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排序方式: 共有316条查询结果,搜索用时 0 毫秒
91.
一种通过分子间氢键自组装的侧链液晶聚合物 总被引:3,自引:0,他引:3
一种通过分子间氢键自组装的侧链液晶聚合物邢佩祥,赵英英,汤心颐,姜炳政(吉林大学化学系,长春,130023)(中国科学院长春应用化学研究所高分子物理开放实验室)关键词氢键,侧链液晶聚合物,近晶相,自组装自Ringsdorf[1]等提出在介晶基团与主链... 相似文献
92.
The Laplacian spread of a graph is defined to be the difference between the largest eigenvalue and the second-smallest eigenvalue of the Laplacian matrix of the graph. In a recent work the trees with maximal Laplacian spread and with minimal Laplacian spread among all trees of fixed order are separately determined. In this work, we characterize the unique unicyclic graph with maximal Laplacian spread among all connected unicyclic graphs of fixed order. 相似文献
93.
Mesoporous (MSU) Ce0.5Zr0.5O2 mixed oxide with a high specific surface area has been synthesized under weak acidic condition in the presence of an anionic surfactant, sodium dodecylbenzenesulfonate. The effect of the pH value on the formation of mesostructure and the thermal stability of the material has been evaluated. The products were characterized by transmission electron microscopy, powder X-ray diffraction and nitrogen adsorption-desorption measurements. The results showed that the as-prepared Ce0.5Zr0.5O2 mixed oxide possessed a specific surface area of 163.3 m^2·g^-1, which had a cubic fluorite-type structure and possessed specific surface areas of 148.4 and 62.4 m^2·g^-1 after calcination at 500 and 800 ℃ for 2 h, respectively. The material showed excellent thermal stability. 相似文献
94.
Six new coordination polymers, namely [Zn1.5(BTC)(L1)(H2O)2].1.5H2O (1), [Zn3(BTC)2(L2)3] (2), [Zn3(BTC)2(L3)1.5(H2O)].H2O (3), [Co6(BTC)4(L1)6(H2O)3].9H2O (4), [Co1.5(BTC)(L2)1.5].0.25H2O (5), and [Co4(BTC)2(L3)2(OH)2(H2O)].4.5H2O (6), where L1 = 1,2-bis(imidazol-1-ylmethyl)benzene, L2 = 1,3-bis(imidazol-1-ylmethyl)benzene, L3 = 1,1'-(1,4-butanediyl)bis(imidazole), and BTC = 1,3,5-benzenetricarboxylate anion, were synthesized under hydrothermal conditions. In 1-6, each of L1-L3 serves as a bidentate bridging ligand. In 1, BTC anions act as tridentate ligands, and compound 1 shows a 2D polymeric structure which consists of 2-fold interpenetrating (6, 3) networks. In compound 2, BTC anions coordinate to zinc cations as tridentate ligands to form a net with (64.82)2(86)(62.8)2 topology. In compound 3, BTC anions act as tetradentate ligands and coordinate to zinc cations to form a net with (4.62.83)2(8.102)(4.6.83.10)2 topology. In compound 5, each BTC anion coordinates to three Co cations, and the framework of 5 can be simplified as (64.82)2(62.82.102)(63)2 topology. For 4 and 6, the 2D cobalt-BTC layers are linked by bis(imidazole) ligands to form 3D frameworks. In 6, the Co centers are connected by micro3-OH and carboxylate O atoms to form two kinds of cobalt-oxygen clusters. Thermogravimetric analyses (TGA) for these compounds are discussed. The luminescent properties for 1-3 and magnetic properties for 4-6 are also discussed in detail. 相似文献
95.
96.
This article represents a systematical examination of the structures of silver(I) sulfonates incorporating neutral ligands. To survey the influence of the properties of neutral ligands on the structures of silver(I) sulfonates, three kinds of sulfonate anions (L1=1-naphthalenesulfonate, L2=p-toluenesulfonate, and L3=1, 3, 6, 8-pyrenetetrasulfonate) and three kinds of neutral ligands (pyrazine, Pyr, a divergent bidentate ligand; hexamethylenetetramine, hmt, a divergent tetradentate ligand; and beta-picoline, Pic, a monodentate ligand) were selected for study, and five novel silver(I) sulfonates containing neutral ligands have been synthesized: [Ag(L1)(Pyr)].H2O, Ag(L2)(Pyr), Ag4(L3)(Pyr)4(H2O)2, [Ag(L1)(hmt)].H2O, and Ag(L1)(Pic)2. The crystal structures have been determined by single-crystal X-ray diffraction, and these compounds show a variety of structures with different dimensionalities. Moreover, the luminescent properties of compounds and are also discussed. 相似文献
97.
