A New Cytotoxic Acetogenin from the Seeds of Annona squamosa

A New Annonaceous acetogenin,squamostolide(1),was isolated from the seeds of Annona squamosa.Its structure was elucidated based on spectroscopic methods and comparison with known compounds.It is the first example of Annonaceous acetogenin with each of the two ends of the aliphatic chain bearing a γ-lactone.Thenew compound exhibited cytotoxic activity in vitro against bel-7402 and CNE2 human tumor cell lines.     

利用相干渡越辐射测量电子束团长度的分析与计算

利用相干渡越辐射(CTR)测量短和超短电子束团长度是国际上束测领域新发展的频域测量技术.文中理论分析和数值计算了北京自由电子激光装置的皮秒级的射频电子束团序列产生的CTR,当辐射波长在长于束长(4ps)时,渡越辐射发生相干增强效应;与非相干渡越辐射相比,当λ≥2πσz时,增强的倍数约等于束团中粒子的数目(10⁸);CTR从亚毫米波到毫米波段呈宽带连续谱特性;渡越辐射能量主要集中在轴线附近,宏脉冲辐射能量高达几毫焦.设计采用偏振型束团长度测量系统,利用CTR自相关技术,实验测量该束团序列的纵向长度,并藉助傅里叶变换光谱法,推求束团电子分布.     

Interface Optical Phonon Modes and Frohlich Electron-Phonon Interaction Hamiltonian in a Multi-shell Spherical Nanoheterosystem

Under dielectric continuum approximation, interface optical (IO) phonon modes and the Frohlich electron-IO phonon interaction Hamiltonian in a multi-shell spherical nanoheterosystem were derived and studied. Numericalcalculations on three-layer and four-layer CdS/HgS spherical nanoheterosystems have been performed. Results revealthat there are four IO phonon modes for the three-layer system and six IO phonon modes for the four-layer system.On each interface, there are two IO phonon modes, the frequency of one is between WTO,CdS and WLO,CdS, and that ofthe other is between WTO,HgS and WLO,HgS. With the increasing of quantum number l, the frequency of each IO modeapproaches one of the two frequency values of the single CdS/HgS heterostructure, and the potential for each IO modeis more and more localized at a certain interface, furthermore, the coupling between the electron-lO phonons becomes weaker.     

ICP-AES测定钛基复合材料中镍、钕和铁的研究

采用ICP－AES法对钛基复合材料中的合金元素镍、钕、铁的测定进行了研究，着重进行了基体元素及待测元素镍、钕、铁之间干扰试验及各元素在测定浓度范围内的线性相关性试验，进行了酸度试验，测定了钛基复合材料中3种元素的含量，得到了较好的精密度和准确度。方法简便、可靠，获得满意的分析结果。     

藻类植物中钙、镁、铁、锰、铜和锌含量分析

本文采用火焰原子吸收光谱法测定了七种藻类植物中钙 ,镁 ,铁 ,锰 ,铜 ,锌六种元素的含量。结果表明 ,藻类植物中含有较丰富的钙 ,镁 ,铁 ,锰 ,锌元素 ,其含量由大到小顺序为Ca >Mg >Fe >Zn >Mn >Cu ,尤以钙的含量最为丰富 ,铜含量较少。本实验结果为探讨藻类植物作为资源开发利用提供了有用数据。     

地下室混凝土墙板裂缝的产生与防治

文章阐述了地下室工程裂缝的产生原因及特征，从设计、施工等方面提出了预防及其控制措施，并通过工程实例予以说明．     

两种边界控制下的线性和半线性分布参数系统的能控性

根据系统分解的方法,讨论在2种边界控制下,通过对能控对域的研究来分析线性和半线性分布参数系统的能控性.     

绿色荧光粉YAGG∶Tb,Gd用于FED的尝试

FED器件的发展迫切需要具有化学和热稳定性 ,高亮度 ,长寿命的新型荧光材料。本文合成了Gd3 +离子共掺杂的YAGG∶Tb获得了YAGG∶Tb ,Gd ,并将其用于 0～ 30 0 0V低压范围 ,对其在不同电压和电流密度下的发光特性进行了测试。结果表明 ,该种材料特性优于ZnO∶Zn并且不存在电压与电流饱和     

Existence of solutions for the time-dependent thermistor equations

The equations describing the behaviour of temperature/flow microsensorsemploy-ing polysilicon thermistors form a degenerate nonlinearparabolic system. One special feature is that different equationsof this system are to be satisfied on different domains. Bymeans of supersolutions and subsolutions, the maximum principle,and fixed point arguments, the authors show the existence ofsolutions to the equations.     

β-环糊精对CTAB胶束催化羧酸酯水解的影响

在pH7.02，25℃下用分光光度法研究了β－环糊精对CTAB胶束催化PNPP，PNPA水解的影响。用胶束催化的相分离模型定量处理实验数据。通过对比结果可以看出，β－环糊精或β-环糊精与CTAB的复合物都不参与胶束的形成，也不影响胶束的聚集数。