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Search Results: 1 - 10 of 95752 matches for " 黄莉蕾 "
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敏化离子Ce3+对Er3+∶YAG的1.6μm波长激光性能的影响

物理学报 , 1999,
Abstract: 测定了Ce3+,Er3+∶YAG中Ce3+离子的吸收截面.用从能级跃迁速率方程和激光传输方程推出的表达式计算了1.6μm波长激光的阈值能量(功率)和斜率效率.表明在Ce3+,Er3+∶YAG中,Ce3+对Er3+离子的激光性能影响与激活离子Er3+的浓度、晶棒大小有关.短晶棒或浓度低的晶体加入Ce3+可降低Er
Er∶YAG晶体1.6μm波长激光输出特性理论分析
,洪 治
物理学报 , 1998,
Abstract: 由跃迁速率方程推出了三能级系统的激光阈值和斜率效率解析式.根据测试的吸收谱,计算了YAG晶体中Er3+离子的吸收截面.分析了1.6μm波长的激光特征.
ANALYSES FOR LASING THRESHOLD AT 2 AND 1.5μm WAVELENGTHS IN Tm:YVO4 CRYSTAL
,洪治
中国物理 B , 2000,
Abstract: From transition-rate-equations and transmission-equations the formulas of threshold power are deduced for an end-pumped laser, in which the probability of cross-relaxation cannot be ignored and the nonradiative transition-probability of the excited state is the same order as the radiative transition-probability of upper level of the lasing transition. The lasing performance of Tm:YVO4 at λ=1.9 and 1.5μm is discussed by dint of these equations of threshold power.
Analysis of the laser performance of Tm3+, Tb3+(Ho3+):YVO4 crystals at ~1.5μm wavelength
,付晏彬,邬良能
中国物理 B , 2003,
Abstract: The absorption spectra of Tb,Tm:YVO_4 and Ho,Tm:YVO_4 are measured. The radiant and non-radiant transition probabilities from higher level to lower level, A_{i,j} and ω_{i,j}, and the cross-elaxation probability are calculated in virtue of Judd-Ofelt and Dexter theories. The fluorescence lifetime of Tm^{3+} in the Tb^{3+} (or Ho^{3+}) co-doped crystal is calculated. It indicates that the lifetime of initial level {}^3H_4 of the laser transition can be shorter than that of terminal level {}^3F_4 of the transition if the atomic percentage of Tb^{3+} (or Ho^{3+}) ions is bigger than about 1 at%: namely, by means of the co-doping Tb^{3+} (or Ho^{3+}) ions the self-termination phenomenon of laser light can be eliminated. Inserting the optic parameters to the formula deduced here on the laser threshold power P^{(4)}_{th} and the slope efficiency η^{(4)}_s of the four-energy-level system, we obtain the relationship of threshold power P^{(4)}_{th} to the concentration of Tm^{3+} ions and discuss the effect of Tb^{3+} (or Ho^{3+}) ion concentration on the laser threshold power P^{(4)}_{th} around 1.5μm wavelength. The result shows that Tb,Tm:YVO_4 crystal is a better choice to make the laser at ~1.5μm wavelength than Ho,Tm:YVO_4 crystal. We give the appropriate composition of (1-2) at% Tb, (1-2) at% Tm:YVO_4, just for reference.
