La_(0.7)Ba_(0.3)Mn_(1-x)Fe_xO_3的巨磁电阻效应及磁性

采用溶胶－凝胶工艺制备Ｌａ０．７Ｂａ０．３Ｍｎ１－ｘＦｅｘＯ３化合物．研究其磁性、导电性和磁电阻效应．结果表明,随着Ｆｅ含量的增加,电阻率增加,铁磁居里温度近似线性下降     

Error analysis about CCD sampling in Fourier transform profilometry

The influence of sampling caused by 2-D solid-state image sensors (CCD) in FTP is discussed in this paper. As we all know, discrete fringe patterns processed by computer are obtained through two samplings. The first one is accomplished in the CCD image plane, and the second is accomplished in A/D convertor of frame grabber. In the previous analysis, sampling is just regarded as a point-sampling process because of ignoring the actual sensor structure of a CCD in the sampling process. Here we discuss the influence of the sensor structure of CCD in FTP, especially the influence from the light-sensitive area size variation. Certain formulas about sampling influence are given, and some simulations and a primary experimental demonstration are carried out to verify our analysis.     

煤硫共生矿床开采中几个问题的分析

对煤硫共生矿床在综合开采、开拓部署、采准、回采工艺及通风安全等几个问题进行了分析探讨。     

Synthesis and luminescence of polyphosphazenes with carbazolyl side chains

Two new blue‐light‐emitting polyphosphazenes ( 1 and 2 ) containing carbazolyl groups as side chains were synthesized from a highly reactive macromolecular intermediate by a nucleophilic substitution reaction. Molecular structural characterization for the polymers was presented by ¹H NMR, IR, and ultraviolet–visible spectra, gel permeation chromatography, and differential scanning calorimetry. The polymers exhibited excellent solubility in common organic solvents and were thermally stable. A fluorescence analysis of the two materials in tetrahydrofuran showed a strong blue light emitting. The quantum yields of the polyphosphazenes were 0.55 for 1 and 0.64 for 2 , relative to quinoline (in 0.1 N H₂SO₄). An electroluminescent diode was fabricated, and a bright blue light was observed; the maximum external quantum efficiency was about 0.026% at an applied forward voltage of 23 V. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3428–3433, 2001     

中国通货紧缩的成因分析

近几年来 ,我国经济增长速度放慢 ,物价指数连续下降 ,出现了通货紧缩现象 ,引起我国经济界的广泛关注 .本文从定量分析的角度 ,采用自组织建模方法对造成我国通货紧缩的因素进行建模分析 ,并据此给出相应的对策     

mRNA差异显示法筛选和克隆东亚飞蝗抗药性相关基因

筛选和克隆东亚飞蝗抗药性相关基因.采用mRNA差异显示法(mRNA diffFerential display PCR,DD-PCR),对比了东亚飞蝗在受到氯氰菊酯杀虫剂的诱导前后,基因表达发生的变化.对差异片段进行了回收,克隆、测序,Northern点杂交验证以及序列分析和同源性比较.东亚飞蝗在受到氯氰菊酯杀虫剂的诱导前后,存在明显的基因表达差异,发现差异表达条带9条,对9条差异表达条带进行克隆、测序,经序列分析和同源性比较和RNA点杂交验证,表明确认其中1条带与东亚飞蝗的抗药性有关.东亚飞蝗的mRNA差异显示证明,该EST序列可能在抗药的发生发展中具有一定的作用.     

ChemInform Abstract: Structural Characterization of Moganite‐Type AlPO4 by NMR and Powder X‐Ray Diffraction.

A new high‐pressure AlPO₄ phase obtained at 5 GPa and 1500 °C is characterized by synchrotron powder XRD and MAS NMR spectroscopy.     

高等学校教师素质内容的探讨

探讨了教师素质的定义，结构和内容，分析了国外高校对教师素质的要求，以及我国高校教师素质的现状，最后提出了教师素质的培养方法。     

语境与英语听说课教学

任何言语行为及其理解都必然发生于特定的语境。听者在交际中决不只是消极地充当信息收受者，也不仅是利用语言知识去获得句子本身的意义，还需要利用语境所提供的线索对句子意义进行处理(增补、删减、过滤等)，才能真正理解话的意义。本文根据语境理论及实际教学经验，着重讨论了语音语境、情景语境和文化语境分析在英语听说课教学中的指导作用。     

Facile one-step synthesis of 2,5-diketopiperazines

We report a one-step protocol for the general synthesis of 2,5-diketopiperazines from an Fmoc-protected amino acid and an amino acid ester. The application of the method is highlighted by rapid and efficient preparation of various 2,5-diketopiperazines.