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451.
Zeitschrift für Physik A Hadrons and nuclei - An Hand einfacher Strömungen werden einige weitere Gründe angeführt, welche auf eine unsymmetrische Spannungsmatrix hinweisen. Auch... 相似文献
452.
Cation conductive membranes, especially highly proton conductive membranes, are of interest not only for chlor-alkali electrolysis but for polymer electrolyte fuel cells as well. The very challenge for electrochemical characterization in this case is the low specific resistance of the polymer required for such applications, which in turn makes resistance measurements a non-trivial problem. We investigate the different possibilities to characterize such membranes. The present part of our work deals with the adequate conditioning and equilibration of membranes designed especially for direct methanol fuel cell applications, with the measurement of the conductivity and with the determination of apparent transport numbers in the membrane. The usefulness of the respective leaching investigations, impedance spectroscopy measurements and concentration potential measurements for the case of membranes made from sulfonated poly(phenylene oxide) is discussed. 相似文献
453.
Frieder W. Scheller Plorian Schubert Dietmar Weigelt Peter Mohr Ulla Wollenberger 《Macromolecular Symposia》1988,17(1):429-439
The specificity of molecular recognition is reflected to a high degree by the selectivity of the respective biosensor response. Therefore, the application of highly specific enzymes offers advantages for analytical purposes. Using lactate monooxygenase in combination with lactate dehydrogenase and pyruvate kinase, sequentially acting enzyme electrodes for lactate, pyruvate, ADP and enzyme activities, e.g. lactate dehydrogenase, creatine kinase and aminotransferases were developed. A high sensitivity was achieved based on the cycling enzyme pairs hexokinase/pyruvate kinase for ATP and ADP, and lactate monooxygenase/malate dehydrogenase for malate and oxaloacetate, respectively. On the other hand, in a sensor for a large group of substances, the unspecific microsomal cytochrome P-450 system was applied. 相似文献
454.
C M Mohr W M King A J Freeman R W Briggs C M Leonard 《The Journal of the Acoustical Society of America》1999,105(5):2738-2745
Understanding the impact of variations in the acoustic signal is critical for the development of auditory and language fMRI as an experimental tool. We describe the dependence of the BOLD signal and speech intelligibility on the intensity of auditory stimuli. Eighteen subjects were imaged on a 1.5-T MRI scanner. Speech stimuli were English monosyllabic words played at five intensity levels. Intrasubject reproducibility was measured on one subject by presenting the stimulus five times at the same intensity level. Intelligibility was measured during data acquisition as subjects signaled when hearing two targets. Each functional trial consisted of four cycles (30 s off-30 s on). Five oblique slices covering primary and association auditory areas were imaged. Activated voxels were identified by cross-correlation analysis and their percent signal change (delta S) was measured. Intersubject differences in activation extent, asymmetry, and dependence on intensity were striking. Volume of activation was significantly greater in the left than in the right hemisphere. Intrasubject reproducibility for delta S was higher than for volume of activation. delta S and intelligibility showed a similar dependence on intensity suggesting that not only intensity but also intelligibility affect the fMRI signal. 相似文献
455.
N.A. Lockwood J.C. Mohr L. Ji C.J. Murphy S.P. Palecek J.J. dePablo N.L. Abbott 《Advanced functional materials》2006,16(5):618-624
We have investigated the culture of human embryonic stem cells (hESCs) on interfaces of the thermotropic liquid crystal, TL205, that are decorated with thin films of the extracellular matrix, Matrigel. hESCs seeded at the liquid‐crystal/Matrigel interface survive for weeks, and cell colonies grow over this time. The cells show levels of differentiation comparable to that observed for cells on Matrigel‐coated glass controls. Polarized and fluorescence microscopy reveal that the orientational order of the liquid crystal is coupled to the presence and organization of Matrigel. This enables straightforward imaging of the reorganization of Matrigel by the hESCs through changes in the appearance of the liquid crystal when observed using polarized light microscopy. The coupling between Matrigel and TL205 thus provides a simple tool for monitoring the reorganization of the Matrigel film over time. Our results suggest new approaches to the culture of cells and measurements of cell–extracellular‐matrix interactions. 相似文献
456.
457.
H. Mohr 《Photochemistry and photobiology》1966,5(5-6):469-482
Abstract— Phytochrome-induced photomorphogenesis in the mustard seedling ( Sinapis alba L.) which can be regarded as being representative of the dicotyledonous seedlings has been analysed. In the present paper a number of arguments are presented, including data on RNA and protein synthesis and on the effects of actinomycin D and puromycin, which support the hypothesis that the 'positive' photoresponses of the seedling can be explained by a differential gene activation through P,30 . 'Positive' photoresponses are those which are characterized by an initiation or an increase of biosynthetic or growth processes (e.g. biosynthesis of anthocyanin; growth of cotyledons). The lag-phase of this type of photoresponse is rather long, 'Negative' photoresponses are those which are characterized by an inhibition of growth processes or other physiological processes like translocation. Here the lag-phase is short. Inhibition of hypocotyl lengthening is a typical response of this sort. The concept of differential gene repression through P 730 may serve as a working hypothesis to approach the causal analysis of phytochrome-induced 'negative' photoresponses. 相似文献
458.
Reaction of C5H5 (CO)2MnAs(Ph)Cl2 with Fe2 (CO)9 afforded the phenylarsenido cluster Fe3 (CO)9 (PhAs)2. The compound has a nido octahedral structure as confirmed by X-ray analysis. 相似文献
459.
460.
S. Mohr 《Tetrahedron letters》1979,20(26):2461-2464
The asymmetric solid-state photodimerization of the oxazolone leads to the trispirodimer ; its structure is elucidated by chemical reactions combined with PSR symmetry considerations. 相似文献