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91.
Radioactive substances may be present in air as dust, fume or vapour. very often attached to the natural aerosol. Many nuclides are produced in the upper atmosphere by the interaction of cosmic rays and atmospheric gases, and as a result of nuclear bomb tests. Radio-iodine has also been released accidentally from nuclear reactors.

Radioactive vapours and aerosols have been used to study mass-transfer between airstreams and surfaces.

The results are applicable to problems such as the travel and deposition of spores and pollen.  相似文献   
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Background  

Nicotinic acetylcholine receptors (nAChRs) are pentameric proteins that are important drug targets for a variety of diseases including Alzheimer's, schizophrenia and various forms of epilepsy. One of the most intensively studied nAChR subunits in recent years has been α7. This subunit can form functional homomeric pentamers (α7)5, which can make interpretation of physiological and structural data much simpler. The growing amount of structural, pharmacological and physiological data for these receptors indicates the need for a dedicated and accurate database to provide a means to access this information in a coherent manner.  相似文献   
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Dykman  M. I.  Mannella  R.  McClintock  P. V. E.  Stein  N. D.  Luchinsky  D. G.  Short  H. E. 《Il Nuovo Cimento D》1995,17(7-8):755-764
Il Nuovo Cimento D - The response of an overdamped system to quasi-monochromatic (high-frequency narrow band) noise (QMN) has been investigated by means of analogue electronic experiments....  相似文献   
96.
The influence of magnesium doping on the properties of tetrakis(thiourea)nickel(II) chloride crystals has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the alkaline earth metal are observed by scanning electron microscopy. The incorporation of Mg(II) into the crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The crystal is further characterized by Kurtz powder technique and dielectric studies.  相似文献   
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The fluid dynamics behavior of shallow fluidized and vibrofluidized beds operating with fresh leaves was investigated with the aim of exploring drying applications in a modified conveyor belt (MCB) system,which may be operated in a fixedor fluidized-bed mode.Leaves of the specimens Duranta repens,Schinus molle,Coleus barbatus,Buxus sempervirens,and Bougainvillea spectabilis were tested with a range of sphericities from 0.063 to 0.213,bulk densities from 0.038 to 0.251 g/cm 3,apparent densities from 0.52 to ...  相似文献   
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We compute the pressure of a finite-density quark-gluon plasma at zero temperature to leading order in hard-thermal-loop perturbation theory, which includes the fermionic excitations and Landau damping. The result is compared with the weak-coupling expansion for finite positive chemical potential &mgr; through order alpha(2)(s) and with a quasiparticle model with a mass depending on &mgr;.  相似文献   
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