103 resultados para beta(1 -> 3 : 1 -> 6)-D-glucans


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Co(En)(3)MoO4 was synthesized by using the method of hydrothermal synthesis and characterized by elemental analysis, IR, ESR and single-crystal X-ray methods. It crystallizes in hexagonal space group P (3) over bar C1 with a=1.596 4(2) nm, b=1.596 4(2) nm, c = 0.993 5(2) nm, alpha=beta=90 degrees gamma=120 degrees, M-c=399.18, V=2.192 6(6) nm(3), D-c=1.814 g/nm(3), Z=6, F(000)=1 2181 R-1=0.070 3, R-w=0.220 7. According to separation of anion which acted on electrostatic potential, the anion and cation ions formed a type of organic and inorganic material.

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The crystal structure and mechanism of the title molecule are described. This crystal is orthorhombic, belonging to space group PC21/B with a=1,002 1(2) nm, b=1.483 0(3) nm, c=2.173 6(4) nm, V=3.230 39(2) nm(3), Z=2, D-c=1.80 g/cm(3), R=0.069 3. The structure was solved by direct method. The tin atom of the title compound exists in two distorted-trigonal-bipyramidal geometry, defined by two carbon, one bromide, one chloride and one oxygen atoms leading to a five-membered chelate ring. In the structure, the five-membered ring containing the intermolecular O-->Sn has a half chair conformation.

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[NH3(CH2)10NH3][ZnCl4], M(r) = 381.51, triclinic, P1BAR, a = 7.296 (1), b = 10.110 (3), c = 12.814 (4) angstrom, alpha = 90.84 (2), beta = 101.17 (2), gamma = 92.52 (2)-degrees, V = 926.13 angstrom 3, Z = 2, D(x) = 1.37 Mg m-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 1.925 mm-1, F(000) = 396, T = 298 K, final R = 0.070 for 1237 unique reflections [I > 3-sigma(I)]. The structure is characterized by layers of inorganic ions sandwiched between layers formed by the paraffinic chains.

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β,β-二烷硫基-α,β-不饱和酮类化合物作为一类具多反应中心的活泼中间体在有机合成中的应用,近20年来已引人注目并进行了深入广泛的研究~[1,2].以往的研究大多是针对β,β-二甲硫基-α,β-不饱和酮类化合物1进行的,而对结构相近的β,β-1,3-亚丙二硫基-α,β-不饱和酮类化合物2的研究较少.对于1类的合成,所用碱的选择至关重要~[1].实验证明叔丁醇钠和叔丁醇钾~[3~5]在1类的合成中效果较好.前文~[6]曾以六甲基二硅氨基锂(LHMDS)为碱高

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[Zn(C12H8N2)2(H2O)2]SO4.6H2O, M(r) = 665.98, triclinic, P1BAR, a = 10.070 (4), b = 12.280 (3), c = 13.358 (2) angstrom, alpha = 109.12 (2), beta = 92.58 (2), gamma = 110.85 (2)-degrees, V = 1433.9 (7) angstrom 3, Z = 2, D(x) = 1.54 g cm-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 10.1 cm-1, F(000) = 692, T = 293 K, R = 0.044 for 3985 observed reflections. The Zn atom is coordinated in a distorted octahedral geometry by four N atoms from two 1,10-phenanthroline (phen) ligands and two water molecules. The intermolecular ring-stacking interactions between the phen ligands occur in two forms: infinite chains and discrete dimers. Hydrogen bonds further stabilize the structure.

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The spectroscopic properties of (Y0.92-xLa0.08Ndx)(2)O-3 transparent ceramics were investigated. According to three intensity parameters (Omega(2),Omega(4),Omega(6)) fitted by the Judd-Ofelt theory, the spectroscopic quality parameter (X-Nd), branching ratio (beta(J,J')), and quantum efficiency (eta) of Nd3+ were determined. It was found that X-Nd of the host, owing to the additive La2O3, was decreased from 1.6 to 0.46; thus beta(J,11/2) was increased from 46% to 56.82%. A figure of merit of the specimens was discussed and compared with Nd:YAG transparent ceramic. (c) 2007 Optical Society of America.

