867 resultados para 811
Resumo:
采用新型荧光衍生试剂2-(11H-苯[a]咔唑)-乙酸(BCA)进行柱前衍生并经荧光检测对脂肪胺进行高效液相色谱(HPLC)分离和质谱定性。衍生物荧光激发和发射波长为λ_(ex)=285 nm,λ_(em)=384 nm。60℃下在乙腈溶剂中用N-乙基-N-[′(3-二甲氨基)丙基]碳二亚胺盐酸盐(EDC)作催化剂,衍生反应15 min后获得稳定的荧光产物。在Hypersil BDS C_(18)(4.0 mm×200 mm,10μm)色谱柱上,采用梯度洗脱对12种脂肪胺衍生物进行了优化分离。采用大气压化学电离源(APCI Source)正离子模式进行质谱定性,实现了各种脂肪胺衍生物的快速、准确测定。脂肪胺的线性回归系数不小于0.999 8,检出限(S/N=3)为5.73~31.3 fmol。
Resumo:
从传统藏药五脉绿绒蒿(Meconopsis quintuplinervia Regel.)全草乙醇提取物中分离得到 6个化合物,利用波谱方法鉴定为 8,9-dihydroxy-1,5,6,10b-tetrahydro-2H-pyrrolo[2,1-a]isoquinolin-3-one(1)、甲氧基淡黄巴豆亭碱(o-methylflavi nantine,2)、黑水罂粟碱(murine,3)、tricin(4)、木犀草素(luteolin,5)以及β-谷甾醇(β-sitosterol,6).其中化合物1,4为首次从该植物中分得.
Resumo:
研究选用耐旱性强的“定西24”和“高原671”与耐旱性弱的“高原448”和“青春533”春小麦品种,在盆栽条件下比较了不同耐旱性品种在拔节后经不同程度水分胁迫后叶片的多种生理参数;叶片相对含水量、净光合速率、叶绿素a、叶绿素b、叶绿素总量和类胡萝卜素含量。结果表明:在土壤相对含水量75%、55%、40%和30%这4个等级上,这些生理指标均随土壤相对含水量的降低而下降,耐旱性强的品种降低慢,且降低幅度小。在水分胁迫下,4个品种叶片的叶绿素a、叶绿素b和叶绿素总量下降,证明此时光合器生理功能遭到破坏;在轻度水分胁迫下,耐旱性强的品种定西24和高原671叶片的类胡萝卜素含量上升;在严重水分胁迫下,4个品种的叶片类胡萝卜素含量明显下降,可能此时自由基积累超过了抗氧化剂的清除能力,从而使细胞受到损伤。根据本研究结果,可以将轻度水分胁迫下叶片类胡萝卜素含量升高作为春小麦品种耐旱性的选择指标之一。
Resumo:
1 引言龙胆科(Gentianacese)植物长梗喉毛花(Comastoma Pedunlulatum[Rogle ex D. Dou] Holub)分布在西藏、青海、甘肃和四川北部,生长在海拔3000 -4800 m的河滩和高山草甸等环境中。《晶珠本草》记载:植物长梗喉毛花比之加滴色淡而软,叶微黄。藏名“桑斗”,藏医常用药。全草入药,性味苦寒,有利湿祛痰、清热解毒、脚肝利胆等功效。
Resumo:
利用同位素稀释-等离子体质谱(ICP-MS)方法测定了黔西水域、威宁等地的东岩区峨眉山玄武岩的铂族元素含量。结果表明,相对于原始地幔,东岩区峨眉山玄武岩的铂族元素发生了较强的分异作用,Os、Ir、Ru、Rh亏损,Pd、Pt发生富集,相对配分模式为Pd-Pt富集型;经球粒陨石及原始地幔标准化的铂族元素配分模式为向左陡倾斜型,具有陡的正斜率,Pd/Ir显著高于原始地幔、球粒陨石、原始上地幔等,而与地幔低度熔融形成的N-MORB、大陆拉斑玄武岩等接近,表明峨眉山玄武岩的物质来源为上地幔熔融程度偏低的玄武岩浆。
Resumo:
The paper proposes the identification method of linear and non-linear chromatographic system. The non-linear isotherms and lumped mass transfer coefficients of chromatography separating sorbitol and mannitol are determined. And the theoretical elution curves calculated by non-linear chromatographic model are more accurate than those calculated by linear chromatographic model.
