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101.
Qiongyou Wu Fanqi Qu Jinqiao Wan Xun Zhu Yi Xia Ling Peng 《Helvetica chimica acta》2004,87(4):811-819
Ribavirin, the only small molecule available so far for treating hepatitis‐C‐virus infection, was recently used in an emergency context to treat patients with severe acute respiratory syndrome (SARS) in the early stages of the disease. To study the mechanisms responsible for the antiviral effects of ribavirin by using a photolabeling approach, we designed, synthesized, and characterized the azidotriazole nucleosides 1 and 2 as photolabeling probes of ribavirin. These probes were synthesized either by performing nucleophilic substitution of the corresponding bromotriazole nucleoside with NaN3 (Scheme 2) or by directly coupling the azidotriazole with the protected ribose sugar (Scheme 4). The azidotriazole nucleosides 1 and 2 showed a fast, clear‐cut photochemical reaction, which suggests that they are promising candidates for use in photolabeling studies. 相似文献
102.
Detection of single molecules, particles, and rapid redox events is a challenge of electrochemical investigations and requires either an amplification strategy or significant averaging for the electrochemical current to exceed the noise level. We consider the minimum number of electrons required to reach the limit of quantification in these electrochemical measurements. A survey of the literature indicates that the state-of-the-art limit in current detection for different types of measurements (e.g. voltammetry, single-molecule redox cycling, ion channel recordings of single molecules, metal nanoparticle collision, and phase nucleation) is independent of the nature of the measurement and increases linearly with reciprocal response time, Δt?1, over ~5 orders of magnitude (from ~10 to ~106 s?1). We demonstrate that the practical limit of quantification requires cumulative measurement of ~2100 electrons during Δt and is determined by statistics of counting electrons, that is, the shot noise in the current. 相似文献
103.
Amorphous poly(ethylene terephthalate) was annealed at temperatures around the glass transition temperature and then heated up in differential scanning calorimeter at 20 °C min−1. It was found that the annealing favored the subsequent cold crystallization and this effect became stronger with increasing annealing temperature. The experimental results were explained by considering the structural change during the annealing. 相似文献
104.
J C Zhu C H Li Y Liu Z H Zhang A X Hou S S Qu 《Journal of Thermal Analysis and Calorimetry》2006,83(1):181-186
After the occurrence of 'Minamata disease' in 1950,
mercury aroused much more attention, and lots of studies concerned have been
made. The purpose of the present paper is to study the effect of mercuric
chloride on the mitochondria suspension isolated from the liver tissue of Cyprinus carpio from the direct viewpoint of energy
by using the microcalorimetric method. The metabolic thermogenic curves of
the mitochondria suspension at 25°C were obtained, and the mitochondria
metabolic thermokinetic equations were established, from which we obtained
the thermodynamic and thermokinetic parameters: thermogenic rate constant
(k), heat output (Q),
average heat power (Pav),
etc. Experimental results indicated that low concentration of mercuric chloride
(5 nmol Hg2+/(mg protein)) stimulates the thermogenesis
of mitochondria, suggesting a strong effect of uncoupling action, while high
concentration of mercuric chloride (20 nmol Hg2+/(mg
protein)) inhibits the metabolism of mitochondria completely, suggesting a
fatal effect on the phosphorylation system. The effect of Hg2+
on mitochondria is concentration-depended, from which the probable reaction
mechanism of Hg2+ to the mitochondria was proposed.
So the microcalorimetric method can be used in the toxicology research. 相似文献
105.
Li Ting Chai Yang Zhou Li Wei Wei Wang Quan Rui Wang Feng Gang Tao 《中国化学快报》2007,18(12):1460-1462
Nation-Teflon bimembrane was used as an efficient support for the preparation and application of heterogeneous palladium catalysts.The supported palladium catalysts exhibit high activity and stability in the Suzuki cross-coupling of aryl bromides with arylboronic acids to afford the corresponding biaryls in good to excellent yields,and can be readily recovered and reused several times without significant loss of activity. 相似文献
106.
