摘要:

During evaporation of water, both18O and2H become enriched. The relation between18δ and2δ no longer obeys the equation of the meteoric water line:2δ = 818δ + 10‰. A simple box model serves to calculate changes in18δ and2δ, depending on relative humidity of the air, temperature and evaporated fraction.

ISSN:0021-1915    

DOI:10.1080/10256018708623830

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Distributions of δ15N and δ13C for biogenic substances in the Antarctic Ocean and in the Otsuchi River estuary in Japan were investigated to construct isotope biogeochemical framework for assessing marine ecosystems. The isotopic compositions of phytoplankton were particularly low in the Antarctic Ocean. High nitrate concentration and high PCO2in the surface sea waters, and the low light intensity seem to enhance the kinetic isotope fractionations that preferred the depletion of15N and13C in the algal body A clear-cut linear relationship between animal δ15N and its trophic level was obtained in the Antarctic system. In the estuary, the variation of isotope ratios were principally governed by the mixing of land-derived organic matter, marine phytoplankton, and seagrasses. A food-chain effect of15N enrichment was also confirmed. An isotopically ordered structure was presented for a marine estuarine ecosystem. The isotopic abundances in a food web vary mainly because of the variation in15N and13C contents of primary producers grown under different circumstantial conditions and because of the enrichment of15N along food chains.

ISSN:0021-1915    

DOI:10.1080/10256018708623831

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The described universal99mTe generator is based on fission product (F. P.)99Mo. Examined is the influence of pH of eluence on99mTe elution efficiency and on99Mo breakthrough in eluates of99mTe generators. The99Mo breakthrough in the repeated elution of the generators on the same day is also controlled. Variations of pH of eluence between 3 to 6 do not influence the99mTe elution efficiency and the99Mo breakthrough. The additional elutions of the generators on the same day are possible. The radionuclidic purity of the obtained eluates meets always the requirements proposed by pharmacopeia. The content of99Mo radioactivity is, under the given experimental conditions, far below the permitted level.

ISSN:0021-1915    

DOI:10.1080/10256018708623832

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The calculation of X-ray yields due to secondary excitation using fundamental parameters is simplified considerably by an approximation proposed in this paper. It consists in the replacement of the isotrope X-ray emission leading to an enhancement by a small number (1, 2 or 3) of single angular components. This procedure is suitable especially for depth dependent concentration functions as profiles or sandwiches and also for primary excitation by particles (e. g. PIXE).

ISSN:0021-1915    

DOI:10.1080/10256018708623833

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The form of the response curve of CR-39 for α-particles at relatively low energies has been established. The investigation included measurements of both bulk- and track-etch rates. The latter was measured as a function of α-particle energies.

ISSN:0021-1915    

DOI:10.1080/10256018708623834

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Catalase was desactivated in aqueous solution by irradiation with gamma-rays or ultrasound with nearly equal yields, if the applied doses were related to the response of a chemical dosimeter. The decrease of the enzymatic activity proceeded in parallel to the release of123iodine from125I-(iodo)-catalase. The same competition kinetics were observed in the radiolytic and sonolytic bleaching of p-nitrosodimethylaniline in the presence of catalase, respectively. It is concluded, that OH-radicals were, responsible for the sonolytic destruction of catalase. Phospholipids exerted a protective effect, which may be useful in the preparation of liposomes as carriers of macromolecules.

ISSN:0021-1915    

DOI:10.1080/10256018708623835

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The results of investigations of boron segregation in cast steel and cast alloy based on nickel are presented. In the investigations the method of neutron induced autoradiography, emulsion autoradiography (for the testing of11C distribution), X-ray microanalysis and X-ray phase-analysis have been utilized. The effect of the heat treatment of cast on a segregation of boron and alloy elements have been defined. The phases containing boron have been identified.

ISSN:0021-1915    

DOI:10.1080/10256018708623836

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

During solvent extraction of(is well as of astatine compounds with higher oxidation states likethe astatine species are changed into astatine of the oxidation state zero at the phase boundary independent on the organic solvent used. At(O) probably reads with cotnponents of the organic phase or with decomposition producte formed by chemical reactions or by radiolysis. The extraction coefficients of the astatine species depend on the experimental conditions applied, the redox potential, and on complex forming reactions or associations, resp. occuring in the aqueous phase.

ISSN:0021-1915    

DOI:10.1080/10256018708623837

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Several systems based on multiwire proportional chambers (MWPC) used to study protein mixtures labelled with3H,14C,32P,35S and125I are described. The detector operates on-line with a computer. Autoradiography imaging is presented on a colour TV-monitor. The spatial resolution of the systems is 1 … 2 mm, and the sensitivity is about 10 pCi/cm2. The systems make it possible to reduce the analysis time by a factor of 100 as compared to the conventional radiography of protein mixtures without destroying the sample. The high sensitivity of the systems allows the required amount of protein to be decreased by two orders of magnitude.

ISSN:0021-1915    

DOI:10.1080/10256018708623838

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0021-1915    

DOI:10.1080/10256018708623839

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor