997 resultados para ddc:690


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利用电喷雾多级串联质谱 (ESI MSn)技术 ,分析了刺五加叶中黄酮类化合物 ,并根据黄酮类化合物的特征显色反应 ,采用紫外 可见分光光度法 ,对刺五加叶中总黄酮的含量进行了测定。分析结果表明 :刺五加叶含有槲皮素及其相关的黄酮甙类化合物 ,其含量达 37.2 5 %。

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The luminescent properties of Gd3PO7:Eu were investigated in W and VUV regions. This phosphor has such strong emissions around 618.5 nn under UV excitation, especially around 209nn, that it has a better colour saturation than that of Y2O3:Eu. It could be a new potential red phosphor for lamp and other applications with W-excitation source or even for displaying devices. In the VUV excitation spectrum of Eu3+ emissions, energy absorptions by Gd3+, Gd-O and PO43- have been observed, on which it can be inferred that there are three kinds of energy transferring processes to Eu-3(+) ions. The energy absorptions of Gd3+, Gd-O and PO43- are induced by 4f --> 4f transitions, a bandgap transition of Gd3PO7 and intramolecular (2t(2) --> 2a, 3t(2)) transition, respectively. The energy transfer efficiency of the PO43- intramolecular transition is lower compared with that of the bandgap transition (Gd-O).

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Three new amphiphilic rare earth complexes with only two organic long chains Ln (MOP)(2)Cl (MOP=monooctadecyl phthalate, Ln=Eu, Tb, Gd) were synthesized and characterized by elemental analysis. The complexes (Eu, Tb) showed good luminescence property with long fluorescence lifetime, whereas the intensity and lifetime of Tb complex are greater than those of Eu complex, By measuring the triplet energy levels of ligand based on energy transfer mechanism, above phenomena have been well explained. The Langmuir films of the complexes on the air/water interface were also studied and the results show that all of them have good film-forming property.

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自从VonHansKuhn[1]首次发表了关于稀土配合物LB膜的研究以来,随着材料科学的不断发展,功能稀土配合物LB膜以其在导电[2,3]、非线性光学[4,5]、磁学[6,7]和光学[8,9]等领域中的优异性能愈来愈引起人们的注意,并取得了可喜的进展…

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The synthesis for lanthanofullerenes was studied by activating the La2O3 containing graphite rod in situ and back-burning the carbide-rich cathode deposite, La@C-2n are efficiently extracted in high temperature toluene, among them, La@C-74 as a new species is added into the soluble lanthanofullerenes, The toluene extraction is first characterized by desorption electron impact (DEI) mass spectrometry, The ESR spectrum of the extraction at room temperature is also discussed.

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采用对掺入La_2O_3的石墨棒原位活化并结合交换电极回放方法制备了产率较高的金属富勒烯,并用甲苯高温热提取的方法有效地提取出La@C_(2n),其中La@C_(74)为可溶性金属富勒烯增加了新成员.同时,首次采用解吸电子轰击质谱对提取物进行了表征,讨论了提取物的ESR谱.

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本文以电化学、薄层电化学,可见·紫外现场光谱电化学和计算机数字模拟等方法,研究了四苯基卟啉合钻在N,N-二甲基甲酰胺和1,2-二氯乙烷溶液中电化学催化还原1,2-二澳乙烷和1,2-二氯乙烷的电极过程,测定了平行催化反应速率常数分别为1.2×10~3和5mol~(-1)·dm~3·S~(-1).

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A novel doping phenomenon of fully reduced polyaniline and poly-o-methyl-aniline, "light-assisted oxidative doping", was found for the first time. The doping reaction was followed by FTIR, UV-VIS, ESR and electrical conductivity measurements. It was shown that the fully reduced polyanilines in the form of HCl-salts undergo a spontaneous transition from an insulator or semiconductor to a conductor when exposed to air and light, and their final molecular chain structures are analogous to those found in HCl-doped common polyanilines.

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The tess potential-concentration curve was first applied to measure the concentration of an alloy. Attempt to use the V-c curve of Al-Li alloy in measuring the diffusion coeffictent of Li atom in liquid aluminium with anode chronopotentiometry at 720℃, was made and D_(Li/Al=4.94×10~(-5)cm~2·s~(-1) was obtained. The value is well consistent wish the theoretical value, D_(Li/Al)=4.85×10~(-5)cm~2·s~(-1) in terms of Stokes-Einstein equation.

