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排序方式: 共有160条查询结果,搜索用时 15 毫秒
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Volkmar Nejedl Michael Panzner Stefan Baunack Ulrich Franz Arnold Luft Klaus Wetzig 《Mikrochimica acta》1998,130(1-2):89-95
The laser induced modification of iron surfaces with atmospheric species was investigated by means of Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). Different laser systems were used for irradiating iron samples in a wide range of the laser processing parameters up to small foci and ultra short pulses.A nitriding of iron connected with an oxidation of the near surface region was observed in the wavelength range between 193 nm and 10.6 m using large foci (0.1 cm2) and short pulses (10...1400ns). In case of small foci (7·10–6cm2) with ns-pulses (50 ns) an enrichment of the iron melt with nitrogen and an advanced oxidation of the surrounding area of the laser spot were detected. When using shorter pulses (200 fs, 40 ps) no indications for a nitriding were found. 相似文献
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Andreas Petri Oliver SeidelmannUwe Eilitz Frank LeßmannStefan Reißmann Volkmar WendischAndrey Gutnov 《Tetrahedron letters》2014
Asymmetric conjugate addition of arylboronic acids to 2-nitroacrylamide in the presence of cationic palladium–Chiraphos complex proceeds with high yield and enantioselectivity (73–89% ee) using as low as 0.05–0.25 mol % of the catalyst. The adducts can be smoothly transformed into the corresponding β2-homophenylglycines in two simple steps. 相似文献
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Lusine Sargsyan Thomas Hippe Hartmut Manneck Volkmar Vill 《Molecules (Basel, Switzerland)》2021,26(4)
The aim of this work was to optimize our natural hair dyeing system which we described in our previous work and to compare with other dyeing systems. Therefore, we investigated concentration limits of matcha and mordant and compared this new dyeing method with commercial permanent systems on the market. Completely unpigmented hair tresses were dyed with matcha powder (camelia sinensis) and iron(II)-lactate. To investigate the wash fastness and concentration limits, the differently dyed hair tresses were spectrophotometrically measured. The comparison of the damage potential for which cysteic acid is an indicator was measured by NIR. The concentration of matcha and mordant are responsible for the intensity of the color results. The higher the matcha or the mordant concentration, the darker the color results of the dyed hair tresses. Hair damage of matcha mordant dyeing is comparable with results of commercial permanent hair coloration systems. Moreover, the results of wash fastness of matcha mordant dyed hair tresses is comparable and even better by tendency to permanent colored hair tresses. 相似文献
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A new method for the determination of spatially resolved phase differences of nonlinear susceptibilities is presented. The technique is based on the interference of the signal field with a reference field. A phase-shifting element that directly changes the phase difference between the two second-harmonic fields is introduced. The reliability of the method is tested by an experiment with two quartz crystals. As a first application, a measurement of the phase difference between domains in antiferromagnetic YMnO(3) is presented. 相似文献
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The mechanism of the reaction of a CdSe-crystal with a lead and sulfur containing gas phase is investigated by means of an electron microprobe and by optical microscopy in the temperature region from 600 to 900°C. The morphology of the reaction layer depends strongly on temperature. In the low temperature region the reaction zone exists of two product layers. Directly at the crystal surface we find a Cd(S, Se) interdiffusion layer but only at some distance from the crystal surface a Pb-chalcogenide layer has been formed.In the high temperature region needles of Pb-chalcogenide are formed directly at the crystal surface. These differences in the morphological feature can be explained by local thermodynamic equilibrium at the phase boundaries. 相似文献
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M. Fiebig D. Fröhlich S. Leute R.V. Pisarev 《Applied physics. B, Lasers and optics》1998,66(3):265-270
2 O3, in which the time-invariant second-harmonic reference can be generated either intrinsically by the crystal or externally
by use of the new technique, so that both methods may be compared. The technique is then used to visualize the domain structure
of YMnO3, an antiferromagnetic crystal which does not provide the time-invariant reference wave intrinsically. The experiments demonstrate
the wide applicability of the method.
Received: 13 June 1997 相似文献
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