叶酸对小鼠卵母细胞体外成熟的影响
,侯绍英,夏 ,赵 艳
癌变·畸变·突变 , 2009,
Abstract: ?背景与目的:探讨叶酸(folicacid,fa)对小鼠卵母细胞体外成熟的影响。材料与方法:实验设次黄嘌呤(hypoxanthine,hx)处理小鼠体外卵母细胞的卵母细胞成熟抑制模型组(hx4mmol/l+m16培养液)、fa组(500μmol/lfa+4mmol/lhx+m16培养液)和m16培养液组,各组卵母细胞培养24h后,在体视显微镜下观测卵母细胞生发泡破裂(germinalvesiclebreakdown,gvbd)和第一极体(thefirstpolarbody,pb1)排出情况,采用免疫荧光染色方法观察染色体和纺锤体的形态结构。结果:m16培养液组、hx模型组和fa处理组的gvbd率分别为98%、22.2%、40.1%,其pb1排出率分别为77.7%、15.5%、27.6%,各组间的差异均具有统计学意义(p<0.05);次黄嘌呤和叶酸对染色体的形态没有影响,而次黄嘌呤使正常的纺锤体变长、变宽、面积变大,fa组较hx模型组增大的纺锤体有所恢复,并接近于正常水平。结论:叶酸可促进小鼠卵母细胞体外减数分裂的重启和成熟。
Analysis of the laser performance of Tm3+: ZBLAN glass at 1.47μm wavelength
,曹国熹,张伦,罗宏雷
中国物理 B , 2004,
Abstract: A formula for the threshold energy of a four-level-system laser in Tm^{3+} doped fluoride glass is derived. The formula contains the parameters of the interaction between the ions and the up-conversion rate of the pump-light. It is discussed that the Tb^{3+} ions and the up-conversion pump-light have an influence on the laser performance of Tm^{3+} ions around 1.47μm wavelength. We draw the following two conclusions. (1) The laser threshold descends obviously due to the doping of Tb^{3+} ions, but the descending gradually flattens out with the increase of the content of Tb^{3+} ions. Its suitable content is (1-2)×10^{20}cm^{-3}. (2) When pump-lights both from the up-conversion and from the ground state excite simultaneously the single-doped Tm^{3+} ions, the threshold energy can reduce and the output energy can increase. In this paper, the energy conversion efficiency from the up-conversion pump-light to the output energy of laser is estimated.
公众太湖蓝藻水华生态风险感知特征研究——以无锡市区为例
杨洁,毕军,,周鲸波,,李凤英,曲常胜
长江流域资源与环境 , 2010,
Abstract: 蓝藻水华暴发已成为全球性生态环境问题。太湖作为流域重要的水源地,2007年蓝藻水华事件的暴发引起公众的高度关注。运用问卷调查法,研究无锡市区489名公众的太湖蓝藻水华生态风险感知特征及其主要影响因素。研究结果表明蓝藻水华生态风险被公众知觉为总体风险是陌生和完全可控的;蓝藻水华暴发原因是陌生和不可控的,这是引起公众风险意识的主要因素。影响公众蓝藻水华生态风险感知水平的主要因素有媒体、信息和个体因素。报纸广播电视是主要的媒体因素。信息因素有灾害信息、灾害治理信息、政府防范措施信息。灾害治理信息的影响作用最大,其次是灾害信息和政府防范措施信息。不同性别、年龄段、教育程度、收入水平及职业的人群,对不同类别的风险信息关注程度不同,影响到个体风险偏好的不同。研究结果有助于决策者更全面地理解蓝藻水华风险的本质,开展风险沟通,针对不同特征的人群选择有效的风险管理方案。〖
掺Nd~(3+)的[Y(Ca)]_3[Al(Zr)]_5O_(12)石榴石单晶
,曾宪标,陈继勤,童利民,董绵豫
硅酸盐学报 , 1995,
Abstract:
由mopip配体构筑的两种金属配合物的合成、表征及晶体结构(英文)
艳菊?,倪 良?,杜 刚?,崔运成?,张文,王 ,郝向荣?
无机化学学报 , 2010,
Abstract: 采用水热法由2种不同金属盐和mopip(mopip=2-(4-methoxyphenyl)-1h-imidazo[4,5-f][1,10]phenanthroline)配体合成了2种新型零维配合物[cd(mopip)3(h2o)9]4n(1)和[mn(mopip)3(h2o)6]2n(2),并对其进行了元素分析、红外光谱表征、热失重和x射线单晶衍射测定。结果表明,每个金属中心离子与来自3个不同mopip分子上的6个氮原子进行配位,形成畸变的八面体构型。
20年来国内信息素养教育研究与实践综述

图书馆杂志 , 2015,
Abstract: ?将国内20年来对信息素养教育的研究分为三个阶段,概述每个阶段的特征和主要成果,分析其中一些热点问题。在此基础上,对国内信息素养教育的发展提出建议,认为将来信息素养教育发展的目标是:以政府为依托,共建共享为主要方式,图书馆及相关部门共同参与,以提高师生信息意识、信息知识、信息能力、信息道德为方向,开展内容丰富、形式多样的教育。
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