窄分散共聚倍半硅氧烷微球的制备与形成机理

将氨丙基三乙氧基硅烷(APS)和苯基三乙氧基硅烷(PTES)在碱催化下水解共缩聚,制备了窄分散的聚氨丙基/苯基倍半硅氧烷(PAPSQ)微球.采用扫描电镜和粒度分析仪研究了APS/PTES摩尔比、水/硅摩尔比、共溶剂、四甲基氢氧化铵(TMAOH)浓度和单体总浓度等反应条件对PAPSQ微球形貌和大小的影响,并对PAPSQ微球在不同反应条件下的形成机理进行了探讨.结果表明:APS/PTES摩尔比为1/4、水硅摩尔比为50、TMAOH浓度为0.025 mol/L、单体总浓度为0.25 mol/L、以乙醇为共溶剂时,PAPSQ微球粒径在0.7～1.0μm之间,呈窄分散性;以氨水为催化剂、异丙醇为共溶剂时,产物微球粒径较大,粒径分布较宽;较低的水硅摩尔比和TMAOH浓度下,只形成部分球形粒子;两单体总浓度过高时,难以形成微球.     

Corrosion behavior and composition analysis of chromate passive film on electroless Ni-P coating

A passive film was formed on electroless Ni-P coating (ENPC) in a bath of K₂Cr₂O₇ 30 g/l. XPS and electrochemical methods were employed to analyze its chemical compositions and corrosion behaviors. The potentiodynamic polarization tests indicated the corrosion current of the passivated sample was 1/30 that of as-plated ENPC. The XPS analysis illustrated the film comprised Cr, Ni and O. The film thickness was evaluated to be a few nanometers according to the sputtering rate of Ar⁺ ion. High-resolution XPS spectra suggested that the detected Cr in film was in the form of trivalent compounds, Cr₂O₃ and Cr(OH)₃.     

Instructional immediacy in the Chinese quantitative reasoning classroom

The present investigation examined instructor immediacy behaviors, students' perceptions of those behaviors, and student math anxiety in Chinese classrooms. Consistent with the American college classroom, a simple causal chain was anticipated in which instructor immediacy behaviors positively induced a psychological response to immediacy, which had a negative influence on math anxiety. Study 1 tested this model in the Chinese college classroom and the model failed. It was speculated that perhaps given the high testing admission standards of Chinese colleges (i.e., the GaoKao), that Chinese college students were a biased sample of only students who had learned to manage their anxieties. Thus, in Study 2, the model was retested among junior and senior high Chinese students. Among junior and senior high Chinese students, the model fit well.     

复方中药一贯煎的抗炎药效评价

为观察复方中药一贯煎的抗炎作用效果,一贯煎全方经过煎煮浓缩后,采用测定角叉菜胶致炎后大鼠左后足的肿胀率,及二甲苯致小鼠耳廓肿胀后耳廓肿胀度,及耳廓肿胀抑制率的方法对一贯煎的抗炎作用效果进行评价。一贯煎浓缩液对大鼠足肿胀有一定的抑制作用,差异明显(p0.05),起效时间相对于阳性对照药物稍长持续时间较长(p0.05);一贯煎浓缩液对二甲苯致小鼠耳廓肿胀也有一定的抑制作用,差异明显(p0.05)。研究结果表明通过行为学观察,可以得知一贯煎具有与阿司匹林相同的抗炎作用。     

大孔吸附树脂对骨胶水解硝化液的脱色处理

研究了骨胶制备羟脯氨酸工艺中大孔吸附树脂对骨胶水解硝化液的脱色处理.使用分光光度法测定骨胶水解硝化液中色素浓度;在原制备羟脯氨酸工艺的基础上,合并了脱色步骤,并采用大孔吸附树脂脱色.结果表明:当H1020树脂对骨胶水解硝化液进行脱色处理的工艺条件为色素相对浓度的0.1667,V(溶液):V(树脂)=5:1,此时树脂对色素的脱除率为0.784,Hyp吸附损失率为0.101,大孔吸附树脂在制备羟脯氨酸工艺中有良好的应用前景.     

