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181.
Qing Dai Chun-Yan Xu Yusuke Sato Keitaro Yoshimoto Seiichi Nishizawa Norio Teramae 《Analytical sciences》2006,22(2):201-203
The recognition ability of pteridine derivatives for nucleobases opposite an abasic (AP) site in an oligodeoxynucleotide (ODN) duplex is enhanced by using a propylene residue (Spacer-C3) as an AP site. The recognition ability is further enhanced both by attaching methyl groups to a fluorescent ligand and by measuring the fluorescence response at 5 degrees C; 6.2 x 10(6) M(-1) of the binding constant is attained between 2-amino-6,7-dimethyl-4-hydroxypteridine and guanine opposite the AP site in water. 相似文献
182.
The introduction of information systems in the medical field has made it possible to accumulate a large amount of health care examination data. Analysis of such data could yield valuable new knowledge about health and disease. In this paper, we propose a method for the analysis of large amounts of medical and health care data, especially images or signals. The proposed method treats data in a multidimensional space without any pre-processing, and the data is classified into groups according to the criterion. The criterion used in this paper is to maximize likelihood calculated from the probability density, which is given by the Parzen estimation method. The result of classification is expressed by a binary tree structure as a hierarchy of clusters. We applied this method to computer-generated data and practical electrocardiogram data, and the results showed its validity. 相似文献
183.
184.
Manabu Nishizawa Shigenori Maruyama Tetsuro Urabe Naoto Takahata Yuji Sano 《Rapid communications in mass spectrometry : RCM》2010,24(10):1397-1404
We present a method for in situ sulphur (S) isotopic analysis of significantly small areas (1.5 µm in diameter) in pyrite using secondary ion mass spectrometry (NanoSIMS) to interpret microbial sulphur metabolism in the early earth. We evaluated the precision and accuracy of S isotopic ratios obtained by this method using hydrothermal pyrite samples with homogeneous S isotopic ratios. The internal precision of the δ34S value was 1.5‰ at the level of 1 sigma of standard error (named 1SE) for a single spot, while the external reproducibility was estimated to be 1.6‰ at the level of 1 sigma of standard deviation (named 1SD, n = 25). For each separate sample, the average δ34S value was comparable with that measured by a conventional method, and the accuracy was better than 2.3‰. Consequently, the in situ method is sufficiently accurate and precise to detect the S isotopic variations of small sample of the pyrite (less than 20 µm) that occurs ubiquitously in ancient sedimentary rocks. This method was applied to measure the S isotopic distribution of pyrite within black chert fragments in early Archean sandstone. The pyrite had isotopic zoning with a 34S‐depleted core and 34S‐enriched rim, suggesting isotopic evolution of the source H2S from ?15 to ?5‰. Production of H2S by microbial sulphate reduction (MSR) in a closed system provides a possible explanation for both the 34S‐depleted initial H2S and the progressive increase in the δ34SH2S value. Although more extensive data are necessary to strengthen the explanation for the origin of the MSR, the results show that the S isotopic distribution within pyrite crystals may be a key tracer for MSR activity in the early earth. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
185.
Isotope separations of potassium and rubidium in chemical exchange system with dicyclohexano-18-crown-6 总被引:2,自引:0,他引:2
K. Nishizawa 《Journal of Radioanalytical and Nuclear Chemistry》2001,249(3):569-571
Chemical isotope effects of potassium and rubidium were studied bythe liquid-liquid extraction using a crown ether of dicyclohexano-18-crown-6.The isotope enrichment factors for unit mass difference were 0.0062+0.0013for potassium and 0.0018+0.0005 for rubidium. The correlation between theobtained isotope enrichment factors and the atomic weights was discussed withthe applicable values of literatures for the alkali metals. 相似文献
186.
Osamu Nishizawa Hideki Misaka Toyoji Kakuchi Toshifumi Satoh 《Journal of polymer science. Part A, Polymer chemistry》2008,46(4):1185-1191
Norbornene polymerization using the commercially available and inexpensive catalyst system, cyclopentadienylzirconium trichloride (CpZrCl3) and isobutyl‐modified methylaluminoxane (MMAO), were carried out over a wide range of polymerization temperatures and monomer concentrations. For the CpZrCl3 catalyst system activated by aluminoxane with a 40 mol % methyl group and a 60 mol % isobutyl group (MMAO40/60), the polymerization temperature and monomer concentration significantly affected the molecular weight (Mn) of the obtained polymer and the catalytic activity. With an increase in the polymerization temperature from 0 to 27 °C, the catalytic activity and Mn increased, but these values dramatically decreased with the increasing polymerization temperature from 27 to 70 °C, meaning that the most suitable temperature was 27 °C. The CpZrCl3/MMAO40/60 ([Al]/[Zr] = 1000) catalyst system with the [NB] of 2.76 mol L?1 at 27 °C showed the highest activity of 145 kg molZr?1 h?1 and molecular weight of 211,000 g mol?1. The polymerization using the CpZrCl3/MMAO40/60 catalyst system proceeds through the vinyl addition mechanism to produce atactic polynorbornene, which was soluble in chloroform, toluene, and 1,2‐dichlorobenzene, but insoluble in methanol. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1185–1191, 2008 相似文献
187.
Norihiko Nishizawa Satoshi Kume Masakazu Mori Toshio Goto Akira Miyauchi 《Optical Review》1996,3(1):29-33
Characteristics of guided acoustic wave Brillouin scattering in polarization maintaining fibers are investigated theoretically and experimentally. Spectra of polarized and depolarized scattering are measured for two different types of polarization maintaining fibers: the PANDA (polarization maintaining and absorption reducing) fibers and the elliptical-jacket fibers. Calculated results are in agreement with the experimental ones in the low frequency region. 相似文献
188.
Fe-sitting sites and the origin of magnetic order in YBa2(Cu0.95Fe0.05)3O7?δ have been studied by comparing the Mössbauer spectra observed before and after heat-treatments at 300°C in vacuum. Both of the major quadrupole doublets D-1 and D-2 are assigned to originate from Fe’s replacing Cu1’s. It is also suggested that fluctuations of Cu2 spins play an important role for inducing the magnetic order. 相似文献
189.
K. Suto T. Kimura J. Nishizawa 《International Journal of Infrared and Millimeter Waves》1995,16(4):691-712
Semiconductor Raman laser can act as a heterodyne demodulator of terahertz-band modulated light wave signals in wideband optical communication systems. We have been developing the semiconductor Raman laser with a waveguide structure composed of a GaP core and AlxGa1–xP cladding layers. The tapered waveguide structure can reduce the threshold pump power by increasing the internal pump power density. Fabricated tapered waveguide semiconductor Raman laser have shown the threshold pump power of 160 mW. Discussion is made on the origin of losses as well as the limit of the low pump power operation. 相似文献
190.
Measurements are reported of TZX1 in BCC3 He whose molar volume dependence is obtained in high accuracy. This dependence is described with an empirical spectral density function different from the often used theoretical one consistently with the thermostatic results. 相似文献