160 resultados para rearranged (4 -> 2)-abeo-clerodane


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研究了两种新型芴类衍生物9,9-二(2-乙基已基)-2,7-二咔唑-9H-芴(简记为DCZF)和9,9-二(2-乙基已基)-2,7-二(2-(4-甲氧基)苯-2,1-乙烯基)芴(简记为BMOSF)在N,N-二甲基甲酰胺(DMF)中的线性吸收和单光子荧光行为,并用脉冲宽度为38ps,重复频率为10Hz的1064 nm Nd:YAG脉冲激光研究了两种化合物的三光子吸收性质.结果表明:两种新材料的最大线性吸收峰分别位于330和380nm,吸收区域覆盖了270-420nm波段.两种化合物的荧光带位于蓝-紫区,中心

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合成了具有大π共轭性的对称型芴类衍生物9,9-二(2-乙基已基)-2,7-(2-(4-甲氧基)苯-2,1-乙烯基)芴(简写为MO-F1u—MO)。通过元素分析、质谱、紫外-可见光谱和红外光谱对其进行了表征。测试了该染料在乙腈、二氯甲烷、四氢呋喃和正己烷4种不同极性溶剂中的线性吸收光谱和单光子荧光谱。结果发现溶剂效应对吸收光谱和荧光光谱表现出不同程度的影响,对产生这些光谱行为的主要原因进行了讨论。

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研究了两种新型D-π-D结构的芴类衍生物4-{7-[4-(二甲基胺)苯基]-9,9-二(2-乙基己基)-9H-芴-2-}-N,N-二甲基苯胺[缩写为B(DMAP)F]和4-{2-[7-(4-氨基苯乙烯基)-9,9-二(2-乙基己基)-9H-芴-2-]乙烯基}苯胺(缩写为BASF)在四氢呋喃(THF)和N,N-二甲基甲酰胺(DMF)中的线性吸收和单光子荧光行为,用脉冲宽度为38ps,重复频率为10Hz的1064nmNd;YAG脉冲激光研究了两种化合物的三光子吸收性质,结果表明:受溶剂效应的影响,两种化合物在

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通过对新合成的芴的一种具有对称性衍生物4-2-(7-(4-氨基苯乙烯基)-9,9-二(2-乙基己基)-9H-芴-2-)乙烯基)苯胺(BASF)的DMF溶液的研究,发现其具有很强三光子吸收频率上转换荧光发射特性,实验测出上转换荧光的波长范围是456-775nm,在510nm处的荧光强度与入射光强的三次方成正比.在0.03mol/L的浓度下就有明显的三光子吸收诱导的光限幅效应.非线性吸收系数和吸收截面分别为y=4.34×10^20 cm^3/W^2和σ3=2.4×10^-39 cm^6/W^2.

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Graded-index (GRIN) fiber lens arrays are fabricated from commercial GRIN fibers to collimate a high-power laser diode array. The beam divergence angles are reduced to 4.2 and 14.7 mrad in the fast and slow axes, respectively. The influences of smile and fluctuation in fiber length are discussed. Using an aspherical focal lens system, about 74% power can be launched into a fiber with a numerical aperture (NA) of 0.22 and a core diameter of 400 mu m. (c) 2008 Society of Photo-Optical Instrumentation Engineers.

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研究了掺铒TeO2-ZnO-PbCl2碲酸盐基氧卤玻璃在977nm激光二极管抽运下的发光和上转换发光特性,结果发现除红外1.53μm^4I13.2→^4I15/2发光外(荧光半高宽高达69nm),该玻璃还存在很强的^2H11/2→^4I15/2(527nm),^4S3/2→^4I15/2(549nm)和^4R9/2→^4I15/2(666nm)可见上转换发光.应用Judd-Ofelt理论计算得到玻璃强度参数Ω1(t=2,4,6)分别为Ω2=5.87×10^20cm^2,Ω4=2.08×10^2-cm^2,

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beta-Ga2O3: Cr single crystals were grown by floating zone technique. Absorption spectra and fluorescence spectra were measured at room temperature. The values of field splitting parameter Dq and Racah parameter B were obtained by the peak values of absorption spectra. The value 10Dq/B=23.14 manifests that in beta-Ga2O3 crystals Cr3+ ions are influenced by low energy crystal field. After high temperature annealing in air, the Cr3+ intrinsic emission was enhanced and the green luminescence disappeared. The strong and broad 691 nm emission was obtained at 420 nm excitation due to the electron transition occurred from T-4(2) to (4)A(2). The studies manifest that the beta-Ga2O3 crystals have the potential application for tunable laser.

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采用传统无压烧结工艺制备Nd^3 +掺杂的氧化镧钇透明激光陶瓷,测试了其吸收和荧光光谱.采用Judd-Ofelt理论对Nd^3 +掺杂量为1 .5at %的样品光谱参量进行了计算.根据吸收光谱,拟合得到三个强度参量分别为:Ω2=6 .57×10^-20cm^2,Ω4=2 .04×10^-20cm^2,Ω6=4 .38×10^-20cm^2.根据这三个参量计算了样品的辐射寿命,跃迁几率,荧光分支比,量子效率和品质因子,并对结果作了分析.

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The Ho:YAP crystal is grown by the Czochralski technique. The room-temperature polarized absorption spectra of Ho:YAP crystal was measured on a c-cut sample with 1 at% holmium. According to the obtained Judd-Ofelt intensity parameters Omega(2) = 1.42 x 10(-20) cm(2), Omega(4) = 2.92 x 10(-20) cm(2), and Omega(6) = 1.71 x 10(-20) cm(2), this paper calculated the fluorescence lifetime to be 6 ms for I-5(7) -> I-5(8) transition, and the integrated emission cross section to be 2.24 x 10(-18) cm(2). It investigates the room-temperature Ho:YAP laser end-pumped by a 1.91-mu m Tm:YLF laser. The maximum output power was 4.1 W when the incident 1.91-mu m pump power was 14.4W. The slope efficiency is 40.8%, corresponding to an optical-to-optical conversion efficiency of 28.4%. The Ho:YAP output wavelength was centred at 2118 nm with full width at half maximum of about 0.8 nm.

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本项目以跨部门多学科(植物分类、解剖学、细胞学、植物化学、栽培学、木材学)手段对海桑属植物进行了综合研究。经4年多学科手段研究发现2个新种,并成功引进一个外来种-无瓣海桑,丰富了我国海桑种质资源。对形态及细胞学的演化趋势探讨了种间亲缘关系,为造林遗传育种提供依据。总结了一套切实可行的栽培技术。通过果胶和木材的综合利用分析为沿海盐渍滩涂营造海桑林增加经济效益提供科学依据。在加速繁殖营造海桑植物纯林研究方面居国际领先地位。

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我所取得以下成果:1、应用零上低温调温,配合保鲜剂处理和一定包装的综合技术,使糯米枝淮枝贮藏保鲜40天以上,好果率分别为98.6%及97.4%;2、防止荔枝果皮褐变技术取得新进展,应用“9005”防腐剂处理,使荔枝在零上低温贮藏2个月,零下低温贮藏8-10个月,进入货架期后,果实的颜色能持续保持鲜红,风味正常;3、继续探讨荔枝果皮褐变机理、贮藏的气体条件及贮藏温度的生理效应,应用基础理论的研究,为提高荔枝贮藏保鲜技术提供重要依据。87-96年应用零上低温保鲜贮运技术,生产部门北运保鲜荔枝,约50多万斤,促进保鲜荔枝向北方市场流通,充实了北方市场上南果的供应,颇受经营部门和消费者的好评,经营部门增加纯盈利约25-30万元。