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首次尝试利用开路电位-浓度曲线法测定合金的浓度,并用阳极计时电位法快速测定Li在液态Al中的扩散系数,720℃下Li在液态Al中的扩散系数D_(Li/Al)=4.94×10~(-5)cm~2·s~(-1),与根据Stokes-Einstein方程计算得到的理论值D_(Li/Al)=4.85×10~(-5)cm~2·s~(-1)相吻合。

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生物电子学技术是基于电子学与生物技术的发展而诞生的新领域。本文阐述并展望在这领域的最新发展。包括:生物计算机与分子计算机,生物传感器,酶电极的生物催化作用,基于离子电极和生物离子学的生物传感器,导电聚合物传感器等。

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虾青素作为饲料添加剂、天然食用色素和生物保健品活性成分,具有很好的应用前景,目前国际市场上价格昂贵,供不应求。雨生红球藻是虾青素的良好资源。但是,由于种种原因限制,红球藻细胞培养仍然不很理想,成为限制工程规模放大和开发该生物资源的瓶颈。那么,是否在光照、温度、pH、营养盐等传统影响因子之处,还有调节红球藻细胞生长的重要因子?目前国内外尚不清楚。在国家自然科学基金和国际科学基金资助下,本论文围绕红球藻是否产生调节细胞周期信号物质的语题,利用红球藻处理过的旧液重新进行该藻培养,去排除其它影响因子的基础上,初步结果表明红球藻确实产生某种物质,抑制自身生长。主要研究结果总结如下:1、在静置培养时,通常难于直接观察到旧液对藻细胞的抑制现象,这主要是由于其它因素(如无机碳等)的存在掩盖了抑制物的作用。因此,不难理解为什么以往研究大多忽视抑制物问题。2、在通气和加富二氧化碳通气培养时,旧液对藻细胞的抑制现象就比较容易发现。该物质可溶于二甲基亚枫等有机溶剂的物质、可以用乙酸乙酯从旧液中提取出来。尽管旧液中存在碳酸根和碳酸氢根等无机碳,但它们不是抑制性信号物质。3、该信号物质的产生与藻培养的时间也有一定关系,藻培养的初期并不大量积累,但在培养过程(特别是在培养的中、后期)逐渐形成,并积累在旧液中。这就可以从一个侧面阐述为什么常常难以长时间维持红球藻细胞的连续培养。4、该信号物质的产生与处理藻细胞密度有关,细胞密度越大,红球藻产生的抑制信号物质就越多。因此,高密度培养和超高密度培养中,抑制物是较为严重地限制红球藻细胞生长的问题之一,可能也是微藻(甚至细胞)培养中值得研究和关注的话题。5、红球藻游动细胞是抑制性物质产生的主要阶段,随着游动细胞转化成不动细胞,该信号物质并没有明显增加的迹象。6、尽管目前还不清楚抑制如何调节红球藻细胞周期,但是,在旧液中或有抑制性物质存在条件下,红球藻游动细胞分裂受阻,数量下降,同时不动细胞数量增加。推测抑制物有抑制游动细胞分裂,和促进游动细胞向不动细胞转化的作用。同时,有关DNA含量和DNA倍性结果也初步表明,红球藻游动细胞DNA复制过程没有受影响,但随后的细胞原生质分裂过程受阻。至于红球藻类细胞的原生质分裂受阻,和该藻细胞周期进入不动细胞阶段之间可能存在的机制,还有待进一步探讨。总之,本论文证明了红球藻在生长过程中向胞外释放降低细胞增长和诱导细胞转化的信号物质,这是细胞生长的又一个限制因子,为提高细胞培养密度和深入了解细胞周期调控机制提供了基础数据。

