963 resultados para ddc: 351.3 - 433


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Dieser Artikel gibt Einblicke in den Verbreitungsgrad von e-Learning-Kursen in öffentlicher Verwaltung und Behörden. Am Beispiel der Bildungsplattform BayLern® der Bayerischen Behörden werden praxisnahe Leitlinien zur Implementierung von e-Learning an Behörden aufgezeigt.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Krankheit Friedrich Stoltzes II, Marie Stoltze in Zürich

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Toll-like receptor 3 (TLR3) participates in the innate immune response by recognizing viral pathogens. To investigate grass carp immune system responding to GCRV (grass carp reovirus) infection, the full-length cDNA sequence and genomic organization of grass carp TLR3 (CiTLR3) was identified and characterized. The full-length genome sequence of CiTLR3 is composed of 5668 nucleotides, including five exons and four introns. The full-length of CiTLR3 cDNA is 3681 bp in length and encodes a polypeptide of 904 amino acids with an estimated molecular mass of 102,765 Da and a predicted isoelectric point of 8.35. Analysis of the deduced amino acid sequence indicated that CiTLR3 has four main structural domains, including a signal peptide sequence, 14 LRR (leucine-rich repeat) motifs, a transmembrane region and a TIR (Toll/interleukin-1 receptor) domain. It is most similar to the crucian carp (Carassius auratus) TLR3 amino acid sequence with an identity of 99%. Quantitative RT-PCR analysis showed that CiTLR3 transcripts were significantly up-regulated starting at day 1 and continued through day 7 following GCRV infection (P < 0.05). These data implied that CiTLR3 is involved in antiviral defense, provide molecular and functional information for grass carp TLR3, and implicate their role in mediating immune protection against grass carp viral diseases. (C) 2009 Elsevier Ltd. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The reactions of [Cp2Mo2(CO)4] (1) with 2,2'-dipyridyl disulphide (C5H4NS-)2, 8,8'-diquinolyl disulphide (C9H6NS-)2 and tetramethyl thiuram disulphide (Me2NC(S)S-)2 in toluene solution resulted in the cleavage of the Mo-Mo triple bond to yield molybdenum complexes [CpMo(CO)2(C5H4NS)] (2), [CpMo(CO)2(C9H6NS)] (3) and [CpMo(CO)2(S2CNMe2)] (4), respectively. The molecular structures of 2, 3 . O=PPh3 and 4 were determined by X-ray diffraction studies. Crystals of 2 are monoclinic, space group P2(1)/n, with Z = 4, in a unit cell of dimensions a = 6.448(1), b = 12.616(2), c = 14.772(2) angstrom, beta = 92.85(1)-degrees. The structure was refined to R = 0.028 and R(w) = 0.039 for 1357 observed reflections. Crystals of 3 . O=PPh3 are triclinic, space group P1BAR, with Z = 2, in a unit cell of dimensions a = 11.351(3), b = 13.409(3), c = 9.895(2) angstrom, alpha = 94.59(2), beta = 90.35(2), gamma = 78.07(2)-degrees. The structure was refined to R = 0.033 and R(w) = 0.037 for 3260 observed reflections. Crystals of 4 are monoclinic, space group P2(1)/a and Z = 4 with a = 12.468(5), b = 7.637(2), c = 13.135(4) angstrom, beta = 96.62(3). The structure was refined to R = 0.032 and R(w) = 0.042 for 1698 observed reflections. Each of complexes 2-4 contains a cyclopentadienyl ligand, a cis pair of carbonyls and a chelate ligand (S,N donor or S,S donor). All the compounds have distorted square-pyramid structures.