单次通过型束流位置探测器的束流位置测量方法

针对当前单次通过型数字束流位置探测器（BPM）有效采样点数少、数据信噪比低、测量分辨率差的问题,提出了一种基于“束流单次通过”的数字BPM测量改进算法。该算法通过模拟信号的功分-延迟-合成,增加了有效采样数据,并通过采样数据的截取与数据拼接、数字滤波等数据处理方式,提高了采样数据的信噪比,并最终实现了BPM测量分辨率的提高。实验结果表明,该算法在不改变模数转换器（ADC）采样率的情况下,将单次通过型BPM的测量分辨率提高了约2倍。该测量方法为提高单次通过型BPM的测量分辨率提供了一种新的解决方案,已成功应用于北京正负电子对撞机（BEPCII）和高能同步辐射光源（HEPS）直线加速器项目中。     

有限个元素的Γ－环一定存在强诣零根

利用符号动力系统中关于有限型子转移的若干深刻结果，得到结论：有限个元素的Γ－环－定存在强诣零根．此外还有比这稍强的结论．     

A STUDY OF HEAT BALANCE IN CHINA

The net income of radiant energy per unit area of the earth's surface (called radiation balance) is mainly divided among the heat flowing to the ground, the heat transferred to the air and the heat for evaporating moisture. Therefore, the heat balance of an area is the balance between radiation balance and the other energy expenditure or compensation caused by its transformation.The heat balance equation of the earth's surface of an area is expressed as R=Q_A LB P, where R is the radiation balance, Q_A the heat exchange between the earth's surface and underlying soil, LB the evaporation heat dissipation (L the latent heat of evaporation and B the amount of evaporation) and P the turbulent heat exchange between the earth's surface and the atmosphere.In this paper, while results are summarized of investigations on the components of heat balance of the earth's surface in China, various methods for determining the components of heat balance are also discussed and analyzed. Using the data of the ordinary met     

双显色双波长分光光度法测定无机多组份体系的研究

本文将双显色双波长分光光度法成功地应用于三组份、四组份同时测定,拟定了一种新颖的处理无机多组份体系的方法。经实验证实,通过适当选择两个显色体系和最佳波长对组,该法不仅能有效地排除干扰,而且可明显提高测定灵敏度,在实践上具有更大的适应性。     

拓扑异构体的研究(Ⅰ)C型与S型拓扑异构体的波谱性质及结构鉴定

利用 ¹H和 ¹³C NMR, IR, UV, SEM对合成的4种C型和S型拓扑异构体进行了结构表征和分析, 发现对于不同拓扑结构的C型和S型分子可以通过 ¹H NMR来鉴别, 而对于相同拓扑结构的S型cis(SC)和trans(ST)分子, C型 cis(CC)和trans(CT)分子则要结合 ¹³C NMR来鉴别. 四种拓扑异构体的IR, UV, 波谱性质以及SEM图象没有显著的差异.     

Influence of the deposition parameters on the transition region of hydrogenated silicon films growth

Hydrogenated microcrystalline and amorphous silicon thin films were prepared by very high frequency plasmaenhanced chemical vapour deposition （VHF PECVD） by using a mixture of silane and hydrogen as source gas. The influence of deposition parameters on the transition region of hydrogenated silicon films growth was investigated by varying the silane concentration （SC）, plasma power （Pw）, working pressure （P）, and substrate temperature （Ts）. Results suggest that SC and Ts are the most critical factors that affect the film structure transition from microcrystalline to amorphous phase. A narrow region in the range of SC and Ts, in which the rapid phase transition takes place, was identified. It was found that at lower P or higher Pw, the transition region is shifted to larger SC. In addition, the dark conductivity and photoconductivity decrease with SC and show sharp changes in the transition region. It proposed that the transition process and the transition region are determined by the competition between the etching effect of atomic hydrogen and the growth of amorphous phase.     

陶瓷与陶瓷基复合材料的疲劳研究进展

本文以相变增韧陶瓷的疲劳为重点，对最近１０年来国内外陶瓷与陶瓷基复合材料的疲劳研究情况作了简要的评述，并对进一步研究提出了一些建议。     

Effect of substrate temperature and pressure on properties of microcrystalline silicon films

In this paper intrinsic microcrystalline silicon films have been prepared by very high frequency plasma enhanced chemical vapour deposition (VHF-PECVD) with different substrate temperature and pressure. The film properties were investigated by using Raman spectra, x-ray diffraction, scanning electron microscope (SEM), and optical transmittance measurements, as well as dark conductivity. Raman results indicate that increase of substrate temperature improves the microcrystallinity of the film. The crystallinity is improved when the pressure increases from 50Pa to 80Pa and the structure transits from microcrystalline to amorphous silicon for pressure higher than 80Pa. SEM reveals the effect of substrate temperature and pressure on surface morphology.     

磷钼蓝分光光度法测定维生素C

基于在一定的反应条件下,维生素C可以定量地将磷钼酸锭还原成磷钼蓝,提出了一种新的测定维生素C的分光光度法。该方法很方便、快速地测定生物、药物等试样中的维生素C,准确度和重复性均达到令人满意的程度。     

便携式X射线荧光仪测定土壤中镍的精度研究

作为一种快速、现场检测的分析方法,便携式X射线荧光光谱(FP-XRF)可以在土壤重金属分析领域获得广泛应用。然而,FP-XRF的测定精度受到一些因素的影响,制约了它的应用。前人的研究已经发现,当元素含量较低时,FP-XRF的测定精度不佳。在现场检测时也会受到土壤湿度效应和粒径的影响。但是尚未有研究对上述因素的影响类型和影响程度进行深入探究。本文以Ni为例,根据准确度和精密度,研究了Ni含量与FP-XRF测定精度的关系,得出了这种影响的临界值;比较了现场测定中土壤湿度效应和粒径对准确度和精密度的影响程度。实验表明,FP-XRF的测定精度与Ni含量相关,临界值为400 mg·kg-1。Ni的浓度低于400 mg·kg-1时,相对标准偏差(RSD)和相对不确定度同时降低,即测定精度随着Ni含量的升高而提高;Ni的浓度高于于400 mg·kg-1时相对标准偏差(RSD)和相对不确定度不再有明显变化,即测定精度不再与Ni含量有关。现场检测中,土壤水分贡献的相对不确定度为3.77%,粒径贡献的相对不确定度为0.56%。土壤湿度效应对准确度和精密度的影响程度都要高于土壤粒径。