967 resultados para vitamin B(12)


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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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Reaction of lanthanoid trichloride with two equivalents of sodium t-butylcyclopentadienide in tetrahydrofuran affords bis(t-butylcyclopentadienyl)lanthanoid chloride complexes (t-BuCp)2LnCl. nTHF (Ln = Pr, Nd, n = 2; Ln = Gd, Yb, n = 1). The compound (t-BuCp)2PrCl.2THF (1) crystallizes from THF in monoclinic space group P2(1)/c with unit cell dimensions a = 15.080(3), b = 8.855(2), c = 21.196(5) angstrom, beta = 110.34(2)degrees, V = 2653.9 angstrom-3 and D(calcd) = 1.41 g/cm3 for Z = 4. The central metal Pr is coordinated to two t-BuCp ring centroids, one chlorine atom and two THF forming a distorted trigonal bipyramid. The crystal of (t-BuCp)2YbCl.THF (2) belongs to the monoclinic crystal system, space group P2(1)/n with a = 7.726(1), b = 12.554(2), c = 23.200(6) angstrom, beta = 97.77(2)degrees, V = 2229.56 angstrom-3, D(calcd) = 1.50 g/cm3 and Z = 4. The t-BuCp ring centroids, the chlorine atom and the oxygen atom of the THF describe a distorted tetrahedron around the central ion of ytterbium.

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用X-射线单晶衍射法测定了硝酸镧与冠醚(2,2)配合物的晶体结构,发现其具有与报道的Eu(NO_3)_3(2,2)配合物不同的配位方式.晶体属于三斜晶系,空间群P(?),晶胞参数为a=10.312(2)(?);b=12.745(3)(?);c=8.917(2)(?);α=103.79(2)°;β=112.73(2)°;γ=83.68(2)°;V=1049.5(5)(?)~3;F(000)=587.88;Z=2.结构用重原子法解出;R值为0.0292.用INDO法计算了配合物的净电荷分布,电子结构、键级.结果表明,镧与配位原子间的键具有一定程度的共价性.镧的5d轨道对共价性的贡献最大,而4f轨道基本上不参与成键.La-N比La-O(醚)间存在较强的作用,增大了配合物的稳定性.

