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191.
G. Maier 《Angewandte Chemie (International ed. in English)》1967,6(5):402-413
Compounds having the norcaradiene structure are stable if one of the double bonds of the norcaradiene also belongs to a benzene ring or if C atoms 1 and 6 are fixed in position by a bridge. A similar effect that favors the norcaradiene form is produced by the incorporation of nitrogen atoms in positions 3 and 4. Cycloheptatriene and most of the simply substituted tropilidenes exist exclusively in the monocyclic triene form. It has been possible in some cases to detect a valence-tautomeric equilibrium between the norcaradiene and the cycloheptatriene ring system. Non-classical stabilization of compounds having norcaradiene or cycloheptatriene structure in the sence of a pseudoaromatic “homobenzene” is only very slight, if it occurs at all. 相似文献
192.
E. A. Maier M. L. Sargentini-Maier F. Rastegar C. Christophe C. Ruch R. Heimburger M. J. F. Leroy 《Fresenius' Journal of Analytical Chemistry》1988,331(1):58-60
Summary The energy dispersive X-ray fluorescence spectrometer (EDXRF) developped together with the Siemens Company (FRG) allows to perform rapid multi-elemental analysis of biological fluids without pretreatment of the samples. The performance of this technique and its features are reported in two different fields: blood analysis and pulmonary investigations. Blood and plasma analysis were performed for more than 2500 patients and a statistical treatment of the data lead to the normal concentrations of trace elements Se, Rb, Cu, Zn, Fe, Ca, Br, K. Toxic elements such as Hg or Pb and also drugs like Au and Pt compounds can be detected even after a long period after treatment. To illustrate the performance of the spectrometer we report the influence of Cis-Pt treatment on the trace element concentrations in plasma of patients with anemia.The EDXRF spectrometry was also used to investigate the inorganic composition of the broncho-alveolar lavage fluids. After determination of the normal concentration range, it was possible to characterize some typical pulmonary diseases due to occupational exposure. Some examples of detected pneumoconiosis and for some patients the presence in the alveoli of elements due to special medication (Amiodarone, Aurothiopropanol-sulfonate) are mentioned.Other fields are being investigated such as: follow-up of Mn dependent enzymes in neuronal and glial cells in culture; origin of lead in dental tissues or composition of lyophilized food powders. They will be briefly discussed.
Energie-dispersive Röntgenfluorescenz in der biomedizinischen Analyse相似文献
193.
194.
T. Rymen J. J. Belliardo B. Griepink E. A. Maier N. Mal A. S. Lindsey 《Fresenius' Journal of Analytical Chemistry》1994,348(1-2):31-36
Summary The Community Bureau of Reference (BCR) of the Commission of the European Communities has produced standard solutions of PCDDs and PCDFs (dirty dozen) to guarantee proper calibration and traceability of results in the certification of these compounds in matrix materials. The purity of each individual isomer has been evaluated on the initial crystals using several analytical methods. Solvents have been checked for impurities. The entire procedure of preparation of the twelve solutions has been performed under strict metrological conditions and will be published elsewhere. All results and the preparation procedure followed are described. The solutions are not certified, but may be obtained from BCR together with an analytical report. 相似文献
195.
196.
W. Günther K. Huber U. Kneissl H. Krieger H. J. Maier 《Zeitschrift für Physik A Hadrons and Nuclei》1980,295(4):333-340
Measurements are presented for the mass and energy distributions of fragments from the photofission of232Th,235U,238U and239Pu. The experiments were performed for bremsstrahlung endpoint energies between 15 and 55 MeV, using silicon surface barrier detectors. The results are discussed with respect to the competition between the symmetric and asymmetric fission modes. 相似文献
197.
R. Alfier D. Alber H. Grawe H. Kluge K. H. Maier R. Schubart D. B. Fossan W. F. Piel Jr. 《Zeitschrift für Physik A Hadrons and Nuclei》1974,267(2):135-143
Conversion coefficients and conversion ratios of someγ-transitions in201Tl and203Tl were measured by means of simultaneous spectroscopy ofγ-quanta and conversion electrons employing intensity calibrated semiconductor detectors. The experiments aimed at a precision as high as possible within the limits of the experimental methode used. Theγ-transitions were of the typeM 1(+E2). From the measured values the penetration parameters of the internal conversion for theM 1 components (λ) together with the multipol mixing ratios (δ2) were deduced. The necessary theoretical coefficients were taken from the tables of Hager and Seltzer. The results are for the ?-forbidden 331 keV transition in201Tl,λ=+4.0±1.0,δ 2=1.78±0.16; for the ?-allowed 361 keV transition in201Tl,λ=+0.5±0.5,δ 2=0.02±0.02; for the ?-forbidden 279 keV transition in203Tl,λ=+ 5.71±0.45,δ 2=1.55±0.08. 相似文献
198.
199.
A technique to prepare metal specimens containing sealed positron sources which permit Doppler broadening and lifetime measurements
up to high temperatures (close to the melting point in the investigated metals Cd, Au, Cu) is presented. 相似文献
200.