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171.
Terrestrial carbonate deposits with a banded layer structure can be good tools for the extraction of past environmental information on global and local scales using trace element concentrations and stable isotope ratios. The absolute age dating is most important for the reconstruction of an environmental chronicle. The measurements of fluorescent annual bandings in stalagmites using a microscopic spectrofluorometer with an XY-stage can be a convenient dating method and are especially effective for young samples whose absolute age is very difficult to be determined by other methods. The number of annual bandings was objectively counted using a personal computer. The optimal conditions for the measurements are discussed. The annual banding in stalagmites is caused by the seasonal differences in the fulvic acid concentrations in the dripping water which forms speleothems. 相似文献
172.
We propose to explain two observed anomalies that suggest extension of the minimal gauge scheme, the eμ production in the e+e? reaction and the anomalous y-distribution in reactions, as being caused by a single object, a heavy muon. With more accurate neutrino data this explanation can readily be distinguished from that of a new quark production. 相似文献
173.
A laser Doppler imaging system with a TV camera has been constructed and velocity distributions of fluid flow in cross sections of a rectangular channel have been measured. Consequently, it has been found that the system has some advantages in comparison with usual laser Doppler velocimeters, for example, the visualization of flow can be easily achieved. 相似文献
174.
Rapid and highly sensitive method for determination of methamphetamine and amphetamine in urine by electron-capture gas chromatography 总被引:1,自引:0,他引:1
M Terada T Yamamoto T Yoshida Y Kuroiwa S Yoshimura 《Journal of chromatography. A》1982,237(2):285-292
A rapid and sensitive method for determination of methamphetamine and amphetamine in urine was developed by using electron-capture gas chromatography. The extraction procedure, the experimental conditions for pentafluorobenzoyl derivative formation and the percentage recovery of the drugs from urine are described. The pentafluorobenzoyl derivative of methamphetamine showed a higher electron-capture sensitivity and was detected in at least 23-fold lower concentration than the heptafluorobutyryl derivative which is commonly used as a derivatizing agent for the amine. The detection limit of pentafluorobenzoyl derivatives of methamphetamine and amphetamine was ca. 10 pg. A concentration as low as 10 ng/ml of methamphetamine and amphetamine in urine was easily detected by this method. 相似文献
175.
In left-right symmetric grand unified theories both the smallness of the neutrino mass and a sizable cosmological baryon excess can be ascribed to a superheavy Majorana lepton. We show, taking SO(10) as the simplest model of this kind, that the largest neutrino mass is constrained to lie between 10?3 eV and 100 eV in order to give the observed magnitude of baryon excess. 相似文献
176.
177.
Isao Horibe Shujiro Seo Yohko Yoshimura Kazuo Tori 《Magnetic resonance in chemistry : MRC》1984,22(7):428-430
The 13C FT NMR spectra of β-D -glucopyranosides (including their tetraacetates) of several secondary allylic and benzylic alcohols were compared with those of methyl β-D -glucopyranoside and the corresponding parent alcohols. The characeristic glucosidation shifts observed for these alcohols may be applicable to the determination of the absolute configuration of the hydroxy group in these alcohols. 相似文献
178.
179.
M. Mekata H. Yamana S. Okamoto K. Yoshimura N. Hosoito T. Shinjo 《Hyperfine Interactions》1988,41(1):495-498
The Mössbauer spectra of 3%57Fe doped CsCoCl3 revealed marked relaxation in all phases. The relaxation was interpreted in terms of propagating domain walls along the magnetic chains together with the transition between the lowest doublet and the low excited singlet levels. The hyperfine field of 24.5T was observed at 4.5K. 相似文献
180.
We present a class of cosmological models in which vacuum collapse to curvature singularity is prevented by the generalized gravitational Casimir energy. The mechanism works in higher dimensions, and gives rise to Kaluza-Klein cosmologies free from singularity. 相似文献