25 research outputs found

    低聚倍半硅氧烷基铁络合物阻燃剂的合成及改性环氧树脂

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    采用Kabachnik-Fields反应合成出含有邻苯二酚功能团、磷杂菲基团和笼型倍半硅氧烷结构基元的新型配体POSS-DOPO-Catechol(PDC),再与Fe3+配位络合形成低聚倍半硅氧烷基铁络合物Fe(PDC)3,进一步加入双酚A型环氧树脂(EP)进行固化制备出EP/Fe(PDC)3复合材料。利用红外、质谱和核磁共振表征配体及络合物的化学结构;通过差示扫描量热分析、热重分析、氧指数测定、微形量热、动态力学实验等方法研究铁络合物Fe(PDC)3的引入对环氧树脂固化温度、热性能、阻燃性能、力学性能及介电性能的影响。结果表明,添加Fe(PDC)3可以降低环氧树脂的固化温度、热释放速率及总热释放量,提高残炭量、氧指数,这是由于铁络合物可以有效促进材料在高温下形成稳定性良好的致密炭层,起到隔氧隔热作用,从而在燃烧过程中阻止材料进一步燃烧。国家自然科学基金资助项目(51573150);;\n福建省自然科学基金计划资助项目(2018J01079);;\n福建省技术重大研发平台项目(2014H2006);;\n福建省科技重大项目(2013HZ0005-1

    Geographic patterns of endemic seed plant genera diversity in China

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    通讯作者 Author for correspondence. E-mail: [email protected][中文文摘]生物特有现象的地理格局及其形成机制是生物地理学的重要研究内容。本文通过整合173个地区的中国种子植物特有属编目资料、环境和空间因子数据,运用多元回归和方差分解的方法,探索了中国种子植物特有属丰富度及其占全部种子植物属丰富度的比例(特有属比例)与环境(生境异质性和气候)和空间因子的关系。结果表明:(1)特有属丰富度及特有属比例具有很强的空间变异性,在华中地区最高,而靠近国界和大陆边缘的地区较低;相比而言,种子植物属丰富度的空间变异性较弱,且表现出显著的纬度梯度性;(2)特有属丰富度及特有属比例主要由空间因子和生境异质性(地形的复杂性)决定,即在大的空间尺度上,地理位置决定一个地区特有属比例的理论值,生境异质性和气候因子对其进行微调;而种子植物属丰富度的地理格局主要受气候和生境异质性的影响。(3)中国种子植物特有属是主观性非常强的概念,特有属比例所反映的植物区系系统发育信息可能会很低;空间因子所解释的方差中到底有多少是系统发育因素,还需要进一步的研究。本文最后讨论了当前特有属定义和判定的不足之处。虽然理论上认为特有属的判定不应以行政边界为标准,但是目前几乎所有的中国特有属划分方法均以国界为准,这在一定程度上降低了中国种子植物特有属概念的科学内涵和在实践中的作用。因此,我们建议在理论和实践中对中国种子植物特有属概念采取审慎的态度。[英文文摘]Endemism describes the phenomenon that the distribution of individual species/taxa is critically restricted to a specific region.Seed plant genera endemic to China(endemic genera) are those with their main geographic distribution range within the borders of China.The geographic patterns of endemic genera can not only guide conservation planning,but these organisms are also important biological resources.We gathered data of 173 localities on environmental and spatial factors,and regional seed plant genera richness(GRN),endemic genera richness(EGRN) and endemic genera ratio(EGR),which was calculated by dividing EGRN by GRN.Multiple regression and variance partitioning were used to examine how environmental and spatial variables affect GRN,EGRN,and EGR.Our results showed that:(1) EGRN and EGR had stronger spatial variability than GRN,with highest values(richness and ratio) in central China and lower near national borders and continental edges.GRN exhibited an evident latitudinal gradient.(2) EGRN and EGR were mainly determined by habitat heterogeneity and spatial factors.Regional theoretical EGR was constrained by its geographical location,and was further adjusted by habitat heterogeneity(topographical complexity) and climatic factors.Geographical patterns of GRN,on the other hand,were mainly determined by climatic conditions and habitat heterogeneity rather than spatial factors.(3) Seed plant genera endemic to China could be rather difficult to define,and probably reflected inadequate information on phylogenetic evolution of local flora.Further studies are needed to examine the variance explained by spatial factors through a phylogenetic lense.Finally,flaws in the definition and classification of seed plant genera endemic to China were discussed.Theoretically,genera endemic to China should not be defined according to the political borders.But,in practice,nearly all the lists of seed plant genera endemic to China proposed by several authors were based on the relationship between the geographic distribution of specific genus and national borders.Thus,we recommend that,the concept of seed plant genera endemic to China should be used carefully in both theoretical research and biodiversity conservation practices.国家重点基础研究发展计划(973)项目(2009CB421105);国家科技支撑计划项目(2006BAC08B04

    气固顺流下行流化床反应器入口结构的实验研究

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    本文针对气固顺流下行流化床流动中在进口段存在不稳定加速区,影响气固反应中两相均匀接触的问题,设计了三种不同的气固进口结构,实验结果证明,使用侧吹式分布器与文氏管串联的结构设计,可以减小或消除进口端操作不稳定的影响,此结构可提供有关使用部门作为设计依据

    立管-翼阀系统的研究Ⅰ.负压差下旋风分离器料腿内的气固流动

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    对负压差下立管 -翼阀系统的气固流动特性进行了理论分析 ,并系统地考察了翼阀结构、操作条件、颗粒物性等对立管 -翼阀系统中气固两相流动的影响 ,得到了稳定操作状态下料腿中料封高度的计算式。hD=MFAρb D(1 0 .1 0 sinβsin(α-β) +76.2 6) +(p2 -p1 )ρbg D -1 1 2 .3 W2ssin(α-β)ρ2bg D +1 9.8W2sρ2bg D+2 .7

    立管-翼阀系统的研究Ⅱ.负压下立管-翼阀系统的最小松动气量

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    考察了引入松动气对立管 -翼阀稳定操作的影响。通过立管内气固流动质量守恒的理论分析 ,得到了系统稳定操作状态下最小松动气量的计算式 :Qr=b1εmfΔpρgρsp0 +b2ρg Umf Ws -b3Δp RWs理论分析与实验证明 ,最小松动气量与立管 -翼阀的结构、引入位置、颗粒物料特性、操作条件等因素有

    立管翼阀系统的研究负压差下旋风分离器料腿内的气固流动

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    对负压差下立管 -翼阀系统的气固流动特性进行了理论分析 ,并系统地考察了翼阀结构、操作条件、颗粒物性等对立管 -翼阀系统中气固两相流动的影响 ,得到了稳定操作状态下料腿中料封高度的计算式。hD=MFAρb D(1 0 .1 0 sinβsin(α-β) +76.2 6) +(p2 -p1 )ρbg D -1 1 2 .3 W2ssin(α-β)ρ2bg D +1 9.8W2sρ2bg D+2 .7
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