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海洋是一个巨大的天然产物宝库,约占地球表面积70%的海洋蕴藏着80%的生物资源。由于海洋生态环境的特殊性,导致海洋生物能够产生大量结构独特多变和活性特殊多样的代谢产物。我国海域辽阔,海洋资源丰富,为寻找结构新颖、生理活性独特的先导化合物,加强对海洋资源的开发利用,本论文对中国沿海的三种海洋红藻和两株放线菌次生代谢产物以及生物活性进行研究,为新药研究与开发提供模式结构和药物前体。 对红藻似瘤凹顶藻Laurencia similis乙酸乙酯萃取物进行分离纯化,从中得到单体化合物35个,通过波谱学方法(IR、MS、NMR等)鉴定了他们的结构。分别为:2, 2, 5, 5, 6, 6-sixibromo-3, 3-bi-1H-indole (1),3,5-dibromo- 1-methyl-indole (2),3',5',6,6'-tetrabromo-2,4-dimmethyldiphenyl ether (3),1,2,5- tribromo-3-bromoamino-7-bromomethylnaphthalene (4),2,5,8-tribromo-3-bromo- amino-7-bromomethylnaphthalene (5),2,5,6-tribromo-3-bromoamino-7-bromo- methylnaphthalene (6), 2,5,6,5',6'-pentabromo-3,4,3',4'-tetramethoxybenzophenone (7), (4E)-1-bromo-5-[(1'S*,3'R*)-3'-bromo-2',2'-dimethyl-6'-methylenecyclohexyl] -3-methylpent-4-ene-2,3-diol (8),4-hydroxy-Palisadin C (9),Isopalisol (10),Luzonensol (11),Palisadin B (12),Aplysistatin (13),Palisadin A (14),5-Acetoxypalisadin B (15),Aristolan-1(10)- en-9-ol (16),Aristol-8-en-1-one (17),Aristolan-9-en-1-one (18),Aristolan-1(10)-en- 9-one (19),Aristofone (20),Aristolan-1(10)-8-diene (21),Aristolan-1,9-diene (22),10-Hydroxyaristolan-9-one (23),7,11,15-trimethyl-3-methylene-hexadecan-1,2-diol (24),3β-Hydroxyergosta- 5,24(28)-dien-7-one (25),Isofucosterol (26),β-sitosterol (27),豆甾-4-烯-3α,6β-二醇 (28),Cholesta-5-en-3β-ol (29),Stigmasterol (30),2,3,5,6-四溴-吲哚 (31),2,3,6-tribromo-1H-indole (32),3,5,6-tribromo-1-methylindole (33),3,5,6-tribromo -1H-indole (34),2,3,5-tribromo-1-methylindole (35),其中化合物1-9为新化合物,化合物10-15、20和化合物24-30均为首次从该种海藻中得到。对新化合物1-9进行PTP1B酶抑制剂活性筛选,新化合物1、3、7显示强的PTP1B酶抑制活性。 对红藻齐藤凹顶藻Laurencia saitoi乙酸乙酯萃取物进行分离纯化,从中得到单体化合物11个,通过波谱学方法(IR、MS、NMR等)鉴定了他们的结构,分别为:2-hydroxyl-Luzofuranone (1),2-hydroxyl-Luzofuranone B (2),4-hydroxyl-Palisudin C (3),2-bromo-γ-ionone (4),Aplysistatin (5),5-Acetoxypalisadin B (6),Palisadin B (7),Palisadin A (8),Pacifigorgiol (9),豆甾-4-烯-3α,6β-二醇 (10),2, 3, 5, 6-四溴-吲哚 (11),其中化合物1-4为新化合物,所有化合物均为首次从该种海藻中得到。通过MTT法对分离得到的新化合物1-4进行肿瘤细胞毒活性筛选,结果显示4个新化合物对所测肿瘤细胞株均无明显的活性。 对红藻瘤状软骨凹顶藻Chondrophycus papillous乙酸乙酯萃取物进行分离纯化,从中得到单体化合物5个,通过波谱学方法(MS、NMR等)鉴定了他们的结构,分别为邻苯二甲酸二丁酯 (1),邻苯二甲酸二异辛酯 (2),胆甾醇 (3),3,7,11,15-tetramethyl-hexadec-2-en-1-ol (4),4-羟基苯甲醛 (5),所有化合物均为首次从该种海藻中得到。 对海洋放线菌M159乙酸乙酯萃取物进行分离纯化,从中得到单体化合物13个,通过波谱学方法(MS、NMR等)鉴定了他们的结构,分别为:5-(4',6'-dihydroxy-6-methyloctyl)furan-2(5H)-one (A),phenethyl alcohol (1),4-羟基苯甲醛(2),anthranilic acid (3),4-Hydroxy-3-methoxy- phenyl-propionic acid (4),5-(6,7-dihydroxy-6-methyloctyl)furan-2(5H)-one (5),p-Hydroxyphenylethyl alcohol (6),3-Indoleacrylic acid (7),Indol-3-carboxylic acid (8),Adenine cordyceposide (9),腺嘌呤核苷(10),尿嘧啶核苷(11),Thymidine (12),其中化合物A为新化合物。所有化合物均为首次从该株放线菌中得到。 对海洋放线菌L211乙酸乙酯萃取物进行分离纯化,从中得到单体化合物15个,通过波谱学方法(MS、NMR等)鉴定了7个结构,分别为:spatozoate (1),anthranilic acid (2),3-Indolylethanol (3),1-Acetyl-β-carbolin (4),p-Hydroxyphen- ylethyl alcohol (5),Indole-3-acetic acid (6),Indol-3-carboxylic acid (7),所有化合物均为首次从该株放线菌中得到。

