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21.
Martin Winterwerber Rouzita Geiger Ursula Predoiu Hans-Hartwig Otto 《Monatshefte für Chemie / Chemical Monthly》2006,137(11):1441-1451
Summary. Reactions of cyanomethanesulfonamides with aromatic aldehydes in the presence of AcOH and piperidine produced the addition products, the 1-cyano-2-arylethenesulfonamides, whereas reactions with benzonitrile
yielded the 2-amino-1-cyano-2-phenylethenesulfonamides only when done in THF with BuLi. No addition products were isolated from the analogue reactions with 2-hydroxybenzaldehyde (salicylaldehyde). Instead,
we obtained 2-imino-2H-chromene-3-sulfonamides with good to excellent yields. These 2H-chromene derivatives allowed a number of transformations, from which the reactions with orthoformates opened an approach
to the hitherto unknown benzopyrano[3,2-e] [1,2,4]thiadiazine ring system. 相似文献
22.
A series of stable heterocyclic indicators with λex = 469–566 nm and λem = 511–652 nm allows the fluorimetric determination of ca. 1–100% partial pressures of oxygen by quenching of fluorescnce, especially in toluene solution. 相似文献
23.
Otto M 《Fresenius' Journal of Analytical Chemistry》2001,369(7-8):738-740
The present situation of analytical chemistry teaching within a chemistry curriculum is exemplified by the reformed chemistry curriculum in Germany. This approach is contrasted with teaching analytical chemistry within a novel curriculum in natural sciences termed 'applied science'. The latter curriculum ensures a superior education in chemistry, physics, biology, mathematics and information science, thus gaining an integrated perspective of analytical chemistry. 相似文献
24.
Tatsuro Ouchi Hirotoshi Fujie Satoshi Jokei Yoshiomi Sakamoto Hidenori Chikashita Takeshi Inoi Otto Vogl 《Journal of polymer science. Part A, Polymer chemistry》1986,24(9):2059-2074
Acryloyl-type polymer fixing 1-β-carbonylethyl-5-fluorouracil residues through D -glucofuranoses via ester bonds was synthesized by means of polymerization of the corresponding monomer and polymer reaction. In order to provide the water-soluble objective polymer, the copolymerization of the acryloyl-type monomer with acrylamide was carried out. The extent of release of 5-FU residues from the copolymer was investigated in the enzyme or nonenzyme system in vitro. Furthermore, the antitumor activities of the water-insoluble homopolymer and water-soluble copolymer obtained were tested in vivo. 相似文献
25.
S. Steffen M. Otto L. Niewoehner M. Barth Z. Bro¿żek-Mucha J. Biegstraaten R. Horváth 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
A gunshot residue sample that was collected from an object or a suspected person is automatically searched for gunshot residue relevant particles. Particle data (such as size, morphology, position on the sample for manual relocation, etc.) as well as the corresponding X-ray spectra and images are stored. According to these data, particles are classified by the analysis-software into different groups: ‘gunshot residue characteristic’, ‘consistent with gunshot residue’ and environmental particles, respectively. Potential gunshot residue particles are manually checked and – if necessary – confirmed by the operating forensic scientist. 相似文献
26.
The optical absorption of anthracene vapour for photon energies from 5 to 8.5 eV was found to differ in finer structure from the spectra reported earlier for parts of this range. Above the strong 1B2u long axis polarized πlπ* transition at 5.24 eV three short axis polarized 1B1u ππ* transitions are assigned on the basis of the oriented gas model in comparison to spectra from anthracene single crystals. A tentative new assignment for most of the additionally observed sharp Rydberg bands leading to the first ionization potential at 7.47 eV is given. 相似文献
27.
Bassam Abu Thaher Jalal A. Zahra Mustafa M. El-Abadelah Hans-Hartwig Otto 《Monatshefte für Chemie / Chemical Monthly》2004,40(9):435-439
Nitrilimines were prepared from N-arylhydrazono chlorides and reacted with -alanine yielding the corresponding amidrazones, which were treated with 1,1-carbonyldiimidazole in THF affording the hitherto unknown 3-acetyl-1-aryl-1,4,5,6-tetrahydro-1,2,4-triazepin-7-ones. 相似文献
28.
van Wijk AA Spaans A Uzunbajakava N Otto C de Groot HJ Lugtenburg J Buda F 《Journal of the American Chemical Society》2005,127(5):1438-1445
To resolve the molecular basis of the coloration mechanism of alpha-crustacyanin, we used (13)C-labeled astaxanthins as chromophores for solid-state (13)C NMR and resonance Raman spectroscopy of [6,6',7,7']-(13)C(4) alpha-crustacyanin and [8,8',9,9',10,10',11,11',20,20']-(13)C(10) alpha-crustacyanin. We complement the experimental data with time-dependent density functional theory calculations on several models based on the structural information available for beta-crustacyanin. The data rule out major changes and strong polarization effects in the ground-state electron density of astaxanthin upon binding to the protein. Conformational changes in the chromophore and hydrogen-bond interactions between the astaxanthin and the protein can account only for about one-third of the total bathochromic shift in alpha-crustacyanin. The exciton coupling due to the proximity of two astaxanthin chromophores is found to be large, suggesting that aggregation effects in the protein represent the primary source of the color change. 相似文献
29.
Optical pH determination has the fundamental disadvantage of measuring a signal that depends on the ionic strength of the sample. The problem originates from the complex relationship between the proton activity and the concentration of the pH-sensitive dye. The effect of ionic strength on the signal depends on the charge of the indicator and its environment, e.g. the immobilisation matrix. We present novel lipophilic fluorescein esters carrying one negative charge. They are embedded in an uncharged, highly proton-permeable hydrogel to give optical pH sensors that show a negligible cross-sensitivity towards ionic strength. The fluorescent dyes differ in their substituents. This variation of substituents results in dissociation constants between 5.5 and 8.5. The indicators were made lipophilic by esterification of the carboxy group with a C(18) alkyl chain. Since their spectral properties are quite similar, two indicators may be used in one sensor. This results in an optical pH sensor with a dynamic range that extends from pH 4.5 to 8. 相似文献
30.
Based on neural network calibration the confidence intervals of aromaticity determination from infrared reflectance spectra of raw brown coals were estimated by means of the bootstrap method, a simplified Monte Carlo Simulation. The standard deviations and the confidence intervals were estimated to characterise the analysis error.It is shown that confidence intervals of non-linear analysis methods like Back Propagation Neural Networks (BPNN) can be estimated by the bootstrap method. The estimated confidence intervals of the calibration confirm the analysis by BPNN. 相似文献