师资预测一类纵横统计推进模型

提出了一个新的人才预测模型,其主要优点是可对残缺原始数据进行加工,且可修正预测值的随机误差影响,预测精度较高.本文还给出了用该模型对某校师资进行预测的实例,得到满意结果.     

一种简易新型长光程薄层光谱电化学池

设计并制作了一种新型长光程薄层光谱电化学池，其具有光程长、灵敏度高、重现性好等特点，且组装简便，电极容易更换，溶液未补偿电阻小，溶液用量少．易清洗．电解池以石墨为工作电极，分别用循环伏安、交流阻抗技术、光谱恒电位技术对其性能进行测试，得到比较满意的结果．     

Chiral separation of synthetic vicinal diol compounds by capillary zone electrophoresis with borate buffer and beta-cyclodextrin as buffer additive.

The investigation on capillary electrophoretic enantioseparation of six synthetic compounds containing vicinal diol groups has been undertaken to acquire the optimum conditions using native beta-cyclodextrin (beta-CD) as chiral selector and borate as a background electrolyte. The separation was carried out in an uncoated capillary (58.5 cm x 75 microm i.d., effective length 48.5 cm) and the effects of several important factors were investigated in detail. The results showed that beta-CD as a chiral selector exhibited good enantioselectivity and that the enantioseparation was greatly influenced by the structure of the diols, the borate concentration and the buffer pH. The optimum performance was obtained for the chiral vicinal diols under the conditions of 200 mM borate buffer of pH 9.8 containing 1.7% beta-CD at an applied voltage of 15 kV and a capillary temperature of 20 degrees C. Under the conditions, four diols were baseline separated with fast analysis time and the good theoretical plate numbers (above 10 x 10(4)) and favorable migration-time reproducibilities (RSDs below 3.0%) were obtained. The separation results were satisfactory.     

浅析加强英语听说能力的培养--从CET改革谈起

交际是学习语言的最终目的.大学英语四、六级考试改革突出了英语听说能力,其目的是促进学生重视英语交际能力.要提高学生英语交际能力,在英语教学中教师应正确处理好几对关系:听与说的关系;交际文化与语言文化的关系;教师与学生的关系;准确与流利的关系等,把握教学原则,从而加强学生的听说能力培养.     

Some existence results on periodic and generalized periodic solutions for singular hamiltonian systems

In this paper, we use the variational method to study the existence of periodic and generalized periodic solutions of planar second order Hamiltonian systems when a singular potential is present. The results obtained are applied to the study of generalized periodic solutions of the Restricted Three-Body Problem and the Planarn-Body Problem.     

Asymmetric synthesis XXVII: Asymmetric catalytic trimethylsilylcyanation of aldehydes by novel Ti-chiral Schiff base complexes

Enantioselective catalytic trimethylsilylcyanations of aldehydes with 48% to 92% e.e. have been studied using the novel Ti-chiral Schiff base complexes. We have found that the catalyst led to high enantoselectivity when the molar ratio of the Schiff base 1 to Ti(O-i-Pr)₄ was 2:1.     

Molar conductivity calculation of Li-ion battery electrolyte based on mode coupling theory

A method is proposed to calculate molar conductivity based on mode coupling theory in which the ion transference number is introduced into the theory. The molar conductivities of LiPF6, LiClO4, LiBF4, LiAsF6 in PC (propylene carbonate) are calculated based on this method. The results fit well to the literature data. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes.     

电子探针定量分析的标准样品——几种多元氧化物单晶

在很高的温度和适宜的生长条件下,分别采用熔盐籽晶法和高温引上法生长了高质量的YAP、NAB、KTP、LN、BBO、SBN等多元氧化物单晶,它们具有优良的物理化学性能,严格的化学比,固定的组成与结构以及较好的化学均匀性和电子束轰击下的稳定性。广泛地用于激光和非线性光学领域。我们选用这些晶体为原材料研制电子探针定量分析的标准样品。经过测量和标定,这些单晶标样符合中华人民共和国国家标准GB 4930-85(电子探针显微分析标准样品通用技术条件)的规定。含有稀土元素的标样如NAB和YAP能发出绿色荧光,是电子显微术中理想的阴极发光材料。     

Interaction Between HMG Proteins (1+2) and the Negative Regulatory Region 1(NCR1) in the 5''''-flanking Sequence of the Human β-globin Gene

The pattern of high mobility group proteins 1 and 2 (HMG1,2) interaction with the 5'-flanking sequence of the human β-globin gene has been analyzed by scanning tunnelling microscopy (STM). A 200 bp negative regulatory region in the 5'-flanking sequence of the human β-globin gene can be folded by HMG proteins 1 and 2 into a circular structure (diameter 70±6) with a linear tail which seems to be a left-handed double helix structure.     

Speciation of V, Cr and Fe by capillary electrophoresis-bandpass reaction cell inductively coupled plasma mass spectrometry

Capillary electrophoresis-dynamic reaction cell inductively coupled plasma mass spectrometry (CE-DRC-ICP-MS) for the speciation of iron(III/II), vanadium(V/IV) and chromium(VI/III) is described. Two different CE migration modes were employed for separating the six metal ions using pre-capillary complexation. One is counter-electroosmotic mode in which iron(III/II) and vanadium(V/IV) ions were well separated using a 60 cm x 75 microm i.d. fused silica capillary. The voltage was set at +22 kV and a 15 mmol l(-1) tris(hydroxymethyl)aminomethane (Tris) buffer (pH 8.75) containing 0.5 mmol l(-1) ethylenediaminetetraacetic acid (EDTA) and 0.5 mmol l(-1) ortho-phenanthroline (phen) was used as the electrophoretic buffer. The other is co-electroosmotic mode in which chromium(VI/III) ions were well separated while the applied voltage was set at -22 kV and a 10 mmol l(-1) ammonium citrate buffer (pH 7.7) containing 0.5 mmol l(-1) diethylenetriaminepentaacetic acid (DTPA) and 0.01% polybrene was used as the electrophoretic buffer. The mass spectra were measured at m/z 51, 52 and 56 for V. Cr and Fe, respectively. The interfering polyatomic ions of 35Cl16O+, 40Ar12C+ and 40Ar16O+ on 51V+, 52Cr+ and 56Fe+ determination were reduced in intensity significantly by using NH3 as the reaction cell gas in the DRC. The detection limits were in the range of 0.1-0.5, 0.4-1.3 and 1.2-1.7 ng ml(-1) for V, Cr and Fe, respectively. Applications of the method for the speciation of V, Cr and Fe in wastewater were demonstrated. The recoveries were in the range of 92-120% for various species.