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N-acetyl-L-glutamic acid, crystallizes in the orthorhombic space group P2(1)2(1)2(1) with unit cell parameters a = 4.747(3), b = 12.852(7), c = 13.906(7) Å, V = 848.5(8) Å3, Z = 4, density (calculated) = 1.481 mg/m3, linear absorption coefficient 0.127 mm−1. The crystal structure determination was carried out with MoKalpha X-ray data measured with liquid nitrogen cooling at 100(2) K temperature. In the final refinement cycle the data/restraints/parameter ratios were 1,691/0/131; goodness-of-fit on F(2) = 1.122. Final R indices for [I > 2sigma(I)] were R1 = 0.0430, wR2 = 0.0878 and R indices (all data) R1 = 0.0473, wR2 = 0.0894. The largest electron density difference peak and hole were 0.207 and −0.154 eÅ(−3). Details of the molecular geometry are discussed and compared with a model DFT structure calculated using Gaussian 98.

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It is accepted that world’s fisheries are not generally exploited at their biological or their economic optimum. Most fisheries assessments focus on the biological capacity of fish stocks to respond to harvesting and few have attempted to estimate the economic efficiency at which ecosystems are exploited. The latter is important as fisheries contribute considerably to the economic development of many coastal communities. Here we estimate the overall potential economic rent for the fishing industry in the North Atlantic to be B€ 12.85, compared to current estimated profits of B€ 0.63. The difference between the potential and the net profits obtained from North Atlantic fisheries is therefore B€ 12.22. In order to increase the profits of North Atlantic fisheries to a maximum, total fish biomass would have to be rebuilt to 108 Mt (2.4 times more than present) by reducing current total fishing effort by 53%. Stochastic simulations were undertaken to estimate the uncertainty associated with the aggregate bioeconomic model that we use and we estimate the economic loss NA fisheries in a range of 2.5 and 32 billion of euro. We provide economic justification for maintaining or restoring fish stocks to above their MSY biomass levels. Our conclusions are consistent with similar global scale studies.

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High- resolution UVES/ VLT spectra of B 12, an extreme pole- on Be star in the SMC cluster NGC 330, have been analysed using non-LTE model atmospheres to obtain its chemical composition relative to the SMC standard star AV304. We find a general underabundance of metals which can be understood in terms of an extra contribution to the stellar continuum due to emission from a disk which we estimate to be at the similar to 25% level. When this is corrected for, the nitrogen abundance for B12 shows no evidence of enhancement by rotational mixing as has been found in other non-Be B-type stars in NGC 330, and is inconsistent with evolutionary models which include the effects of rotational mixing. A second Be star, NGC330-B 17, is also shown to have no detectable nitrogen lines. Possible explanations for the lack of rotational mixing in these rapidly rotating stars are discussed, one promising solution being the possibility that magnetic fields might inhibit rotational mixing.

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La indoeuropeización de Europa: Genes y topónimos Modera: MTRO. DAVID BECERRA ISLAS Martes 17 de marzo Salas A y B 12:00 horas; Los celtas y los grupos "italoides" de la península Ibérica Modera: DRA. CAROLINA PONCE HERNÁNDEZ Miércoles 18 de marzo Sala de Consejo Técnico 12:00 horas; Nuevos hallazgos documentales sobre los indoeuropeos en España Modera: DRA. LOURDES ROJAS ÁLVAREZ Lunes 23 de marzo Salón 01 de Educación Continua 12:00 horas

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Dissertação de mestrado, Tecnologia de Alimentos, Instituto Superior de Engenharia, Universidade do Algarve, 2013

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Ancien possesseur : Argenson, Antoine-René de Voyer (1722-1787 ; marquis de Paulmy d')

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Ancien possesseur : Argenson, Antoine-René de Voyer (1722-1787 ; marquis de Paulmy d')

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Ancien possesseur : Gilles, Albert (1873-1959)

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Ancien possesseur : Gilles, Albert (1873-1959)