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1.
In order to establish a correlation between the different types of soils using hyperfine and magnetic parameters as climatic and environmental proxies, we have studied the differentiation of soil developed around 38.5° south latitude, in the central Pampas of Argentina, by means of Mössbauer spectroscopy and environmental magnetism. The soils transect (climosequence) investigated stretches from the drier west (around 64° W) to the more humid east (at around 59° W) in the Buenos Aires Province, covering a distance of 600 km. The soils studied developed during recent Holocene geologic times in a landscape characterized by small relict plateaus, slopes and depressions, dunes and prairies. The parent material consists of eolian sandy silts overlying calcrete layers. The low mean annual precipitation in the western parts of the region gives rise to soils without B-horizons, which limits the agricultural use of land. The preliminary results show an increase of the paramagnetic Fe3+ relative concentration from west to east in the soils investigated. Magnetite is probably mainly responsible for the observed enhancement in the susceptibility values. The magnetic response of the parent material is similar to that of the loess part of the previously investigated loess–paleosol sequences of the Argentine loess plateau. 相似文献
2.
Balbo-Block M Bartel C Lentz D Preugschat D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(4):881-893
The radical alkylation of tetraethylammonium pentacarbonyl(cyano)chromate 1 yielded the halogenated ethyl isocyanide complexes [(CO)5Cr(CN-CClX-CClYF)] 3 (a, X= Cl, Y= F; b, X = F, Y= F and c, X=Y= Cl). Dehalogenation of 3 using zinc in diethyl ether gave [(CO)5Cr(CN-CX=CFY)] 4. The compounds 4a, b reacted with various nucleophiles exclusively at the difluoromethylene group. The unstable phosphorane 5, which is formed on reaction of 4b with trimethylphosphane, decomposed thermally and on hydrolysis yielding pentacarbonyl(1,2-difluoroethenyl isocyanide)chromium (6). The cyano substituent can be introduced in the beta position of the isocyanide function by reaction of 4a, b with potassium cyanide, leading to the formation of [(CO)5Cr(CN-CX=CF-CN)] (7). Reactions of 4a, b with organolithium or organomagnesium compounds yielded [(CO)5Cr(CN-CX=CF-R)] (8) and [(CO)5Cr(CN-CF=CF-C...C-CF=CF-NC)Cr(CO)5] (10). The trimethylsilyl group in 8a, b, d could be removed by a solution of potassium carbonate in methanol leading to [(CO)5Cr(CN-CX=CF-Cn-H)] (11) (n=2,4). Octacarbonyldicobalt reacted with 8e under coordination of the C-C triple bond to the hexacarbonyldicobalt fragment, resulting in the cluster compound 12. The crystal and molecular structure of 8i, 11 a, b, and 12 were elucidated by X-ray crystallography. The alkenyl and alkynyl isocyanides CN-CCl=CF2 (13a), CN-CF=CF2 (13b), CN-CCl=CClF (13c), CN-CF=CFH (14), CN-CC-H (15), CN-CC-CN (16), and CN-CCl=CF-CN (17) were obtained by flash vacuum pyrolysis of 4a, 4b, 4c, 6, and 7a, respectively. 相似文献
3.
Winfried Mientus Hans-Georg Bartel Werner Haberditzl Hans-Joachim Spitzer 《Monatshefte für Chemie / Chemical Monthly》1980,111(3):597-606
A normalization of the wave functions by means of the theoretical exact Multiple-Scattering-(MS)-formalism is discussed within the framework of the SCF-X-SW-method. For the atomic and extramolecular regions the integrals of normalization can be easily determined and the results can be described by the corresponding electronic charges. The calculation of the integral of the interatomic region is problematic. The needful volume integration is only necessary to theGreen's functions of the wave functions and can be solved by means of the residual theory. The further analytical calculation of the surface integrals leads to a complicated formalism which can be numerically evaluated. 相似文献
4.
