夹层技术修复楔状缺损的疗效对比观察

目的:探讨夹层技术修复楔状缺损的疗效.方法:选择个体条件相仿的楔状缺损患牙,共计360颗,分别采用光固化复合树脂、玻璃离子水门汀和夹层技术充填修复,并对1年疗效进行比较.结果:三组方法成功率经统计,夹层技术与另二组比较有高度显著性差异(P＜0.05).夹层技术是修复楔状缺损较好的方法.     

NA样本的一类线性U-统计量的强大数律

在权{ani:1≤i≤n，n≥1}满足Aa=lim n→∞ sip Aa，n=limn→∞ sup(1/n n∑|ani|α)1/α＜∞的条件下，讨论了NA列{X，Xi：i≥1}构成的一类线性U-统计量的Marcinkiewicz型强大数律．     

(Ⅲ)m=0型二次系统的极限环问题,(Ⅱ)

本文讨论了在条件0＜l＜(1)/(2), n＜0下,(Ⅲ)m=0型二次系统的极限环问题,证明了该系统在某些条件下最多只有一个极限环.     

M估计存在的条件

本文给出了M估计存在的条件,并从分析上给予了证明,从统计的角度解释了这些条件的统计意义。     

M估计存在的条件

本文给出了M估计存在的条件,并从分析上给予了证明,从统计的角度解释了这些条件的统计意义.     

螺旋槽端面干气密封的参数研究

螺旋槽干气密封试验分析了干气密封螺旋槽几何参数对开启力、功耗、泄漏率和气膜刚度的影响,并通过理论计算对试验数据给予了验证.理论计算和试验结果的对比表明了试验数据的可靠性.整体来讲,在其他参数固定的条件下,槽深比、螺旋角对密封性能的影响较为突出,而槽数、密封坝宽度比、槽台宽比、压力比对密封性能的影响相对较弱.最后给出密封结构和试验条件下的最优几何参数取值范围(12＜Ng＜18,14°＜β＜16°,0.4＜αg＜0.6,0.3＜l＜0.5,1.6＜δ＜1.8,10＜Pr＜20).     

失效率局部成比例的伽玛分布和威布尔分布顺序统计量的随机比较

在独立情形下伽玛分布和威布尔分布顺序统计量的随机比较基础上,给出了随机变量以一般随机序局部大于和局部依序列条件递增的概念.讨论失效率函数局部成比例这种非独立条件下的伽玛分布和威布尔分布的顺序统计量的随机比较,得出当形状参数不变、尺度参数占优条件下二元最小顺序统计量的随机关系.此外,基于这种情形,得出威布尔分布顺序统计量是局部依序列条件递增的.     

量子统计向经典统计过渡的条件

从三种统计分布出发，讨论量子统计向经典统计过渡的条件，也即经典统计适用的物理条件。常温或高温下的原子、分子可以用经典统计，高密度下的电子，即使温度较高，也应使用费未分布计算。     

逆抽样条件下风险差的检验

建立了不同的统计量对逆抽样条件下病例对照组实验中的风险差进行检验.这些统计量分别是Wald统计量,Score统计量和似然比统计量.然后采用Fisher-Score的方法求解感兴趣参数的方差.采用近似的方法计算各统计量条件下犯第1类错误的概率和功效.多数情况下,Score统计量比较好,特别是针对感兴趣的样本量小于30的条件下,Score统计量犯第1类错误的概率能控制在置信水平以下.     

公路隧道排水管防结晶措施室内试验探究

为了探究排水管内的结晶行为和差异，结合现场调研和结晶堵塞理论，采用室内模型试验，探究了6种排水管材质、纳米涂层及硅磷晶阻垢剂在排水管内的结晶规律。结果表明：流量是影响管材改善效果的主要因素，小流量条件下，不同排水管材质、纳米涂层防结晶的效果不明显，结晶量均很大；大流量条件下，各工况结晶量均很低，结晶量从小到大依次为：纳米涂层＜聚四氟乙烯（PTFE）＜聚乙烯（PE）＜聚丙烯（PPR）＜双壁波纹管（HDPE）＜聚氯乙烯（PVC）＜钢管＜硅磷晶，表面能低、接触角大的排水管材质在较大流量条件下具有一定的预防结晶作用；小流量条件下排水管内结晶物以重力沉积居主导，并促进异相成核作用，而大流量条件下的沉积作用与管材的材料特性密切相关，且剥蚀作用占绝对主导。     

