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500 个结果
  • 简介:维生E作为聚烯烃主抗氧剂的应用可以说是20世纪90年代聚合物稳定化领域的一个重要成果。维生E的有效成分为a-生育酚(ATP),ATP不仅显示极高的抗氧活性,而且可以消除或降低塑料包装材料内的异味,因此塑料包装业特别是食品和医药的生产厂商对此表现出极大兴趣。

  • 标签: 维生素E 抗氧剂 塑料包装材料 有效成分 抗氧活性 生产厂商
  • 简介:水溶性的维生C是一种人体必需的营养物质.维生C是含有烯二醇基的多羟基内酯结构,利用其水溶液在波长265nm处有较强烈的紫外吸收峰,建立了直接用紫外分光光度法测定新鲜蔬菜中维生C含量的方法.实验结果表明,维生C的含量在1.0~12.0μg/mL内线性关系良好,线性方程为A=0.06603c+0.01974(R2=0.99751),检出限为0.044μg/mL,样品加标回收率为97.5%~105.4%.方法操作简单,准确度高,对新鲜蔬菜的测定结果令人满意.

  • 标签: 新鲜蔬菜 维生素C 紫外分光光度法
  • 简介:X-rayimagingistheconventionalmethodfordiagnosingtheorthopedicconditionofapatient.ComputerizedTomography(CT)scanningisanotherdiagnosticmethodthatprovidespatient’s3Danatomicalinformation.However,bothmethodshavelimitationswhendiagnosingthewholeleg;X-rayimagingdoesnotprovide3Dinformation,andnormalCTscanningcannotbeperformedwithastandingposture.Obtaining3Ddataregardingthewholeleginastandingpostureisclinicallyimportantbecauseitenables3Danalysisintheweightbearingcondition.Basedontheseclinicalneeds,ahardware-basedbi-planeX-rayimagingsystemhasbeendeveloped;itusestwoorthogonalX-rayimages.However,suchmethodshavenotbeenmadeavailableingeneralclinicsbecauseofthehightcost.Therefore,weproposedawidelyadaptivemethodfor2DX-rayimageand3DCTscandata.Bythismethod,itispossibletothreedimensionallyanalyzethewholeleginstandingposture.TheoptimalpositionthatgeneratesthemostsimilarimageisthecapturedX-rayimage.Thealgorithmverifiesthesimilarityusingtheperformanceoftheproposedmethodbysimulation-basedexperiments.Then,weanalyzedtheinternal-externalrotationangleofthefemurusingrealpatientdata.Approximately10.55degreesofinternalrotationswerefoundrelativetothedefinedanterior-posteriordirection.Inthispaper,wepresentausefulregistrationmethodusingtheconventionalX-rayimageand3DCTscandatatoanalyzethewholelegintheweight-bearingcondition.

  • 标签: 2D-3D REGISTRATION 3D analysis X-RAY CT
  • 简介:用HNO3-HClO4混酸溶解养生堂维生C片,用电感耦合等离子体质谱法测定其中的无机元素,实验表明养生堂维C中Fe,Na,Ca,Mg,K,Zn和Cu的含量较为丰富。方法灵敏可靠,测量相对标准偏差〈3.3%,回收率在99.5oA~103.6%,实验结果为探讨养生堂维生C对人体的保健作用提供了参考数据。

  • 标签: 电感耦合等离子体质谱法 维生素C 无机元素
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  • 简介:Thenew-typetractionboundaryintegralequationsdevelopedbyHuandwithnohypersingularintegralareappliedtoanalysisof3Dfinitecrackedbodies.Anumericalalgorithmforgeneral3Dproblemsandasemi-analyticaloneforaxisymmetricproblemsarepresented.Someexamplesofthickplatesandcylindricalcolumnsincludingpenny-shapedcrack(s),andrectangularplatesincludinganellipticalcracknormaltothesurfaceareanalyzed.Thecomparisonbetweenpresentresultsandthoseinliteratureshowsthehighaccuracyandeffectivenessofthepresentmethod.

