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排序方式: 共有2355条查询结果,搜索用时 265 毫秒
961.
Yu Xia DIAO Yang TIAN Si Hui ZHAN Wen Xing ZHANG* Xiu Ling JIAO Dai Rong CHEN School of Chemistry Chemical Engineering Shandong University Jinan 《中国化学快报》2003,14(7):740-743
Recently, the thermal decomposition of heteronuclear complexes has become apromising method for the preparation of di- or tri-metallic oxides because the complex as precursor has the special microstructure, the controlled stoichiometry of the metals and lower decomposition temperature 1. In order to investigate Ba-V-O system, which has the special magnetic behavior 2, we synthesized the title complex as the precursor of this material. On the other hand, microporous constructions existing in… 相似文献
962.
A ligand-free nickel-catalyzed Kumada cross-coupling of aryl bromides and tert-butyl Grignard reagents led to the formation of a series of tert-butyl aryls in moderate to good yields, excellent tBu/iBu ratios, and good functional group compatibility. A radical coupling process is indicated and a mechanism with a Ni(I)-Ni(III) catalytic cycle is proposed. 相似文献
963.
ShengAnTANG ZhiWeiDENG JunLI HongZhengFU YueHuPEI SiZHANG WenHanLIN 《中国化学快报》2005,16(3):353-355
From the marine sponge Jaspis sp., a new isomalabaricane triterpenoid 22, 23-dihydrostellettin D (1) was isolated, and its structure was established on the basis of IR, MS and extensive 2D NMR spectroscopic analysis. It is a unique skeleton compound rarely obtained from Chinese marine organisms. 相似文献
964.
A study of the enhanced (ca. 100 ×) fluorescence intensity of the Eu3+-diphacinone-ammonia system by Y3+ was made using a colloidal suspension. The excitation and emission wavelengths were 330 and 612 nm, respectively. The fluorescence intensity was a linear function of the concentration of europium in the range 6.0 × 10?11–8.0 × 10?7 M. The detection limit was 8.0 × 10?14 M. The standard addition method was used for the determination of europium in rare earth oxides, with satisfactory results. 相似文献
965.
Si‐Jia Xue Qing‐Dong Wang Jing‐Zhi Li 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):o666-o668
In the title compound, C15H15N5O3S, two parallel intermolecular N—H⋯S hydrogen bonds, forming an eight‐membered ring, link two molecules into a dimer unit; these dimer units linked into a chain of edge‐fused rings by weak C—H⋯O hydrogen bonds. 相似文献
966.
K. Yuan R. J. Kahan C. Si A. Williams S. Kirschner M. Uzelac E. Zysman-Colman M. J. Ingleson 《Chemical science》2020,11(12):3258
The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C–H borylation sequence. The brominated-Bn-PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E1/2 = −0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C–H borylation installs useful C–Br units onto the Bn-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D–A–D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C–H borylation sequence. 相似文献
967.
968.
A new method for the synthesis of 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine(TAAT)is described.The key intermediate 4,4′,6,6′- tetra(azido)hydrazo-1,3,5-triazine(TAHT)was synthesized by nucleophilic substitution in the case of sodium azide as nacleophile. N-Bromosuccinide(NBS)was used as oxidant to oxidize TAHT by a tractable operation under mild reaction condition.The target compound TAAT was obtained with a facile process and high overall yield of 81%.The structures of TAAT and its intermediates were identified by spectroscopic methods. 相似文献
969.
2H-1,2,4-噻二唑并[2,3-α]嘧啶衍生物的合成及除草活性研究(Ⅴ) 总被引:8,自引:3,他引:8
合成了10个未见文献报道的目标化合物,结构经IR,^1H NMR,MS和元素分析确 证。初步除草活性测定结果表明:目标化合物具有高效、选择除草活性,主要抑制 双子叶植物(如油菜)的生长,而对单子叶植物(如玉米)具有较好的促进生长作 用。 相似文献
970.