滇西富碱斑岩型多金属矿稀有气体同位素组成特征及地质意义*

通过对滇西富碱斑岩型多金属矿区稀有气体同位素组成的研究表明,黄铁矿和石英脉等流体包裹体中3He/4He值主要为0.160 8~3.470 0 Ra,远高于地壳特征值,而整体略低于地幔特征值;20Ne/22Ne和21Ne/22Ne平均值分别为11.271和0.032 2,接近地幔同位素组成;40Ar/36Ar和38Ar/36Ar平均值分别为395.51和0.197 6,均高于大气比值,而低于MORB比值;128~136Xe/130Xe值与大气相比均表现出过剩的特征。综合研究表明,滇西多金属矿区包裹体中稀有气体同位素组成在显示含矿流体的幔源特征的同时,又表现出强烈的地壳特征;成矿流体主要源于深部地幔,在参与交代蚀变过程中,其性质由熔浆向热液过渡,同时引发壳幔物质叠加混染,正是这种流体作用构成了滇西新生代富碱斑岩多金属成矿的内在统一制约因素。     

He and Ar isotope geochemistry of pyroxene megacrysts and mantle xenoliths in Cenozoic basalt from the Changle–Linqu area in western Shandong

We performed a combined study of He–Ar isotopes and element geochemistry for pyroxene megacrysts and mantle xenoliths from Cenozoic basalt in the Changle–Linqu area in western Shandong.The results are used to trace the evolution of subcontinental lithospheric mantle after destruction of the North China Craton.The3He/4He ratios of pyroxene megacrysts,websterite,and dunites are 7.0–7.7 Ra,7.4 Ra,and 7.0–7.7 Ra,respectively.They are related to the origin of host basalts,and are slightly lower than that of mid-ocean ridge basalts(MORB).Their40Ar/36Ar ratios are much lower than that of MORB and close to that of air.The lherzolites and wehrlites represent the fragments of the newly accreted lithospheric mantle,and their REE and trace elements indicate that they experienced melt metasomatism and partial melting.The3He/4He ratios of their olivine are slightly lower than that of MORB,but3He/4He ratios of their clinopyroxene are low(2.3–7.1 Ra)and display an inverse correlation with(La/Yb)N.The40Ar/36Ar ratios of these clinopyroxene are much lower than that of MORB and close to the air ratio.Combining existing studies of petrology,Sr–Nd–Pb isotopes,O isotopes,trace elements,and Mg isotopes,we infer that the juvenile lithospheric mantle in the Changle–Linqu area was metasomatized by oceanic crust-derived melts,which transfer the supracrustal Ar isotope signatures to the mantle sources.The low4He abundance and low3He/4He ratios of clinopyroxene in the lherzolites and wehrlites are ascribed to metasomatism by crustal melts from the subducted Pacific plate.     

Radiation dose rate estimates to marine biota resulting from the routine radioactive releases of the nuclear power plants in Daya Bay

Five marine organisms in Daya Bay are selected for estimating the dose rates. Internal exposure and its 5 pathways are also considered. The concentrations of 43 kinds of background and additional radionuclides in seawater are from the survey of background radioactivity and the prediction of routine radioactive releases of the 4 reactors. Point source dose distribution functions are used to estimate the dose rates to various organisms from α and β radiation. Monte-Carlo method is used to determine the absorbed fractions in the organisms from γ radiation. Results indicate that the background dose rates are 2.72 mGya · a^-1 to phytoplankton and 1.75 mGy · a^-1 to zooplankton. The dose rates to other organisms are in the range of 0.31–0. 49 mGy · a^-1. The additional dose rates from the routine releases are varied to different organisms. They reach the range of 5.7–6.1 times of the background dose rates to benthic crustaceans and mollusks, which are 8.3%–15.3% to fishes, and only 0.2% to plankton. β internal irradiation from additional radionuclides is the critical pathway to plankton.¹³¹I and⁶⁰Co are the major contributors to zooplankton, while¹⁰³Ru,⁶⁰Co and⁵⁸Co are the main contributors to phytoplankton. γ external irradiation from sediment is the critical pathway to benthic organisms.⁵⁸Co and⁶⁰Co are the main contributors. The main pathways to fishes are internal β and γ irradiation.¹²⁴Sb is the critical radionuclide.     

