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排序方式: 共有61条查询结果,搜索用时 265 毫秒
1.
Zongxia Guo Yubao Song Ruiying Gong Youbing Mu Yi Jiang Ming Li 《Supramolecular chemistry》2013,25(5-6):383-391
Biomolecule-directed self-assembly of π-conjugated oligomers has attracted great attention in the past decade. In this contribution, two conjugates composed of quaterthiophene and tetrapeptide (Gly-Val-Gly-Val) were synthesised, namely peptide–thiophene–peptide (PTP) and thiophene–peptide–thiophene (TPT), to investigate the influence of peptide content ratio and its location in the molecular structures on the nanostructures and properties of the assemblies. Both conjugates formed organogels consisting of left-handed twisted nanostructures; however, anti-parallel β-sheets were observed in PTP while parallel β-sheets were obtained for TPT, although in both cases oligothiophenes adopted an H-like stacking mode. Obvious solvent-induced supramolecular chirality inversion from the oligothiophene segment was observed for PTP while such phenomenon was not clear for TPT. PTP and TPT gels also showed different stabilities towards temperature increase, as evidenced by variable-temperature circular dichroism study. From the data, it is suggested that the rational design of the location and ratio of peptide plays a key role in constructing materials with determined properties based on peptide–thiophene conjugates. 相似文献
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复杂网络广泛存在于日常生活,首先,给出几类标准的网络模型;然后,利用稳定性控制方法设计并实现了具有时滞与非时滞耦合的复杂网络模型快速控制;最后,通过构造优化Lyapunov函数,讨论其模型的射影同步问题,得到了系统全局稳定的条件和有效的控制器,以实例数值验证其方法的可行性。 相似文献
4.
In this paper, we study a nematic liquid crystals system in three-dimensional whole space ?3 and obtain the time decay rates of the higher-order spatial derivatives of the solution by the method of spectral analysis and energy estimates if the initial data belongs to L1?3 additionally. 相似文献
5.
Weijie Jiao Zhen Lei Xu Zhao Kun Wang Ailing Ma Lei Du Ruiying Hou Jing Han Meng Chen 《Biomedical chromatography : BMC》2020,34(9):e4869
To investigate the effect of ligustrazine on the pharmacokinetic profile of tanshinol after intravenous administration in rats, a sensitive liquid chromatography tandem mass spectrometry method was developed and validated for quantitative determination of tanshinol and ligustrazine in rat plasma. After prepared by protein precipitation, the analytes were separated on a Waters Acquity HSS T3 column (100 × 2.1 mm, 1.8μm) and eluted by 0.1% formic acid in water and acetonitrile at a flow rate of 0.4 ml/min. The precursor–product ion transitions were m/z 197.0 → 135.0 for tanshinol, m/z 417.1 → 255.1 for liquiritin (internal standard) in negative ion mode and m/z 137.1 → 55.0 for ligustrazine in positive ion mode. To avoid the interference of tanshinol metabolite transformation, the stability of analytes in samples collected after administration was assessed. The validated method was successfully applied to a pharmacokinetic study after intravenous administration of single tanshinol and Danshen Chuanxiongqin Injection. After Danshen Chuanxiongqin injection administration, the values of elimination half-time, area under the concentration–time curve and Co were 0.36 ± 0.13 h, 1.29 ± 0.37 μg/ml h and 10.51 ± 2.58 μg/ml for male rats, respectively. In the single tanshinol group, the corresponding values were 0.56 ± 0.24 h, 1.85 ± 0.44 μg/ml h and 14.11 ± 2.26 μg/ml for male rats—30–40% higher than those for the Danshen Chuanxiongqin Injection group. There was a significant different between male and female rats. This study provided information on the influence of ligustrazine on the pharmacokinetic characteristics of tanshinol after intravenous administration of Danshen Chuanxiongqin Injection in rats, which will be helpful for its clinical application. 相似文献
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Poly[(glycidyl methacrylate)-co-(glycerol monomethacrylate)]-grafted magnetic microspheres were prepared by graft random copolymerization via ATRP from polymer microspheres with dispersed Fe(3)O(4) nanoparticles. Penicillin G acylase (PGA) was immobilized onto the polymer brush-grafted magnetic microspheres. The immobilized PGA prepared with initial glycidyl methacrylate/glycerol monomethacrylate ratios of 40/60 to 60/40 possessed higher catalytic activity than that prepared with higher proportions of glycidyl methacrylate in the initial monomer mixture. The immobilized PGA showed high thermal stability and enhanced tolerability to the pH variance. 相似文献
8.
Four cobalt(II) compounds, [Co(Bim)(IA)(H2O)2]n·0.5nH2O (1), [Co(Bim)(MA)(H2O)2]n (2), [Co2(Bim)2(MA)2]n·nH2O (3), and [Co3(Bim)4(TA)2(H2O)2]n·2.5nH2O (4), have been synthesized by solvothermal reactions of cobalt(II) salts with 1,1′-(5-methyl-1,3-phenylene)bis(1H-imidazole) [Bim] and aromatic polycarboxylic acids (H2IA = isophthalic acid, H2MA = 5-methylisophthalic acid, and H3TA = trimesic acid) as coligands. The four complexes were characterized by IR and UV?vis spectra, elemental analyses, X-ray powder and single-crystal diffractions, and thermogravimetric analyses (TGAs). 1 features a zigzag polymeric macrocycle chain containing a nanotubular channel, which is constructed by bridging the folded 20-membered macrocyclic [Co2(Bim)2] subunits with IA ligands. 2 represents a double-chain structure containing 18-membered macrocyclic [Co2(Bim)(MA)] subunits. Both 3 and 4 are 2-D porous coordination polymers but have different architectures. In 3, cage-like [Co4(Bim)2(MA)4] subunits are 4-connected nodes that are further bridged by another half-set of Bim ligands to form a 2-D helical structure containing one-dimensional achiral channels and alternately arranged left- and right-handed helical tubular channels. In 4, Bim ligands bridge three crystallographically independent Co centers into sharply distorted left- and right-handed helices which are further connected by TA ligands to form a meso layer about 3.0 nm monolayer thickness with a unique (3,4)-connected topology. The structural diversities of coordination polymers 1–4 are tuned by the flexible coordination number of Co and coligand polycarboxylates. Thermal analyses show that the main frameworks of all compounds remain stable to 352 °C. Moreover, the interesting color changes of crystals 1–4, varying from pink to purple and dark blue, result from the d → d* transitions of chromophoric Co2+ in different coordination geometries as determined by the UV–vis spectra in combination with crystal structure analyses. 相似文献
9.
In this paper, we study the time‐decay rates of the solution to the Cauchy problem for a nematic liquid crystals system via a refined pure energy method. In particular, the optimal decay rates of the higher‐order spatial derivatives of the solution are obtained. The negative Sobolev norms are shown to be preserved along time evolution and enhance the decay rates. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
10.
针对无线传感器网络中节点被窃听和盗用对数据安全传输所带来的影响,提出了一种基于网络编码的容错路由(fault-tolerant routing based on network coding,FR-NC).该路由算法利用网络中大多数节点能正确传输数据的特点,通过选举保证数据一致性,从而防止了盗用节点对数据的篡改;同时对随机编码系数进行加密,起到了对数据安全的监督和保护作用.通过对实验结果的分析,可以发现当网络中存在一定数量的盗用节点时,FR-NC具有较好的健壮性. 相似文献