痕量苯酚阻抑动力学光度法的测定

文章研究了稀硫酸介质中,痕量苯酚阻抑溴酸钾氧化中性红褪色的指示反应,据此建立了阻抑动力学光度法测定痕量苯酚的新方法。结果表明,在0.1~5μg/ml范围内符合比耳定律,检出限为0.01065!g/mL。该法用于工业废水中苯酚的测定,结果满意。     

巧求两小球对心弹性碰撞后的速度

本文用对称性原理推导出两小球对心弹性碰撞后的速度公式,具有求解简单,宜于推广,以高中生学习物理有很大的帮助。     

磷钨酸四甲基铵光催化降解活性艳橙溶液的研究

制备了磷钨酸四甲基铵并对其进行了初步表征。在光催化反应仪中,以紫外灯为光源,以磷钨酸四甲基铵为光催化剂,用正交实验探讨了光催化降解活性艳橙溶液的最佳条件。结果表明,对于10mg/L活性艳橙溶液,当pH=2.5,催化剂的用量为0.5g/L,光催化降解时间为30min时,脱色率达到最大值83.6%。最后,测定了该条件下反应的化学动力学参数。     

MPP／PEPA复配阻燃PP的制备及其热降解动力学研究

利用双辊混炼机制备了共混型阻燃聚丙烯（PP）材料,并用热重（TG—DTG）方法研究了PP、PP／MPP、PP／PEPA和PP／MPP／PEPA在N2气氛下以不同升温速度时的热降解动力学行为,以此探讨阻燃性能与热降解行为的关系。试验发现,加入阻燃剂后材料的初始分解温度降低。利用Kissinger法和Flynn-Wall法求取了材料的活化能,发现两种方法求取的结果相一致．添加阻燃剂后,材料的活化能均比PP高。说明阻燃剂使PP提前分解成炭．产生隔热、隔氧作用,阻止了PP的进一步氧化分解。     

Comparison of learning in two context-based university chemistry classes

ABSTRACT

Context-based learning (CBL) is advocated as beneficial to learners, but more needs to be understood about how different contexts used in courses influence student outcomes. Gilbert defined several models of context that appear to be used in chemistry. In one model that achieves many criteria of student meaning-making, the context is provided by ‘personal mental activity’, meaning that students engage in a role to solve a problem. The model’s predicted outcomes are that students develop and use the specialised language of chemistry, translate what they learn in the immediate context to other contexts, and empathise with the community of practice that is created. The first two of these outcomes were investigated in two large-enrolment university chemistry courses, both organised as this CBL model, in which students were introduced to kinetic molecular theory (KMT). Sample 1 students (N₁?=?105) learned KMT through whole-class kinaesthetic activity as a human model of a gas while focusing on a problem identifying substances in balloons filled with different gases. Sample 2 students (N₂?=?110) manipulated molecular dynamics simulations while focusing on the problem of reducing atmospheric CO₂. Exam answers and pre-/post-test responses, involving a new KMT context, were analysed. Students in Sample 1 demonstrated a stronger understanding of particle trajectories, while Sample 2 students developed more sophisticated mechanistic reasoning and greater fluidity of translation between contexts through increased use of chemists’ specialised language. The relationships of these outcomes to the contexts were examined in consideration of the different curriculum emphases inherent in the contexts.     

微分形式的变分原理及应用

利用D'Alembert-Lagrange微分变分原理和等时变分,推出了速度空间和加速度空间的微分变分原理,在坐标空间微分变分原理的基础上,建立了坐标空间的三种基本动力学方程形式,实现了微分变分原理的统一.举例说明应用.     

高碘酸钾氧化龙胆紫催化动力学光度法测定微量碘的研究

在乙酸-乙酸钠缓冲溶液及NaCl的介质中,碘能催化高碘酸钾氧化龙胆紫的褪色反应.据此建立了催化动力学测定微量碘的新方法.此方法的检出限为CL=6.7×10-2μg/mL,碘的线性范围为:0.2728mg/L～54.56mg/L,可直接用于加碘食盐、海带中碘的测定,结果满意.     

血清CA-19-9测定对胰腺癌的诊断价值

目的：寻求胰腺癌的诊断方法，方法：用免疫放射分析法（IRMA）检测血清CA－19－9含量，106例血清CA－19－9含量3700u/L，进行追踪随访，结果：106例中，胰腺癌66例，结肠癌15例，胆管癌13例，肺癌9例，结论：检测血清CA－19－9含量，有利于胰腺癌的诊断和与结肠癌，胆管癌，肺癌等恶性肿瘤的鉴别。     

Using chimeric piggyBac transposase to achieve directed interplasmid transposition in silkworm Bombyx mori and fruit fly Drosophila cells

The piggyBac transposon has been long used to integrate foreign DNA into insect genomes. However, undesirable transgene expression can result from random insertions into the genome. In this study, the efficiency of chimeric Gal4-piggyBac transposase in directing integration onto a DNA target plasmid was evaluated in cultured silkworm Bombyx mori Bm-12 and fruit fly Drosophila Schneider 2 (S2) cells. The Gal4-piggyBac transposase has a Gal4 DNA-binding domain (DBD), and the target plasmid has upstream activating sequences (UAS) to which the Gal4 DBD can bind with high affinity. The results indicate that, in the Bm-12 and S2 cells, transpositional activity of Gal4-piggyBac transposase was increased by 4.0 and 7.5 times, respectively, compared to controls, where Gal4-UAS interaction was absent. Moreover, the Gal4-piggyBac transposase had the ability of directing piggyBac element integration to certain sites of the target plasmid, although the target-directing specificity was not as high as expected. The chimeric piggyBac transposase has the potential for use in site-directed transgenesis and gene function research in B. mori.     

两组分混合颗粒流的有效热导率

根据稠密气体运动学理论,运用随颗粒速度而变化的自由程理论计算了两组分混合颗粒流的有效热导率．当Biot数小于0．1时,解析结果可适用Blot数和Fourier数的乘积（BiFo）的整个范围．在适当BiFo数的条件下,讨论了组分颗粒浓度、总的颗粒固体体积百分含量v和BiF0数对热导率的影响,结果表明增加小颗粒的浓度或减少小颗粒的尺寸可提高混合颗粒流的有效热导率．