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东海陆架是世界上最宽阔的陆架之一,面积达770 000 km2左右。在末次冰盛期(LGM),东海海平面下降120~130 m左右,绝大部分陆架暴露出海面。而冲绳海槽是第四纪以来一直保持海洋环境的东海深海区。本文以冲绳海槽北部PC-1岩芯为材料,通过分析该孔的孢粉,加上详细的AMS 14C测年,恢复了周边地区24 cal.kaBP以来的古植被,并推测古环境和古气候变化,重点讨论了LGM时期出露大陆架上发育的植被。 PC-1孔(31°27.5′N,128°24.8′E)位于黑潮支流对马暖流东侧,水深590 m,柱长812 cm。孢粉分析按间隔8 cm取样,个别为4~6 cm,共分析了103个孢粉样品。利用9个AMS 14C数据建立年龄标尺,用Calib5.1.0软件进行年龄校正。通过相邻样品深度的线性内插获得每个样品的年龄,采用外延法得到顶部和底部的校正年龄分别为351cal aBP、24 280 cal aBP,孢粉样品的时间分辨率平均为230 a。 根据孢粉百分比和沉积率的变化,可划分出四个带:Ⅰ带(812~715 cm,24.2~21.1 cal. kaBP)、Ⅱ带(715~451 cm,21.1~15.2 cal. kaBP)、Ⅲ带(451~251 cm,15.2~10.8 cal. kaBP)、Ⅳ带(251~0 cm,10.8~0.3 cal. kaBP),分别对应MIS 3末期、末次冰盛期、冰消期和全新世。末次冰盛期草本植物花粉占优势,孢粉沉积率较高,此时草本花粉主要来源于出露的大陆架,其上发育了以蒿属为主的草地植被,气候比较寒冷干燥;冰消期海平面开始回升,松属花粉含量升高,草本植物花粉含量下降;全新世以木本植物花粉占绝对优势,栗属-栲属花粉迅速增加,蕨类孢子含量升高,草本植物花粉含量锐减,孢粉沉积率降低,由于海平面回升,大陆架被淹没,此时孢粉主要来源于日本岛,九州地区生长了以栲属、栎属为主的常绿阔叶与落叶阔叶林,气候温暖湿润。 叶枝杉属花粉在整个岩芯中零星出现。叶枝杉属植物分布于菲律宾吕宋北部至塔斯马尼亚和新西兰气候潮湿的山地林中,该属花粉在岩芯中的出现,可能暗示了黑潮的影响或者是较强的夏季风。 草本植物与松属花粉百分比变化很好的反映了海平面的升降,松属花粉含量较高指示海平面较高。对岩芯中主要类型的花粉百分比进行了频谱分析,显示存在千年尺度的准周期变化,有明显的6.8,3.8,2.2,1.6 ka的周期。 孢粉样品中的炭屑统计表明,末次冰消期炭屑含量最高,可能因为末次冰消期降雨量增加,炭屑可被降水带到沉积地点沉积下来;全新世的炭屑浓度较高,尤其在晚全新世,出现了一个峰值,究其原因可能与气候变化和人类活动有关。

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Three new dibenzocyclooctadiene lignans, wilsonilignans A-C (1-3), together with nine known ones, were isolated from the fruits of Schisandra wilsoniana. The structures of 1-3 were elucidated by spectroscopic methods including extensive 1D and 2D NMR techniques. Compounds 1-3 were also evaluated for their anti-HIV-1 activities and showed bioactivity with EC50 values of 3.26, 6.18, and 2.87g/ml, respectively.