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background. The prevalence of early childhood caries (ECC) is high in developing countries; thus, sensitive methods for the early diagnosis of ECC are of prime importance to implement the appropriate preventive measures. Aim. To investigate the effects of the addition of early caries lesions (ECL) into WHO threshold caries detection methods on the prevalence of caries in primary teeth and the epidemiological profile of the studied population. Design. In total, 351 3-to 4-year-old preschoolers participated in this cross-sectional study. Clinical exams were conducted by one calibrated examiner using WHO and WHO + ECL criteria. During the exams, a mirror, a ball-ended probe, gauze, and an artificial light were used. The data were analysed by Wilcoxon and Mc-Nemar's tests (a = 0.05). Results. Good intra-examiner Kappa values at tooth /surface levels were obtained for WHO and WHO + ECL criteria (0.93 /0.87 and 0.75 /0.78, respectively). The dmfs scores were significantly higher (P < 0.05) when WHO + ECL criteria were used. ECLs were the predominant caries lesions in the majority of teeth. Conclusions. The results strongly suggest that the WHO + ECL diagnosis method could be used to identify ECL in young children under field conditions, increasing the prevalence and classification of caries activity and providing valuable information for the early establishment of preventive measures.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We report the synthesis of [(3-chlorobenzamido)methyl]triethylammonium chloride in a reaction of N-(chloromethyl)-3-chlorobenzamide and triethylamine in dry acetone. The structure of the newly synthesized compound was characterized with1H-NMR,13C-NMR, FTIR and Mass spectroscopy. © 2015 by the authors; licensee MDPI, Basel, Switzerland.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The photodenitrogenation of vinyl azides to 2H-azirines by using a photoflow reactor is reported and compared with thermal formation of 2H-azirines. Photochemically, the ring of the 2H-azirines was opened to yield the nitrile ylides, which underwent a [3 + 2]-cycloaddition with 1,3-dipolarophiles. When diisopropyl azodicarboxylate serves as the dipolarophile, 1,3,4-triazoles become directly accessible starting from the corresponding vinyl azide. © 2013 Cludius-Brandt et al.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本文采用曲面间的保角变换,将球面润滑问题变换为平面润滑问题,导出等角螺线槽球形轴承的承载能力和气膜刚度的近似解析表达式和最佳槽型参数。本文结果适用于小压缩数和小偏心的情况。