大叶香茶菜辛素的晶体结构和分子结构

程培元和许美娟等人,从抗癌中草药大叶香茶菜(Rabdosia Macrophylla)中分离得一种新的、饱和的贝壳杉型二萜类化合物:C_(24)H_(36)O_9,定名为大叶香茶菜辛素(Rabdophyllin-A,以下简称为大叶辛素)。从化学和光谱学数据可得出如下的结构式。     

蒙古药阿木日－6中金属元素的原子光谱分析

测定了常用蒙古药阿木日－６中金属元素的含量，为将来进一步探讨该药中金属元素，特别是微量元素与其药效的关系以及准确检验此种药物提供了实验数据．     

双室型沸点升高仪

任何非挥发性溶质溶于溶剂后,都能使溶剂的蒸气压下降,因此溶液的沸点必然高于纯溶剂。如果溶液浓度很小,同时又无电离或缔合现象发生,则溶液的沸点升高与浓度成正比。应用理想溶液定律,可以推导出: △T_b=1000×K_b/M_2×W_2/W_1 (1)式中△T_b为沸点升高值,W_1为溶剂的克数,W_2为溶质的克数,M_2为溶质的分子量,K_b为溶剂的沸点升高常数,是一个决定于溶剂而与溶质无关的数值。为此,如能测出溶液的沸点升高,即可求出溶质的分子量。这个方法原理十分简单,是物理化学中测定分子量的经典方法之一。但是,由于实验精确度的限制,直到五十年代初,还只限于用来测量分子量约为几千的     

Eu-Y-Ba-Cu-O系超导体的穆斯堡尔效应研究

本实验利用X射线衍射及穆斯堡尔效应分别研究了高T_c超导材料(Eu_zY_(1-z))_(0.3)Ba_(0.7)·CuO_(3-δ)(X=0.5、0.7、1.0)的结构和超精细相互作用。实验表明,该物质为单相正交结构,铕离子在晶格中处于三价态,周围为一种配位情况,~(151)Eu核处存在不对称电场。铕含最增加时,则晶胞体积增大,同质异能移位减小。在零电阻温度下,~(151)Eu核处的电子密度减小,电场不对称性增大。     

具有生物活性的有机锗化合物的研究新进展

综述了近年来发现的具有各种生物活性的六类有机锗化合物的合成及生物活性，即倍半锗和介吗川类有机化合物，锗氧杂、锗氮杂及锗硫杂环酮类化合物，呋喃、噻唑、咪唑、嘧啶取代锗烷及其类似物，烷锗醇、烷锗醚和烷锗酮类化合物，卟啉锗类化合物，其它具有生物活性的有机锗化合物这六类有机锗化合物，并对该领域的研究前景作了展望。     

LED背光显示器对不同年龄人视网膜照度、节律效应和蓝光危害的影响

研究了视网膜照度、节律效应和蓝光危害随年龄的变化规律.采用光谱仪测量了4款常见发光二极管背光显示器显示白色和蓝色时的归一化光谱分布,然后结合不同年龄人眼的晶状体透射谱,计算了视网膜照度因子、节律因子和蓝光危害能效因子,得到三者与年龄的变化规律.研究表明:对于同一发光二极管背光显示器,视网膜照度因子、节律因子和蓝光危害能效因子均随年龄的增加而显著减小;同一人眼的视网膜照度因子随显示器类型的变化较小;对于年轻人,不同类型显示器的蓝光危害能效因子和节律因子差异明显,特别是显示蓝色时,但是,对于老年人,不同类型显示器的蓝光危害能效因子和节律因子差异较小.     

Crystal growth and spectral properties of Tb:Lu_2O_3

The crystal growth,x-ray diffraction pattern,absorption spectrum,emission spectrum,and fluorescence lifetime of a Tb:Lu_2O_3 single crystal were studied.Excited at 483 nm,the peak absorption cross-section was calculated to be 3.5×10~(-22)cm~2,and the full width at half maximum was found to be 2.85 nm.The Judd-Ofelt(J-O)intensity parameters ?_2,?_4,and ?_6 were computed to be 3.79×10~(-20)cm~2,1.30×10~(-20)cm~2,and 1.08×10~(-20)cm~2,with a spectroscopic quality factor ?_4/?_6 being 1.20.The emission cross-sections of green emission around 543 nm and yellow emission around 584 nm were calculated to be 9.43×10~(-22)cm~2 and 1.32×10~(-22)cm~2,respectively.The fluorescence lifetimeτexp of ~5D_4 was fitted to be 1.13 ms.The data suggest that the Tb:Lu_2O_3 crystal could be a potential candidate for green and yellow laser operation.     

Dynamical Evolution of an Effective Two-Level System with PT Symmetry

We investigate the dynamics of parity-and time-reversal(PT) symmetric two-energy-level atoms in the presence of two optical and one radio-frequency fields. The strength and relative phase of fields can drive the system from the unbroken to the broken PT symmetric regions. Compared with the Hermitian model, Rabi-type oscillation is still observed, and the oscillation characteristics are also adjusted by the strength and relative phase in the region of the unbroken symmetry. At the exception point, the oscillation breaks down. To better understand the underlying properties we study the effective Bloch dynamics and find that the emergence of the PT components of the fixed points is the feature of the PT symmetry breaking and the projections in the x–y plane can be controlled with high flexibility compared with the standard two-level system with the PT symmetry. It helps to study the dynamic behavior of the complex PT symmetric model.