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Extracellular polymeric substances (EPS) from four filamentous cyanobacteria Microcoleus vaginatus, Scytonema javanicum, Phormidium tenue and Nostoc sp. and a coccoid single-cell green alga Desmococcus olivaceus that had been separated from desert algal crusts of Tegger desert of China, were investigated for their chemical composition, structure,and physical properties. The EPS contained 7.5-50.3% protein (in polymers ranging from 14 to more than 200 kD, SDS-PAGE) and 16.2-46.5% carbohydrate (110-460 kD, GFC). 6-12 kinds of monosaccharides, including 2-O-methyl rhamnose, 2-O-methyl glucose, and N-acetyl glucosamine were found. The main carbohydrate chains from M. vaginatus and S. javanicum consisted mainly of equal proportion of Man, Gal and Glc, that from P. tenue consisted mainly of arabinose, glucose and rhamnose. Arabinose was present in pyranose form, mainly alpha-L 1 --> 3 linked, with branches on C4 of almost half of the units. Glucose was responsible for the terminal units, in addition of having some units as beta1 --> 3 and some as beta1 --> 4 linked. Rhamnose was mainly 1 --> 3 linked with branches on C2 on half of the units. The carbohydrate polymer from D. olivaceus was composed mainly of beta1 --> 4 linked xylose, galactose and glucose. The galactose part was present both in beta-pyranose and -furanose forms. Arabinose in alpha-L-furanose form was mainly present as 1 --> 2 and 1 --> 2, 5 linked units, rhamnose only as alpha 1 --> 3 and xylose as beta 1 --> 4. The backbone of the polysaccharide from Nostoc sp. was composed of beta-1 --> 4 linked xylose, galactose and glucose. Most of the glucose was branched on position C6, terminal glucose and 2-O-methyl glucose units are also present. The relationship between structure, physical properties and potential biological function is discussed. (C) 2003 Elsevier Ltd. All rights reserved.

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A method for fabrication of long-wavelength narrow line-width InGaAs resonant cavity enhanced (RCE) photodetectors in a silicon substrate operating at the wavelength range of 1.3-1.6 mu m has been developed. A full width at half maximum (FWHM) of 0.7 nm and a peak responsivity of 0. 16 A/W at the resonance wavelength of 1.55 mu m have been accomplished by using a thick InP layer as part of the resonant cavity. The effects of roughness and tilt of the InP layer surface, and its free carrier absorption, as well as the thickness deviation of the mirror pair on the resonance wavelength shift and the peak quantum efficiency of the RCE photodetectors are analyzed in detail, and approaches for minimizing them toward superior performance are suggested. (C) 2007 Elsevier B.V. All rights reserved.

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本工作合成了一种含异氰酸酷功能基团的不饱和单体,(3-异氰酸酯基-4-甲基)苯氨基甲酸-2-丙烯配(TAI)。以过氧化二异丙苯(OCP)为引发剂,该单体被用于乙烯丙烯共聚物(EPM)的自由基溶液接枝官能化。纯化后的接枝产物(EPM-g-TAI)的傅立叶变换红外光谱中存在2273cm-l异氰酸酷基团(-NCO),表明异氰酸醋单体已经接枝到乙丙共聚物上。接枝率采用化学滴定和红外光谱的方法确定。与EPM相比,EPM-g-TAl的分子量分布(MMO)变窄。采用旋转流变仪测定了EPM-g-TAl的流变行为。EPM-g-TAl的表观粘度高于EPM且随接枝率的增加而增加。采用接触角测定的表面分析表明,对于给定的的极性测定液体接枝产物的接触角随接枝率的增加而增大;我们同时得到接枝产物的表面自由能(75)以及表面自由能的色散分量(γs)和表面自由能的极性分量(γsρ),这些参数随接枝率提高而增大的趋势使我们可以定量估计接枝反应对改善极性的贡献。本工作研究了(3一异氰酸酯基-4-甲基)苯氨基甲酸-2-丙烯醋(TAl)官能化乙烯丙烯共聚物(EPM-g-TAI)与尼龙6(PA6)的反应共混。傅立叶变换红外光谱表明,由于EPM-g-TAl中的异氰酸醋基(-NCO)与尼龙6中的端胺基(-NH2)之间的化学反应:EPM-g-TAI/PA6谱图中3299cm-1处的阵日伸缩振动峰变窄变高,1640cm-1处阵日变形振动峰和1547cm-1处阵日弯曲振动峰变强。同时研究了共混体系的热性能、流变性能、机械性能和形态特征。OSC结果表明,在相同的共混组成下,EPM-g-TAI/PA6共混体系中尼龙6的结晶烩(△Hc)到氏于EPM/PA6共混体系中的尼龙6,这种差别随着共混物中乙烯丙烯共聚物含量的增加而增大,说明反应共混体系中尼龙6的结晶受到一定的限制;EPM-g-TAI/PA6共混体系的复数粘度和贮能模量高于相应的EPM/PA6共混体系;与相同组成的EPM/PA6相比,EPM-g-TAI/PA6中分散相的粒子尺寸更小,粒子分布更均匀,界面粘合更强;反应共混后的机械性能如拉伸强度、杨氏模量,弯曲强度和模量、缺口及非缺口冲击强度均随着接枝率的提高而增加。

