2014年广东高考理综化学试题赏析及思考

对2014年广东高考理综化学试题进行研究,先整体分析试题特点,后局部赏析试题内容亮点,挖掘试题功能,继而反思试题启示与备考策略,以达到探究命题规律和助推教学研究的目的。     

一种新型比色荧光双通道水相检测氰根离子的化学传感器

合成了一种新型的,能在含水介质中比色荧光双通道单一选择性识别CN^-的传感器分子1-羟基萘甲叉酰肼乙基-3-羟基萘甲叉酰肼甲基苯并咪唑溴鎓盐(J1)。 在J1的DMSO/H₂O (体积比3:2)HEPES 的缓冲体系(pH=7.2)中分别加入F^-、Cl^-、Br^-、I^-、AcO^-、HSO₄^-、ClO₄^-、H₂PO₄^-、SCN^-和CN^-等阴离子后,只有CN^-的加入会使得溶液颜色发生明显的变化,由无色变为深黄色。 相应地在J1的DMSO/H₂O (体积比4:1)HEPES的缓冲体系(pH=7.2)中加入CN^-,溶液发出明亮的黄色荧光。 这一识别过程,不会受到其它阴离子的干扰。 紫外-可见光谱的最低检测限为1.57×10^-7 mol/L,检测线性范围为3.875×10^-4~2.15×10^-2 mol/L。 荧光光谱的最低检测限为4.63×10^-6 mol/L,检测线性范围为0.8×10^-4~1.60×10^-3 mol/L。 此结果表明,J1是一种良好的用于识别 CN^-的化学传感器,在含水介质中对CN^-具有选择性好、灵敏度高以及抗干扰性强的识别性能。 与此同时,基于J1对于CN^-的高选择性识别我们制备了CN^-的检测试纸,该试纸能够方便、快捷、准确地检测水中的CN^-。     

A numerical approach for pressure transient analysis of a vertical well with complex fractures

A new well test model for a vertical fractured well is developed based on a discrete-fracture model in which the fractures are discretized as one dimensional (1-D) entities. The model overcomes the weakness of complex meshing, a large number of grids, and instability in conventional stripe-fracture models. Then, the discrete-fracture model is implemented using a hybrid element finite-element method. Triangular elements are used for matrix and line elements for the fractures. The finite element formulation is validated by comparing with the semi-analytical solution of a single ver-tical fractured well. The accuracy of the approach is shown through several examples with different fracture apertures, fracture conductivity, and fracture amount. Results from the discrete-fracture model agree reasonably well with the stripe-fracture model and the analytic solutions. The advantages of the discrete-fracture model are presented in mesh gen-eration, computational improvement, and abilities to handle complex fractures like wedge-shaped fractures and fractures with branches. Analytical results show that the number of grids in the discrete-fracture model is 10%less than stripe-fracture model, and computational efficiency increases by about 50%. The more fractures there are, the more the com-putational efficiency increases.     

Residual stress in the cylindrical drawing cup of SUS304 stainless steel evaluated by split-ring test

The residual stresses in the wall of a SUS304 stainless steel cylindrical drawing cup were evaluated by split-ring tests, and the influences of stamping die parameters on the residual stress were investigated. A new theoretical model of a split-ring test was developed to evaluate the residual stress in a ring, which was verified to be reasonable and reliable by numerical simulations with ABAQUS code and by nanoindentation tests. Seven groups of split-ring tests were completed, and the residual stresses were calculated according to the theoretical model. The split-ring test results showed that the circumferential residual stress in the wall of the SUS304 stainless steel cylindrical drawing cup was very large and did not change with the different die corner radius.The circumferential residual stress first increased with the increase of drawing punch–die clearance, then was almost unchanged when the clearance increased greater than blank thickness 1 mm. Thus, a smaller clearance was suggested to be chosen to reduce the residual stress in the wall of the SUS304 stainless steel drawing cup.     

利用四段式测试题诊断高一学生化学键迷思概念

使用改编自迈阿密大学牛津分校Stacey Lowery Bretz的"化学键概念表征量表",并通过加设信心指数将其扩充为四段式测试题。利用本测试工具对浙江省2所普通高中共260名学生进行测试。结果显示,被试存在"高信心指数错解"和"低信心指数正解"的情况,并探查出7个典型的化学键迷思概念,其中4个为呈现出较高信心指数的真性迷思概念。信心指数在一定程度上弥补了二段式工具的缺陷。     

乙烯的实验室制备及性质检验的实验改进

在采用乙稀利为原料制备纯净乙烯的研究基础上,从药品配置、实验操作和装置优化等方面对乙烯的实验室制备及性质检验进行了科学改进,希望对高中化学教学有一定的启示作用。     

胶体金在地沟油快速检测中的创新应用

实验证明与地沟油反应的胶体金溶液颜色更深,透光度低。胶体金能够定性地检测、分辨食用油与地沟油。     

定性检验牛奶中的营养素

利用常用仪器、微型实验和相应物质的特征反应,对牛奶中所含营养素进行定性检验,结果表明：牛奶中含有蛋白质、维生素、钙、镁、磷、钾、铁元素。该实验具有微型化、绿色化、简约化和生活化的特质。     

Construction and cosmic-ray test of the new inner drift chamber for BESIII

A new inner drift chamber has been built which can replace the aged part of the BESIII drift chamber when needed. The design of the new inner drift chamber can minimize the ineffective area in the very forward and backward region and hence reduce the background event rate. With this design, the new inner drift chamber is expected to have a longer lifetime and improved performance due to the lower occupancy. The endplates and the cylinder were machined with high precision. Wire stringing was performed after the mechanical structure was assembled, and good quality of wire stringing was ensured by measurement of the tension and leakage current of the wires. After completion of the physical construction of the new chamber, a cosmic-ray test was carried out to test its performance. The results of the cosmic-ray test show that the new inner chamber achieves a spatial resolution of127 μm and a d E/dx resolution of 6.4%, which satisfies the design specifications.     

基于MEMS压阻传感器的低功耗高过载测试系统设计

为了检验弹体在高冲击环境下的工作情况,提出了一种基于压阻传感器的高过载、低功耗的测试系统设计方案。该系统可承受2×105g的过载冲击测试,且具有采样率高、体积小、功耗低的特点。通过打靶实验验证:在过载测试过程中该系统具有承受高冲击的能力,并能精确地采集到信号微弱变化,保证了弹体在飞行中记录数据的准确性。