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861.
862.
Summary We study Sobolev space functions with prescribed growth properties on large spheres. In particular, we prove a weighted Poincaré
type inequality for such functions. An extension to weighted Sobolev spaces is sketched.
Sunto Si studiano funzioni che appartengono a certi spazi di Sobolev e che hanno crescita assegnata su sfere di grande raggio. Per tali funzioni si dimostra una disuguaglianza di tipo Poincaré con peso. Si indica inoltre anche una estensione di tale risultato a funzioni in spazi di Sobolev con peso.相似文献
863.
864.
A technique is proposed for improving the accuracy of the heat of fusion of semicrystalline polymers by DSC. The results of three commercially available instruments are compared. 相似文献
865.
866.
867.
超软X射线流气式正比计数管 总被引:2,自引:0,他引:2
介绍了一种用于测量183~933eV超软X射线的圆柱形、侧窗式、流气式正比计数管,工作气体是0.11MPa的P-10气体或氦气-丙烷混合气体。计数管内径为φ25mm,直径为φ0.3mm的入射窗是由厚度80~90μgcm~2聚乙烯甲醛制成的。该计数管的特点:(1)薄窗,对软X射线透过率高。(2)流气式,工作寿命长。(3)能量分辨率好。(4)计数率高(1×10~(14)个/s)。(5)可测能区宽(0.183~10keV)。(6)可以方便更换窗膜材料、厚度及窗口直径。近几年来该计数管已经为高强度低能X光源提供较好监测。 相似文献
868.
A. Mahoui J. Lapasset D. G. Sannikov J. Moret P. Saint Grégoire 《Zeitschrift für Physik B Condensed Matter》1995,99(4):543-549
The crystal structure [(C2H5)4N]2CuCl4 has been determined by X-ray diffraction at 243K. The room temperature phase (phase I) belongs to the space group P42/nm [1] whereas the low temperature phase (phase II) is orthorhombic and belongs to the space group Pnna. The phase transition at Tc=258K is of improper ferroelastic type and it is associated with the ordering of the CuCl4 2? and a partial ordering of the [(C2H5)4N]+ ions which are disordered in the high temperature tetragonal phase. At lower temperature, there occurs another instability which could correspond to a complete ordering in the crystal. 相似文献
869.
P. Davies 《Accreditation and quality assurance》1996,1(6):240-246
Laboratory accreditation is becoming increasingly accepted around the world as a means of identifying technically competent
laboratories. It is also being used as a mechanism for the acceptance of test data both nationally and internationally. The
concept and mechanisms of accreditation have been developed over the past 50 years. The first national laboratory accreditation
system appeared in Australia in 1947. This organisation, known as the National Association of Testing Authorities (NATA),
has since taken a leading role in developing accreditation practices that are now used world-wide in evaluating testing, measurement
and calibration laboratories. This paper examines the development of the world's first and largest laboratory accreditation
system, and looks at the difficulties and triumphs in gaining acceptance and recognition by government and industry of the
benefits of laboratory accreditation.
Received: 24 June 1996 Accepted: 25 June 1996 相似文献
870.
P. G. Baranov N. G. Romanov A. Hofstaetter A. Scharmann C. Schnorr F. J. Ahlers K. Pierz 《JETP Letters》1996,64(10):754-759
Two types of excitons, localized at opposite interfaces and characterized by different magnitudes of the exchange interactions
at the same radiation energies, are simultaneously in type-II GaAs/AlAs superlattices. It is shown that the additional long-wavelength
luminescence line in superlattices grown with growth interruptions after the GaAs layers is due to the recombination of an
exciton localized at an inverted interface in regions where the quantum-well width is increased by one monolayer.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 10, 701–706 (25 November 1996) 相似文献