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以褐藻裙带菜(Undaria pinnatifida)、萱藻(Scytosiphon lomentarius)、海蒿子(Sargassum confusum)、叉开网地藻(Dictyopteris divaricata)、海带(Laminaria japonica)、囊藻(Colpomenia sinuosa)、鼠尾藻(Sargassum thunbergii)、水云(Ectocarpus confervoides)为材料,对其色素-蛋白质复合物的分离技术及其特性进行了系统研究。通过对裙带菜色素-蛋白质复合物分离技术及其影响因素的研究,确立了褐藻的PAGE分离方法。采用Tris-Gly电泳分离系统,以非离子去污剂DMG或DIG为增溶剂(DMG: Chl=20: 1, DIG: Chl=50: 1, 4 ℃增溶1 h),10%的分离胶浓度,丙烯酰胺与甲叉双丙烯酰胺的比例为30: 0.8,从裙带菜中成功地分离出8条含色素的蛋白质复合物带。采用Anderson命名系统,以高等植物菠菜为参照,将其命名为CPIa, CPI, CPa, LHC_1, LHC_2, LHC_3, LHC_4和LHC_5。游离色素较少。通过对三种褐藻的色素-蛋白质复合物的表观分子量测定、光谱学研究以及对裙带菜色素-蛋白质复合物的多肽组成分析,揭示了褐藻各种色素-蛋白质复合物的特征。CPIa是褐藻分子量较大的PSI复合物,为墨角藻黄素-叶绿素 a/c-蛋白质复合物。CPI是褐藻的PSI核心复合物,为P700-叶绿素 a-蛋白质复合物。CPa是褐藻的PSII复合物,为墨角藻黄素-叶绿素 a/c-蛋白质复合物。其余5条为捕光色素-蛋白质复合物,LHC_1和LHC_3是墨角藻黄素-叶绿素 a/c-蛋白质复合物,LHC_2, LHC_4和LHC_5是叶绿素 a/c-蛋白质复合物。根据裙带菜色素-蛋白质复合物的多肽分析结果并与高等植物比较,提出褐藻PSI和PSII的结构模型。褐藻PSI和PSII的反应中心多肽与高等植物相同,捕光复合物明显区别。褐藻LHCI和LHCII的多肽组成相同,都是由单一的20 kDa多肽组成。褐藻叶状体、叶绿体、类囊体膜和PSI复合物的77 K 荧光发射光谱具有特异性,缺少高等植物PSI特征的730 nm 荧光峰。叶状体的77 K 荧光发射光谱按荧光主峰的波长分为两种类型,一种类型的荧光主峰在690 nm,另一种类型的在705-720 nm。三种褐藻PSI复合物的77 K 荧光发射光谱相同,有两个分别们于680 nm和715 nm 的发射峰。褐藻的77 K 荧光特异是由PSI的结构决定的。根据褐藻PSI复合物的荧光特性以及去污剂增溶动力学分析结果,推动F715来自褐藻核心色素-蛋白质复合物,F680来源于PSI复合物中的捕光复合物。褐藻PSI复合物中缺少高等植物发射730 nm 荧光的LHCIb复合物的能量传递模型。

