2007年广东高考物理试题评析

2007年广东高考是施行新课程改革后的第一次高考．《考试大纲》明确要求，命题要“符合选拔性考试的规律和要求，体现普通高中新课程理念，反映物理课程标准的整体要求．着重考查学生的基础知识、基本能力、科学素养和运用所学知识分析问题、解决问题的能力”．作为实施新课程后的第一次高考，笔者认为物理试题体现了上述要求．命题突出了改革的特点，从命题思想、试题设计、内容取材、题序布局，到落实《考试大纲》中所要求的五种能力考查要求等，都能巧妙地加以整合，     

Calculation of Interaction Potentials between Spherical and Deformed Nuclei

The interaction potential for spherical-deformed reaction partners is calculated. The shape, separation and orientation dependence of the interaction potential and fusion cross section of the system ^32S＋^154Sm are investigated within the double-folding model of the deformed nuclei. The effective nucleon-nucleon interaction is taken to be the M3Y-Reid potential. The density is considered for three terms of the expansion using the truncated multipole expansion method, which is a deformed Fermi shape With quadrupole and hexadecapole for the density distribution of ^154Sm. It is found for the interaction potential that the height and the position of barrier strongly depend on the deformations, the orientation angle of the deformed nucleus, and hence produce great effects on fusion cross section. The integrated fusion cross section is in good agreement with the experimental data.     

甘肃临泽小枣多糖提取及抗氧化性

研究了甘肃临泽小枣的抗氧化活性.采用邻二氮菲-Fe<'2+>-H<,2>O<,2>氧化法、邻苯三酚自氧化法以及卵黄脂蛋白不饱和脂肪酸过氧化体系对小枣多糖抗氧化作用进行了测定.临泽小枣多糖对羟自由基、超氧阴离子自由基均有清除能力,并能抑制卵黄脂蛋白脂质过氧化作用,在相同浓度下,多糖提取液对羟自由基清除能力最强、抑制卵黄脂...     

钠灯下α-蒎烯光敏氧化反应中区域选择性的催化调控

发展了一种简单有效的α-蒎烯光敏催化氧化方法,该方法以高压钠灯为绿色光源,内循环氧气作为氧化剂和搅拌气,自制水浴式光化学反应器.考察了催化剂种类和反应条件对α-蒎烯转化率和产物选择性的影响.结果表明,α-蒎烯可通过催化一步生成单萜醇、醛和酮,且通过催化剂的酸碱协同作用可调节产物的区域选择性.当以N,N-二甲基甲酰胺为溶...     

Fast light of CsI（Na） crystals

The responses of different common alkali halide crystals to alpha-rays and gamma-rays are tested in this research. It is found that only CsI(Na) crystals have significantly different waveforms between alpha and gamma scintillations, while others do not exhibit this phenomena. The rise time of the fast light is about 5 ns and the decay time is 17±12 ns. It is suggested that the fast light of CsI(Na) crystals arises from the recombination of free electrons with self-trapped holes of the host crystal CsI. Self-absorption limits the emission of fast light of CsI(Tl) and NaI(Tl) crystals.     

Nonlinear inversion of ultrasonic guided waves for in vivo evaluation of cortical bone properties

Ultrasonic guided waves (UGWs), which propagate throughout the entire thickness of cortical bone, are attractive for the early diagnosis of osteoporosis. However, this is challenging due to the impact of soft tissue and the inherent difficulties related to multiparametric inversion of cortical bone quality factors, such as cortical thickness and bulk wave velocity. Therefore, in this research, a UGW-based multi-parameter inversion algorithm is developed to predict strength-related factors. In simulation, a free plate (cortical bone) and a bilayer plate (soft tissue and cortical bone) are used to validate the proposed method. The inversed cortical thickness (CTh), longitudinal velocity (V_L) and transverse velocity (V_T) are in accordance with the true values. Then four bovine cortical bone plates were used in in vitro experiments. Compared with the reference values, the relative errors for cortical thickness were 3.96%, 0.83%, 2.87%, and 4.25%, respectively. In the in vivo measurements, UGWs are collected from the tibias of 10 volunteers. The theoretical dispersion curves depicted by the estimated parameters (V_T, V_L, CTh) match well with the extracted experimental ones. In comparison with dual-energy x-ray absorptiometry, our results show that the estimated transverse velocity and cortical thickness are highly sensitive to osteoporosis. Therefore, these two parameters (CTh and V_T) of long bones have potential to be used for diagnosis of bone status in clinical applications.     

Amplitude modulation excitation for cancellous bone evaluation using a portable ultrasonic backscatter instrumentation

The ultrasonic backscatter (UB) has the advantage of non-invasively obtaining bone density and structure, expected to be an assessment tool for early diagnosis osteoporosis. All former UB measurements were based on exciting a short single-pulse and analyzing the ultrasonic signals backscattered in bone. This study aims to examine amplitude modulation (AM) ultrasonic excitation with UB measurements for predicting bone characteristics. The AM multiple lengths excitation and backscatter measurement (AM-UB) functions were integrated into a portable ultrasonic instrument for bone characterization. The apparent integrated backscatter coefficient in the AM excitation (AIB_AM) was evaluated on the AM-UB instrumentation. The correlation coefficients of the AIB_AM estimating volume fraction (BV/TV), structure model index (SMI), and bone mineral density (BMD) were then analyzed. Significant correlations (|R| = 0.82-0.93, p < 0.05) were observed between the AIB_AM, BV/TV, SMI, and BMD. By growing the AM excitation length, the AIB_AM values exhibit more stability both in 1.0-MHz and 3.5-MHz measurements. The recommendations in AM-UB measurement were that the avoided length (T1) should be lower than AM excitation length, and the analysis length (T2) should be enough long but not more than AM excitation length. The authors conducted an AM-UB measurement for cancellous bone characterization. Increasing the AM excitation length could substantially enhance AIB_AM values stability with varying analyzed signals. The study suggests the portable AM-UB instrument with the integration of real-time analytics software that might provide a potential tool for osteoporosis early screening.     

基于CC2531的安全监测预警系统设计

为解决目前基层军营安全监测手段存在的高功耗、高成本、实时性较差、易被破坏等问题,选用CC2531和CC2591作为ZigBee通信模块芯片,布设多种传感器,搭建无线传感网,以PC机为监测主机,制定通信协议,设计出军营无线安全监测与预警系统;实现一平方公里范围内温度、湿度、人体入侵、可燃气体烟雾浓度等信息的远程监测与自动预警;以不同距离监测哈尔滨十二月份室外温度、相对湿度为试验,无数据丢失,温湿度测量误差不大于2%,表明系统具有高可靠性、高精度、低功耗、灵活易用等优点,具有广阔的应用前景。     

利用软X射线双频光栅剪切干涉技术诊断金等离子体

激光辐照靶产生的等离子体电子密度的诊断对于惯性约束聚变、等离子体物理、高能量密度物理等相关领域的研究具有重要意义,特别是中、高Z材料等离子体临界面附近的电子密度分布信息的测量.采用波长13.9 nm的类镍银软X射线激光作为探针,利用双频光栅剪切干涉技术尝试诊断了激光辐照金平面靶产生的等离子体的电子密度分布.实验获得了清晰的干涉条纹图像,通过对条纹的初步处理,测量到的最高密度达到了约1.4倍临界密度.通过与相关理论程序模拟结果对比,发现实验与模拟存在一定的偏差,为进一步优化模拟程序提供了有益的参考.通过实验,充分表明了软X射线激光双频光栅干涉技术在诊断中、高Z材料临界密度附近区域等离子体方面的实用性.