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471.
A micro-sampling technique, which requires sample volumes of less than 100 μl, is used for multi-element analysis by i.c.p. emission spectrometry. One drop of sample solution in a teflon cup is nebulized through a capillary tube. Internal standardization with yttrium improves the precision of measurement. The method is applied to the analysis of serum and whole blood samples, after dilution or digestion. 相似文献
472.
Vertex operators (primary fields) are constructed for the conformal field theory on P
1 by means of A
1
(1) modules. The commutation relations of vertex operators induce monodromy representations of the braid group on the spaces of vacuum expectations of compositions of vertex operators. 相似文献
473.
Yukihiro Ishii 《Optics and Lasers in Engineering》1991,14(4-5):293-309
Laser-diode (LD) interferometry based on heterodyne techniques is described. The developments covered include: sinusoidal phase- modulating, distance-measuring feedback and phase-shifting interferometry. The wavelength is controlled by the laser injection current and is continuously or stepwise changed to introduce a time-varying phase difference between the two beams of an interferometer with unbalanced optical path lengths. A feedback interferometer is described with electronics to stabilize the phase shift and to lock the interferometer on a preset phase condition by controlling the injection current of the LD. An automated phase-measuring interferometric system is developed in which the laser current is changed to synchronize intensity data acquisition with the clocks of a charge-coupled device. A typical experimental result shows measurements of the profile of a diamond- turned Al surface. 相似文献
474.
We have investigated detection of the anion radical and the divalent anion of tetracyanoquinodimethane (TCNQ) by acetonitrile-CE under anaerobic conditions. With electrolysis at a potential of 0.0 V (vs. Ag/AgCl), an acetonitrile solution of TCNQ turned green, characteristic of the TCNQ anion radical (TCNQ-). Only one peak of the anionic compound was observed in CE of the electrolysis solution and it should be that of TCNQ-. Then, the electrolysis potential was shifted to -0.8 V expected to be sufficient potential for the further reduction of TCNQ-, and the solution turned almost colourless. In CE analysis of the latter solution, another anionic component possessing a larger electrophoretic mobility than that of TCNQ- was detected, and it was decomposed immediately under aerobic conditions. This product was strongly suggested to be the divalent anion of TCNQ, and the present method would contribute notably to detection of the unstable species. 相似文献
475.
Novel reference molecules for quantitation of genetically modified maize and soybean 总被引:22,自引:0,他引:22
Kuribara H Shindo Y Matsuoka T Takubo K Futo S Aoki N Hirao T Akiyama H Goda Y Toyoda M Hino A 《Journal of AOAC International》2002,85(5):1077-1089
New quantitation methods based on a real-time polymerase chain reaction (PCR) technique were developed for 5 lines of genetically modified (GM) maize, including MON810, Event176, Bt11, T25, and GA21, and a GM soy, Roundup Ready. Oligonucleotide DNA, including specific primers and fluorescent dye-labeled probes, were designed for PCRs. Two plasmids were constructed as reference molecules (RMs) for the detection of GM maize and GM soy. The molecules contain the DNA sequences of a specific region found in each GM line, universal sequences used in various GM lines, such as cauliflower mosaic virus 35S promoter and nopaline synthase terminator, and the endogenous DNA sequences of maize or soy. By using these plasmids, no GM maize and GM soy were required as reference materials for the qualitative and quantitative PCR technique. Test samples containing 0, 0.10, 0.50, 1.0, 5.0, and 10% GM maize or GM soy were quantitated. At the 5.0% level, the bias (mean-true value) ranged from 2.8 to 19.4% and the relative standard deviation was <5.2%. These results show that our method involving the use of these plasmids as RMs is reliable and practical for quantitation of GM maize and GM soy. 相似文献
476.
Mitsuji Yamashita Valluru Krishna ReddyPutta Mallikarjuna Reddy Yukihiro KatoBuchammagari Haritha Kazumitsu SuzukiMasaki Takahashi Tatsuo Oshikawa 《Tetrahedron letters》2003,44(17):3455-3458
An efficient method is described in the synthesis of several novel deoxy phospha sugar pyrimidine nucleosides in racemic form, analogs of normal sugar nucleosides, in high yields by treatment of (±)-2-aminophospholane 1-oxide with several, α-cyano-, -acetyl-, -ethoxycarbonyl-β-ethoxy-N-ethoxycarbonylacrylamides. 相似文献
477.
Two new steroidal saponins were isolated from the Chinese folk medicine called Gualou-xiebai-baijiu-tang. The structures were determined to be spirost 25(27)-ene-2beta,3beta-diol-3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranoside and 26-O-beta-D-glucopyranosyl-22alpha-hydroxy-5beta-furost-25(27)-ene-1beta,3beta,6beta,26-tetraol-3-O-beta-D-galactopyranoside, respectively, based on chemical evidences and spectral analysis. 相似文献
478.
A novel immunoanalyser system based on the human olfactory function has been developed and successfully applied to immunoassay for Candida albicans. After the immunoreaction of C. albicans and its antibody (IgG), the reaction solution was added gently to a phosphate buffer solution in a conical reaction vessel. The buffer in this vessel was previously saturated with Versalide (1,1,4,4-tetramethyl-6-ethyl-7-acetyl-l,2,3,4-tetrahydronaphthalene) as an odour marker and its odour was sensed by the nose of a tester immediately above the vessel. The addition of a sufficient amount of the reaction solution caused the disappearance of the odour. As the buffer level was raised and the surface area increased, the odour appeared again. A relationship was obtained between the change in buffer level until the odour reappeared and the concentration of C. albicans in the reaction solution. Based on this principle, C. albicans could be determined in the range 102– 105 cells ml?1. 相似文献
479.
A facile method for the synthesis of thiophene derivatives via the reaction of readily accessible dienol silyl ethers with elemental sulfur is described. Dienol silyl ethers and elemental sulfur, when heated at 180 °C in the presence of MS4A, provided 3-siloxythiophene derivatives in yields up to 98%. In this reaction, thiophene derivatives might be formed through 1,2-dithiines and eight-membered cyclic tetrasulfides. 相似文献
480.
The design of cone-fixed calix[4]arene analogs by takingsyn-[2.n]metacyclophanes as a building block
Yukihiro Okada Jun Nishimura 《Journal of inclusion phenomena and macrocyclic chemistry》1994,19(1-4):41-53
Rigidified calix[4]arene analogs were synthesized fromsyn-[2.n]metacyclophanes as a building block. Their structure was firmly locked in the cone conformation. An enlarged calix[4]arene analog was obtained after the cyclobutane ring cleavage of the parent analog by Birch reduction. Several ionophores have been derived from the analogs and been found to select the larger ions during the extraction of alkali metals, transition metals, and lanthanoids. The ionophore having oligoethylene glycol units showed an effective catalytic activity for SN2 reactions such as ester synthesis, Williamson ether synthesis, and Finkelstein reaction in several media.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes. 相似文献