糠醛系弱碱性阴树脂的合成及研究

糠醛与二乙基胺反应生成带有叔胺基的呋喃衍生物,同时开环缩聚制得了糠醛系弱碱性阴离子交换树脂。通过所得弱碱树脂的性能测定及相应FTIR谱的解析研究,探讨了不同反应条件对树脂结构与性能的影响,研究了糠醛及其衍生物在碱性条件下开环聚合的反应过程。     

力学一题

一个边长为a的立方体,其密度p大于水的密度p水,将其放入一盛水容器内,使它正好被水浸没,如图一所示.松手后使该物体的一面沿容器些向下运动,初速度为零.试描述该物体的运动情况. 按照物体在水中的浮沉条件,只要 P>P水,物体就下沉.但值得注意的是,本题中物体的一面与容器壁相接触,两者之间无水渗入,故当物体在下沉过程中,在竖直方向除了受到向下的重力G和向上的浮力F以外,还受到物体与容器壁之间的摩擦力f,方向向上,如图二所示,而f是随着水对物体的水平压力N的增大而增大的,N又是随着深度的增加而增大的,故当物体运动到某一深度时,将停止…     

改進幾何作業批改方法的體驗——批改作業和課外輔導相結合

在中學裏,批改數學練習本,一般的說,目前還是一個存在的問題,特別是批改幾何練習本困難最多,問題最大,因此許多老師大多採取“全面檢閱,輪改抽查,重點批改,加强總結”等辦法,最近數學通報上又介紹了一種批改紙片上的習題的辦法(1955年2月號),這些方法,雖然都有着一定的優點,能節省老師們一定的時間和精力,使他們能更好地進行備課和學習,以及進修等工作,但根據目前學生的知識質量,學生的學習態度舆學習方法的情况來說,特別是對初中的學生青少年們來說,這些批改方法的實際效果和作用究竟有多大,還有值得研究的地方,我認為這些方法(包括全批全改在內)都有下列幾個共同的缺點: 1.不管全批全改也好,重點批改也好,輪改抽查也好,當練習本發給同學後,他們是否認     

Influence of annealing conditions on impurity species in arsenic-doped HgCdTe grown by molecular beam epitaxy

Based on our previous work,the influence of annealing conditions on impurity species in in-situ arsenic (As)-doped Hg 1 x Cd x Te (x ≈ 0.3) grown by molecular beam epitaxy has been systematically investigated by modulated photoluminescence spectra.The results show that (i) the doped-As acting as undesirable shallow/deep levels in as-grown can be optimized under proper annealing conditions and the physical mechanism of the disadvantage of high activation temperature,commonly assumed to be more favourable for As activation,has been discussed as compared with the reports in the As-implanted HgCdTe epilayers (x ≈ 0.39),(ii) the density of V Hg has an evident effect on the determination of bandgap (or composition) of epilayers and the excessive introduction of V Hg will lead to a short-wavelength shift of epilayers,and (iii) the V Hg prefers forming the V Hg-As Hg complex when the inactivated-As (As Hg or related) coexists in a certain density,which makes it difficult to annihilate V Hg in As-doped epilayers.As a result,the bandedge electronic structures of epilayers under different conditions have been drawn as a brief guideline for preparing extrinsic p-type epilayers or related devices.     

Study of new boson W_1~± in the Minimal Higgsless Model at the LHC

The Minimal Higgsless Model predicts the existence of new vector gauge boson W1± . By the process PP → W1± qq → W±Z0qq, Z0 → l+l-, W±→ qq (l=e,μ; q is hadronized to be jets), we study the sensitivity of searching for this possible vector gauge boson in the level of generator events of signal and backgrounds, then give integrated luminosity required to discover 5σ signal as a function of W1± mass. The generator for the signal PP→W1± qq→W±Z0qq at tree level is developed with the Minimal Higgsless Model and th...     

