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41.
42.
分别在Hartree-Fock和密度泛函B3LYP理论下,用6-31G*基组研究了C60和C70分子的静电势,比较了这方法计算得到上述分子静电势值的大小,静电势图形和静电势差值曲线,分析了富勒烯的电子相关效应. 相似文献
43.
Carol A. Loeschorn Charles J. Kelley Robert N. Hanson Michael A. Davis 《Tetrahedron letters》1984,25(32):3387-3390
The addition of methyl Grignard to diethyl acetamido(cyanoselenobenzyl)malonates 3 and 4 at ?78° followed by hydrolysis yields the 3-(4-and 3-methylselenophenyl)alanines 1 and 2. 相似文献
44.
Amr Nour Al-Deen Douglas J. Cecchini Roger W. Giese 《Journal of chromatography. A》1992,600(2):229-233
A method has been developed in which the DNA of leukocytes (as the buffy coat from blood) is isolated in the form of its constituent deoxynucleotides. The steps in this method are as follows: (1) lyse the leukocytes with sodium dodecyl sulfate (SDS) and enzymatically digest the proteins and RNA, (2) remove the SDS on a non-polar adsorbent (Bio-Beads SM-4) and then trap the DNA on a quaternary amine silica cartridge, (3) wash the column with 1 M NaCl-buffer, (4) digest the DNA on the column with staphylococcal nuclease and (5) elute the digested DNA with 0.5 M NaCl-buffer and digest it further with bovine spleen phosphodiesterase II to deoxynucleotide-3′-monophosphates. From a 40-μl sample of butty coat was obtained 126 ± 14 μg (two experiments, eight sample total) of deoxynucleotides. Reversed-phase high-performance liquid chromatography, which removed the added enzymes, showed only peaks for deoxynucleotides. For comparison, the amount of deoxynucleotides obtained from the leukocytes by an automated phenol extraction procedure was 101 ± 5.4 μg (one experiment in triplicate). 相似文献
45.
利用商品化ITO玻璃导电层的温阻效应, 无需任何微加工手段, 实现了自加热和传感的芯片温度自动程序控制, 最大程度地减小了传感滞后对温度控制稳定性的影响, 温度控制的稳定性达到了0.2 ℃, 升温速度最快可达20 ℃/s以上, 在冷却风扇辅助下降温速度最快达到了8 ℃/s. 芯片温控单元的引线从传统的两对(一对用于传感, 一对用于加热)减少为一对. 通过在该芯片上直接构建多个开放微池反应器的方法成功地实现了λDNA 157 bp片段的并行扩增. 将该芯片置于倒置荧光显微镜样品台上, 以蓝色(575 nm)发光二极管为光源, 以光电倍增管为检测手段检测了dsDNA和SYBR Green Ⅰ嵌合物的荧光强度随温度的实时变化曲线. 相似文献
46.
Anderson PE Badlani RN Mayer J Mabrouk PA 《Journal of the American Chemical Society》2002,124(35):10284-10285
This contribution reports the first synthesis of conducting polymers (CPs), specifically, polyaniline (PAn) and polypyrrole (PPy), in supercritical carbon dioxide (scCO2). CPs synthesized electrochemically in scCO2 were characterized with cyclic voltammetry (CV), four-point probe conductivity, scanning electron microscopy (SEM), and UV-vis spectroscopy. Preliminary data indicate that CPs synthesized by this method exhibit novel morphology and high conductivity comparable to that synthesized by traditional methods. 相似文献
47.
Magnetic NiFe particles were synthesized through hydrothermal method using hydrazine as reductant. Composite particles with core-shell structure were further achieved by depositing silicon dioxide generated via carbonation decomposition of sodium silicate solution on the surface of magnetic cores. Characterized by XRD, the Ni9Fe particles are of fcc-type structure, and the structure of magnetic cores in composite particles was maintained despite being covered by SiO2 shell. The existence of SiO2 shells in the composite particles were demonstrated by SEM, EDS and IR. The results from TG and VSM indicated that the shell structure affected the physiochemical properties. The composite particles exhibited remarkable resistance to oxidation in comparison with Ni9Fe particles due to being protected by SiO2 shell. Meanwhile, both of them are soft magnetic materials, but Ms, Mr and Hc in Ni9[email protected]2 particle decreased compared with magnetic NiFe particles. The formation mechanisms of Ni9Fe micro-particles and composite Ni9Fe particles were discussed. 相似文献
48.
Millea KM Kass IJ Cohen SA Krull IS Gebler JC Berger SJ 《Journal of chromatography. A》2005,1079(1-2):287-298
The performance characteristics of multidimensional liquid chromatographic protein separations were evaluated using on-line electrospray mass detection, and a novel workflow for automated LC/MS data processing. Two-dimensional ion exchange/reversed-phase LC separations of Escherichia coli cytosol were conducted using either a continuous linear or discontinuous step gradient in the first dimension. Chromatographic profiles of the top 100 most abundant components were characterized to assess overall separation reproducibility within each mode, and to characterize differences in component distribution between the two modes of operation. Analysis of the resulting data indicates that multidimensional separations of complex protein mixtures can be done reproducibly. Furthermore, under the conditions employed within this study, a linear first dimension gradient was more effective at fractionating the protein mixture, distributing fewer major components to multiple second dimension cycles than an equivalent step gradient. The application of on line mass spectrometry, and automated processing of the resulting data, proved valuable for producing component level analysis of multidimensional protein separations. 相似文献
49.
A DETAILED investigation of the temperature dependence of the fluorescence quantum yield φf can yield–directly or indirectly–significant information about behavior of excited states of organic molecules, such as the temperature effect on radiationless transitions and on photochemical reactivity. Variation of the temperature changes the viscosity of the solvent and, in conjunction with measurements of φf ( T ), allows investigations of diffusion-controlled processes. For example, energy transfer and quenching processes as well as excimer or exciplex formation fall into this category. Recent review articles by Weller (1962) and Birks (1970) deal with this topic. Moreover, Huber and Mantulin (1972) have suggested that restraints placed upon geometric modifications of the excited molecule by temperature-induced changes in the solvent cage (variation of site structure) are reflected in a varying φf .
The purpose of this note is to describe and verify a simple procedure, accurate to about ± 5%, for measuring the relative fluorescence quantum yield as a function of temperature. A quantum yield study of 9,10-diphenylanthracene between room temperature and 77°K is employed to demonstrate the capabilities of this method. In addition, we consider an example of diffusion-controlled quenching by oxygen measured over a wide temperature range. 相似文献
The purpose of this note is to describe and verify a simple procedure, accurate to about ± 5%, for measuring the relative fluorescence quantum yield as a function of temperature. A quantum yield study of 9,10-diphenylanthracene between room temperature and 77°K is employed to demonstrate the capabilities of this method. In addition, we consider an example of diffusion-controlled quenching by oxygen measured over a wide temperature range. 相似文献
50.