缺中子~(130)Pm和~(128)Pr核的EC/β~+衰变研究

171MeV 36Ar束轰击96Ru靶由熔合蒸发反应生成了130 Pm和12 8Pr核 .由氦喷嘴快速带传输系统将反应产物送到低本底区 .基于X γ t,γ γ t符合测量 ,首次建立了130 Pm的 (EC + β+)衰变纲图 .重新研究了12 8Pr核的衰变 ,订正和补充了γ射线 ,建立了新的 (EC + β+)衰变纲图

基于重离子径迹模板法的纳米线制备与性能研究

本文从纳米材料概念及特性分析入手，介绍了当前纳米线制备方法及其应用，重点对基于重离子径迹模板法的纳米线制备与性能研究进行阐述，本文具体研究内容包括以下几个方面：利用电化学沉积法在重离子径迹模板中制备出直径从30到500 nm、包括单晶和多晶结构的银纳米线阵列，实验结果表明所制备的银单晶纳米线沿(111)面择优取向生长；直径为100 nm的银纳米线在温度低于50 K时，电阻急骤减小。不同直径金纳米线利用电化学沉积法在重离子径迹模板中成功制备，利用XRD测得所制备金纳米线沿(200)面择优取向生长。对金纳米线阵列紫外吸收光谱研究表明，吸收光谱峰位随直径的增加向长波方向移动，同时半高宽增加。当入射光与金纳米线有一定夹角时，其吸收峰随着夹角的增加向短波方向移动。另外，金纳米线在空气中的氧化现象通过其紫外吸收光谱被间接观察到。利用电化学共沉积技术在重离子径迹模板中成功制备出InSb半导体纳米线，通过实验证明，InSb半导体纳米线共沉积电位位于-1.3-1.4 V之间。通过对Cu/Co多层纳米线研究发现，所制备出的Cu/Co多层纳米线具有好的柔韧性，不容易在层间发生断裂

Theoretical study on the formation mechanism of Iso-CH2I-Cl

The dissociation and isomerization reaction mechanism on the ground-state potential energy surface for CH2ClI are investigated by ab initio calculations. It is found that the isomer iso-CH2I-Cl can be produced from either the recombination of the photodissociation. fragments or the isomerization reaction of CH2ClI, rather than from isomerization reaction of iso-CH2Cl-I. Further explanations of experimental results are also presented. (C) 2003 Wiley Periodicals, Inc.

Synthesis and characteristics of the human serum albumin-triazine chiral stationary phase

Human serum albumin (HSA) was successfully bonded to silica with s-triazine as activator. The coupling reaction by this method was rapid and effective. The triazine-activated silica is relatively stable and can be installed for at least 1 month without obvious loss of reactivity when stored below 30 degreesC, pH below 7. It was observed that the amount of bound HSA reached 120 mg/g silica calculated from the UV absorbance difference of the HSA solution. d,l-tryptophan was selected as the probe solute to characterize the properties of HSA bonded s-triazine chiral stationary phase, and separation factor of 9.4 was obtained for d,l-tryptophan. Furthermore, the amount of effective HSA on silica was measured by high-performance frontal analysis, and only 16.8 mg/g silica was responsible for the resolution of d,l-tryptophan. These results indicate that the amount of both the bound and effective HSA on silica with triazine as activator was much higher than those by the Schiff base coupling method. Different kinds of enantiomers were resolved successfully on the aminopropylsilica-bonded HSA s-triazine chiral stationary phase. (C) 2000 Wiley-Liss, Inc.

密度对三种豆科牧草生产力和水分利用率的影响

研究播种密度对3种豆科牧草生产力和水分利用效率的影响,以探讨其在草地农业系统中的合理优化模式。结果表明:沙打旺(Astragelus adsurgens)在高密区第2年生产力最高(18321 kg.hm-2),第3年开始下滑;苜蓿(Medicago sativa)在中、高密区生产力的增幅和增量差别不显著,以第3年最高(22563和22108kg.hm-2);胡枝子(Lespedeza daurica)在中密区第3年最高(7856 kg.hm-2);加大密度使沙打旺提早进入生长盛期,第2年即达到高生产力和较高水分利用效率;苜蓿以中密区(20~30株/m2)效果最好;达乌里胡枝子的生产力和水分利用率偏低,在黄土塬区草地农业中没有优势。

l-序列的采样元素分布及k-错线性复杂度

证明了极大周期FCSR序列的任意采样序列在一个周期内0,1元素分布几乎平衡,利用这一分布性质研究了连接数为强2-素数的l-序列的k-错线性复杂度,结果显示这类l-序列具有非常稳定的线性复杂度。

XAFS at Eu-L-3 edge and UV-VUV excited luminescence of europium doped strontium borophosphate prepared in air

The local structure and the valences of europium in SrBPO5:Eu prepared in air were checked by means of XAFS at Eu-L-3 edge. From the EXAFS results, it was discovered that the doped europium atoms were nine-coordinated by oxygen atoms and the distances of bond Eu-O were 2.42 Angstrom in the host. From the XANES data, it was found that the divalent and trivalent europium coexisted in the matrix. The emission spectra excited by VUV or UV exhibited a prominent broad band due to the 4f(6)5d-4f(7) transition of Eu2+ ions, which indicated that the trivalent europium ions were reduced in air in the matrix at high temperature by the defects [V-Sr]" formed by aliovalent substitution between Sr2+ and Eu3+ ions. The VUV excitation spectra in 100-200 nm range showed that the matrix had absorption bands with the maxima at about 130 and 150 nm, respectively.

Synthesis and crystal structure of (1,3-(Bu2C5H3)-Bu-t)(2)Sm(mu-Cl)(2)Li(THF)(2)

Anhydrous SmCl3 reacts with two equal of Li(1-3-(Bu2C5H3)-Bu-t) to give a complex (1,3-(Bu2C5H3)-Bu-t)(2) Sm(mu -Cl)(2)Li(THF)(2) (C34H58Cl2LiO2Sm, M-r = 726.99), monoclinic, space group P2(1)/n, a = 10.615(2), b = 21.037(4), c = 17.166(3) Angstrom, beta = 93.60(3)degrees, V = 3825.7 (13) Angstrom (3), Z = 4, D-c = 1.262 Mg/m(3), mu = 1.699 mm(-1) and F(000) = 1508, final R = 0.0387 and wR = 0.0741 for 5320 observed[I greater than or equal to2 sigma (I)] reflections. The average Sm - C distance is 2.73 Angstrom. Sm - Cl1 and Sm - Cl2 distances are 2.719 (2) and 2. 697 (2) Angstrom, respectively. Two 1, 3-(Bu2C5H3)-Bu-t-ring centroids and two mu (2)-bridging chloride atoms around Sm atom form a distorted tetrahedron.

吸附杂多化合物对亚硝酸根的电催化还原

详细地研究了吸附在热解石墨电极表面的ＳｉＭｏ１２Ｏ４０４－以及Ｄｙ（ＳｉＭｏ１１Ｏ３９）２１３－和吸附在玻碳电极表面的Ｐ２Ｗ１８Ｏ６２６－的电化学行为，结果表明这些杂多化合物修饰电极在酸性条件下均对ＮＯ２－的还原有很好的催化作用，其催化电流与ＮＯ２－的浓度的平方根里线性关系。