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排序方式: 共有112条查询结果,搜索用时 15 毫秒
21.
Gertrud Bernhart Margrit Braun Manfred Müller Dieter Rinne Manfred Rogge 《Analytica chimica acta》1989
(Comparison of analytical results for common anions obtained by ion chromatography and classical methods.)The concentrations of chloride, nitrate, and sulphate were determined in ground-water samples by ion chromatography and by the classical titrimetric, photometric, and gravimetric methods. The results were compared by an orthogonal regression procedure. The criteria established and the tests of the confidence intervals of the orthogonal regression function indicate that the results obtained by the different analytical methods are similar for chloride and sulphate but not for nitrate. 相似文献
22.
M. Rogge G. Fischer U. Pindur D. Schollmeyer 《Monatshefte für Chemie / Chemical Monthly》1996,127(1):97-102
Summary The cycloadducts3,5, and7, readily available from methoxy-substituted 3-vinylindoles1 and2, were dehydrogenated withDDQ to the coplanar [a]-anellated carbazoles4,6, and8. Compound4a, also characterized by X-ray structural analysis, shows significant cytotoxicity against K562 und RXF393 human tumor cell lines.
[a]-Anellierte Carbazole mit Antitumoraktivität: Synthese und Cytotoxizität
Zusammenfassung Die aus den methoxysubstituierten 3-Vinylindolen1 und2 zugänglichen Cycloaddukte3,5 und7 lassen sich mitDDQ zu den coplanar-anellierten Carbazolen4,6 und8 dehydrieren. Verbindung4a, die auch durch eine Röntenstrukturanalyse charakterisiert wurde, zeigt signifikante Cytotoxizität gegen Humantumor-Zellinien (K562 und RXF93).相似文献
23.
I. Katayama G. P. A. Berg S. A. Martin J. Meissburger W. Oelert A. Retz M. Rogge J. G. M. Römer G. Gaul H. Hasai J. L. Tain L. Zemlo 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1986,3(1):73-77
Target thickness dependences of3He1+ yields from Al, Ni, Ag and Au targets were measured at 68, 99 and 130 MeV incident3He2+ energies, leading to electron stripping and capture cross sections. The results are compared with current theories. 相似文献
24.
Acidity Constant (pKa) Calculation of Large Solvated Dye Molecules: Evaluation of Two Advanced Molecular Dynamics Methods
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Thierry De Meyer Prof. Bernd Ensing Sven M. J. Rogge Prof. Karen De Clerck Prof. Evert Jan Meijer Prof. Veronique Van Speybroeck 《Chemphyschem》2016,17(21):3447-3459
pH‐Sensitive dyes are increasingly applied on polymer substrates for the creation of novel sensor materials. Recently, these dye molecules were modified to form a covalent bond with the polymer host. This had a large influence on the pH‐sensitive properties, in particular on the acidity constant (pKa). Obtaining molecular control over the factors that influence the pKa value is mandatory for the future intelligent design of sensor materials. Herein, we show that advanced molecular dynamics (MD) methods have reached the level at which the pKa values of large solvated dye molecules can be predicted with high accuracy. Two MD methods were used in this work: steered or restrained MD and the insertion/deletion scheme. Both were first calibrated on a set of phenol derivatives and afterwards applied to the dye molecule bromothymol blue. Excellent agreement with experimental values was obtained, which opens perspectives for using these methods for designing dye molecules. 相似文献
25.
K De Witte N Rogge L Cherchye T Van Puyenbroeck 《The Journal of the Operational Research Society》2013,64(11):1595-1606
Teaching and research are widely regarded as the two key activities of academics. We propose a tailored version of the popular Data Envelopment Analysis methodology to evaluate the overall performance of university faculty. The methodology enables accounting for the potential presence of economies of scope between the teaching and research activities. It is illustrated with a dataset of professors working at a Business and Administration department of a university college. The estimation results reveal that overall the performance scores of faculty decrease if we allow for spillovers from research to teaching and vice-versa. 相似文献
26.
Sellier H Lansbergen GP Caro J Rogge S Collaert N Ferain I Jurczak M Biesemans S 《Physical review letters》2006,97(20):206805
We report on spectroscopy of a single dopant atom in silicon by resonant tunneling between source and drain of a gated nanowire etched from silicon on insulator. The electronic states of this dopant isolated in the channel appear as resonances in the low temperature conductance at energies below the conduction band edge. We observe the two possible charge states successively occupied by spin-up and spin-down electrons under magnetic field. The first resonance is consistent with the binding energy of the neutral D0 state of an arsenic donor. The second resonance shows a reduced charging energy due to the electrostatic coupling of the charged D- state with electrodes. Excited states and Zeeman splitting under magnetic field present large energies potentially useful to build atomic scale devices. 相似文献
27.
We present a variable temperature scanning tunneling microscopy and spectroscopy study of the Si(553)-Au atomic chain reconstruction. This quasi-one-dimensional system undergoes at least two charge density wave (CDW) transitions, which can be attributed to electronic instabilities in the fractionally filled 1D bands of the high-symmetry phase. Upon cooling, Si(553)-Au first undergoes a single-band Peierls distortion, resulting in period doubling along the chains. This Peierls state is ultimately overcome by a competing x3 CDW, which is accompanied by a x2 periodicity in between the chains. These locked-in periodicities indicate small charge transfer between the nearly 1/2-filled and 1/4-filled bands. The presence and the mobility of atomic-scale dislocations in the x3 CDW state indicates the possibility of manipulating phase solitons carrying a (spin, charge) of (1/2, +/- e/3) or (0, +/-2e/3). 相似文献
28.
This paper builds on Van Puyenbroeck and Rogge's (2017) ‘indirect’ multiplicative Benefit-of-the-Doubt (BoD) index number framework, in which the linear, data-driven BoD-model is used to estimate the importance of various sub-indicators within a geometric composite index (CI). We present an integrated framework that combines optimistic and pessimistic BoD-based weighting that enables to (1) establish the degree of unbalance in countries’ policy portfolio mix, (2) identify multiple underlying factors to explain inter-temporal evolution, and (3) explain for differences in country policy performances under the different weighting schemes following a multiplicative Bortkiewicz decomposition. In doing so, we use alternative optimistic and pessimistic BoD-models as existing models suffer from potential drawbacks in the identification of a country's comparative strengths and weaknesses. We illustrate our results with social inclusion data for the EU-countries for the period 2008-2013. 相似文献
29.
30.
Dieter Naumann Christian Schultz Jens Born Fritz Rogge Harald Labischinski 《Mikrochimica acta》1988,94(1-6):379-383
FT-IR and X-ray techniques were used to get an insight into the structure of synthetic Salmonella lipid A membranes. While FT-IR was sensitively providing structure information at the molecular level from different parts of the molecule, X-ray scattering gave data on long-range order phenomena and on fatty acid chain packing pattern. The lipid A membranes exhibited lamellar structures throughout the temperature range of 4°C to 60°C and showed up to three temperature induced transitions. The main transitionT
3 at 47°C was assigned to anL
–L
transition. The weak features atT
1 andT
2 localized between 15 and 40°C seemed to be connected to packing phenomena of lipid A aggregates within the distorted lattice. 相似文献