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991.
992.
L. S. de C. Oliveira M. T. X. Silva A. Vasquez J. A. H. da Jornada 《Hyperfine Interactions》1991,66(1-4):267-270
An exploratory Mössbauer spectroscopy study of the Fe-C system in the C rich region, prepared by high pressure-high temperature treatment near the graphite-diamond stability line, was made. The results obtained for the different processing conditions give no evidence of Fe intercalation in graphite. The presence of some water in the cell produced hydrated Fe complexes, which can explain the deleterious effect of water or hydrogen in the high pressure diamond synthesis. 相似文献
993.
Eggenhffner R. Masini R. Bellingeri E. Cimberle M. R. Ferdeghini C. Costa G. A. Kaiser E. Signorelli E. 《Il Nuovo Cimento D》1994,16(10):1659-1664
Il Nuovo Cimento D - The formation of Hg-based HTSC materials was investigated through the development of non-conventional techniques. The former was based on a singlestep synthesis at temperatures... 相似文献
994.
Transition temperatures (TN1) from the nematic lyotropic liquid-crystalline phase to the isotropic phase were measured for the system cetyltrimethylammonium bromide (CTAB) water in the presence of small amounts of 3-stilbene carboxylic acid (3SC), 4-stilbene carboxylic acid (4SC) and Δ2/2'-bi-(2H-l,4-benzothiazine) (BT). TNI, increases as a function of trans-3SC or trans-4SC concentration, ranging from 01 to 08 wt %, by up to 12°C. A further increase in TNI between 2 and 5°C can be achieved by photochemically converting the solubilized trans stilbene derivatives to the cis isomers. Irradiation of a trans-3SC containing sample at a temperature just above TNl leads to a light-induced phase transition to the lyotropic liquid-crystalline phase. Solubilization of trans-BT causes a slight decrease of TNI while photoisomerization to cis-BT increases TNI by 1°C. 相似文献
995.
M A Alliegro K D Dyer E J Cragoe B M Glaser M C Alliegro 《Journal of chromatography. A》1992,582(1-2):217-223
An assay for amiloride was devised for efficient use with the wide variety of analogues available. Amiloride was extracted from 1-ml plasma samples by elution from a C8 preparative column with 6% acetonitrile-45% methanol-5.4% acetic acid, adjusted to pH 4.0 with trimethylamine. Samples were lyophilized, resuspended in 50% methanol, filtered through 0.22-microns Spin-X cartridges, applied to a reversed-phase C18 column, and eluted in a 0-50% acetonitrile gradient in 0.4% acetic acid, pH 4.5 (1.2 ml/min). Detection by ultraviolet absorbance at 360 nm was linear from 1 to 1000 ng. Versatility of the method was demonstrated with the analogues benzamil, 6-hydro-, 6-iodo-, 5-hexamethylene-, and 5-chlorobenzyl-2',4'-dimethylbenzyl-amiloride. 相似文献
996.
Stirling渐进公式的一个新的构造证明 总被引:3,自引:1,他引:2
本文用简易的分析工具,对n!给出了一个精确等式,从而导出Stirling渐近公式(2)的一个新的简短证明. 相似文献
997.
998.
Observed neutrino mixing can be described by a tribimaximal MNS matrix. The resulting neutrino mass matrix in the basis of a diagonal charged lepton mass matrix is both 2–3 symmetric and magic. By a magic matrix, I mean one whose row sums and column sums are all identical. I study what happens if 2–3 symmetry is broken but the magic symmetry is kept intact. In that case, the mixing matrix is parameterized by a single complex parameter Ue3, in a form discussed recently by Bjorken, Harrison, and Scott. 相似文献
999.
M. Froese C. Champagne J. R. Crespo López-Urrutia S. Epp G. Gwinner A. Lapierre J. Pfister G. Sikler J. Ullrich J. Dilling 《Hyperfine Interactions》2006,173(1-3):85-92
The precision of atomic mass measurements in a Penning trap is directly proportional to the charge state q of the ion and,
hence, can be increased by using highly charged ions (HCI). For this reason, charge breeding with an electron beam ion trap
(EBIT) is employed at TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN) on-line facility in Vancouver, Canada. By bombarding
the injected and trapped singly charged ions with an intense beam of electrons, the charge state of the ions is rapidly increased
inside the EBIT. To be compatible with the on-line requirements of short-lived isotopes, very high electron beam current densities
are needed. The TITAN EBIT includes a 6 Tesla superconducting magnet and is designed to have electron beam currents and energies
of up to 5 A and 60 keV, respectively. Once operational at full capacity, most species can be bred into a He-like configuration
within tens of ms. Subsequently, the HCI are extracted, pass a Wien filter to reduce isobaric contamination, are cooled, and
injected into a precision Penning trap for mass measurement. We will present the first results and current status of the TITAN
EBIT, which has recently been moved to TRIUMF after assembly and commissioning at the Max-Planck-Institute (MPI) for Nuclear
Physics in Heidelberg, Germany. 相似文献
1000.
The synthesis and complexation properties of 1,4-dimethyl-8-[2-(2-pyridyl)ethyl]-1,4,8,11-tetraazacyclotetra-decane ( 2 ) are described. This ligand forms with Cu2+ two complexes, one of which has been characterized by X-ray structure analysis. The structural, spectral, and kinetic studies indicate that the two Cu2+ complexes are isomers with the macrocycle in the trans-III and trans-I configuration. The rate of the interconversion of the trans-I isomer to the thermodynamically more stable trans-III species is proportional to [OH?]. A mechanism for this reaction is proposed. 相似文献