Valerio Magnasco Massimo Ottonelli Giuseppe Figari Marina Rui Camilla Costa 《Journal of Molecular Structure》1998,430(1-3):231-239
The real spherical tensor theory of long-range intermolecular coefficients developed in previous papers is applied to derive explicit formulae for the first three dispersion coefficients for like centrosymmetric linear molecules. The expansion of angle-dependent coefficients in associated Legendre polynomials allows one to identify the isotropic and anisotropic components of the dispersion interaction in terms of London dispersion constants, the treatment of higher coefficients being simplified by the coupling of the elementary (l, l′)-polarizations to resultant angular momenta LA and LB onto each molecule. The contributions from all coupling schemes are given explicitly for C6, C8, C10, and numerical results are presented for H2-H2 using two-term reduced spectra values from the Kaiserlautern group. 相似文献
107.
The contribution of the Institute for Reference Materials and Measurements to the certification of the B, Cd, Cu, Mg, and Pb content of a synthetic water sample used in Comparison 12 of the International Measurement Evaluation Programme (IMEP-12) is described. The aim of the IMEP programme is to demonstrate objectively the degree of equivalence and quality of chemical measurements of individual laboratories on the international scene by comparing them with reference ranges traceable to the SI (Système International d'Unités). IMEP is organized in support of European Union policies and helps to improve the traceability of values produced by field chemical measurement laboratories. The analytical procedure used to establish the reference values for the B, Cd, Cu, Mg, and Pb content of the IMEP-12 sample is based on inductively coupled plasma-isotope-dilution mass spectrometry (ICP-IDMS) applied as a primary method of measurement. The measurements performed for the IMEP-12 study are described in detail. Focus is on the element boron, which is particularly difficult to analyze by ICP-MS because of potential problems of low sensitivity, high mass discrimination, memory effects, and abundance sensitivity. For each of the certified amount contents presented here a total uncertainty budget was calculated using the method of propagation of uncertainties according to ISO (International Organization for Standardization) and Eurachem guidelines. For all investigated elements with concentrations in the low micro g kg(-1) and mg kg(-1) range (corresponding to pmol kg(-1) to the high micro mol kg(-1) level), SI-traceable reference values with relative expanded uncertainties ( k=2) of less than 2 % were obtained. 相似文献
108.
109.
采用高温固相法合成出层状锂离子电池正极材料LiNi1/3Mn1/3Co1/3O2。通过XRD、ICP、SEM和电化学测试手段对产物的结构、组成、形貌及电化学性能进行了研究。XRD结果表明此方法合成的LiNi1/3Mn1/3Co1/3O2具有标准的α-NaFeO2型层状结构,SEM照片显示颗粒粒径大约在500 nm左右,粒径分布较窄。以20 mA·g-1电流密度放电,充放电电压在2.8~4.4 V之间,其首次放电比容量为170 mAh·g-1,40次循环容量保持率为85.3%。进一步加入石墨导电剂后,同样条件下首次放电比容量变为179 mAh·g-1,50次循环容量保持率为89.6%。容量衰减主要发生在前10次循环。XRD和SEM测试表明循环初期容量衰减的原因是由材料本体结构变化和界面反应共同作用的结果。 相似文献
110.
介绍用X-射线荧光光谱仪测定钛铁中Si、Mn、P、Al含量的方法,通过试验确定了合适的研磨时间、压力和保压时间,用压片法制样,建立了各元素的工作曲线,各元素的测定范围分别为Si3.00%~6.00%,Mn1.00%~3.00%,P0.030%~0.070%,Al5.00%~9.00%。通过强度测量得到测定Si、Mn、P、Al的相对标准偏差分别为0.074%、0.308%、0.383%、0.040%,精密度满足测试要求。将该方法测定结果与化学法比对,准确度满足国家标准方法分析误差的要求。 相似文献