonal, very compressed dorsoventrally, and the hypotheca is truncated with one transparent, robust spine on each antapical plate.

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GaInNAs/GaAs single-quantum-well (SQW) lasers have been grown by solid-source molecular beam epitaxy. N is introduced by a home-made de-active plasma source. Incorporation of N into InGaAs decreases the bandgap significantly. The highest N concentration of 2.6% in a GaInNAs/GaAs QW is obtained, corresponding to the photoluminescence (PL) peak wavelength of 1.57 mum at 10 K. The PL peak intensity decreases rapidly and the PL full width at half maximum increases with the increasing N concentrations. Rapid thermal annealing at 850 degrees C could significantly improve the crystal quality of the QWs. An optimum annealing time of 5s at 850 degrees C was obtained. The GalnNAs/GaAs SQW laser emitting at 1.2 mum exhibits a high characteristic temperature of 115 K in the temperature range of 20 degrees C- 75 degrees C.

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中国第一座波力试验电站——珠江口岸式波力电站于1990年2月15日试发电成功。该电站位于珠江口大万山岛的南岸,面向浩瀚南海。设计波况H1/10=1.5m,T=6.5s.计划装机容量为8kW,第一台为3kW无刷爪极式发电机组,输出110V直流电,第二台为5kW无刷单相交流同步发电机组,输出220V交流电。目前投入试发电的是3kW机组。本文将介绍该电站气室性能模型试验,空气透平与气室性能匹配设计,岩坎爆破施工,实海条件下电站气室性能试验和发电试验结果。

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本论文将二茂铁基团引入聚苯胺链,合成导电或导磁聚苯胺。取得的主要结果如下: 1、合成了抗磁性的二茂铁单磺酸并用于掺杂聚苯胺,掺杂态聚苯胺的电导率可达2.34´10-1 S/cm,二茂铁单磺酸氧化后掺杂聚苯胺的电子顺磁共振(EPR)上出现了g» 4的新信号。二茂铁单磺酸被FeCl3氧化后,随氧化程度的增加,室温电导率下降1-2个数量级,但材料的磁化率增加,表现出宏观反铁磁性。用I2氧化二茂铁单磺酸掺杂的聚苯胺,其电导率为4.50´10-2 S/cm,在低温下具有铁磁性耦合,外斯温度为15 K。 2、合成了两种草酸根桥联的双金属阴离子与导电聚苯胺的杂化材料。杂化材料同时具有反铁磁性和导电性,外斯温度分别为-19.16 K和-22.10 K,电导率分别为4.8×10-3S/cm和1.2×10-5S/cm。 3、合成了聚邻、间位二茂铁苯胺。可溶的聚邻二茂铁苯胺显示铁磁性,外斯温度为25 K,饱和磁强度为6.89 emu/g。与碘或四氰基对苯醌二甲烷(TCNQ)反应所得配合物的外斯温度分别提高到50 K和104 K,饱和磁强度分别为6.51 emu/g 和4.36 emu/g,在低温下观察到了反铁磁性耦合。难溶的聚间二茂铁苯胺显示宏观抗磁性。 关键词:二茂铁单磺酸,导电导磁性聚苯胺,聚邻二茂铁苯胺,铁磁性耦合

