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41.
Ernst Bayer Gerd Wahl und Heinz Günther Witsch 《Fresenius' Journal of Analytical Chemistry》1961,181(1):384-390
Zusammenfassung Es werden zwei neue, sehr selektive Trennflüssigkeiten, Äthylenglykol-bis(propionitril)-äther und Glycerin-tri(propionitril)-äther, angegeben. Die Trennflüssigkeiten sind so selektiv wie ,-Bis(propionitril)-äther, erlauben aber höhere Arbeitstemperaturen von 140° bzw. 170°C. An Säulen kleinen Querschnittes wird die präparative Trennung größerer Mengen unter Ausnutzung der Selektivität dieser Trennflüssigkeiten aufgezeigt.Die Trennwirksamkeit und die Belastbarkeit von Säulen verschiedenen Durchmessers zwischen 1–10 cm wird angegeben. Die Trennwirksamkeit liegt in der gleichen Größenordnung wie die der analytischen Säulen. Die Belastbarkeit steigt proportional dem Querschnitt an.I. Mitteilung: E. Bayer u. H. G. Witsch, diese Z. 170, 278 (1959). 相似文献
42.
Zusammenfassung Das Nicotellin enthält wahrscheinlich nicht, wie die meisten anderen Tabakalkaloide, 2 N-Atome in der Molekel, sondern hat die Formel C15H11N3. Es werden gewichtige Gründe dafür beigebracht, es als 3,2;6,3-Terpyridyl (I) aufzufassen. Diese Hypothese wird durch Synthese des damit isomeren 3,2;4,3-Terpyridyls (V) und Vergleich der Infrarotspektren der beiden Terpyridyle mit denen von 4 bekannten Bipyridylen gestützt. Betrachtungen über eine mögliche Synthese des Nicotellins in der Pflanze führen zu Versuchen, diese Synthese in vitro nachzuahmen; diese Versuche geben aber eine andere Verbindung, wahrscheinlich das 1,5-Di--pyridyl-pentadien-(1,4)-on-(3).Herrn Prof. Dr.L. Ebert zum 60. Geburtstage in aufrichtiger Verehrung gewidment. 相似文献
43.
Ernst Schaumann Erwin Kausch Karl-Heinz Klaska Rolf Klaska Otto Jarchow 《Journal of heterocyclic chemistry》1977,14(5):857-860
The crystal and molecular structures of the cycloadduct from isopropyl[α-(dimethylthio-carbamoyl)isopropyl]carbodiimide and methyl isothiocyanate were determined by single-crystal X-ray methods. The product was established to be 2-(1-isopropyl-3,5-dimethyl-4,6-dithioxo-hexahydro-1,3,5-triazine-2-ylidenamino)-N,N-dimethylthioisoburyramide, in which contrary to expectations based on hybridisation the heterocyclic ring adopts a boat conformation. 相似文献
44.
Ernst M Detken A Böckmann A Meier BH 《Journal of the American Chemical Society》2003,125(51):15807-15810
Proteins are not always available in amounts desirable for solid-state magic-angle spinning (MAS) nuclear-magnetic resonance (NMR) spectroscopy. To maximize the signal-to-noise ratio achievable with small samples, the filling factor must be optimized by using small-diameter MAS rotors. These rotors have the added benefit of allowing higher radio frequency field amplitudes during polarization transfer steps and during decoupling periods as well as allowing higher spinning frequencies. We demonstrate the advantages of relatively fast MAS (30 kHz using a 2.5 mm rotor) compared to MAS at 12 kHz for the 10.4 kDa model protein Crh with 93 residues and show that the signal-to-noise ratio in two-dimensional correlation spectra can be significantly improved by taking advantage of optimized pulse sequences available with rapid MAS. 相似文献
45.
Ernst Meyer 《Angewandte Chemie (International ed. in English)》1970,9(8):583-589
The principles of the topological encoding of formulas and machine searching are briefly described. These methods have been developed to the point where it is now possible to carry out a computer search for a given structural fragment without the risk of false drops. It is also possible to carry out searches whose requirements, while well-defined and readily used by chemists, cannot be represented exclusively by element symbols and chemical bonds. 相似文献
46.
Ernst Berger David W. T. Griffith Gerhard Schuster Stephen R. Wilson 《Mikrochimica acta》1988,95(1-6):239-241
The use of an integrating sphere for the measurement of absorption spectra of thin films is described. The thin film (for example a rare gas matrix) is grown directly on the inside surface of the sphere. Multiple reflections inside the integrating sphere lead to significant enhancement of weak absorptions of the film, increasing the sensitivity of such measurements. 相似文献
47.
Ingrid Fischler Rosi Wagner Ernst A.Koerner Von Gustorf 《Journal of organometallic chemistry》1976,112(2):155-165
The photochemical reaction of the trinuclear complex Fe3(CO)10NSi(CH3)3 under hydrogen leads to substitution of the bridging carbonyl group by two hydrogens. The resulting complex H2Fe3(CO)9NSi(CH3)3 acts as a catalyst in the photochemical hydrogenation of olefins and dienes. 相似文献
48.
Doz. Dr. Friedrich Höfler Ernst Brandstätter 《Monatshefte für Chemie / Chemical Monthly》1975,106(4):893-904
The reactions of Ge2(C6H5)6 with HCl and HBr lead in nearly quantitative yields to the 1,1,2,2-tetrahalo derivatives Cl2(C6H5)GeGe(C6H5)Cl2 (I) and Br2(C6H5)GeGe(C6H5)Br2 (II), resp. The Si?Ge bond of (C6H5)3SiGe(C6H5)3 is cleaved under the conditions of hydrohalogenation. The vibrational spectra of Ge2Br6, Ge2(C6H5)6, I, and II are reported. The influence of vibrational coupling on ν GeGe in these compounds is discussed in detail, including vibrational calculations. 相似文献
49.
Ernst Nowak 《Zeitschrift für Physik B Condensed Matter》1981,45(2):173-176
In the Hubbard model for crystals of the AB-type all information on the system is already contained in the set of eigenstates where the number of sites equals the number of electrons or exceeds it by one. We prove this by deriving relations among the eigenstates with different numbers of particles which do not rely on the well-known transformation of electrons to holes. In this context a new good quantum number is identified. We report on results for the one-dimensional case. 相似文献
50.
Frank Herwig Köhler Hans Jürgen Kalder Ernst Otto Fischer 《Journal of organometallic chemistry》1975,85(2):C19-C22
Carbon-13 NMR data are reported for trimethyltin derivatives containing ERn groups where E C, Si, Ge, Sn, N, O and S including a series of cyclic amines with ring sizes from three to seven. Coupling constant values for the homologous series of fourth group derivatives give goood correlations with the electronegativity of E. The observation of the two-bond, ¦ 2J(119SnE13C) ¦ couplings only in the derivatives containing bulky R groups is rationalized by a bimolecular exchange of ERn groups in the concentrated solutions studied. 相似文献