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Er3+ -doped strontium lead bismuth glass for developing upconversion lasers has been fabricated and characterized. The Judd-Ofelt intensity parameters Omega(1) (t = 2,4,6), calculated based on the experimental absorption spectrum and Judd-Ofelt theory, were found to be Omega(2) = 2.95 x 10(-20), Omega(4) = 0-91 X 10(-20), and Omega(6) = 0.36 x 10(-20) cm(2). Under 975 nm excitation, intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions H-2(11/2) --> I-4(15/2), S-4(3/2) I-4(15/2), and F-4(9/2) --> I-4(15/2) respectively were observed. The upconversion mechanisms are discussed based oil the energy matching and quadratic dependence on excitation power, and the dominant mechanisms are excited state absorption and energy transfer upconversion for the green and red emissions. The long-lived I-4(11/2) level is supposed to serve as the intermediate state responsible for the upconversion processes. (C) 2004 Published by Elsevier B.V.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

贮氢合金是镍一金属氢化物电池的核心材料,其综合性能的改善是提高镍一金属氢化物电池性能的关键。本研究以探索镍一金属氢化物电池新型负极材料为目的,以非ABS型贮氢合金为研究对象,采用X射线衍射、Rietveld分析、恒电流充/放电、P-C-T曲线及线性微极化等方法,从基础和潜在应用等方面详细研究了非ABS型合金的结构与电化学性能。对La-Ni体系中非ABS型二元合金的结构和电化学性能的研究表明,LaNi_(228)具有最优异的高倍率充电性能;La_2Ni_7合金电极的高倍率放电性能最佳;La_7Ni_3在低温条件下表现出较好的放电性能。然而,所有得到的La-Ni合金电极容量远低于其理论容量。因此,必须通过进一步研究,如元素取代、热处理、表面处理等来提高其电化学容量。对RENi_3(RE=La,Ce,Pr,Nd,Sm,Gd,Th,Dy,Ho,Er,Y)研究表明:YNi_3合金因其具有最大的晶胞体积,最小的密度,而表现出最好的高倍率充/放电性能及低温放电性能,但其高温放电性能需要进一步提高,以满足实际应用的要求。用Al、Mn、Ti、Fe、Sn、Si、Cr、M。、Cu和Co十种元素取代Ni进行了大量的配方筛选工作。得到了大量的实验数据,并发现LaNi_(3.7)Al_(0.3)合金电极电化学放电容量最高,达290.8mAh/g;LaNi_(3.7)Mo_(0.3)合金电极的高倍率放电性能最好,在以4200mA/g的电流密度下进行放电时,其放电容量仍达到145.8mA/g;而I镍一金属氢化物电池新型负极材料研究镍一金属氢化物电池新型负极材料的研究Al的取代会使合金电极性能对温度不敏感。以我们的实验为基础,进一步进行合金配方的微调,具有可能开发出具有实用价值的贮氢合金的潜力。在Ar保护下用真空电弧炉熔炼合成了四种Lal一xMg:(NICoAI)3.6体系贮氢合金,制成姐卜Ni电池负极,通过恒电流充/放电方法研究了其电化学性能。结果表明:Lal一xMg:(NiCoAI)3.6体系金属氢化物电极较容易活化,室温下具有优异的高倍率放电性能,在以4200mA/g电流放电时,La卜汉gx(NICoAI)36合金电极的放电容量是ABS型合金电极的3倍,达152hah/g,显示出良好的动力学特性。R,入1兮Ni(R:raree田劝,Ca,Y)型合金因能吸引/释放1.8一1.87%质量的HZ而被认为是种很有希望的贮氢合金。但其吸/放氢平台过高,循环寿命短。如何提高Rh厦g剑19循环稳定性是这类合金能否成功商业化的关键。研究发现,Co能够显著提高ABS型合金电极的循环寿命,但其价格太贵。人们发现Al在提高电极寿命方面与C。有类似的作用,但Al元素的添加因其在碱性电解质的作用下在电极表面易生成致密的氧化膜而不利于氢的扩散,进而对高倍率放电性能不利。入物在提高电极表面活性,改善其高倍率放电性方面作用明显。本工作在前面的基础上用Al和MO联合取代Ni,以期待同时改善La一Mg一Ni一Co合金的循环稳定性和高倍率放电性能。详细研究了La07Mg03Ni切一(A105Mo05)x(x:o,0.2,0.4,0.6,0.8)系列贮氢合金的晶体结构和电化学性能。X射线衍射及Rietveld分析发现:所有La07Mg03Ni4D一x(A105Mo05)x合金均为包含PuNi3结构的六方LaZMgNig相、CaCus结构的LaNis主相及L匆Ni7,LaN儿和LaNi杂相的多相结构。合金中La(La,Mg)剑19相及LaNis相的晶格参数及晶胞体积均随合金中Al和Mo含量的增加而增大。用电化学方法测得的RC一T曲线显示:Al和'fo部分取代Ni降低了氢的平台压力。随合金中Al和Mo含量的增加,电极的电化学容量从329.7(x=0)、徽橇毓孺鑫盆一11瀚加至365.物A吨(=0.6)后又降低到351.3毗吨(x=0.8)。当以1200m刀g的电流密度进行放电时,其I{RD从62.0%沁0)增加到82.1%沁0.8)。线性微极化结果显示:Al和Mo的添加增大了合金表面的交换电流密度,因而也改善了合金电极的高倍率放电性能。另外,Al和M。取代合金中的Ni增大了氢在电极合金中的扩散系数(D),改善了La07Mgo3Ni4。一x(Alo5M。。5)x(X=o,0.2,0.4,0.6,0.8)合金电极的低温放电性能(LTD)。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

IEECAS SKLLQG