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排序方式: 共有6517条查询结果,搜索用时 31 毫秒
971.
Effective extraction and simultaneous determination of Sudan dyes from tomato sauce and chili‐containing foods using magnetite/reduced graphene oxide nanoparticles coupled with high‐performance liquid chromatography
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Ming‐Yue Zhang Man‐Man Wang Yu‐Lan Hao Xin‐Ran Shi Xue‐Sheng Wang 《Journal of separation science》2016,39(9):1749-1756
A simple, effective, and robust magnetic solid‐phase extraction method was developed using magnetite/reduced graphene oxide nanoparticles as the adsorbent for the simultaneous determination of Sudan dyes (I, II, III, and IV) in foodstuffs. The magnetite/reduced graphene oxide nanoparticles were characterized by X‐ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. The extraction parameters including extraction time, elution solution, and elution time and volume were investigated in detail. Such magnetite/reduced graphene oxide nanoparticles based magnetic solid‐phase extraction in combination with high‐performance liquid chromatography and variable wavelength detection gave the detection limits of 3–6 μg/kg for Sudan I–IV in chili sauce, tomato sauce, chili powder, and chili flake samples. The recoveries were 79.6–108% at three spiked levels with the intra‐ and inter‐day relative standard deviations of 1.2–8.6 and 4.5–9.6%, respectively. The feasibility was further performed by a comparison with commercial alumina‐N. This method is suitable for the routine analysis of Sudan dyes due to its sensitivity, simplicity, and low cost. 相似文献
972.
A Variety of Phase‐Transition Behaviors in a Niccolite Series of [NH3(CH2)4NH3][M(HCOO)3]2
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Ran Shang Sa Chen Ke‐Li Hu Prof. Bing‐Wu Wang Prof. Zhe‐Ming Wang Prof. Song Gao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(18):6199-6203
A niccolite series of [bnH22+][M(HCOO)3]2 (bnH22+=1,4‐butyldiammonium) shows four kinds of metal‐dependent phase transitions, from high temperature para‐electric phases to low‐temperature ferro‐, antiferro‐, glass‐like, and para‐electric phases. The conformational flexibility of bnH22+ and the different size, mass, and bonding character of the metal ion lead to various disorder‐order transitions of bnH22+ in the lattice and relevant framework modulations, thus different phase transitions and dielectric responses. The magnetic members display a coexistence or combination of electric and magnetic orderings in the low‐temperature region. 相似文献
973.
Sunyoung Kim Dan-Bi Kim Sanghee Lee Jisu Park Dongbin Shin 《Natural product research》2016,30(24):2798-2804
This study investigates the comprehensive organosulphur compounds and evaluation of antioxidant activities in Allium hookeri, called hooker chive. The non-volatile and volatile organosulphur compounds were determined by high-performance liquid chromatography-photodiode array detector (HPLC-PDA) and gas chromatography-mass spectrometry (GC-MS), respectively. Among 11 non-volatileorganosulphur compounds, methiin and cycloalliin were major compounds. A total of 42 volatile compounds were identified and allyl methyl sulphides and dimethyl sulphides were primarily volatiles. The total phenols ranged from 19.32 to 71.19 mg gallic acid equivalents (GAE)/g. The antioxidant capacities expressed IC50 values ranged from 9.59 to 38.54 mg/mL for DPPH radical scavenging activity and from 0.39 to 2.36 for ferric reducing antioxidant power assay. The results were proposed as useful tools for evaluating the nutraceutical of hooker chive. 相似文献
974.
In this paper, we present an extention of Hyers–Ulam stability of Sahoo–Riedel’s points for real-valued differentiable functions on [a, b] and then we obtain stability results of Flett’s points for functions in the class of continuously differentiable functions on [a, b] with f′(a) = f′(b). 相似文献
975.
976.
[structure: see text] Three phosphorus(V) porphyrins with axial carbazole-based dendritic substituents (D-A-D) have been designed and synthesized, which are nonfluorescent due to their effective electron transfer from the carbazole dendron to the excited porphyrin within the dendritic matrix. The incident photon to current conversion efficiencies (IPCE) spectra demonstrate that the molecular structure of the dendrimers can significantly affect the photovoltaic response to the visible light. 相似文献
977.
Benzimidazole-based tripodal receptor: highly selective fluorescent chemosensor for iodide in aqueous solution 总被引:2,自引:0,他引:2
We synthesized a novel tripodal fluorescent receptor bearing benzimidazole motifs as recognition sites in the pods of the receptor. The recognition behavior of the receptor toward various anions was evaluated in CH3CN/H2O (9:1, v/v) solution. The receptor showed changes in fluorescent intensity only with I-, but it showed no significant changes on addition of other anions such as F-, Cl-, Br-, HSO4-, NO3-, CH3COO-, and H2PO4-. 相似文献
978.
979.
980.
Glycosidases are a large subgroup of carbohydrate-processing enzymes that hydrolytically cleave the glycosidic bond. Glycans formed by the action of glycosidases are involved in various biological processes. Genetic abnormalities in glycosidases are associated with inherited diseases. Thus, characterization of the catalytic activities of glycosidases is of great importance. Herein, we describe a simple and rapid approach for determining glycosidase activity profiles using coumarin-conjugated glycoside cocktails. [reaction: see text]. 相似文献