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在长寿命产品的可靠性增长试验过程中,由于人员、观测设备或其他方面的原因,可能会造成某些试验数据丢失或未观测到的现象。对这类小子样变总体缺失数据情形,提出了Bayes可靠性增长分析方法。首先利用Box-Tiao技术构造先验分布,然后利用非齐次Poisson过程原理和缺失数据的产生机制,得到可靠性增长缺失数据的似然函数,再用Bayes统计推断方法得到产品各研制阶段结束时的可靠性水平,同时给出了缺失数据下增长模型的拟合优度检验方法。最后通过一个示例说明了该方法在工程上的应用。 相似文献
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蜜蜂外激素9—ODA和9—HDA的合成 总被引:2,自引:0,他引:2
6-溴-2-己酮在Li2CuCl4催化下与γ-溴代巴豆酸甲酯进行格氏偶联,合成王物质9-羰基-(E)-2癸烯酸(9-ODA),将其还原得到了另一蜂王物质9-羟基-(E)-2-癸烯酸(9-HDA)。该法是合成9-ODA和9-HDA的新路线。 相似文献
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The title complex,6,6-(3,3,5,5-tetra-tert-butylbiphenyl-2,2-diyl)bis(oxy)di-di-benzo[d,f]-[1,3,2] dioxaphosphepine(C52H56O6P2·C6H14,Mr = 881.99),was synthesized,and the structure was determined by X-ray single-crystal diffraction.The crystal belongs to the orthor-hombic system,space group Pbca,with a = 11.8400(13),b = 25.381(3),c = 34.243(4) ,V = 10290(2)3,Z = 8,Dc = 1.139 g/cm3,μ = 0.131 mm-1,T = 152(2) K,F(000) = 3768,the final R = 0.0773 and wR = 0.1820 for 9721 observed reflections with I > 2σ(I).The neighboring two molecules form a dimmer by face-to-face π…π interactions. 相似文献
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Two Cu(Ⅱ) complexes of [Cu(2,6-DPC)(Hnta)(H_2O)]·H_2O(2,6-DPC = 2,6-pyridinedicarboxylic-carboxylate, Hnta = nicotinic acid) and [Cu_2(2,4-D)_4(Hnta)_2](2,4-D = 2,4-dichlorophenoxyacetic-carboxylate) were synthesized and successfully obtained as single crystals in this paper. The supramolecular structures of the complexes from zero to three dimensions and the weak intermolecular force in the crystal were analyzed. The single-crystal structures of the complexes were further analyzed by Hirshfeld surface analysis. The competition capacity of the complexes about calf thymus DNA(ct-DNA) was also analyzed by fluorescence spectroscopy. The ability of complexes to cleave the plasmid DNA(pBR322-DNA) was determined by gel electrophoresis assay. And at last, the complexes' cytotoxic activities were reviewed for four kinds of cancer cell lines(HeLa, MCF-7, HepG, SKOV-3), showing that the coordination polymer has anti-tumor activity and cytotoxicity. 相似文献
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瑞香烷型二萜类天然产物拥有5/7/6三环骨架的复杂分子结构, 含有多个手性中心, 通常在C3、C4、C5、C9、C13、C14、C20等位置含有手性羟基; 其中, 诸多化合物在C9、C13、C14位置的手性羟基之间形成特定的原酸酯结构. 该类天然产物在抗HIV、抗癌、抗白血病、亲神经性、杀虫、细胞毒性等方面显示显著的生物活性. 瑞香烷型的密集的高氧化数的多环骨架和其引人注目的生物活性吸引了众多研究者的合成兴趣, 尽管迄今为止成功的全合成报道依然鲜见, 但合成化学家对其多环骨架的构建已发展了大量有益的策略和方法, 在此对相关合成工作进行归纳综述. 相似文献