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测定了管藻目绿藻刺松藻和假根羽藻的叶状体、叶绿体及类囊体膜的吸收光谱和低温荧光光谱,并同软丝藻等5种非管藻目绿藻和菠菜进行了比较。证实绿藻普遍缺少作为高等植物 PSI 标志的 730nm 的低温长波荧光,其长波发射峰在 710 ~ 715nm 以及 695nm 荧光也不明显。采用和的 PAGE 法从刺松藻、假根羽藻、软丝藻和菠菜中分别得到 11 种、11 种、7 种和 9 种色素蛋白复合物,并测定了各复合物的分子量、Chl a/b、叶绿素的分布、多肽组成和结构关系,以及吸收光谱、低温荧光发射和激发光谱等各种光谱特性。刺松藻和假根羽藻的 CPIa_(1-2) 复合物的荧光发射主峰分别在 698、690 和 685nm,软丝藻 CPIa 在 715nm,菠菜 CPIa_(1-2) 分别在 729 和 722nm。两种管藻目绿藻的 LHCI 与 CII 的结合程度较菠菜和软丝藻更紧密,其 CPI 复合物中仍含有一定量的,710 ~ 715nm 荧光呈隐现状态。用二次 PAGE 法将刺松藻和假根羽藻的 CPIa 和 CIP 再分离,得到 PSI 的捕光复合 LHCI,为管藻黄素-Chl a/b-蛋白复合物, Chl a/b=1.2,含有 27.5、26.2、26 和 24.5kDa 四种多肽,77K 荧光峰在 682 ~ 683nm。LHCI 没有发射高等植物 730nm 荧光的相应组分是管藻目绿藻缺少 730nm 荧光的主要原因。核心复合物 CCI 含有 67 和 56kDa 两种多肽,与软丝藻和菠菜相似,但 3 种藻类核心复合物的 77K 荧光峰在 715nm,而菠菜在 720nm。刺松藻和假根羽藻有 LHCI 存在时,715nm 荧光峰不明显,随着 LHCI 的解离,荧光逐渐显现。刺松藻 PSI 中与 CCI 结合最紧密的是 LHCI 的 27.5 和 24.5kDa 多肽,两个 26 kDa 多肽的结合较为松散。用差速离心法对刺松藻、假根羽藻、软丝藻及菠菜的 PSI 颗粒进行了初步的分离。PSI 粗提物的 77K 长波荧光发射峰分别在 710、712、713 和 730nm,与 PAGE 法得到的结果相符。刺松藻和假根羽藻的 PSII 核心复合物 CPa 与菠菜相同,都含有两个 33kDa 核心多肽及 40 ~ 47 kDa 的内天线蛋白。从两种管藻目绿藻中首次分离到 6 种 LHCII 捕光复合物,其中 LHCP_(1-3),四种都是管藻黄素- Chl a/b-蛋白复合物, Chl a/b=0.7 ~ 0.9。刺松藻和假根羽藻中含量最高、最稳定的捕光复合物是分子量最大的 LHCP_1 由 34.4、31.5、29.5、28.1 和 26.5kDa 多肽构成,其中 34.4 和 31.5kDa 多肽在菠菜和软丝藻中没有对应组分。LHCP_1 再分离结果表明,分子量较小的捕光复合物都是 LHCP_1 的组成部分,但分子量最小的 Fca_1 和 Fca_2 与其它复合物的关系尚不确定。31.5 和 29.5 kDa 多肽是 LHCP_1 的核心,34.4、28.1 和 26.5kDa 多肽位于外侧;整个 LHCP_1 以 28.1 和 26.5kDa 多肽与 CCII 紧密结合,构成 PSII。根据刺松藻和假根羽藻光系统结构及其特异性的研究结果,提出了一个管藻目绿藻 PSI 和 PSII 色素蛋白复合物结构关系模型,并与高等植物的模型做了比较。讨论了光合作用两个光系统结构和特性的进化过程,指出 730nm 低温荧光峰不能作为管藻目乃至非管藻目绿藻 PSI 的表征。管藻目绿藻同杂色藻类在这方面有相似性。

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The North Atlantic spring bloom is one of the largest annual biological events in the ocean, and is characterized by dominance transitions from siliceous (diatoms) to calcareous (coccolithophores) algal groups. To study the effects of future global change on these phytoplankton and the biogeochemical cycles they mediate, a shipboard continuous culture experiment (Ecostat) was conducted in June 2005 during this transition period. Four treatments were examined: (1) 12 degrees C and 390 ppm CO2 (ambient control), (2) 12 degrees C and 690 ppm CO2 (high pCO(2)) (3) 16 degrees C and 390 ppm CO2 (high temperature), and (4) 16 degrees C and 690 ppm CO2 ('greenhouse'). Nutrient availability in all treatments was designed to reproduce the low silicate conditions typical of this late stage of the bloom. Both elevated pCO(2) and temperature resulted in changes in phytoplankton community structure. Increased temperature promoted whole community photosynthesis and particulate organic carbon (POC) production rates per unit chlorophyll a. Despite much higher coccolithophore abundance in the greenhouse treatment, particulate inorganic carbon production (calcification) was significantly decreased by the combination of increased pCO(2) and temperature. Our experiments suggest that future trends during the bloom could include greatly reduced export of calcium carbonate relative to POC, thus providing a potential negative feedback to atmospheric CO2 concentration. Other trends with potential climate feedback effects include decreased community biogenic silica to POC ratios at higher temperature. These shipboard experiments suggest the need to examine whether future pCO2 and temperature increases on longer decadal timescales will similarly alter the biological and biogeochemical dynamics of the North Atlantic spring bloom.