Isolation and identification of new prenylated acetophenone derivatives from Acronychia oligophlebia
Qian-Wen Niu Neng-Hua Chen Zhong-Nan Wu Ding Luo Ying-Ying Li Yu-Bo Zhang 《Natural product research》2019,33(15):2230-2235
Three new prenylated acetophenone derivatives, acronyculatin P (1), acronyculatin Q (2), and acronyculatin R (3) were isolated from the leaves of Acronychia oligophlebia. Their structures were identified by extensive analyses of spectroscopic data (IR, UV, ESI-HRMS, 1D and 2D NMR) and comparison with the literatures. In addition, the cytotoxic activity against MCF-7 cells of the compounds were evaluated by the MTT assay and the IC50 values were 56.8, 40.4 and 69.1?μM, respectively. 相似文献
98.
壳聚糖-硅基凝胶微球作为固定化金属螯合亲和色谱基质的研究 总被引:1,自引:0,他引:1
采用溶胶凝胶及微乳液技术制备了以壳聚糖-硅基杂化材料为骨架并带有金属离子螯合官能团的球形基质(CSHB),并对该基质的制备条件及结构形貌进行了研究与表征。实验表明,当微乳液反应体系的组分为:100mL壳聚糖溶液(2%m/V)、100mL Span乳化剂、250mL环己烷、13.3mL四乙氧基硅烷(TEOS)、1.33mL 3-缩水甘油丙氧基三甲氧基硅烷(GPTMS)和亚氨基二乙酸(IDA)0.802g时,可获得粒径均匀,刚性较好的微球。红外光谱证明了该基质是一种多组分的杂合材料,差热分析数据表明该杂合材料的热稳定性随反应体系中GPTMS的含量增加而增大。CSHB通过动态吸附金属离子Cu2 与Ni2 后,可对金属螯合蛋白产生配位吸附作用。Cu2 -CSHB柱对牛血清蛋白(BSA)具良好的可逆吸附能力,蛋白能被咪唑等金属离子螯合剂洗脱,回收率达76.6%。BSA在CSHB柱上的吸附率只有4.7%,表明CSHB对蛋白的非特异吸附较低。Ni2 -CSHB柱对过氧化氢酶(CAT)也显示出初步的纯化效果,一步纯化倍数为2.43倍。该基质有望用于具有组氨酸纯化标签的基因工程表达蛋白的分离与纯化。 相似文献
99.
以六水合氯化镍、七水合硫酸钴、氧化石墨烯(GO)和赤磷为原料,利用原位水热法,在不添加任何表面活性剂的情况下,合成了磷化钴镍/还原氧化石墨烯(NiCoP/rGO)纳米复合材料,并通过XRD、SEM、TEM、IR、Raman等对该复合材料进行了表征.结果表明,所得复合材料由NiCoP纳米颗粒和还原氧化石墨烯片层结构组成,NiCoP纳米颗粒尺寸大约为20 nm,均匀分布在rGO片层结构表面上,同时探讨了复合材料的形成过程.另外,复合材料的吸附脱除实验表明,所得复合材料对多种染料都具有非常好的吸附作用,因此,在污水处理方面有较大的应用价值. 相似文献
100.
Ying-Ying Yang Yong-Liang Zhang Xian-Zi Dong Zhen-Sheng Zhao 《Optics Communications》2011,284(13):3474-3478
We have proposed an asymmetric bowtie 2-color controller and analyzed its resonance frequency spectra and temporal responses. The results show improved optical properties of the asymmetric bowtie 2-color controller as compared to symmetric bowties. The improved optical properties are a broad bandwidth of the plasmonic spectrum consisting of two resonant peaks, a high field enhancement in the gap of the bowtie structure, and a large effective enhancement volume. The system might have applications in the generation of XUV light via high-harmonic generation as well as in ultrabroadband sensors and multicolor optoelectronic filters. 相似文献