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31.
A novel and facile synthetic protocol for the construction of benzazepine and benzoxepine derivatives through a copper(I)‐catalyzed reaction of 2‐(2‐ethynylphenyl)‐1‐tosylaziridine or 2‐(2‐ethynylphenyl)oxirane with sulfonyl azides is disclosed. A ketenimine is the key intermediate during the reaction process. 相似文献
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本文对于具有终对象的范畴定义了四个一般正合列.在Abel范畴同调代数里,对于具有零对象的任何范畴四个一般正合列与通常的正合列相同 相似文献
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介绍了使用光学自反关联存储技术进行符号替换运算的数学模型、数字模拟结果以及使用可编程LCTV液晶空间光调制器组成光电混合系统的实现符号替换的方法。这种符号替换运算具有很强的容错能力。 相似文献
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Xiancui Zhu Yuzhe Jiang Jun Chen Shaowu Wang Zeming Huang Shan Zhu Xu Zhao Wenrun Yue Jun Zhang Weikang Wu Xiangyang Zhong 《中国化学》2020,38(5):478-488
A series of dinuclear rare‐earth metal alkyl complexes {[μ‐η2:η1:η1‐3‐( L NCH)(CH2SiMe3)Ind]RE(CH2SiMe3)(THF)}2 ( L 1 = 2‐tBuC6H4, RE = Y, Gd, Dy, Er, Yb; L 2 = 2,4,6‐Me3C6H2, RE = Dy, Er; Ind = indolyl) and {[μ‐η2:η1:η1‐3‐( L NCH2)Ind]RE(CH2SiMe3)(THF)}2 ( L 1, RE = Y, Dy, Er, Yb; L 2, RE = Er, Yb) bearing 3‐arylamido functionalized indolyl ligands having diverse bonding modes with metal ions were synthesized either by the insertion reaction of the imino group to the RE—C bond or by the alkane elimination reaction. In the preparation of above complexes, rare‐earth metal alkyl complexes [μ‐η5:η1:η1‐3‐( L 2NCH)(CH2SiMe3)Ind]Gd(CH2SiMe3)(THF)}2 with a μ‐η5:η1:η1 coordination mode to the gadolinium ion and {[μ‐η3:η1:η1‐3‐( L 2NCH2)Ind]Dy(CH2SiMe3)(THF)}2 with a μ‐η3:η1:η1 coordination mode to the dysprosium ion were unexpectedly isolated. The reactions of 3‐( L 2N=CH)Ind with Er(CH2SiMe3)3(THF)2 at room temperature, generated a tetranuclear imino‐indolyl erbium intermediate {[μ‐η1:η1‐3‐( L 2N=CH)Ind]Er(CH2SiMe3)2(THF)}4, which can transform into the amido functionalized indolyl erbium complex in hot toluene. Moreover, the reactivities of the newly synthesized ytterbium complex with N‐heterocyclic compounds were investigated, affording the corresponding products of the mixed pyridyl‐indolyl, imidazolyl‐indolyl, and ortho‐metalated complexes. The yttrium complexes showed a high regioselectivity and steroselectivity for the isoprene polymerization with 1,4‐trans selectivity up to 91.7% and 1,4‐cis selectivity up to 96.1% in the presence of cocatalysts, respectively. 相似文献
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大学物理实验中学生的心理障碍及克服 总被引:3,自引:0,他引:3
影响学生实验的心理因素较多。本就学生们的自卑心理进行剖析并提出教师在实验教学中应注意的问题。 相似文献
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Reactions of [WES3]2- (E = S, O) with CuX (X = NCS, CN, I) in the presence of bix (bix = 1,4-bis(imidazole-1-ylmethyl)benzene) in DMF or CH3CN resulted in the formation of two novel 2D --> 3D interpenetrating coordination polymers [S2W2S6Cu4(bix)2]n (1) and {[WS4Cu4(NCS)2(bix)3].CH3CN}n (2), a noninterpenetrating 3D polymer {[WS4Cu2(bix)].DMF}n (3), and two 2D sheet polymers [WS4Cu3(CN)(bix)]n (4) and {[OWS3Cu3(bix)2][I].DMF.2H2O}n (5), depending on the reaction temperature and the reagents used. Compound 1 contains a hexagonal prism of W2Cu4S6 cluster core, which serves as a 4-connecting node to link equivalent nodes via bix ligands, forming a 2D (4,4) net. In 2, a WCu4S4 core, which also acts as a 4-connecting node, connects the neighboring nodes either through single or double bix bridges, affording a different 2D (4,4) sheet. Inclined interpenetration occurs between two stacks of 2D sheets in the total structure of 1, while 2 involves a parallel interpenetration between the adjacent layers, both creating a 3D network. Compounds 1 and 2 represent the first examples of interpenetrating (4,4) frameworks with clusters as nodes and bidentate pyridyl-based ligands as linkers. Unlike 1 and 2, compound 3 has a noninterpenetrating 3D network, which is composed of the inorganic 1D (WS4Cu2)n chains linked by cis and trans bix ligands. Compound 4 features an inorganic 1D (WS4Cu3)n chain structure, which is linked by CN groups and bix ligands to form an infinite 2D network. Compound 5 is a 2D layer polymer with large inner cavities. 相似文献
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