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101.
Gregory A. Cutter 《Analytica chimica acta》1978,98(1):59-66
A method is described for the determination in natural waters of selenite, selenate, dimethyl selenide, and dimethyl diselenide. The detection limits are in the parts per trillion range. The volatile methyl species are removed from the sample with a stripping gas. The inorganic forms are selectively reduced to the hydride, and also stripped from the sample. A liquid nitrogen trap is used to collect both the selenides and the generated hydrides. Separation of the methyl species is accomplished by gas chromatography. All the species are detected by an atomic absorption spectrometer equipped with a quartz tube furnace. 相似文献
102.
Some New azo sulphonamide derivatives containing 8-hydroxyquinoline moiety and their complexes with some transition metal ions vz. Fe+3, Co+2, Ni+2, Cu+2, and Hg+2 have been prepared and characterised. The stereochemistry as well as the type of bonding around the metal ions were determined on the basis of microanalysis, IR and UV-VIS spectra, conductivity and magnetic moment measurements; the thermal behaviour of the complexes was also studied. The metal ions coordinate exclusively to the 8-hydroxyquinoline moiety. The biological activity of the complexes was tested against a number of bacteria. Chelation of the metal ions to the ligands induces a remarkable increase in their antimicrobial activity. 相似文献
103.
Growth of TGS crystals using uniaxially solution‐crystallization method of Sankaranarayanan‐Ramasamy
N. Balamurugan M. Lenin G. Bhagavannarayana P. Ramasamy 《Crystal Research and Technology》2007,42(2):151-156
The recently discovered crystal growth method called uniaxially solution‐crystallization method of Sankaranarayanan–Ramasamy (SR) is modified in some aspects and used for growth of triglycine sulphate (TGS) crystals. The modification leads to the simplicity, reduction of cost and avoided the temperature fluctuations. The 〈010〉 direction of TGS is very important and used for fabrication of infrared detectors. Using this method, the 〈001〉, 〈010〉 directional crystals of TGS were successfully grown in a glass crystallizer. The grown crystal was characterized by HRXRD, UV‐Visible and dielectric studies. The results prove the suitability of the modified SR method for oriented TGS crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
104.
E. Marinari G. Parisi D. Rossetti 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(4):495-500
We study the dynamical behavior of the Sherrington Kirkpatrick model. Thanks to the APE supercomputer we are able to analyze
large lattice volumes, and to investigate the low T region. We present a new and precise determination of the remnant magnetization and of its time decay exponent, of the energy
time decay exponent, and we discuss aging phenomena in the model. We exclude validity of naive aging, and propose different
options that fit the numerical data.
Received: 14 August 1997 / Revised: 2 December 1997 / Accepted: 30 January 1998 相似文献
105.
Summary The ferromagnetic behaviour is analysed in terms of a new physical mechanism based on superradiance. We show that if thed-electrons’ plasma is in a superradiant state, then ferromagnetism arises in transition metals such as Fe, Co and Ni. Satisfactory
agreement with experimental information on several important quantities is obtained. 相似文献
106.
G. Onori 《Il Nuovo Cimento D》1989,11(10):1467-1479
Summary The temperature dependence of the adiabatic compressibility of solution of lithium chloride in water has been determined for
different solute concentrations from 4 to 8 wt%. A simple model has been employed to interpret the data in terms of the size
and compressibility of the hydration shells. The data have been compared with previously obtained compressibility data for
NaCl, KCl and CsCl aqueous solutions.
To speed up publication, the author of this paper has agreed to not receive the proofs for correction. 相似文献
107.
Summary Polycrystalline thin films of the ferromagnetic semiconductor HgCr2Se4 have been prepared for the first time on insulating MgAl2O4 single-crystal substrates by molecular-beam deposition and subsequent annealing with HgSe. The optimum conditions for preparing
single-phase thin films of HgCr2Se4 were obtained. The magnetoresistance and Hall effects of these films were measured from 77 to 295 K in magnetic fields up
to 1.19·106 A/m. It becomes evident that these electrical properties of the films are affected by the interdiffusion layers in the films
near the substrates or the magnetically disordered layers such as amorphous or grain boundaries in the films.
Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16,
1982. 相似文献
108.
J. Schnelzer R. Montbrun B. Pilawa G. Fischer G. Venturini E. Dormann 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(1):11-23
Zero-field nuclear magnetic resonance (NMR) of all NMR isotopes (175Lu, 55Mn, 73Ge, 69,71Ga) in LuMn6Ge6-xGax, 0 ≤ x ≤ 1, is used to monitor the variation of the hyperfine interaction with the sequence of antiferromagnetic - helimagnetic
- ferromagnetic arrangement of the manganese moments of subsequent Kagomé net planes achieved by variation of the gallium
content x. According to the 55Mn-NMR results, the local Mn moment varies by less than ±5% in this series. 175Lu-NMR proves canting of the antiferromagnetic sublattices in LuMn6Ge6. The anisotropy of the Ge magnetic hyperfine interaction decreases with increasing separation from the hexagonal Lu plane,
whereas the absolute value of its isotropic part is only qualitatively correlated with the average separation of the six nearest
Mn neighbours. Due to the anisotropic magnetic and electric hyperfine interaction at Ge and Ga sites, the non-collinear magnetic
structures are clearly reflected by the NMR spectra, which are described quantitatively in this contribution. The preferred
Mn moment direction rotates away from the c direction with x.
The conduction or bonding electron spin polarization at the Ga nuclei is increased by 35–80% compared to the Ge nuclei. We
argue that this is related with the variation of the magnetic order with the Ga content. 相似文献
109.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1475-1490
Acrylamide/vinyl acetate and acrylamide/vinyl propionate copolymers were prepared by solution polymerization using benzoyl peroxide as the initiator. The copolymer composition was determined from the percent nitrogen in the copolymers. The stability constants and related thermodynamic parameters (e.g., ΔG°, ΔH°, and ΔS°,) of the interpolymer complexes with Poly(ethyleneimine) were determined by using Osada's method. These parameters have been correlated with the sequence distribution of monomer units in the copolymer chains which were obtained from 13C{1H} NMR spectroscopy. The sequence distribution of the comonomer units in the copolymer chains influence the association between the copolymers and the polyelectrolyte which is reflected on the stability of the interpolymer complexes. 相似文献
110.
Deciding whether a planar graph (even of maximum degree 4) is 3-colorable is NP-complete. Determining subclasses of planar graphs being 3-colorable has a long history, but since Grötzsch’s result that triangle-free planar graphs are such, most of the effort was focused to solving Havel’s and Steinberg’s conjectures. In this paper, we prove that every planar graph obtained as a subgraph of the medial graph of any bipartite plane graph is 3-choosable. These graphs are allowed to have close triangles (even incident), and have no short cycles forbidden, hence representing an entirely different class than the graphs inferred by the above mentioned conjectures. 相似文献