苯胺蓝分光光度法测定痕量铬(Ⅵ)

在HCI介质中,铬(Ⅵ)与过量I-反应生成黄色 I-3,继而与水溶性苯胺蓝阳离子形成离子缔合物,使得苯胺蓝溶液褪色,其在605nm处产生一个强吸收峰.在最佳实验条件下,Cr(Ⅵ)的浓度在4.0×10-7-1.2×10-5mol/L范围内符合比耳定律.表观摩尔吸光系数ε为1.10×106L·Mol-1·cm-1.该法用于分析测定沱江水样中Cr(Ⅵ)的含量,结果令人满意.     

Single-Photon Detection at Telecom Wavelengths

A single-photon detector based on an InGaAs avalanche photodiode has been developed for use at telecom wavelengths. A suitable delay and sampling gate modulation circuit are used to prevent positive and negative transient pulses from influencing the detection of true photon induced avalanches. A monostable trigger circuit eliminates the influence of avalanche peak jitter, and a dead time modulation feedback control circuit decreases the afterpulsing. From performance tests we lind that at the optimum operation point, the quantum efficiency is 12% and the dark count rate 1.5 × 10^-6 ns^-1, with a detection rate of 500 kHz.     

Observation of Quantum Beat in Rb by Parametric Four-Wave Mixing

Two coupled paralnetric four-wave-mixing processes in Rb atoms are studied using perturbation theory, which reveals clear evidence of tile appearance of quantum beat at 608cm^-1, corresponding to the energy difference of the 7s - 5d states of Rb atoms, in the parametric four-wave-mixing signals. A pump-probe technique is utilized to observe the quantum beat. Tinle-varying characteristics of the quantum beat are investigated using time-dependellt Fourier transform. The results show that the time-varying characteistics of the quantum beat not oldy offers a sensitive detecting method for observing the decay of atomic wave packets, but also provides a potential tool for monitoriHg the dissociation of molecules.     

四川瓜蒌具钙拮抗作用化学成分的光谱研究(Ⅱ)

瓜蒌皮系葫芦科植物瓜蒌（Trichosanthese)的干燥成熟果皮，为常用中药，具清热涤痰、宽胸散结、润燥肠之功效，用于肺热咳嗽、胸痹心痛、乳痛肺痛、大便秘结等。瓜蒌皮重在清热化痰、利气宽胸。文献报道^[1]它还具有抗癌、抗细菌和真菌的作用。但瓜蒌皮在钙拮抗作用方法的研究未见报道，我们在这方面作了一些工作，对瓜蒌皮的分离物进行了成分的测试，对其结果进行了分析讨论。     

Poly(N‐vinylcarbazole) chemically modified graphene oxide

A new soluble donor‐acceptor type poly(N‐vinylcarbazole)‐covalently functionalized graphene oxide (GO‐PVK) has been synthesized by reaction of DDAT (S‐1‐dodecyl‐S′‐(α,α′‐dimethyl‐α″‐aceticacid)trithiocarbonate)‐PVK with GO‐toluene‐2,4‐diisocynate. The incorporation of sufficient amount of PVK chains makes the modified GO nanosheets readily dispersible in organic solvents. The resulting material exhibits an enhanced solubility of 10 mg/mL in organic solvents. Covalent grafting of PVK onto the edge and surface of GO nanosheets did not change the carbazole absorption in the ultraviolet region, but substantially reduced the absorption intensity of GO in the visible region. The intensity of the emission band of GO‐PVK at 437 nm was a little bit quenched when compared with that of DDAT‐PVK, suggesting intramolecular quenching from PVK to GO. Such intramolecular quenching process may involve energy or electron transfer between the excited singlet states of the PVK moiety and the GO moiety. The HOMO/LUMO values and the energy bandgap of GO‐PVK experimentally estimated by the onset of the redox potentials are ?5.60, ?3.58, and 2.02 eV, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2642–2649, 2010     

风险投资决策的模糊分析模型

从不确定性的一个侧面——模糊性的角度研究选择风险资产投资组合的问题，在对模糊预期收益率获取方法研究的基础上，将预期收益率表示为模糊数，对于一定的预期收益率，在每一确信度水平上，以偏离中心值的程度作为风险的度量，对于不允许卖空的情况建立优化决策模型，研究优化决策模型解的性质，并通过数值例子分析了收益一风险之间的关系。得到了风险一收益率曲线。根据这一曲线，投资者可以结合自己的偏好、直观地选择自己的投资方向。     

模糊权数与方案排序

讨论了由Fuzzy权数导出方案排序中的问题，提出了评价Fuzzy权数取值大小及取值集中程度的两个指标，并据此给出了由Fuzzy权数导出方案排序的方法。     

关于有限阿贝尔群单因子个数的均值(Ⅱ)

令ｔ（Ｇ）为有限阿贝尔群Ｇ的单因子个数．本文得到了∑｜Ｇ｜≤ｘｔ（Ｇ）带有更好余项的渐近公式．     

火焰原子吸收光谱仪与流动注射分析仪的联用

1975年丹麦的Ruzicka和Hanson.E[1]首次提出流动注射分析(FIA)的概念,指出化学分析可以在非平衡的动态条件下进行,而且适应性广泛,分析效率高,试样和试剂消耗量少,检测精度高,设备简单.30多年来,流动注射分析得到了迅速发展,已