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排序方式: 共有117条查询结果,搜索用时 15 毫秒
91.
Zusammenfassung Über ihre einfach herstellbaren Kupplungsprodukte mit Echtrotsalz AL konnten Phenol und sämtliche isomeren Kresole und Xylenole dünnschichtchromatographisch getrennt werden. Die eindeutige Identifizierung aller Einzelkomponenten wurde durch Kombination von insgesamt drei chromatographischen Läufen mit einem Zeitbedarf von je etwa 30 min erreicht. Das als Schichtmaterial benutzte Kieselgel G wurde mit Dikaliumcarbonat bzw. Oxalsäure modifiziert. Als Fließmittel fanden Dichlormethan-Essigsäureäthylester-Diäthylamin (9253) und Chloroform-Essigsäureäthylester-Äthanol (9352) bei Kammersättigung und reines Benzol bei Normalsättigung Verwendung.
Den Herren U. Strauss und A. Werdehausen danken wir für die gewissenhafte und geduldige Mitwirkung bei den sehr umfangreichen experimentellen Arbeiten. 相似文献
Summary Phenol and all isomeric cresols and xylenols have been separated by thin-layer chromatography via their easily obtainable products of coupling with Fast Red Salt AL. Well defined identification of all components has been achieved by combination of three chromatographic runs (time each about 30 minutes). Silica gel G modified with potassium carbonate resp. oxalic acid has been used as layer material, while methylene chloride:nacetic acid ethylester:ndiethylamine=9253 and chloroform:n acetic acid ethylester:nethanol=9352 (chamber saturation) as well as benzene (normal saturation) served as solvents.
Den Herren U. Strauss und A. Werdehausen danken wir für die gewissenhafte und geduldige Mitwirkung bei den sehr umfangreichen experimentellen Arbeiten. 相似文献
92.
E. Knappe und D. Peteri 《Fresenius' Journal of Analytical Chemistry》1962,190(4):380-386
Zusammenfassung Unter Anwendung einer direkten Hydrier-Differenz-Methode wurden mit dem Fließmittelsystem Diisopropyläther-Ameisensäure-Wasser und der stationären Phase Polyäthylenglykol M 4000 (auf Kieselgur) g-Mengen von Maleinsäure, Fumarsäure, Glutaconsäure, Citraconsäure, Itaconsäure und Mesaconsäure dünnschichtchromatographisch identifiziert.II. Mitteilung: Knappe, E., u. D. Peteri: diese Z. 188, 352 (1962).Frau L. Beck und Frau I. Rohdewald danken wir für die gewissenhafte Mitwirkung an den experimentellen Arbeiten. 相似文献
93.
P. Davies W. -D. Emmerich S. Knappe 《Journal of Thermal Analysis and Calorimetry》1993,40(3):1025-1030
The capabilities of the new NETZSCH thermo-microbalance TG 209 are illustrated by four applications from the polymer industry. 相似文献
94.
D. Krennrich R. Knappe B. Henrich R. Wallenstein J.A. L’huillier 《Applied physics. B, Lasers and optics》2008,92(2):165-174
This paper reports on efficient generation of cw laser radiation at 0.9 and 1.3 μm in different neodymium doped laser hosts.
The thermal, mechanical and optical properties as well as the laser performance of Nd:YAG, Nd:YAlO3, Nd:YVO4 and Nd:GdVO4 are studied in numerical simulations as well as in experimental investigations. For example an output power of more than
4.0 W is generated in Nd:YVO4 at the 914 nm 4F3/2→4I9/2 transition using a pump power of 19 W. In Nd:GdVO4 more than 6.0 W are obtained at the 1342 nm 4F3/2→4I13/2 laser transition by using a pump power of 19.3 W. The spatial beam quality of both lasers is diffraction limited with an
M2 value of less than 1.1.
PACS 42.70.Hj; 42.55.Xi; 42.60.Pk 相似文献
95.
D. Krennrich R. Knappe B. Henrich R. Wallenstein J.A. L’huillier 《Applied physics. B, Lasers and optics》2008,92(2):175-183
This paper reports on the generation of picosecond (ps) laser pulses by self-phase-adjusting additive-pulse-mode-locking (PSA)
at wavelengths of 0.9 and 1.3 μm. The main objective of this work was to investigate and compare the characteristic optical
properties of ps lasers based on different Nd-doped laser crystals like Nd:YAG, Nd:YAlO3, Nd:YVO4 and Nd:GdVO4. As a result of these investigations a mode-locked Nd:YVO4 laser for example, generated, ps pulses at 1.3 μm with a duration of 7 ps, a repetition rate of 160 MHz and an average power
of 4.7 W. At 0.9 μm pulses with a duration of 1.9 ps were obtained at a repetition rate of 158 MHz and an average power of
2.8 W.
PACS 42.70.Hj; 42.65.Re; 42.65.Ky 相似文献
96.
97.
98.
Paul J. Ganssle Hyun D. Shin Dr. Scott J. Seltzer Dr. Vikram S. Bajaj Dr. Micah P. Ledbetter Prof. Dmitry Budker Dr. Svenja Knappe Dr. John Kitching Prof. Alexander Pines 《Angewandte Chemie (International ed. in English)》2014,53(37):9766-9770
Nuclear magnetic resonance (NMR) relaxometry and diffusometry are important tools for the characterization of heterogeneous materials and porous media, with applications including medical imaging, food characterization and oil‐well logging. These methods can be extremely effective in applications where high‐resolution NMR is either unnecessary, impractical, or both, as is the case in the emerging field of portable chemical characterization. Here, we present a proof‐of‐concept experiment demonstrating the use of high‐sensitivity optical magnetometers as detectors for ultra‐low‐field NMR relaxation and diffusion measurements. 相似文献
99.
S. Knappe J. Kitching L. Hollberg R. Wynands 《Applied physics. B, Lasers and optics》2002,74(3):217-222
We measure the properties of coherent population trapping (CPT) resonances in Cs vapor cells as a function of temperature.
We expected the CPT signal to increase with higher vapor density, but instead the signal fades away above a certain density.
Two possible density-dependent explanations are discussed: spin-exchange collisions, which are found to give no relevant contribution
at the temperatures considered here, and increased absorption due to the optical thickness of the vapor. The dependence of
the dark-line resonance amplitude as a function of cell temperature can be well represented by a simple model based on the
optical thickness of the vapor as a function of temperature.
Received: 30 November 2001 / Published online: 7 February 2002 相似文献
100.
We report a diode-pumped picosecond Nd:GdVO4 regenerative amplifier system designed for micro-machining applications. Nd:GdVO4 was chosen as gain material because it offers – in comparison to the commonly used Nd:YVO4 – improved thermal properties and a larger gain bandwidth. At the maximum repetition rate of 200 kHz, the system generated 6.8-ps-long pulses with a pulse energy of 65 μJ, which corresponds to an average output power of 13 W. At 100 kHz, the pulse energy increased to 123 μJ, whereas the average power of 12.3 W remained almost identical. The broadening of the pulses due to gain narrowing was investigated in dependence on the number of cavity round trips and on the repetition rate. At 200 kHz, the injected 5.3-ps-long pulses broadened slightly to about 6.8 ps. 相似文献