First-principles studies of the adsorption of O2 on Al （001）

Oxidationisaubiquitousphenomenonofnature.Theeconomiclossduetooxidationisverylargeeveryyear.Theinvestigationoftheadsorptionofoxygenonthesur-facesofmetalsisofgreatimportanceforbetterunder-standingoftheoxidationmechanismbecauseitistheverybeginningstageofoxidationofmetals.Itisgenerallybe-lievedthattheprocessofO2adsorptiononmetalsisinanorderofO2?O?O-?O2-,andthefollowingstagesareoxidenucleation,growthandtheoxidefilmformation.Astheprocessofadsorptionistooquicktobeobservedbyexperiments,atheoreticals…     

海南三七的挥发性成分研究

 分析了云南西双版纳产的海南三七挥发性成分.采用同时蒸馏萃取GC-MS联用技术对其挥发性成分进行分析,从中分离鉴定了51个挥发性成分,主要的成分为α-蒎烯(6.83%)、茨烯(13.00%)、β-蒎烯(18.97%)、茨酮(5.80%)、沉香醇氧化物(5.11%)等.表明云南产海南三七挥发性成分较丰富,多为萜类及其含氧衍生物,其中蒎烯含量最高,且其中含有多种芳香性物质和活性成分.     

媒体报道下随机SIQS流行病模型的动态行为研究

研究了媒体报道干预策略下的随机SIQS流行病模型.构造合适的Lyapunov函数,使用Itô公式和马尔可夫半群理论,证明了基本再生数R₀^s可用于控制随机流行病模型的动态行为,即如果再生数R₀^s<1,并且在其他条件下,疾病将消亡;如果再生数R₀^s>1,并且在其他条件下,疾病是持久性的.结论表明：大的白噪声可以抑制疾病的爆发,这为制定有用的控制策略来调节疾病的动态行为提供有效帮助.最后通过数值模拟验证了这一结果.     

Surface modification of γ-Al2O3 by sodium ions

¹H/²³Na double resonance NMR techniques were employed to study the modification of surface hydroxyls on γ-Al₂O₃ by sodium ions. ¹H→²³Na cross polarization (CP) experiment can resolve three kinds of sodium cations that are closely associated with surface hydroxyl groups, while the signal of deposited salt-Na₂CO₃, which is not connected to surface hydroxyl groups, is completely suppressed. ¹H{²³Na} spin echo double resonance experiments reveal the surface modification in more detail. At low Na⁺ coverage (5%, 10%), the acidic hydroxyl groups are preferentially coordinated with sodium ions, while both the acidic and the basic hydroxyl groups are accessible for sodium ions at high coordination that causes proton of the OH groups to be easily dissolved, which is evidenced by the fact that with calcination temperature of the catalysts increasing, the acidic hydroxyl groups are preferentially removed and only the basic hydroxyl groups remain when the calcination temperature is raised to 600℃.     

关于极大Euler 3-序列(dp=4)的平面实现

研究d     

Pollen indication to source plants in the eastern desert of China

Pollen analysis is one of the important resources for the reconstruction of palaeoclimate and palaeovegetation. The relationship between modern pollen and vegetation is the foundation of pollen analysis. Owing to its complexity and importance, many polynologists and plant-ecologists have been studying on it[1―17]. In 1963, M. B. Davis gave the definition of R-values[2] that have carried forward the quantitative relationship between pollen and vegetation. However, R-value is changeable for d…     

盆地气候条件下成都城区O_3与NO_2相互作用的时间尺度分析

应用去趋势互相关分析法对比分析了成都市2013年7月1日至8月31日和2014年1月1日至2月28日等2个时间段4个大气环境监测站点近地面O3与前体物(NO2)小时平均浓度的相关性及其时空演化尺度特征.研究表明,成都市4个监测站点近地面O3与NO2小时平均浓度波动的相关性在一定时间尺度内具有长期持续特征.并对成都市夏季和冬季近地面O3与NO2相关性进行了对比分析,探讨了导致此种差异的原因.结果表明,不同的气象条件下成都市O3与NO2相互作用的时间尺度存在显著差异.其差异性可能与成都市独特的盆地气候特点以及当地夏季与冬季太阳光辐射、日照数、气温等气象因子有关.研究结果有助于进一步加深对盆地气候条件下成都市O3污染特征的认识.