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41.
42.
43.
Rydberg spectra are shown to provide a spectral fingerprint that is sensitive to molecular structure in unique ways. The concepts are demonstrated using a set of isomeric fluorophenols and a sequence of aliphatic diamines. In the fluorophenols, the sensitivity extends to the placement of a single hydrogen atom and can be traced to the molecular charge distributions associated with the locations of atoms and functional groups with respect to the charge center. Experiments on tetramethyl diamines demonstrate that the structural sensitivity encompasses the extended molecular structure, including parts of the molecule that are remote from the ionization center. This global structure sensitivity makes Rydberg fingerprint spectroscopy uniquely suited to characterize structures of large-scale molecular systems. 相似文献
44.
A D C, spectrochemical method using the STALLWOOD jet has been developed for the determination of Li, Na, K and Rb in silicate minerals and rocks. Samples are mixed with graphite and Cs2CO3 in tho ratio 2 : 1 : 1, and Cs serves as internal standard. Precision and accuracy is satisfactory. 相似文献
45.
Magnetic field decoupling experiments in the optically excited states of NO2 yield decoupling signals with a width of 10 to 40 mG. We attribute these signals to the non-rigidity of the excited molecule. 相似文献
46.
K. Huckert R. Rhode O. Roglin R. Weber 《Mathematical Methods of Operations Research》1980,24(1):47-60
Summary A mixed integer multiple criteria model is formulated for scheduling problems. Its solution is obtained by an interactive method based on the Tchebycheff-approximation. For solving greater problems some modifications are discussed at the end of the paper, which are essentially based on the notion of heuristic efficiency.
Zusammenfassung Da bei Ablaufplanungsproblemen häufig mehrere Zielsetzungen zu beachten sind, wird im folgenden Beitrag hierzu ein gemischt-ganzzahliges multikriterielles Entscheidungsmodell formuliert. Seine Lösung erfolgt mit Hilfe eines interaktiven Verfahrens. Zur numerischen Lösung größerer Problemstellungen sind einzelne Verfahrensmodifikationen erforderlich, die im wesentlichen auf dem im letzten Abschnitt eingeführten Begriff der heuristischen Effizienz aufbauen.相似文献
47.
R. Naumann und Ch. Weber 《Fresenius' Journal of Analytical Chemistry》1971,253(2):111-113
Zusammenfassung Eine Methode zur potentiometrischen Titration von Sulfid mit Natriumplumbat(II)lösung an einer sulfidsensitiven Membranelektrode wird beschrieben. Sie eignet sich zur Bestimmung von 10–4% Sulfid in Gegenwart von Cl–, Br–, J–, SCN–, SO3
2–, S2O3
2–
Wir danken Herrn Dr. K. Obst für wertvolle Hinweise und Diskussionen. 相似文献
Titration of sulphide with a sulphide-ion sensitive electrode
A method is described for the titration of sulphide with sodium plumbate(II) solution using a sulphide-sensitive electrode. The method is suitable for the determination of 10–4% of sulphide in the presence of Cl–, Br–, J–, SCN–, SO3 2–, S2O3 2–.
Wir danken Herrn Dr. K. Obst für wertvolle Hinweise und Diskussionen. 相似文献
48.
In recent years capillary chromatography has gained popularity for trace analyses. Most often UV or electrochemical detection is employed because the small peak volumes make post-column derivatization challenging. We have developed a simple method based on flow injection for determining contributions to peak broadening from post-column reactors. The only requirement for application of our methodology is that diffusion be in the Taylor regime so that radial concentration gradients are relaxed enabling mixing purely by diffusion. 相似文献
49.
Wolfgang Oppolzer Roland Achini Emil Pfenninger Hans Peter Weber 《Helvetica chimica acta》1976,59(4):1186-1202
The N-allyl-N-cinnamyl amide 10 undergoes thermal cyclization to a 2:1-mixture of the trans- and cis-benz(f)isoindolines 11a and 12a . By comparison, the thermolysis of the corresponding bis-cinnamylamide 14 proceeds in a highly stereoselective manner to give the cis-fused[4+2]-adduct 16a . Similarly, the trans-fused stereoisomeric adducts 30a and 31a were obtained with high stereochemical control on heating the N-allyl-N-diphenylallyl amide 28 . The thermal transformations 4 → 5 + 6a and 17 → 18a + 20a show the competitive formation of [2+2]-adducts. An alternative approach to (substituted) benz[f]isoindolines 16 via the all-cis-isomer 24a has been developed. The described structures have been assigned on the basis of spectral evidence, chemical correlations and by X-ray-diffraction study of the isomer 16b . These results illustrate the utility of substituent interactions in order to direct intramolecular cyclo-additions at will towards either endo- or exo-products. 相似文献
50.
Analysis of high-resolution NMR spectra elucidation has been known for many years. Hard-and software development now permits
the implementation of such programs on personal computers. The structural information hidden in complex proton NMR spectra
becomes easily accessible by using graphical user interfaces and direct data exchange between programs. A new mode has been
implemented in 1D WIN-NMR to support the analysis of multiplet patterns with first order rules. Structure display, direct
export mechanisms to the simulation program WIN-DAISY, and an archiving possibility complete the state-of-the-art data analysis.
Some practical examples are given.
Received: 25 October 1996/Revised: 6 March 1997/Accepted: 10 March 1997 相似文献