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本文简要评述了生物膜领域的发展过程及研究现状,介绍了关于生物膜的一些基本性质和理论。采用电化学、光谱学以及扫描探针显微镜等方法对支撑双层磷脂膜、磷脂浇铸膜和泡囊等不同的模拟生物膜体系进行了研究。主要结果如下:1.将磷脂与芦丁的混合物滴于玻碳电极表面制备出了嵌有芦丁的磷脂浇铸膜,并以此膜为模拟生物膜的模型研究芦丁在磷脂膜内的电化学行为,以及芦丁对还原型辅酶烟酞胺腺漂吟二核昔酸(NADH)的催化氧化。芦丁与磷脂膜牢固地结合,在pH 7.4的磷酸缓冲溶液中,嵌在磷脂膜内的芦丁显示了准可逆电化学行为,也显示出很好催化氧化NADH的能力,使氧化电流明显增大。同时,与5*10~(-3)mol/L的NADH在裸玻碳电极上的电化学行为相比,其氧化过电位降低了约220 mV。2.在玻碳电极表面制备了嵌有芦丁的磷脂浇铸膜,嵌在磷脂膜内的芦丁显示了准可逆电化学行为。利用这种浇铸膜作为模拟生物膜的模型研究了芦丁对抗坏血酸的催化氧化,磷脂膜一方面与芦丁牢固结合,另一方面为芦丁催化抗坏血酸的氧化提供了理想的生物环境,在pH 7.4的磷酸缓冲溶液中,芦丁能有效地催化氧化抗坏血酸,使抗坏血酸的氧化过电位与裸玻碳电极上的电化学行为相比降低了约100 mV。该修饰磷脂膜和芦丁的玻碳电极对抗坏血酸的测定线性范围为2*10~(-4) mol/L-1.4*10~(-3) mol/L。3.将含有四硫富瓦烯(TTF)和黄嘿吟氧化酶的二甲基二(十二烷基)澳化钱(D DAB)泡囊滴于热解石墨电极表面,制备出一种基于磷脂浇铸膜的黄嘿吟生物传感器。TTF由于其可以有效地转移电子而被选作为电子媒介体,用安培检测的方法研究了工作电位、pH值对黄嘿吟传感器的影响。该传感器的响应时间小于10秒,其检测黄嘿吟线性范围从4*10~(-7)mol/L到2.4*l0~(-6)mol/L,最低检测限为3.2*10~(-7) mol/L。4;将辣根过氧化物酶(HRP)固定在修饰于玻碳电极表面的DDAB浇铸膜内,获得了IIR卫的直接电化学,并以此开发出一种不需媒介体的还02传感器,该传感器对H_2O_2的响应时间约5s,其检测姚。2线性范围从l*10~(-3) mol/L到4*10~(-3)mol/L,同时该传感器也显示出良好的重现性及稳定性。5,利用循环伏安的方法研究了HRP分子在双肉豆范磷脂酰胆碱(DMPC)磷脂膜内的电化学行为,并获得了一对氧化还原峰,说明了DMPC磷脂膜促进了HRP分子的电子传递,同时HRP分子仍保持对H_2O_2的催化生物活J险。UV一vis和CD的检测结果说明HRP分子在与磷脂膜相互作用后,其二级结构没有改变,而三级结构变得松散,这种三级结构的松散可能是使HRP分子的活性基团有所暴露,使得电子传递更容易。AFM实验同样也显示了HRP分子与DMPC磷脂膜间的强烈作用。

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由于生物传感器在临床、环境、食品等领域具有广阔的应用前景,近年来发展迅速。本论文以“十五”国家科技攻关重大项目《科学仪器研制与开发》的子课题《有机-无机杂化材料膜BOD生物传感器及BOD快速测定仪的研制与开发》为契机,进行了高稳定的BOD生物传感器的研究与开发;将自组装技术和纳米技术相结合,探索了一种制备性能稳定的酶生物传感器的新方法。主要结果如下:目前水污染经常必测的水质监测指标之一的生化需氧量(BOD)存在着测量时间长、不能及时反映水质变化、不能有效地进行信息反馈等缺点,为了解决这些问题,展开了快速、稳定的BOD生物传感器方面的研究:通过对微生物进行筛选,选择性能稳定的、对有机物降解能力强的微生物制备微生物膜;通过对各种固定化材料的比较,筛选出以硅的溶胶掺杂聚乙烯醇接枝聚乙烯毗睫的有机-无机杂化材料固定微生物制备微生物膜,该新型有机-无机掺杂材料不仅有效地防止了薄膜的开裂,而且由于其含有大量的轻基而具有良好的生物相容性。选择适当的溶液作标准溶液,能够改进生物传感器法与传统的五天法结果的一致性,可以进一步拓宽BOD生物传感器的应用范围。所研制的BOD生物传感器能在10 min左右测定BoD含量,稳定性和重现性良好;用于实际样品的测走,所得结果与标准稀释法一致;该传感器保存12个月经活化后至少具有80%以上的活性,可连续使用90天以上。通过对流路系统、恒温系统等的研究,与江苏江分电分析仪器厂的研究人员一起制备了XSF-1型在线BOD监测仪样机三台,并顺利通过了中国科学院院级鉴定。首先将金电极或玻碳电极表面功能化,再依次组装金纳米粒子和酶,制得性能稳定的生物传感器。这样制备的HRP生物传感器,实现了HRP的直接电化学,对H_2O_2还原具有很高的催化活性,响应速度快(<2.5s)、灵敏度高、重现性好,并且具有长期稳定性。由此提供了一种组装金纳米粒子固定生物大分子的方法,由于金纳米粒子与生物大分子之间有较强的相互作用,酶或蛋白质能被牢固地固定在电极表面,而且金纳米粒子能够促进电子转移,从而有助于实现酶或蛋白质的直接电化学;该方法可多层组装金纳米粒子,从而增加酶载量;此外,该传感器也可与产物含过氧化氢的氧化还原酶联用制备双酶或多酶生物传感器。

