排序方式: 共有12条查询结果,搜索用时 31 毫秒
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对近10年来费里尔型重排反应(包括Ⅰ型费里尔重排、Ⅱ型费里尔重排和费里尔-皮塔西斯重排反应)的研究进展作了简要综述,并介绍了近来费里尔型重排反应应用于复杂的活性分子合成中的研究所取得的进展. 相似文献
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铒镱共掺光波导激光器的稳态特性 总被引:1,自引:0,他引:1
从光波导激光器的工作理论出发,研究了铒镱共掺磷酸盐波导激光器的稳态特性。利用重叠因子简化了980 nm光抽运的铒镱共掺波导激光器四能级模型的速率-传输方程;在忽略自发辐射的情况下,利用数值模拟的方法,得到了铒镱共掺波导激光器的输出与Er3+/Yb3+离子浓度、泵浦功率、波导长度等参量之间的关系曲线。理论分析结果表明,选择合适的铒镱离子浓度是制作铒镱共掺波导激光器的关键。采用980 nm波长的泵浦光,泵浦功率为80 mW,Er3+浓度取20×1026/m3左右,Yb3+/Er3+浓度比为7~10,波导长度为20 cm左右时,可以得到最大输出光功率。 相似文献
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Asymmetric Syntheses Aided by Biocatalysts 总被引:1,自引:0,他引:1
This article summarizes the achievements of the authors‘ group in the area of biocatalyst-catalyzed organic reactions in recent 10 years. A strain of Geotrichum sp. obtained by screeninu is capable of stereoselectlvely reducing a number of carbonyl compounds. In many cases, the stermghemistry is complementary with that obtained by baker‘ s yeast. Therefore, this microorganism provides a useful pathway to the preparation of alcohol eompounds with specific configurations. On the other hand, a nmmber of plant sourees have been screened for oxynitrilases and the hydrocyanation reactions of various arylcarboxalde-hydes have been investigated.A“micro-aqueous reaction system“ was invented,by which a serles of novel optically active cyanohydrins were prepared.On this hasis,a high through-put comtimasous reaction system has been designed.This paper also deseribes examples of the syntheses of bio-active compounds by using the optieally active compounds obtained from the above mentioned catalytic reactions as precursors. 相似文献
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采用Nb管和高Sn含量的Cu-Sn,Cu-Sn-Ti,Cu-Sn-In合金之间的内扩散法制备了Nb_3Sn多芯超导复合线,研究了Nb_3Sn反应扩散热处理条件和添加元素Ti、In对Nb_3Sn反应层生长动力学、组织结构和超导性能的影响。结果表明:母材中添加适量的第三元素Ti或In均提高Nb_3Sn反应层生长速率,与In相比,Ti的效果更为显著.添Ti样品的T_c值在母材添Ti量为0.4w/o处出现峰值,比末添Ti样品的T_c值升高0.3K.添Ti样品的H_(c2)(o)值随母材添Ti量增加单调提高,当母材添Ti量为0.76w/o时,其H_(c2)(o)值由未添Ti样品的21T提高到大约29T.在4.2K和15T脉冲背景磁场(脉冲上升时间t_m=10ms)下,添Ti和添In样品的J_c(non Cu)值分别可达6×10~4Acm~(-2)和2.5×10~4Acm~(-2). 相似文献
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