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排序方式: 共有294条查询结果,搜索用时 15 毫秒
1.
M. I. Al-Jarallah Fazal-ur-Rehman F. Abu-Jarad A. Al-Shukri 《Radiation measurements》2003,36(1-6):445-448
An indoor radon survey of a total of 269 dwellings, with one dosimeter per house, distributed in four Saudi Arabian cities was carried out. The objective of this survey was to carry out indoor radon measurements of two cities in the Eastern Province, Khafji and Hafr Al-Batin and to compare this with two cities in the Western Province, Al-Madina and Taif. The survey provides additional information about indoor radon concentrations in Saudi Arabia. The results of the survey in these cities showed that the overall minimum, maximum and average radon concentration were 7,137 and 30 Bqm−3, respectively. The lowest average radon concentration (20 Bqm−3) was found in Hafr Al-Batin, while the highest average concentration was found in Khafji (40 Bqm−3). 相似文献
2.
M. Aglietta B. Alessandro P. Antonioli F. Arneodo L. Bergamasco A. Campos Fauth C. Castagnoli A. Castellina C. Cattadori A. Chiavassa et al. 《Il Nuovo Cimento C》1992,15(4):441-446
Summary A search for cosmic gamma-ray bursts in the GeV energy range has been performed by means of the EAS-TOP Extensive Air Shower
array at Campo Imperatore (Gran Sasso Laboratories) during the period March–December 1990. In 2566.5 hours of measurement
the obtained upper limit to the rate of bursts of amplitude >2% of the cosmic-ray intensity and time duration τ=1 s, isR≤7.9y−1 (90% c.l.). Assuming for γ-rays a differential energy spectrumS(E
0
)≈E
0
−2.5
, the corresponding upper limit to the energy flux of γ-rays with energy >5 GeV in bursts of duration τ≤1 s is Φ<8.3·10−5erg cm−2. 相似文献
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采用溶胶 -凝胶法合成了YAG∶Nd ,Re(Re =Pr,Sm ,Dy)系列化合物 ,研究了它们的光谱性质 .结果表明 :Pr3 + ,Sm3 + ,Dy3 + 对YAG基质中Nd3 + 的发光具有猝灭作用 ,属于有害杂质 ,在激光晶体原料中必须除去 相似文献
7.
稀土在鼠肝中的物种分布 总被引:23,自引:0,他引:23
采用 ICP-MS、微量蛋白层析分离技术 ,研究了长时间、低剂量混合稀土及短时间、高剂量硝酸镧分别对大鼠及小鼠作用后 ,稀土在鼠肝中的代谢累积及其物种分布 .结果表明 ,鼠肝中各稀土含量随给药剂量的增加而增大 ,其累积速度大小顺序为 La>Ce>Nd>Pr;经柱层析分离未得到与稀土特异结合的鼠肝蛋白 ;稀土可与多种鼠肝蛋白 (包括多种重要的酶 )结合 ,在一定条件下 ,稀土与其结合蛋白可发生解离 相似文献
8.
Antonio Doménech María Teresa Doménech‐Carbó Howell G. M. Edwards 《Electroanalysis》2007,19(18):1890-1900
Multivariate chemometric methods are applied for identifying earth pigments from square‐wave voltammetric measurements performed at pigment‐modified paraffin‐impregnated graphite electrodes allowing for a separation between hematite‐based earths, French ochres, Spanish ochres, siennas, umbers and green earths. This methodology is applied to the identification of the pigments in samples from the ceiling frescoes of Antonio Palomino (dated 1707) in the vaulted nave of the Sant Joan del Mercat church in Valencia (Spain). These frescoes suffered considerable damage by fire during the Spanish Civil War in 1936, resulting in severe chemical and chromatic alterations. Electrochemical data, supported by scanning electron microscopy/energy dispersive X‐ray microanalysis and Raman spectroscopy, indicate that thermal stress induced the transformation of goethite‐based yellow ochres into hematite and magnetite. 相似文献
9.
方俊 《中国科学B辑(英文版)》1991,(1)
In the linear inversion of the radial variation of the parameters of the Earth by usingthe observed frequencies of various normal modes of free oscillation of the earth, it is neces-sary to know the values of the kernels of the parameters ρ, μ and λ. This paper describesthe methods of the derivation of the formulas of these kernels. This is the first part of thepaper in which only the toroidal oscillations are considered. They are much simpler thanthose of the spheroidal ones, that we will consider in the second part of the paper. The data of the two types of oscillations are equally important in the solution of theinversion problem, and should be employed simultaneously, and we know that the toroidaloscillations are much simpler than the spheroidal ones, it seems wise to divide the whole programof the inversion problem into steps: first, by employing the toroidal data to correct the twoparameters ρ and μ in the mantle, then by using the spheroidal data to correct the remain-ing parameters, i.e. th 相似文献
10.
Evan M. Benbow 《Journal of solid state chemistry》2006,179(12):3989-3996
Eighteen new intermetallic compounds RMn2TrxZn20−x (2<x<7; R=rare-earth metal; Tr=Al, In) were synthesized using low-melting mixtures of (Tr/Zn) as a solvent. Structural refinement using single-crystal X-ray diffraction data shows that the compounds are substituted variants of the cubic CeCr2Al20-type structure (Fd-3m, Z=8; unit cell parameters vary from a=14.1152(3)Å for YbMn2Al5.3Zn14.7 to a=14.8125(4)Å for SmMn2In5.9Zn14.1). The Zn and Tr elements show site preferences in the indium compounds, but not in the aluminum analogs. The substitution of trielide element for zinc modifies the valence electron count of the compounds to allow for the incorporation of Mn into the structure. Magnetic susceptibility data show no evidence of magnetic ordering down to 3 K. 相似文献