Yb3+离子在氟化物玻璃中的红外光谱性质

根据测得的Ｙｂ＾３＋离子在氟锆酸盐玻璃（ＺＢＬＡＮ）中的吸收光谱和荧光光谱,分析了Ｙｂ＾３＋离子在氟锆酸盐玻璃中的吸收特性和发光特性;计算了Ｙｂ＾３＋离子的发射截面σｅ,讨论了Ｙｂ＾３＋离子的再吸收效应;增加Ｙｂ＾３＋离子掺杂浓度不会发生浓度淬灭效应。     

5-O-三苯硅基-4＂-O-酰基阿维菌素B1a的合成和生物活性

酯化;5-O-三苯硅基-4＂-O-酰基阿维菌素B1a的合成和生物活性     

Stability and bifurcation of unbalance rotor/labyrinth seal system

The influence of labyrinth seal on the stability of unbalanced rotor system was presented . Under the periodic excitation of rotor unbalance , the whirling vibration of rotor is synchronous if the rotation speed is below stability threshold, whereas the vibration becomes severe and asynchronous which is defined as unstable if the rotation speed exceeds threshold . The. Muszynska model of seal force and shooting method were used to investigate synchronous solution of the dynamic equation of rotor system. Then , based on Floquet theory the stability of synchronous solution and unstable dynamic characteristic of system were analyzed.     

Fabrication and electrical properties of a carbon nanotube quantum dot

Single-walled carbon nanotubes (SWNTs) were synthesized by pyrolyzing methane (CH₄) at a temperature of 900℃ on SiO₂ substrates pre-coated with iron nano-particles. Electrical contacts were fabricated onto one of the SWNTs by using an electron beam lithography process. Coulomb blockade and single-electron tunnelling characters were found at low temperatures, indicating that the SWNT in-between the electrodes forms a quantum dot. It is found that the Coulomb gap of the quantum dot is about 8.57 meV, and the factor \alpha , which converts the gate voltage to the true electrostatic potential shift, is around 200 for this device.     

色味连锁物质的稳定态及其相变

简要介绍和评述了色味连锁物质的稳定态及其相变,指出高密强相互作用物质由于夸克配对出现了一些奇异相。重点介绍色味连锁（CFL）物质及其中的Goldstone-mode凝聚现象。在考虑奇异数对应化学势μs≠0的情况下,CFL物质中K^0和K^-0都可能发生凝聚。随着重子数密度的增高,强作用物质呈现出丰富相结构,在核物质相与CFL相之间可能存在其它相,但最简单的可能相变过程是直接从核物质相变为CFL物质。这种相变可有两种过程,即两相间仅存在一个极小界面或出现两相混合区域。另外还重点讨论了K^-介子凝聚对相变的影响。Quark matter at high density has a rich phase structure. Goidstone-mode may condense in the color-flavor-locked （CFL） phase matter. We review the stability of CFL phase and its phase transition, as well as the effect of nonzero strangeness chemical potential on the CFL phase of dense quark matter. It is pointed out that, depending on the value of μs, both K^0 and K^-0 may condense in the CFL matter. As a function of quark chemical potential, other phases may intervene between the nuclear-matter and CFL phase. The simplest possibility, however, is a transition between nuclear and CFL matter. Such a transition could occur either at a single sharp interface or through a mixed phase region. The effect of discontinuous K^- meson condensation on the phase transition is also discussed. [     

月光花素甲中DC-2b的NMR与结构研究

该文研究了从月光花叶中提取,并用高压液相色谱收集制备,命名为DC-2b化合物的一维及二维NMR谱.通过对它的一维,¹H-NMR,¹³C-NMR宽带去偶,DEPT及选择性INEPT和二维¹H-¹H COSY,NOESY及¹³C-¹H COSY等谱图的综合分析研究,确证了它的结构.     

中国乌头之研究——Ⅵ.雪上一枝蒿的生物碱(2)

从云南省昭通县产的雪上一枝蒿中共分得生物碱五种,其中三种为已知物,即烏头碱、次岛头碱和一枝蒿乙素,另二种为新生物碱,暂名为一枝蒿戊素和己素。一枝蒿戊素的分子式为C₂₄H₃₉O₆N,其示性式为C₁₉H₂₂(OH)₃(OCH₃)3-(N·C₂H₅);一枝蒿己素的分子式为C₂₄H₃₉O₇N,其示性式为C₁₉H₂₁(OH)₄(OCH₃)₃(N·C₂H₅);另从云南省东川县出产的雪上一枝蒿中,尚分得一新生物碱,暂称为一枝蒿庚素,分子式为C₂₁H₃₁O₃N,其示性式为C₁₉H₂₄(:O)(OH)₂(N·C₂H₅)。     

电感耦合等离子发射光谱法测定植株中的硼

1引言 硼是植物必需的微量元素之一。测定植物中硼的方法有甲亚胺比色法、姜黄素比色法、等离子发射光谱法、原子吸收分光光度法等。由于硼的原子化温度较高,原子吸收分光光度法测硼已很少用。姜黄素比色法灵敏度高,但由于显色条件要求严格。不易操作。目前应用最广泛的是甲亚胺比色法和等离子发射光谱法。后者不仅快速、方便、准确,而且其待测液可同时测定磷、钾、硫、铜、锌、铁、锰等植物必需元素的含量,能在实际应用中发挥着更加重要的作用。本实验借鉴石墨炉原子吸收基体改进剂的原理,在样品干灰化中加入适量的Mg（NO3）2或者CaCl2溶液,可使灰化温度从500℃提高到700℃而硼不挥发损失,用ICP-AES测定硼干扰少,检出限为0．0045mg／L,可满足植物测硼的需要。     

应力引起的镍钛单晶形状记忆合金相变的实验研究

在单晶形状记忆合金试样中,由于没有晶粒之间的约束,它的马氏体相界面移动比多晶容易,用实验方法研究其相变的特点,对建立新的理论模型有意义,因而对它的实验分析显得重要。本文利用高分辨率的CCD系统监测到NiTi单晶形状记忆合金在拉伸时的相变伪弹性的过程;利用X射线衍射法得到了NiTi单晶试样在拉伸方向的晶向;运用高分辨率的云纹干涉技术,获得了应力引起的NiTi单晶形状记忆合金相变时的变形场;利用高分辨率、高灵敏度的红外相机记录了NiTi单晶在拉伸状态下的温度变化规律;对低温下NiTi单晶的拉伸性能做了初步的研究,得到一些有意义的现象。     

偏振态移位键控光混沌通信系统的保密性

为了评判偏振态移位键控(PolSK)光混沌通信系统的保密性强弱,先要验证它的混沌特性,因此对该系统的信号进行了分析。利用三种方法判定该信号是否具有混沌特性:在三维相空间观察奇异吸引子;分别从最大李氏(Lyapunov)指数满足的方程出发以及wolf法计算其最大李氏指数;并计算其自功率谱密度函数。结果明显观察到奇异吸引子,算得最大李氏指数分别为0.0364和0.0106,都大于零,自功率谱为噪声背景、宽峰的连续谱;从而判定该系统传输的信号确实是混沌信号。另一方面,用最小伪邻点算法计算该系统信号的嵌入维数,结果达到6维,说明该系统具有中高维度混沌特性;结合系统的抗攻击性分析,得出结论:相比于一般的混沌掩盖方案,该系统具有较强的保密性和安全性。