954 resultados para 342.06
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A resonant-cavity enhanced reflective optical modulator is designed and frabricated, with three groups of three highly strained InGaAS/GaAs quantum wells in the cavity, for the low voltage and high contrast ratio operation. The quantum wells are positioned in antinodes of the optical standing wave. The modulator is grown in a single growth step in an molecular beam epitaxy system, using GaAs/AIAs distributed Bragg reflectors as both the top and bottom mirrors. Results show that the reflection device has a modulation extinction of 3 dB at -4.5 V bias.
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Resonant cavity enhancement (RCE) typed optical detector and modulator which operating at wavelength band of 1.06 μm is reported. The peak quantum efficiency of detector is reasonably high as 50% without bias, and the photocurrent contrast ratio of modulator is 3.6 times at -3.5 V as compared to 0 V. The incident angle dependence of RCE device's photoelectric response is investigated carefully.
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ＫＪ８５－０６项目是“八五”期间由中国科学院资助的最大的生态学研究计划．１９个研究所、２０个试验站、５３０余名科技人员参加了该项计划，５年总经费１０００万元．研究工作取得了重大进展，迄今已发表论文４５０余篇、专著３部，尚有大量论文与多部专著将陆续出版．本文简要介绍了有关主要研究进展，并就生态系统优化管理研究和生态过程、人类活动影响联网研究提出了两点主张．
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本文采用真空下气体输运技术制备RE_(0.06)La_(0.94)Nb_2O_6Cl(RE=Pr、Eu、Tb、Dy)小单晶和多晶粉末样品。测定其晶体结构与LaNb_2O_6Cl的晶体结构相同,为正交晶系;Eu_(0.06)La_(0.94)Nb_2O_6Cl小单晶的晶胞参数为:a=9.751,b=7.321,c=8.364。观察RE_(0.06)La_(0.94)Nb_2O_6Cl(RE=Pr、Eu、Tb、Dy)的特征激发光谱和发射光谱及其能量传递现象。
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The relation between otolith weight (OW) and the age of marine fish is studied. A total of 222 individuals of bighead white croaker, Pennahia macrocephalus were sampled seasonally in the mouth of the Beibu Gulf, the South China Sea, in 2007. Since there are no significant differences in sagittal OW between otolith in pairs (Pa parts per thousand yen0.05), the undamaged left sagittal otolith is used for age determination. The highest correlations among standard length, OW and fish ages are confirmed by linear, exponential and multinomial regression. Results show that sagittal OW overlaps only occasionally among age groups, and to individuals with similar standard length, the older and slower-growing fish has a heavier otolith because of the continued otolith material deposition. There are differences in sagittal OW among different age groups and significant positive linear relationship with age (P < 0.05). The age readings can be verified by plotting the sagittal OW versus the standard length for age groups, and the individuals with similar standard length but in different ages can be separated by sagittal OW frequency analysis. Mostly, the predicted ages using the regression between sagittal OW and ages are closed to the observed ages by counting annulus on scale. It indicates that the sagittal OW analysis is a useful technique for validating the accuracy of age determination by annuli counts, especially for individuals of similar size. Furthermore, the technique is applied for Pennahia macrocephalus with discussion in this paper.
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O Município de Machadinho d´Oeste, em Rondônia foi escolhido para um estudo de longo prazo. Já são 10 anos de acompanhamento de mais de 450 pequenas propriedades rurais e cerca de 250 variáveis biofísicas, sócio-econômicas e ambientais. A duração deste projeto é de 100 anos. Os estudos pedológicos da área do "Projeto de Assentamento Machadinho" teve como objetivos identificar os solos das Glebas e implementar uma base de dados do meio físico em escala municipal, através do uso de técnicas de geoprocessamento (SIG´s); bem com o caracterizar e avaliar química, física e morfologicamente os perfis de solos representativos das principais unidades identificadas, a fim de promover o desenvolvimento agrícola da região e fornecer subsídios para estudos em áreas semelhantes na Amazônia.
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2005
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Postal card to George Whitaker. Mailed from Ocean Grove, NJ. Dated June 27, 1881.
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Letter from Daniel Whedon to nephew, Daniel Avery Whedon. Dated February, 6, 1868.