Resumo:
Williams, Howard, G.W.F.Hegel (1770-1831): Cyfundrefn, Ysbryd a Hanes (University of Wales Press, 2005), pp.30-48
Resumo:
Mishuris, G; Kuhn, G., (2001) 'Asymptotic behaviour of the elastic solution near the tip of a crack situated at a nonideal interface', Zeitschrift f?r Angewandte Mathematik und Mechanik 81(12) pp.811-826 RAE2008
Resumo:
La idea que motiva el presente trabajo se refiere a entender cómo generalizan los estudiantes de bachillerato y qué tipo de pensamiento les permite hacerlo, para ello planteamos a un grupo de estudiantes del IEMS actividades donde se debe identificar un patrón que predice una secuencia geométrica, como un primer acercamiento a la idea de generalización. Este patrón debe ser descrito de forma algebraica (fórmula). En este artículo mostraremos dos tipos de formulaciones distintas construidas por los estudiantes para abordar el problema con distintos tipos de pensamiento que nos permiten mirar aspectos que podrían determinar el éxito o fracaso del desarrollo cognitivo puesto en marcha por los estudiantes.
Resumo:
This chapter discusses the code parallelization environment, where a number of tools that address the main tasks, such as code parallelization, debugging, and optimization are available. The parallelization tools include ParaWise and CAPO, which enable the near automatic parallelization of real world scientific application codes for shared and distributed memory-based parallel systems. The chapter discusses the use of ParaWise and CAPO to transform the original serial code into an equivalent parallel code that contains appropriate OpenMP directives. Additionally, as user involvement can introduce errors, a relative debugging tool (P2d2) is also available and can be used to perform near automatic relative debugging of an OpenMP program that has been parallelized either using the tools or manually. In order for these tools to be effective in parallelizing a range of applications, a high quality fully inter-procedural dependence analysis, as well as user interaction is vital to the generation of efficient parallel code and in the optimization of the backtracking and speculation process used in relative debugging. Results of parallelized NASA codes are discussed and show the benefits of using the environment.
Resumo:
This paper concerns a preliminary numerical simulation study of the evacuation of the World Trade Centre North Tower on 11 September 2001 using the buildingEXODUS evacuation simulation software. The analysis makes use of response time data derived from a study of survivor accounts appearing in the public domain. While exact geometric details of the building were not available for this study, the building geometry was approximated from descriptions available in the public domain. The study attempts to reproduce the events of 11 September 2001 and pursue several ‘what if’ questions concerning the evacuation. In particular, the study explores the likely outcome had a single staircase survived in tact from top to bottom.
Resumo:
The X-ray crystal structures of (I), the base 4030W92, 5-(2,3-dichlorophenyl)-2,4-diamino-6-fluoromethyl-pyrimidine, C11H9Cl2FN4, and (II) 227C89, the methanesulphonic acid salt of 5-(2,6-dichlorophenyl)-1-H-2,4-diamino-6-methyl-pyrimidine, C11H11Cl2N4 center dot CH3O3S, have been carried out at low temperature. A detailed comparison of the two structures is given. Structure (I) is non-centrosymmetric, crystallizing in space group P2(1) with unit cell a = 10.821(3), b = 8.290(3), c = 13.819(4) angstrom, beta = 105.980(6)degrees, V = 1191.8(6) angstrom(3), Z = 4 (two molecules per asymmetric unit) and density (calculated) = 1.600 mg/m(3). Structure (II) crystallizes in the triclinic space group P (1) over bar with unit cell a = 7.686(2), b = 8.233(2), c = 12.234(2) angstrom, alpha = 78.379(4), beta = 87.195(4), gamma = 86.811(4)degrees, V = 756.6(2) angstrom(3), Z = 2, density (calculated) = 1.603 mg/m(3). Final R indices [I > 2sigma(I)] are R1 = 0.0572, wR2 = 0.1003 for (I) and R1 = 0.0558, wR2 = 0.0982 for (II). R indices (all data) are R1 = 0.0983, wR2 = 0.1116 for (I) and R1 = 0.1009, wR2 = 0.1117 for (II). 5- Phenyl-2,4 diaminopyrimidine and 6-phenyl-1,2,4 triazine derivatives, which include lamotrigine (3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine), have been investigated for some time for their effects on the central nervous system. The three dimensional structures reported here form part of a newly developed data base for the detailed investigation of members of this structural series and their biological activities.