激光与近视眼治疗

 近视眼给亿万患者带来了极大的痛苦.配戴眼镜不仅不能从根本上治疗近视,而且还会给患者的生活带来许多不便.因此,寻找更好、更有效的治疗方法是眼科医生和科学家们的共同心愿.     

手性schiff碱金属配合物N,N′-双水杨醛缩-1,2-环己二胺合镍(Ⅱ)的光谱研究

利用红外、拉曼光谱研究一种手性schiff碱金属配合物N,N′双水杨醛缩1,2环己二胺合镍(Ⅱ)的结构特点。表明(R,R)—SALEN—Ni(Ⅱ)和(S,S)SALEN-Ni(Ⅱ)的光谱完全相同,而与外消旋体的光谱有很大差别     

固相萃取-高效液相色谱法测定浓缩苹果汁中的多菌灵残留量

报道了固相萃取-高效液相色谱法测定浓缩苹果汁中多菌灵残留量的方法.样品经适量水稀释后,C18固相萃取柱提取净化,用V(甲醇)∶V(二氯甲烷)=1∶1淋洗,HPLC法测定.在添加水平为0.10,0.50,2.0 mg/kg时,多菌灵的回收率在92.6%～108.3%之间;RSD＜3% (n=6),检出限为0.02 mg/kg,该方法的测定结果满足农药残留量的检测要求.     

氧化铝柱上的Beckmann重排反应——一个新的异(口恶)唑啉环合副产物

在氧化铝柱上进行Beckmann重排反应,经Craig等证明是一个反应温和,得率高的反应。我们在研究吗啡受体激动剂和拮抗剂的工作中,用7α乙酰基6.14乙烯撑-四氢蒂巴因肟的对甲苯磺酸酯(la)和它的N-烯丙基类似物1b,在氧化铝柱上成功地进行了Beckmann重排反应,合成了相应的7α-乙酰胺基衍生物2a得率65%,和2b得率55%。同时,在苯-氯仿洗脱液中还得到一个极性较小的化合物3a得率7.7%,和3b得     

Grain size and its distribution in NiTi thin films sputter-deposited on heated substrates

Grain size and its distribution in NiTi thin films sputter-deposited on a heated substrate have been investigated using the small angle x-ray scattering technique. The crystalline particles have a small size and are distributed over a small range of sizes for the films grown at substrate temperatures 370 and 420℃. The results show that the sizes of crystalline particles are about the same. From the x-ray diffraction profiles, the sizes of crystalline particles obtained were 2.40nm and 2.81nm at substrate temperatures of 350 and 420℃, respectively. The morphology of NiTi thin films deposited at different substrate temperatures has been studied by atomic force microscopy. The root mean square roughness calculated for the film deposited at ambient temperature and 420℃ are 1.42 and 2.75nm, respectively.     

水性黏结剂海藻酸钠和果胶酸钠对锂离子电池石墨负极电化学性能的影响

利用循环伏安和恒电流充放电测试,结合扫描电镜观测,研究了水性黏结剂海藻酸钠和果胶酸钠对石墨负极电化学性能的影响.结果表明,石墨负极在这两种黏结剂中均可以进行有效的嵌锂脱锂循环,且电化学循环性能较好,50次循环后可逆比容量损失不超过5%.两种水性黏结剂在改善石墨电极的嵌脱锂循环性能方面具有较好的发展前景.     

芳酰腙铜(Ⅱ)和锌(Ⅱ)配合物的合成、晶体结构及抗菌活性

合成了一对结构类似的双核铜和锌配合物,Cu₂(L¹)₂ (1)和[Zn₂(L²)₂(CH₃OH)₂] (2),其中L¹和L²分别是2-溴-N'-(2-羟基-5-甲基苯亚甲基)苯甲酰肼(H₂L¹)和2-氯-N'-(2-羟基-5-甲基苯亚甲基)苯甲酰肼(H₂L²)的二价阴离子,通过元素分析、红外光谱以及单晶X射线衍射表征了它们的结构.配合物1以三斜晶系P1空间群结晶,其晶体学参数:a=0.914 11(6) nm,b=1.180 04(7) nm,c=1.359 36(9) nm,α=101.928(2)°,β=91.399(2)°,γ=107.873(2)°,V=1.359 3(2) nm3,Z=2,R₁=0.054 0,wR₂=0.118 9,GOF=0.970.配合 物2以单斜晶系P21/c空间群结晶,其晶体学参数:a=1.216 97(9) nm,b=1.214 96(9) nm,c=1.212 83(9) nm,β=110.939(1)°,V=1.674 8(2) nm3,Z=2,R₁=0.034 1,wR₂=0.068 9,GOF=1.024.X射线分析表明2个化合物都是中心对称的双核配合物,其中配合物1中的Cu原子是平面正方形配位构型,配合物2中的Zn原子是四方锥配位构型.还通过MTT法研究了这两个配合物的抗细菌(大肠杆菌,金黄色葡萄球菌,枯草芽孢杆菌和铜绿色假单胞菌)和抗真菌(白假丝酵母菌和黑曲霉菌)活性.     

93Nb(n,2n)92mNb反应截面测量

用活化法以^27Al(n,α)^24Na反应截面为中子注量标准，对14MeV能区中子引起的^93Nb(n,2n)^92mNb反应截面进行了测量。中子能量由硅探测器法测定。     

窄禁带稀磁半导体二维电子气的拍频振荡

通过对调制掺杂的n型Hg_0.82Cd_0.16Mn_0.02Te/Hg_0.3Cd_0.7Te第一类量子阱中磁性二维电子气磁阻拍频振荡的研究，发现温度、栅压的变化都会引起磁阻拍频节点位置的变化.从对拍频的分析中，可以将依赖于栅压的Rashba自旋-轨道分裂和依赖于温度的巨大塞曼分裂区分开来. 关键词： 磁性二维电子气 自旋分裂 sp-d交换相互作用 拍频     

Dynamic properties of epidemic spreading on finite size complex networks

The Internet presents a complex topological structure, on which computer viruses can easily spread. By using theoretical analysis and computer simulation methods, the dynamic process of disease spreading on finite size networks with complex topological structure is investigated. On the finite size networks, the spreading process of SIS （susceptibleinfected-susceptible） model is a finite Markov chain with an absorbing state. Two parameters, the survival probability and the conditional infecting probability, are introduced to describe the dynamic properties of disease spreading on finite size networks. Our results can help understanding computer virus epidemics and other spreading phenomena on communication and social networks. Also, knowledge about the dynamic character of virus spreading is helpful for adopting immunity policy.