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典型的真核生物有四种rRNA(18S、5.8S、28S和5SrRNA)。一般18S、5.8S和28S的基因分别由转录间隔区(ITS)隔开而位于同一个转录单位上构成一个rRNA基因拷贝,多个rRNA基因拷贝串联形成rDNA。rDNA聚集在一起构成核仁组织区(NOR),成为核仁发生的位置。5SrRNA基因除在少数真核生物(如:酵母)中是和18S、28S rRNA基因位于同一个转录单位上外,一般是处在核仁以外的区域。贾第虫一度被认为是现存最原始的真核生物。支持这一观点的一个重要证据之一就是它还不具核仁结构。那么它的rDNA与典型真核生物的相比会有怎样的特点呢?本文在基因组的水平上对贾第虫的rDNA进行了全面调查分析,并对5S rRNA及其相关蛋白进行重点研究,得到如下结果和结论: 1)贾第虫的18S rRNA(1448bp)基因和28S rRNA(2300bp)基因比其他一些真核生物的(一般为1800bp和3400bp)要小的多,甚至比一些原核生物的相应的rRNA基因还要小。不仅如此,其5.8S rRNA基因和28SrRNA基因之间的转录间隔区(ITS2)比典型真核生物的对应区域也要短得多(只有54bp),且GC含量较高。结构预测表明该间隔区不能形成在许多真核生物中所能形成的保守的二级结构。更特别的是,贾第虫基因组中的rRNA基因序列大部分都是不完整的,并且不按照18S-5.8S-28S rRNA基因顺序排列,也没有多个完整拷贝顺序排列的区域。这提示贾第虫rRNA基因可能是以一种不同于典型真核生物的方式聚集的。因此本文认为以上这些特点可能与贾第虫不能形成典型核仁结构有关。 2)本文从贾第虫基因组中鉴定出了5S rRNA基因,并实验验证了其表达及其完整基因序列所编码的5S rRNA具有典型真核生物的T型二级结构,且具有绝大多数保守位点。RT-PCR表明该基因具有转录活性。该结果否定了前人的贾第虫没有5S rRNA的实验结果。并表明贾第虫尽管很原始,但其5S rRNA基因仍然是独立存在的和单独转录的。贾第虫基因组中总共有8个5S rRNA基因拷贝(且其中还有一个拷贝具有15个bp的异常插入)这大大低于一般真核生物的拷贝数。这些5S rRNA基因也不形成串联排列的区域。 我们还在贾第虫中鉴定出在真核生物中唯一与5S rRNA接触的核糖体蛋白L5蛋白并验证了其表达,该序列与其他真核生物的L5蛋白相似性很高,这提示贾第虫在5S rRNA基因转录出核后与L5蛋白结合形成5S RNP的过程可能与典型的真核生物是一致的。此外,我们从贾第虫中鉴定不出符合典型真核生物TFIIIA因子特征的蛋白,这提示贾第虫5S rRNA的转录起始以及转录后出核的机制可能与典型真核生物不同。过去对贾第虫的研究表明高等真核生物里RNA聚合酶III所独有的四个亚基在贾第虫中找不到同源物,而这样不完整的RNA聚合酶III已经可以在贾第虫中完成5S rRNA的转录了,这表明RNA聚合酶III所独有的这些亚基可能是为了完成其他功能而进化出来的。

