90 resultados para LEAD 210


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The spectral properties in different concentration of Yb ions (0.5-5 mol%)-doped silica glasses are explored in this paper. The glasses are prepared by traditional melting method. The absorption spectra and the fluorescent lifetime (tau(f)) are measured at room temperature and low temperature (18 K). The stimulated cross-section (sigma(emi)) and potential laser properties (beta(min), I-sat, I-min) are calculated based on the absorption spectra. The absorption cross-section (sigma(abs)) are in the range 1.08 x 10(-20) - 1.18 x 10(-20) cm(2) in different glasses, the fluorescence lifetime (tau(f)) change from 1.9 to 1.2 ms with the increase of Yb3+ concentration. The potential laser properties indicate that lead silica glass is a good host for highly Yb ion doping glass. (c) 2005 Elsevier B.V. All rights reserved.

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The electronic structures and absorption spectra for the perfect PbMoO4 crystal and the crystal containing lead vacancy V-Pb(2-) with lattice structure optimized are calculated using density functional theory code CASTEP. The calculated absorption spectra of the PbMoO4 crystal containing V-Pb(2-) exhibit three absorption bands peaking at 2.0 eV (620 nm), 3.0 eV (413 run) and 3.3 eV (375 nm), which are in good agreement with experimental values. The theory predicts that the 390 nm, 430 nm and 580 run absorption bands are related to the existence of V-Pb(2-) in the PbMoO4 crystal.

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We report the first demonstration, to our knowledge, of the femtosecond laser operation by using a new alloyed Yb:GYSO crystal as the gain medium. With a 5 at. % Yb3+-doped sample and chirped mirrors for dispersion compensation, we obtained pulses as short as 210 fs at the center wavelength of 1093 nm. The average mode-locking power is 300 mW, and the pulse repetition frequency is 80 MHz. (C) 2008 Optical Society of America

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博优210是华南晚籼杂交稻的“高优”组合,1993和1994年通过省区试和大面积试种表证,1995年5月通过广东省品种委员会审定,具国内同类型品种领先水平。其主要技术经济指标:1、米质1级至特2级(达出口标准),精米率75%,正精米率71%;2、两年省区试产量名列第二位和第一位,比对照组合增产1%和2%,大田一般亩产450公斤;高产的552公斤,比主栽组合博优64增产30公斤;3、高抗稻瘟病,中抗白叶枯病,后期较耐低温;4、较早熟,全生育期118天,比主栽组合博优64早2至3天;5、制种容易,一般亩产200公斤。由于综合性状优良,而具有较高的经济效益和社会效益,种1亩博优210可增值219元,另因少施或不施农药,减少环境污染,而具有一定的生态效益。

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博优210是华南晚籼杂交稻的“高优”组合,1993和1994年通过省区试和大面积试种表证,1995年5月通过广东省品种委员会审定,具国内同类型品种领先水平。其主要技术经济指标:1、米质1级至特2级(达出口标准),精米率75%,正精米率71%;2、两年省区试产量名列第二位和第一位,比对照组合增产1%和2%,大田一般亩产450公斤;高产的552公斤,比主栽组合博优64增产30公斤;3、高抗稻瘟病,中抗白叶枯病,后期较耐低温;4、较早熟,全生育期118天,比主栽组合博优64早2至3天;5、制种容易,一般亩产200公斤。由于综合性状优良,而具有较高的经济效益和社会效益,种1亩博优210可增值219元,另因少施或不施农药,减少环境污染,而具有一定的生态效益。博优210均适宜华南各省晚稻区种植,越南亦大量引进试种。种植面积发展异常迅速,1993年3600亩,1994年10万亩,1995年约90万亩,预计1996年将超过300万亩,行家预测,博优210在“九五”期间必将成为华南晚稻主栽组合。发表在《中国水稻科学》等7篇论文,是杂交稻优质育种和优质高产育种的规律性研究结果,对杂交稻育种具有一定指导意义。成果达国内领先水平。

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The disulfide-bridged hendecapeptide ( CWTKSIPPKPC) loop, derived from an amphibian skin peptide, is found to have strong trypsin inhibitory capability. This loop, called the trypsin inhibitory loop ( TIL), appears to be the smallest serine protease inhib

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Acid-sensing ion channels (ASICs) are emerging as fundamental players in the regulation of neural plasticity and in pathological conditions. Here we showed that lead (Pb2+), a well known neurotoxic metal ion, reversibly and concentration-dependently inhib

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Numerous observations in clinical and preclinical studies indicate that the developing brain is particular sensitive to lead (Pb)'s pernicious effects. However, the effect of gestation-only Pb exposure on cognitive functions at maturation has not been studied. We investigated the potential effects of three levels of Pb exposure (low, middle, and high Pb: 0.03%, 0.09%, and 0.27% of lead acetate-containing diets) at the gestational period on the spatial memory of young adult offspring by Morris water maze spatial learning and fixed location/visible platform tasks. Our results revealed that three levels of Pb exposure significantly impaired memory retrieval in male offspring, but only female offspring at low levels of Pb exposure showed impairment of memory retrieval. These impairments were not due to the gross disturbances in motor performance and in vision because these animals performed the fixed location/visible platform task as well as controls, indicating that the specific aspects of spatial learning/memory were impaired. These results suggest that exposure to Pb during the gestational period is sufficient to cause long-term learning/memory deficits in young adult offspring. (C) 2003 Elsevier Inc. All rights reserved.