要重视对学生进行解题受挫训练

要重视对学生进行解题受挫训练臧立本（江苏省丹阳中学２１２３００）针对中学生解数学题时常见的不求甚解、眼高手低、怕苦畏难状况，有计划地使学生在解题中经受挫折，不仅可以强化对基本知识．基本技能的掌握，而且可以培养学生战胜困难的决心和勇气一提高学生的心理素...     

ANALYTICAL AND ITERATIVE SEMICLASSICAL SOLUTIONS FOR THE GIANT MAGNETORE-SISTANCE IN MAGNETIC MULTILAYERS

Based on the semiclassical theory of Camley and Barnas(C-B), the problem of solving the giant magnetoresistance in magnetic multilayets (F_i/N_i)_n/F_n+1 is comprehensively discussed with both the bulk and interface spin-dependent scatterings being involved. The solution of this problem is attributed to the solution of G-coefficients (G's). First, we point out that for large n the analytical solution in close form ia hard to obtain and a recent attempt made in the literature failed in general. Second, a new choice of local spin quantization-axes is adopted for reducing (in comparison with C-B) the number of G's and several exact infer-ences are drawn in order to further simplify the solution of G's. Finally, an iteration method for solving G's is developed, which, we believe, is the simplest one among the numerical methods in this area and leads naturally to the analytical solutions with close expression in the case of small n. Such solutions are given for symmetric sandwich as well as superlattice.     

关于量子不变量及其与量子相位关系的几点注记

基于量子不变量构造定理，简化地导出和扩充了Lewis和Riesenfeld的结果．指出所谓的Lewis-Riesenfeld相位一般没有物理意义；为了使其有物理意义，不变量必须取特殊形式．文中给出了这种形式．以磁场中的自旋系统为例，作了具体讨论． 关键词：     

平行与垂直磁化下多层磁膜巨磁电阻与外磁场关系的唯象理论计算

用Ｃａｍｌｅｙ和Ｂａｒｎａｓ等人的唯象理论方法，计算了相邻铁层间具有反铁磁耦合的层数较多的Ｆｅ／Ｃｒ多层膜，在外磁场平行和垂直于膜面情况下的磁电阻与外磁场的关系，并与实验结果作了比较，符合得较好。在计算中利用对称性条件，对Ｃａｍｌｅｙ和Ｂａｒｎａｓ等人的理论进行了简化，求出了电子分布函数和磁电阻的显式解。     

超声辅助萃取/气相色谱-质谱测定沉积物中的对苯二酚

建立了超声波辅助萃取,乙酸酐衍生化后用气相色谱-质谱(GC - MS)法测定沉积物中对苯二酚的分析方法.对超声辅助萃取影响因素如萃取溶剂、超声功率、萃取次数和萃取时间进行了优化.在优化条件下,对苯二酚的回收率为85%～92%,相对标准偏差(RSD)为3.0% ～7.2%,线性范围为0.05～10 mg/L,检出限为12...     

强化珠心算普及教学管理发挥开智功能 服务基础教育

我们七台河市新兴区是全省第一个普及珠心算教育的实验区,是2007年3月起步．从小学一年级开始逐年推进到五年级,截止目前,全区在校小学生5000余人全部接受珠心算教育。同时,全区民办幼儿园3000余名幼儿和1000余名在校幼儿班儿童也全部接受了珠心算教育。先后举办四期教师培训班,每期分三个阶段集中学习培训,合计学满360课时,全区已有629人获得珠心算教师培训证书．80％的教师和领导参加了培训。累计投入近百万元教学经费,校校建立题库、配置印刷机。     

洞穴水理化特征及影响因素初探——以金华双龙洞为例

通过对双龙洞洞穴滴水、岩石裂隙水、地下河水和瀑布水进行连续三个月水样采集,分析水化学成分及物理性质。结果显示:洞穴滴水EC、Ca2+、Mg2+、HCO3-浓度均大于岩石裂隙水、瀑布水和地下河水相应的浓度。洞穴滴水的Ca2+、Mg2+、HCO3-主要来源于碳酸盐岩的溶解,洞顶土壤厚度、植被覆盖率以及气温、降水量与Ca2+、Mg2+、HCO3-浓度呈正相关关系。洞穴滴水的滴率、Ca2+、Mg2+、ρ(Mg)/ρ(Ca)比值对气候环境有一定的响应,但洞穴内部存在地域差异。     

微型近红外光谱技术快速鉴别霍山石斛种类（英文）

霍山石斛是一种非常珍贵的中药材,具有很高的商品价值和药用价值。不同种的霍山石斛具有不同的商品价格和药效作用,因此需要建立一种快速且绝对无损的方法来鉴别不同种的霍山石斛。该实验,采用微型近红外光谱仪MicroNIR 1700实现对来自于三个不同种的五个不同商品等级的霍山石斛鉴别研究。经光谱预处理、波段选择及主成分数优化后所建最佳SIMCA模型结果的识别率和拒绝率均达到100%,表明微型近红外光谱仪MicroNIR 1700能够成功实现对五类霍山石斛的快速及绝对无损鉴别。     

与LPC214x处理器USB方式通信的编程技术

USB通信具有更方便、灵活、高效等特点,逐渐代替传统的RS-232、RS-485等通信方式,可用来解决测井过程数据传输量大的难题。主控芯片为LPC214x处理器的地面面板系统可与电脑以USB通信方式通信,在上位机中用C#、C++等语言进行编程,分别调用动态库EasyUSB214x,实现了计算机与LPC214x处理器USB方式通信,并阐述了编程过程的实现方法及其关键技术。通过测试后发现,利用C++调用动态库进行USB通信的程序运行时较为稳定。测井软件主体功能程序利用C#开发,C++开发USB通信程序,C#与C++组合开发的编程方法解决了测井数据高速传输的需求。     

Performance improvement of Ga N-based light-emitting diodes transferred from Si(111) substrate onto electroplating Cu submount with embedded wide p-electrodes

Crack-free Ga N/In Ga N multiple quantum wells(MQWs) light-emitting diodes(LEDs) are transferred from Si substrate onto electroplating Cu submount with embedded wide p-electrodes. The vertical-conducting n-side-up configuration of the LED is achieved by using the through-hole structure. The widened embedded p-electrode covers almost the whole transparent conductive layer(TCL), which could not be applied in the conventional p-side-up LEDs due to the electrodeshading effect. Therefore, the widened p-electrode improves the current spreading property and the uniformity of luminescence. The working voltage and series resistance are thereby reduced. The light output of embedded wide p-electrode LEDs on Cu is enhanced by 147% at a driving current of 350 m A, in comparison to conventional LEDs on Si.