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The growth of GaInNAs/GaAs quantum wells (QW) was investigated by solid-source molecular beam epitaxy. N was introduced by a dc-active plasma source. The effect of growth conditions such as on the N incorporation and photoluminescence (PL) intensity of the QWs has been studied. The PL peak intensity decreased and the PL fun width at half maximum increased with increasing N concentrations. The highest N concentration of 2.6% in a GaInNAs/GaAs QW was obtained, and corresponding to a PL peak wavelength of 1.57 mum at 10K. Rapid thermal annealing at 850degreesC significantly improved the crystal quality of the QWs. An optimum annealing time of 5s at 850degreesC was obtained. A GaInNAs/GaAs SQW laser with the emitting wavelength of 1.2 mum and a high characteristic temperature of 115 K was achieved at room temperature.

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本文介绍了大庆3号煤油在超临界条件下热裂解特性的实验研究。通过改进的煤油二级加热系统以及裂解产物收集和分析系统,研究了煤油在温度 700-1100K,压力 3.5-4.5MPa,以及驻留时间 0.6/1/2.5s 时的热裂解吸热特性。同时实验测量了裂解产物的成分以及裂解混合物的流量随温度、压力、驻留时间的变化。研究发现:裂解特性,如裂解度、化学热沉、裂解产物成分均随裂解温度、驻留时间显著变化,而受压力的影响不大。当裂解度大约 45%时,裂解反应的化学热沉达到最大值,该值随着驻留时间的增大而减小。气相产物的成分分析结果表明随着裂解温度的升高和驻留时间的增大,产物中饱和烃的比重增加,因此反应的吸热能力明显减小。在目前的裂解条件下,可获得的最大化学热沉为0.5MJ/kg,小于美国JP-7燃料的最大热沉0.7 MJ/kg(裂解度60%)。

