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961.
Summary The potential of liquid chromatography-mass spectrometry (LC-MS) has been studied for the simultaneous determination of sixteen carbamate and organophosphorus pesticides in honeybees using a traditional sample preparation protocol based on acetone extraction and dichloromethane partitioning. The performances of both atmospheric pressure chemical ionization (APCI) and electrospray (ES) interfaces were compared. APCI offered better sensitivity and specificity for a higher range of pesticides. Limits of quantification were from 0.01 to 0.17 mg kg–1, at which recoveries obtained were between 64 and 93%, except for pirimicarb that was at 13%, with relative standard deviations ranging from 7 to 20%. Fenitrothion, fenoxycarb, methiocarb and phoxim were found in bees from Valencian Community beehives at concentrations between 0.03 and 3.75 mg kg–1. 相似文献
962.
963.
Y. Nagame M. Asai H. Haba K. Tsukada I. Nishinaka S. Goto A. Toyoshima K. Akiyama M. Sakama Y. L. Zhao S. Ichikawa H. Nakahara 《Physics of Atomic Nuclei》2003,66(6):1131-1136
The present status of heavy element nuclear chemistry research at JAERI (Japan Atomic Energy Research Institute) is reviewed. Production of the transactinide nuclei 261Rf and 262Db via the reactions of 248Cm(18O,5n) and 248Cm(19F, 5n), respectively, at the JAERI tandem accelerator is reported. Study of the aqueous chemistry of Rf is being carried out with a newly developed rapid ion-exchange separation apparatus. Anion-exchange behavior of Rf in acidic solution is briefly discussed. Recent experimental results on decay studies of neutron-deficient actinide nuclei using the gas-jet coupled JAERI-ISOL are given. We also discuss characteristics of nuclear deformation properties at scission in symmetric and asymmetric fission of actinides. Prospects for studies in the near future are briefly considered. 相似文献
964.
S. Y. Wang S. C. Chen S. D. Lin C. J. Lin C. P. Lee 《Infrared Physics & Technology》2003,44(5-6):527-532
InAs/GaAs quantum dot infrared photodetectors were fabricated with quantum dots grown at three different temperatures. Large detection wavelength shift (5–14.5 μm) was demonstrated by changing 40 degrees of the epitaxy temperature. The smaller quantum dots grown at lower temperature generate 14.5 μm responses. The detectivity of the normal incident 15 μm QDIP at 77 K is 3 × 108 cm Hz1/2/W. A three-color detector was also demonstrated with quantum dots grown at medium temperature. The three-color detection comes from two groups of different sizes of dots within one QD layer. This new type of multicolor detector shows unique temperature tuning behavior that was never reported before. 相似文献
965.
在Brueckner-Hartree-Fock理论框架内, 研究了同位旋非对称核物质中质子和中子单粒子势的动量相关性及其随同位旋非对称度的变化, 在此基础上计算了同位旋对称势, 并讨论了三体核力的影响. 结果表明同位旋对称势对于同位旋非对称度的依赖性很弱, 但对于动量和密度均有较强的依赖性. 当密度固定时, 同位旋对称势随动量增加而减小. 尽管三体核力对于质子和中子单粒子势的动量相关性有较大影响, 但对同位旋对称势的影响很小. 还与目前重离子碰撞输运理论模型中所使用的各种参数化的唯象对称势进行了比较. 相似文献
966.
Y. V. Bludov A. J. Kirichenko A. E. Kogut V. V. Kutuzov V. A. Solodovnik 《Radiophysics and Quantum Electronics》2005,48(12):927-933
We experimentally study a new type of resonator, namely, a barrel-shaped dielectric resonator with whispering-gallery modes
which is formed by the cutting dielectric hemisphere. Compared with a hemispherical dielectric resonator, the E type oscillation
spectrum of such a resonator is rarefied with respect to the azimuthal index. Comparative analysis of the electromagnetic
characteristics of the barrel-shaped dielectric resonator and half-disk dielectric resonators shows that the radiation losses
of the mode energy from the spherical surface are smaller than those from the cylindrical surface. This fact stimulates the
high values of the internal Q-factor of modes of the barrel-shaped dielectric resonator.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 12, pp. 1041–1048, December 2005. 相似文献
967.
W. Shi Y.J. Ding C. Fang Q. Pan Q. Gu 《Applied Physics A: Materials Science & Processing》2003,77(3-4):567-570
The optimal corona-poling temperature of polymer films was accurately determined by measuring the temperature dependence of the in situ second-harmonic (SH) intensity profile under the applied poling electric field. The in situ SH intensity profile was first measured by probing both the surface voltages and the poling currents induced by surface/space charges for the corona-poled polymer films. Moreover, charge effects on the stability of the chromophore orientation were first studied by using the thermally stimulated discharge-current technique. PACS 72.20.Jv; 42.65.Ky; 73.61.Ph; 81.40.Tv 相似文献
968.
The frequency or dispersion relation for the least‐squares mixed formulation of the shallow‐water equations is analysed. We consider the use of different approximation spaces corresponding to co‐located and staggered meshes, respectively. The study includes the effect of Coriolis, and the dispersion properties are compared analytically and graphically with those of the mixed Galerkin formulation. Numerical solutions of a test problem to simulate slow Rossby modes illustrate the theoretical results. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
969.
X. Y. You 《Heat and Mass Transfer》2003,40(1-2):75-81
Active feedback control for the onset of Rayleigh-Bénard Convection in temperature-dependent-viscosity liquids is investigated.
In this paper, three major problems are addressed: (1) The results of Tang-Bau control are improved by considering the effects
of temperature-dependent viscosity; (2) A more efficient two-plate control strategy is presented. A phenomenon of coalescence
of the unstable modes is observed as the controller gain is large enough; (3) A simple way to estimate the critical Rayleigh
number under the effects of temperature-dependent viscosity is described. Numerical results show that the effects of temperature-dependent
viscosity on the critical Rayleigh number should be taken into account in some cases and the onset of Rayleigh-Bénard convection
can be effectively delayed or advanced by the active feedback control strategies studied here. 相似文献
970.