Rheological Behaviors of Poly(Vinylidene Fluoride)/“Bud-Branched” Nanotubes Nanocomposites

Bud-branched nanotubes, fabricated by growing metal particles on the surfaces of multiwall carbon nanotubes (MWCNTs), were used to prepare poly(vinylidene fluoride) (PVDF)-based nanocomposites. The melt viscoelastic behaviors of PVDF and its nanocomposites were characterized. The results showed that the introduction of both the MWCNTs and bud-branched nanotubes (MWCNTs-B) increased the storage modulus, loss modulus, and complex viscosity of the nanocomposites. However, the bud-branched nanotubes were more efficient to increase the elasticity than the MWCNTs that have relatively smooth surfaces. In particular, it was observed that the bud-branched nanotubes caused an increase of normal force and crossover modulus, while for MWCNTs, no variation in the normal force and a decrease of the crossover modulus were observed.     

一类具有无穷边界值的二次奇摄动边值问题

研究一类具有无穷边界值的二次奇摄动Robin边值问题解的存在性与解的渐进行为,重点关注边界值的奇异程度对解的边界层行为的影响;同时将所得的结果与Chang及Howes的结果(带正常边界值)进行比较.研究表明:(1)当边界值大小为O(1/)时,得到的边界层大小为O( ln ),这比Chang及Howes带正常边界值的情形提高了O(ln )量级;(2)增大边界值的奇性至O(1/ r),这里r >1,边界层大小的量级不变,依然为O( ln );(3)若要使得边界层大小为O(1),则边界值的大小需为O(e?1/).最后给出一个算例验证得到的结果.     

Ruin Probability in a Semi-Markov Risk Model with Constant Interest Force and Heavy-Tailed Claims

In the present paper, we consider a kind of semi-Markov risk model (SMRM) with constant interest force and heavy-tailed claims, in which the claim rates and sizes are conditionally independent, both fluctuating according to the state of the risk business. First, we derive a matrix integro-differential equation satisfied by the survival probabilities. Second, we analyze the asymptotic behaviors of ruin probabilities in a two-state SMRM with special claim amounts. It is shown that the asymptotic behaviors of ruin probabilities depend only on the state 2 with heavy-tailed claim amounts, not on the state 1 with exponential claim sizes.     

关于液体内大规模声处理中空化研究的几点思考——再论声空化工程

再次强调了大规模液体中超声处理、以及为此目的研究声空化的重要性。提出了对这项应用中声空化行为的几点思考,重点是关于声空化的"强度"以及关于电动力式和流体动力式两类产生空化系统所产生空化的不同特性。     

领导授权行为和下属授权期望匹配对工作绩效的影响

以往绝大多数研究探讨了领导授权行为对下属的影响，却忽略了下属视角期望的影响。为此，基于内隐领导理论和期望理论，从二元的视角探究了“领导授权行为”和“下属授权期望”匹配状况对下属工作绩效的影响，并构建了领导授权行为和下属授权期望通过工作投入影响下属工作绩效的理论模型，以试图弥补现有研究忽略下属作用的不足。通过多项式回归与响应面分析，对来自4个城市6家公司收集的168对领导-下属配对数据进行分析，研究表明：①领导授权行为和下属授权期望有4种匹配情况，领导授权行为和下属授权期望一致时，对下属工作绩效的积极影响高于匹配不一致的情形。②当匹配一致时，“领导高-下属高”比“领导低-下属低”时对下属工作绩效的积极作用更显著。③当匹配不一致时，“领导低-下属高”比“领导高-下属低”时对下属工作绩效的积极影响更大。④工作投入在领导授权行为和下属授权期望匹配和工作绩效之间起中介作用。