  • 标签: principal integral crack stress INTENSITY factor
  • 简介:Theboundaryelementmethodforthemodalanalysisoffreevibrationfor3-Danisotropicstructuresusingparticularsolutionshasbeendeveloped.Thecompletepolynomialsofordertwoareusedtoconstructtheparticularsolutionsforgeneralanisotropicmaterials.Thenumericalresultsfor3-Dfreevibra-tionanalysisofanisotropiecantileverbeambythemethodpresentedisingoodagreementwiththeresultsus-ingtheRitztechnique.Foranisotropicmaterials,thenumericalresultscalculatedfromtheproposedmethodareingoodagreementwiththeresultsfromMSC.NASTRAN.

  • 标签: BOUNDARY ELEMENT method ANISOTROPIC structure particular
  • 简介:为在一个三维的围住的领域的不可压缩的二进制液体混合物的进化的二个不同模型被考虑。他们由3D组成不可压缩的海军司烧方程,使外部力量遭到到时间依赖者并且结合了一个对流Allen-Cahn或Cahn-Hilliard方程。如此的系统能被看作海军司烧方程的归纳到二阶段的液体。用轨道途径,作者为两个系统证明轨道引起注意的人的存在。

  • 标签: 流体混合物 三维轨迹 吸引子 STOKES方程 二元 不可压缩
  • 简介:Reactionsofthe6-hydroxy-thiopyrano[3,4-c]pyridine-5-carbonitrilederivative1withα-halo-carbonylcompoundsgavetheortho-substitutedintermediates2a-cwhichwereconvertedintofuro[2,3-b]thiopyrano[4,3-d]pyridines3a-cbyfusionofafuranmoietyunderbasicconditions.Furthercyclizationof3a-cledtoafusionofapyrimidinering,yieldingthetetracyclicproducts6,7and8.Inaddition,condensationof6withvariousaromaticaldehydesaffordedthecorrespondingimines9a,b.Mannichreactionof7gaveproducts10a,b.

  • 标签: Synthesis AROMATIC ALDEHYDES products MANNICH reaction
  • 简介:基于自然边界减小检验一个nonoverlapping领域分解方法。D-N的开发轮流出现的算法;为外面的球形的领域学习D-N方法的集中;D-N的分离形式的讨论轮流出现的算法。

  • 标签: DOMAIN DECOMPOSITION D-N Algorithm EXTERIOR ID
  • 简介:A3-DnonlinearproblemofsupercavitatingflowpastanaxisymmetricbodyatasmallangleofattackisinvestigatedbymeansoftheperturbationmethodandFourier-cosine-expansionmethod.Thefirstthreeorderperturbationequationsarederivedindetailandsolvednumericallyusingtheboundaryintegralequationmethodanditerativetechniques.Computationalresultsofthehydrodynamiccharacteristicsandcavityshapesofeachorderarepresentedfornonaxisymmetricsupercavitatingflowpastconeswithvariousapex-anglesatdiffer-entcavitationnumbers.Thenumericalresultsarefoundingoodagreementwithexperimentaldata.

  • 标签: supercavitating flow PERTURBATION METHOD NONLINEAR solution
  • 简介:Soilconsolidationwouldinducevariationsofitstransportcoefficientssuchashydraulicconductivityanddiffusioncoefficient.Thispaperpresentsastudyoftheinfluenceofbarrierconsolidationontransportcoefficients,anda3Dtransportmodelbasedonmixturetheoryisproposedfordescribingthelinersthatinvolvecirculardefectsinthegeomembrane.TheelastoplasticALPHAmodelisrevisedbyusingthespatiallymobilizedplane(SMP)criterionforsimulatingthedeformationofthesoils.Then,the3Dmodelcouplingthenonlinearconsolidationandcontaminantadvection-diffusionissolvedusingthefiniteelementsoftwareABAQUS.Theresultsshowthattheimportanceofreducingthedefectsizeinthegeomembraneandthelinerporositytocontrolthecontaminantconcentrationincrease.

  • 标签: 三维模型 迁移模型 污染物 输运系数 ABAQUS 土体固结