Diphenylphosphorylazide N3P(O)(OPh)2 reacts with Pt(PPh3)3, Pt(PPh3)2(C2H4), trans-RhCl(CO)(PPh3)2, Ru(CO)3(PPh3)2, CoCl2(PPh3)2 and CuCl(PPh3)2 to give the azido complexes Pt(PPh3)2(N3)R, Pt(PPh3)2(N3)2R2, the urylene complex RhCl(PPh3)2(RNCONR) and the phosphine imine complexes Ru(CO)3(RPPh3)2, CoCl2(RNPPh3)2, CuCl(RNPPh3)2, respectively, (RP(O)(OPh)2). The oxidative addition of n-C6F13SO2N3 to Pt(PPh3)4 and Pt(PPh3)2(C2H4) affords the complexes Pt(PPh3)2(N3)R and Pt(PPh3)2(N3)2R2, respectively, (RSO2C6F13. The compounds are characterized by elemental analysis and by their IR spectra. 相似文献
5.
The single-particle densityρ(r) of a system of fermions can be calculated in a tractable way as the Laplace inverse of the Bloch density describing the system. The complex integrals involved can be solved very easily by the saddle-point method. The semiclassical nature of this approach is illustrated in the simple example of the single-particle level density of a harmonic oscillator potential. It is then applied to calculate the total energy of particles in different mean field potentials. The exact Bloch density being generally unknown, different approximate forms are used in our calculations which correspond to a partial resummation of the Wigner-Kirkwood?-expansion. The resulting local densities reproduce the exact density distributions on the average, without quantal oscillations. They are well defined everywhere, even beyond the classical turning point, in contrast to the original Wigner-Kirkwood approach. 相似文献
6.
J. Bartel D. Boosé K. Dietrich K. Pomorski J. Richert 《Zeitschrift für Physik A Hadrons and Nuclei》1991,339(1):155-170
Giant shape vibrations of fission fragments are described in a simple model which is based on nuclear transport theory. The friction and inertial parameters are calculated within the linear response and cranking theory, respectively. The initial conditions are chosen in the scission region following the conventional picture of the fission process at low energy. The emission of electromagnetic radiation by the form vibration is treated classically.Dedicated to Prof. Dr. H.J. Mang on the occasion of his 60th birthday 相似文献
7.
Motivated by the high potential of shape memory alloys (SMA) in several industrial applications, we investigate the material response under cyclic loading. In particular, the focus is set on the modelling of functional fatigue, which results in the deterioration of the specific features of SMA. In fact, functional fatigue restricts SMA in terms of its applicability for real structures and workpieces. This necessitates the development of material models which take this phenomenon into account. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
Bartel L. van der Waerden 《Mathematische Annalen》1930,102(1):337-362
Ohne Zusammenfassung 相似文献
9.
Vossen A Seidl R Adachi I Aihara H Aushev T Balagura V Bartel W Bischofberger M Bondar A Bračko M Browder TE Chang MC Chen A Chen P Cheon BG Cho K Choi Y Eidelman S Feindt M Gaur V Gabyshev N Garmash A Golob B Perdekamp MG Haba J Hayasaka K Horii Y Hoshi Y Hou WS Hyun HJ Inami K Ishikawa A Iwabuchi M Iwasaki Y Iwashita T Joshi NJ Kichimi H Kim HO Kim MJ Ko BR Kumita T Lange JS Lee MJ Lee SH Leitgab M Li Y Liu C Liventsev D Louvot R McOnie S Miyata H Miyazaki Y Mizuk R Mohanty GB Nakano E 《Physical review letters》2011,107(7):072004
The interference fragmentation function translates the fragmentation of a quark with a transverse projection of the spin into an azimuthal asymmetry of two final-state hadrons. In e(+)e(-) annihilation the product of two interference fragmentation functions is measured. We report nonzero asymmetries for pairs of charge-ordered π(+)π(-) pairs, which indicate a significant interference fragmentation function in this channel. The results are obtained from a 672 fb(-1) data sample that contains 711 × 10(6) π(+)π(-) pairs and was collected at and near the Υ(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. 相似文献
10.
Semiclassical expansions derived in the framework of the Extended Thomas-Fermi approach for the kinetic energy density τ(
r) and the spin-orbit density
J(
r) as functions of the local density ρ(
r) are used to determine the central nuclear potentials V
n(
r) and V
p(
r) of the neutron and proton distribution for effective interactions of the Skyrme type. We demonstrate that the convergence
of the resulting semiclassical expansions for these potentials is fast and that they reproduce quite accurately the corresponding
Hartree-Fock average fields.
Received: 12 February 2000 / Accepted: 14 March 2002 相似文献