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本论文由三章组成。第一、二章分别报道钩藤、蹄叶橐吾的化学成分研究工作。从两种药用植物中共分离和鉴定了37 个化合物,其中有1 组6 个新的骨架相似的鞘糖脂类同系物及5 个新的倍半萜类化合物。第三章概述了艾里莫芬烷内酯类化合物的研究进展。 第一章报道钩藤(Uncaria rhynchophylla)带钩茎枝乙醇提取物的化学成分。采用正、反相硅胶柱层析等分离方法,运用NMR、MS 等波谱技术共分离鉴定得到22 个化合物,分属于五环三萜类化合物、鞘糖脂类化合物等,其中有1 组6个新的鞘糖脂类化合物同系物,另外有7 个化合物首次从该植物中分离得到。 第二章报道蹄叶橐吾(Ligularia fischeri)根部乙醇提取物化学成分的分离纯化和结构鉴定。通过正、反相硅胶柱层析等分离纯化和MS、NMR 等波谱解析,共分离鉴定得到18 个化合物,其中5 个是新化合物。它们的结构分别确定为3β-acetyl-6β, 8α, 10β-trihydroxyeremophila-7(11)-en-8, 12-olide (23), 3β-acetyl-8β,10β-dihydroxy-6β-(2-methylbutyryloxy)-eremophilenolide (24), 3β-acetyl-6β, 10β-dihydroxyeremophila-7(11), 8(9)-dien-8, 12-olide (25), 3β-acetyl-6β, 10β-dihydroxyeremophila- 7(11), 8(9)-dien-8, 12-olide (26), (3aR, 4R, 5S, 7aS)-2-acetyl-7ahydroxy-3a, 4, 5, 6, 7, 7a-hexahydro-1H-inden-5-yl acetate (27)。这5 个化合物经体外生物活性测试,结果表明化合物23 具有抑制酪氨酸磷酸酯酶的活性, 其IC50 值为1.30 μg/ml。 第三章概述了近二十年来艾里莫芬烷内酯类化合物的研究进展,包括其结构及药理活性两个方面,列举了从23 种植物中分到的114 个艾里莫芬烷内酯类化合物,同时也对其主要生物活性进行了总结。 This dissertation consists of three chapters. The first and second chapters elaborate the phytochemical investigation of Uncaria rhynchophylla and Ligularia fischeri. Thirty-seven compounds, including six new ones, were isolated and identified by spectroscopic methods and X-ray diffraction experiments. The third chapter is a review on the study progress of Eremophilanolides. The first chapter focus on the isolation and identification of chemical constituents from Uncaria rhynchophylla. Twenty-two compounds were isolated from the roots of U. rhynchophylla by repeat column chromatography over normal and reversed phase silica gel. Those compounds mainly belonged pentacyclic triterpenoids and sphingolipids. Among them, a series homologues of six sphingolipids were new compounds and seven compounds were firstly reported in this plant. The second chapter is about the phytochemical investigation of L. fischeri. Eighteen compounds were isolated and identified. Among them, four new erem-ophilanolides and a new dinoreremophilane derivative were characterized as 3β-acetyl-6β, 8α, 10β-trihydroxyeremophila-7(11)-en-8, 12-olide (23), 3β-acetyl-8β, 10β-dihydroxy-6β-(2-methylbutyryloxy)-eremophilenolide (24), 3β-acetyl-6β, 10β-dihydroxyeremophila-7(11), 8(9)-dien-8,12-olide (25), 3β-acetyl-6β, 10α-dihydroxyeremophila- 7(11), 8(9)-dien-8,12-olide (26), (3aR,4R,5S,7aS)-2-acetyl-7a-hydroxy-3a, 4, 5, 6,7, 7a-hexahydro-1H-inden-5-yl acetate (27) by spectroscopic analysis and confirmed by X-ray crystallography analysis. It was revealed that compound 23 has the ability to inhabit the PTP1B in vivo. And its IC50 is 1.30 μg/ml. The third part is a review on the study progress of Eremophilanolides.

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The 4d photoabsorption spectra of I2+, I3+, and I4+ have been obtained in the 70-127 eV region with the dual laser-produced plasma technique at time delays ranging from 400 to 520 ns. With decreasing time delay, the dominant contribution to the spectra evolves from the I2+ to the I4+ ions, and each spectrum contains discrete 4d-nf transitions and a broad 4d-epsilon f shape resonance, which are identified with the aid of multiconfiguration Hartree-Fock calculations. The excited states decay by direct autoionization involving 5s or 5p electrons, and rates for the different processes and resulting linewidths were calculated. With increasing ionization, the 4d-epsilon f shape resonance become intense and broader in going from I2+ to I3+, and then vanishes at I5+. In addition, the discrete structure of the calculated spectrum of each ion gradually approaches the corresponding shape resonance position. Based on the assumption of a normalized Boltzmann distribution among the excited states and a steady-state collisional-radiative model, we reproduced spectra which are in good agreement with experiment.

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研究了 Ba Li F3中 Gd3+和 Eu2 +的光谱性质及 Gd3+对 Eu2 +的能量传递过程 ,讨论了传递机理 .Gd3+的含量 (物质的量分数 )为 0 .3 %时 ,传递效率最高 ,传递几率 PSA=1 .3 5× 1 0 5s- 1 .当 Gd3+的含量高于 0 .3 %时 ,由于 Gd3+ 和 Eu2 + 竞争吸收 Gd3+ 占优势 ,增加 Gd3+ 含量 ,竞争吸收比相应增加 ,Eu2 + 自身吸收光子数目减少 ,发射强度降低