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联吡陡及其衍生物不仅用于化工和药物合成的中间体,而且具有独特的赘合作用,可被用于金属催化剂配体等方面,因此它的合成方法研究引起了人们广泛的兴趣。但是非对称联吡陡的合成日前方法仍很少。本文利用己经被成功使用于其他含氮杂环的二碳合成子-1,5-二氮杂戊二烯(vinamidiniulnsalts),合成了单取代的2,2'-,2,3'-,2,4,一二类联吡陡。在合成1,5-二氮杂戊二烯的过程中:确立了一条以四甲氧基丙烷为原料一步合成l,5一二氮杂戊二烯的简捷,经济,易工业化的合成路线,并成功进行了公斤级的放大实验;优化了1,5-二氮杂戊二烯的亲电取代反应,高收率的获得溟代,硝化的1,5-二氮杂戊二烯;优化了从取代乙酸合成p取代1,5-二氮杂戊二烯的合成方法,高收率的获得九种p芳基取代1,5-二氮杂戊二烯。本文研究了非对称联吡睫合成的一种新方法:在碱性条件下,取代的1,5-二氮杂戊二烯盐各种乙酞基吡陡亲核加成的产物,不经分离直接和氨进行[3+2+1〕的成环反应,可以高收率的合成出单取代的2,2气,2,3气,2,4气三类联吡陡。这一方法己经被成功的应用于芳基取代,卤素取代,硝基取代以及无取代基的1,5-二氮杂戊二烯与三种乙酞基吡陡的反应。这种成环反应的收率与1,5-二氮杂戊二烯俘位的吸电子特征相关。因此,针对不同取代基的1,5-二氮杂戊二烯在溶剂,碱的选择以及反应温度的控制等方面进行了优化。从而成功合成出近30种单取代的非对称联吡陡。一这种合成方法,原料价格低廉,实验操作简单,而且收率高,非常适合大量合成的要求。

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一、根据凝胶色谱柱的单分散校准关系和试样的实效关系在概念和实质上的区别以及两者在理论上的定量速率,建议了一个从一组重均和数均分子量已确知的多分散试样的实验谱图同时订定凝胶色谱柱的分子量校准关系和扩展因子的计算觅数方法。用聚苯乙烯和聚丁二烯订定的扩展因子—算出体积依赖关系相互重合,与试样的结构无关。如将扩展因子视作常数时,其具体数值可从实验谱图的方差与实效关系和单分散校准关系的斜率比值之间的定量连系得到选定。二、对高1,2聚丁二烯的级份和原试样作了凝胶色谱、光散射和粘度的测量。建议了从一组分布宽度不等的试样的凝胶色谱数据和光散射及粘度测定结果求得单分散[3]-M方程的三种不同方法。用三种方法所得高1,2聚丁二烯的单分散[3]-M方程相互重合。三、导得了从凝胶色谱图所得乙均分子量的扩展改正因子。由光散射得到了乙均迥转半径与乙均分子量的实验数据,订定了单分散1,2聚丁二烯在溶液中的分子尺寸与分子量间的关系。对实验数据作进一步的分析,获得了高1,2聚丁二烯的特性比和空间住阻因子的具体数值,并讨论了1,2结构含量对形态结构的影响。

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Resonant cavity enhancement (RCE) typed optical detector and modulator which operating at wavelength band of 1.06 μm is reported. The peak quantum efficiency of detector is reasonably high as 50% without bias, and the photocurrent contrast ratio of modulator is 3.6 times at -3.5 V as compared to 0 V. The incident angle dependence of RCE device's photoelectric response is investigated carefully.