一种高质量的2 kb/s语言编码算法MWI

提出一种高质量的低速率语言编码算法ＭＷＩ,该算法对传统的波形插值算法ＷＩ进行了全面的改进。ＭＷＩ采用了一种更加合理的插值模型,包括统一的清音和浊音分析合成模型、新的典型波形的提取和表示方法,并且采用动态规划的算法增加基音周期估计的准确性。由于不依赖于准确的清浊音判别,ＭＷＩ具有更强的抗噪声能力。ＭＷＩ的参数设置也有利于更加有效的参数量化。随着编码速率的下降,ＭＷＩ的质量虽然呈下降的趋势,但在２ｋｂ／ｓ的速率下,它仍然能给出具有很高清晰度和自然度的合成语音。构造的完整的ＭＷＩ２ｋｂ／ｓ的声码器,具有很高的自然度和可懂度。     

Theoretical study of the ring‐closing reaction of 5′‐AMP to cAMP and H2O in the gas phase

The ring‐closing reaction of 5′‐adenosine monophosphate (5′‐AMP) to generate cyclic 3′, 5′‐adenosine monophosphate (cAMP) and H₂O was theoretically investigated at the B3LYP/6‐31G**level. It was found that the ring‐closing reaction of 5′‐AMP may proceed in a synchronous way or in a stepwise way. For the latter, the reaction is a multichannel elimination reaction including inner H transfer. The potential energy surface of Path 3 is lowest in all the ring‐closing reaction paths. In addition, H shuttling reaction with the participation of a water molecule to act as a shuttle were also studied at the same level. The calculations indicate that the participation of a water molecule facilitates hydrogen transfer reaction. Our present calculations rationalized all the possible reaction channels. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

超声波作用下的糖精相转移催化N—苄基化反应的研究

超声波作用下的糖精相转移催化Ｎ－苄基化反应的研究嵇学林刘华黄昆（江苏镇江医学院有机化学教研室镇江２１２００１）关键词超声波相转换催化糖精苄基化有机声化学近年来，由于超声波（Ｕｌｔｒａｓｏｕｎ，缩写Ｕ．Ｓ）在有机合成中应用的不断发展，逐渐形成了一门新兴...     

Direct Electrochemistry of Cytochrome C on the Glassy Carbon Electrode Modified with 1-Pyrenebutyric Acid/MWNTs

With 1-Pymnebutyric acid （PBA） and multiwalled carbon nanotubes （MWNTs）, glassy carbon electrode modified was successfully prepared. In phosphate buffer solution （pH 7,0）, the direct electrochemistry of cytochrome C （Cyt C） was realized. In the cyclic voltammetry experiment two pairs of redox peaks ofCyt C were observed at 0.018 V and -0.314 V （vs. SCE）, respectively. The redox reaction at 0.018 V was diffusion controlled, while the redox reaction at -0.314 V was adsorption controlled.     

Simultaneous determination of triterpene saponins in ginseng drugs by high-performance liquid chromatography

A HPLC method for the simultaneous determination of 11 triterpene saponins with four-type aglycones (protopanaxadiol, protopanaxatriol, ocotillol and oleanolic acid types) in Ginseng drugs was developed and validated. Using a gradient of acetonitrile and 10 mM K-phosphate buffer (pH 5.80) as the mobile phase and UV detection at 196 nm, more than 18 ginsenosides with different aglycones were separated satisfactorily within 60 min. The detection limits (signal/noise> or =3) were 0.1 microg for ginsenosides Rb1, Rc, Rd, Re and Rg1, chikusetsusaponin III, and notoginsenoside R2, 0.2 microg for gisenoside Ro and chikusetsusaponin IVa, 0.3 microg for chikusetsusaponin IV, and 3 microg for majonoside R2. The calibration curve of each saponin had a correlation coefficient close to 1. Intra- and interday precisions were less than 2.1% (n=5) and 3.3% (n=15), respectively. The recovery rates of extraction were in the range of 96.4-102.7% for all ginsenosides. By adopting this method, the determinations of 11 ginsenosides in three Ginseng drugs derived from Panax ginseng, Panax vietnamensis var. fuscidiscus and Panax japonicus (Japan) were achieved.     

Study of the Fluorescence System of Europium–Enoxacin and its Applications

 This paper is the study of the fluorescence enhancement of Eu³⁺-1-ethyl-6-fluoro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridin-3-carbonic acid (enoxacin, EFLX) system by surfactants. It was found that sodium dodecylbenzenesulfonate (SDBS) exhibits great enhancement on the fluorescence of the Eu-EFLX system. The molar ratio is 1:2:1 for Eu:EFLX: SDBS. Under the optimum conditions, the fluorescence intensity is a linear function of europium in the range of 1.0 × 10⁻⁸ ∼ 5.0 × 10⁻⁶ mol/L, the detection limit is 1.0 × 10⁻⁹ mol/L. The application of the Eu-EFLX-SDBS system for the determination of trace europium in rare earth samples gave satisfactory results. Received October 19, 2000. Revision August 10, 2001.     

Preparation of isoprostanes and neuroprostanes

A new approach to isoprostanes and neuroprostanes featuring cis-dialkyl stereochemistry at the cyclopentane ring has been developed by employing an intramolecular cross-coupling reaction of an alkyl iodide and a tethered alkenylsiloxane for stereoselective installation of a functionalized omega-side chain.     

Studies on the Binding Mode of Pinacyanol Chloride to Nucleic Acids

The interaction of pinacyanol chloride(PC) with nucleic acids has been investigated by a series of experiments.Extensive hypochromism,appreciable peak shifts,isosbestic points and new peaks of the product of binding to nucleic acids in the spectra were observed.They showed that the interaction between PC and nucleic acids occurred.The results from absorption spectra of DNA,DNA melting,electrophoresis and fluorescence polarization studies have indicated that PC binds to DNA in nonintercalative way.Consistent with the nonintercalation,the studies of fluorescence titration and absorption titration specified that the binding of PC to nucleic acids occurred by an outside stacking binding,in which nucleic acids served for acting templates,The fact that the new absorption peaks of bound PC at ca,485nm are just close to the absorption bands of Haggregate of PC at high concentrations without DNA further supports the outside stacking binding mode,In addition,other evidence indicated that the interaction between PC and nucleic acids is not purely electrostatic.     

分散聚合水基聚苯胺乳胶微球制备与表征

水溶性空间稳定剂聚乙烯吡咯烷酮（PVP）存在时，采用分散聚合制备水溶性单分散的聚苯胺(PAn)乳胶粒子，采用透射电子显微镜（TEM）观察粒子形态及尺寸；利用紫外-可见吸收光谱对胶体分散体系进行表征.实验结果表明，当PAn含量较少（w< 16.78％）时， PAn-PVP复合乳胶粒子呈米粒状；当PAn含量较大（w >23.22％）时， PAn-PVP复合乳胶粒子呈球形.