由ψ（2S）→π~＋π~－J／ψ道测量J／ψ轻子道衰变分支比

利用北京谱仪（ＢＥＳ）上取得的ψ（２Ｓ）数据，对ψ（２Ｓ）→π＋π－Ｊ／ψ，Ｊ／ψ→１＋１－和Ｊ／ψ→任意末态两个过程进行了细致的研究，得到Ｊ／ψ的轻子道衰变分支比为Ｂ（Ｊ／ψ→ｅ＋ｅ－）＝（５．９０±０．０７±０．１６）％和Ｂ（Ｊ／ψ→μ＋μ－）＝（５．９６±０．０８±０．１６）％，由此给出Ｂｅ／Ｂμ的值为０．９９０±０．０１８±０．０２４．假定Ｂｅ＝Ｂμ，Ｊ／ψ的轻子道衰变分支比为Ｂ（Ｊ／ψ→１＋１－）＝（５．９３±０．０５±０．１６）％．上述结果可用来估计强相互作用耦合常数αｓ和ＱＣＤ减除参数∧．     

受控核聚变两大途径的对比与结合

目前人们探索受控核聚变主要是从两个方向着手：磁约束受控核聚变和惯性约束受控核聚变，但目前还无法判定到底哪一种途径更为可取，文章首先对这两种途径进行对比，指出各自的特点和困难，在此基础上提出了一种结构相对简单，成本相对较低的三轴六极磁镜系统设想，希望能将磁约束和惯性约束和惯性约束结合起来，以实现受控核聚变反应。     

多体相互作用对高压固氦状态方程的影响

采用量子化学自洽场方法及原子团簇理论对固氦晶格原子势能进行多体展开，定量确定了最近邻原子间距R在0.26—0.175nm之间，短程的两体到五体相互作用对晶体结合能及压缩特性的贡献，并对不同间距下多体展开式的截断位置进行了讨论. 结果表明：当最近邻原子间距R在0.26—0.175 nm之间取值，在具有hcp相结构的晶格中，氦原子势能的多体展开式是一收敛的交错型级数，该级数中两体项、四体项为正值，而三体项、五体项为负值. 当R在0.26—0.23 nm之间取值时, 仅保留级数中两体和三体项就能很好地描述晶格原子势能；当R在0.23—0.20 nm之间取值，多体展式需要展开到四体相互作用项；当R在0.20—0.175 nm之间取值必须再加入五体项贡献. 考虑到五体相互作用后，理论计算已能圆满地解释目前固氦等温压缩数据，其最大压力达 60GPa. 关键词： 固氦 状态方程 多体相互作用     

An Atomic Force Microscopy Investigation of the Tracks Made by C1^＋－C4^＋ Bombardment on CR－39 Detectors

Carbon micro-clusters are accelerated by an HI-13 tandem accelerator. The plastic nuclear track detectors CR-39are irradiated by C1-C4 beams from the HI-13 tandem accelerator and the tracks in CR-39 are studied using anatomic force microscope (AFM). The depths and diameters of C1-C4 tracks are measured for the first time in ananometre scale. An enhancement of the energy loss is obtained for carbon clusters related to single carbon ionswith the same velocity. The results show that the AFM observation is very useful in the quantitative analysis ofclusters in the track detector CR-39.     

Bright Solitons in an Atomic Tunnel Array with Either Attractive or Repulsive Atom-Atom Interactions

Taking a coherent state representation, we derive the nonlinear Schroedinger-type differential-difference equations from the quantized model of an array of traps containing Bose-Einstein condensates and linked by the tunnelling process among the adjacent traps. It is shown that no matter whether two-body interactions among atoms are repulsive or attractive, a nearly uniform atom distribution can evolve into a bright soliton-type localized ensemble of atoms and a lump of atom distribution can also be smeared out by redistributing atoms among traps under appropriate initial phase differences of atoms in adjacent traps. These two important features originate from the tailoring effect of the initial phase conditions in coherent tunnelling processes, which differs crucially from the previous tailoring effect coming mainly from the periodicity of optical lattices.     

In替代(La2/3Ca1/3)(Mn(3-2x)/3In2x/3)O3体系巨磁电阻效应的研究

采用固态反应法制备了In替代的(La_2/3Ca_1/3)(Mn_(3-2x)/3In_2x/3)O₃(x=0.00，0.10，0.15)体系.通过测量其零场和1.6T磁场下样品的电阻-温度关系以及一定温度下磁电阻率与磁场的关系.发现随In³⁺替代量的增加其磁电阻峰和电阻峰均向低温方向移动，同时巨磁电阻效应减弱，磁电阻峰也展宽.这是由于In³⁺替代量的变化，引起 关键词：     

轻核中中子间的对相互作用和中子晕

选择Skyme势E作为两核子间唯象相互作用,在Hartree-Fock理论中结合粒子数守恒方法处理同类核子间的对相互作用,计算了Li和Be的丰中子同位素的结构,计算表明中子间的对相互作用和双中子晕之间存在紧密的联系.     

Giant Positive Magnetoresistance in Grain-Oriented CxCo1-x Alloys

The grain-oriented CxGo1-z (x = 0.9, 0.5) samples were fabricated by the hot.pressing method. The microstruc-ture was observed by an x-ray diffractometer and a scanning electron microscope. The resistance against the applied magnetic field was measured by a standard four-polnt probe method at different temperatures. The magnetoresistance and the magnetization ratio were studied as a function of magnetic field in the range of -1800 kA/m-1800 kA /m at different temperatures from 50 K to 300 K. The magnetoresistance of grain-oriented GxGo1-x is positive. The maximum positive MR of 98% at 50 K and 34% at 300 K was obtained under 1800 kA/m magnetic field in the C0.9Go0.1 sample.     

线性扫描伏安法研究美托拉腙与DNA的相互作用

在NaOH(pH 10.0)介质中,美托拉腙分别在-1.810 V和-2.075 V处具有2个还原峰,DNA的加入导致美托拉腙的2个还原峰峰电位正移,峰电流下降,表明美托拉腙与DNA之间发生了相互作用,形成了非电活性的化合物.考察了时间、温度、扫描速率、离子强度等条件对该相互作用的影响;结合DNA对美托拉腙紫外吸收光谱的影响,推断美托拉腙分子与DNA分子的相互作用是通过嵌插方式结合.在优化条件下,反应体系在-2.075 V处的还原峰电流I_(pa)与DNA的质量浓度在6 ～36 mg/L范围内呈较好的线性关系,相关系数为0.994 8,检出限为3 mg/L;通过对反应机制的研究,得到美托拉腙与DNA间的结合常数β为1.334×10~4 L/mol,结合数为2.