选择性双向顺序压缩感知重建动态磁共振成像

压缩感知是一种新兴技术,该技术能够用远低于奈奎斯特采样频率采集的信号恢复出原始信号. 压缩感知成像方法大大提高了心脏磁共振成像的采集速度,已有的方法主要利用动态图像时间相关及心脏的周期性运动特征,如采用在时间维做傅立叶变换或求解每帧数据跟参考帧数据的差异获取稀疏数据,满足压缩感知重建的要求. 该文提出了选择性双向顺序压缩感知重建算法,利用相邻帧的差异更小的特点,获取更加稀疏的差异数据,同时利用动态图像的周期性,以目标函数积分为判据,在时间顺序和时间逆序两个方向选择效果更好的方向进行数据重建,降低图像伪影和噪声. 该选择算法,可以在不增加重建时间的情况下,选择双向顺序重建中最佳的结果. 该文对心脏磁共振图像数据进行了数据处理实验,并且跟传统压缩感知算法、参考帧差异方法及匙孔成像方法进行了比较. 结果表明：该方法无论从视觉效果还是从统计结果上,都有很大的改善.     

多孔硅/TiO2纳米线光阳极的制备及其光电催化性能

使用金属辅助化学刻蚀(MACE)法与水热法,改变贵金属粒子的刻蚀时间,制备不同n型多孔硅/TiO_2纳米线光阳极。通过扫描电镜(SEM)和X射线衍射仪(XRD)对光阳极样品进行表征,结果显示多孔硅宏孔的尺寸会随着刻蚀时间延长而增大,由0.1μm变化到0.4μm,多孔硅表面长有TiO_2纳米线为金红石相及少量锐钛矿相。测试结果显示刻蚀35 min的多孔硅/TiO_2样品具有最高的减反射率,在模拟太阳光下具有较高的光电流(光电流密度)活性,且在1.5 V外加偏压下具有最高的光电催化活性。这是由于刻蚀35 min的多孔硅基底具有优异的减反射性能,同时多孔硅与Ti O_2纳米线复合形成光阳极之后具有异质结效应和窗口效应,使得多孔硅/TiO_2纳米线光阳极具有优异光电化学性能。     

L-Shell X-Ray Yields and Production Cross Sections of Zr and Mo Bombarded by Slow Highly Charged Ar16+ Ions

The L-shell x-ray yields of Zr and Mo bombarded by slow Ar16＋ ions are measured. The energy of the Ar^16＋ ions ranges from about 150 keV to 350 keV. The L-shell x-ray production cross sections of Zr and Mo are extracted from these yields data. The explanation of these experimental results is in the framework of the adiabatic direct- ionization and the binding energy modified BEA approximation. We consider, in the slow asymmetric collisions such as Ar and Mo/Zr, the transient united atoms （UA） are formed during the ion-surface interaction and the direct-ionization is the main mechanism for the inner-shell vacancy production. Generally, the theoretical results are in good agreement with the experimental data.     

Preparation and Characterization of BPO Film as Electrode for Using of FeRAM

Conductive perovskite BaPb03 （BPO） films as a potential electrode material of PZT capacitors used in ferroelectric random access memory are prepared by rf magnetron sputtering. An x-ray diffractometer and standard four probe method are employed to investigate the dependence of growth conditions on crystal structure and conductivity of BPO films. It is found that BPO films with perovskite phase can be obtained at substrate temperatures above 425℃, and the sample with the lowest resistivity is obtained at 450℃ under pure argon atmosphere. Using this BPO film as electrode, ferroelectric properties of BPO/PZT/BPO and Pt/PZT/BPO sandwiched structures are evaluated. Their remanent polarization and coercive field are 36.6 ℃/cm^2 （81.3 k V/cm） and 36.9℃/cm^2 （89.1 kV/cm）, respectively. The coercive field of the former structure is lower than that of the latter, but remanent polarizations are almost the same. In addition, the results imply that BPO electrode is helpful to improve the fatigue resistance of PZT. The reasons are discussed.     

不同退火方式得到的PbTiO3薄膜的红外光谱研究

利用改进的solgel工艺,通过快速热退火和慢速退火两种方式在Si衬底上制备了PbTiO3多晶薄膜,并采用红外反射光谱对PbTiO3薄膜进行了研究,观察到了薄膜中所有红外活性的8个声子模,发现两种退火方式得到的薄膜的光谱存在差异:前者的声子模频率除了三个变化不明显外,其余都低于后者.认为影响声子模行为的主导因素是薄膜中存在的应力,其中软模对应力的影响最为敏感 关键词：