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991.
Monodispersed quantum dots (QDs)-encoded polymer microbeads were generated using a simple capillary fluidic device (CFD). The polymer and QDs solution was emulsified into monodispersed microdroplets by the CFD and obtained droplets were solidified via solvent evaporation. Polymer microbeads can be fabricated in a range of different sizes through changing the flow rates of the two immiscible phases, and have a highly narrow size distribution and uniform shape. QDs-encoding capacity of the microbeads was investigated through adjusting the concentrations and ratios of QDs in the polymer solution. Mono-color encoded microbeads with five intensities and a dual-color QDs-encoded 5×5 microbeads array were obtained, and the spectral profiles of the microbeads were examined by a fluorescent microscope coupled with a spectral imaging system. QDs-tagged microbeads prepared with this method were more stable than the porous beads swollen with QDs in the buffer with various pH and crosslinking chemicals. Finally, the application of such microbeads for biomolecule detection was demonstrated by conjugation of rabbit IgG molecules on the surface of the microbeads via carboxyl groups, which were then detected by fluorophores-labeled goat-anti-rabbit IgG antibodies. 相似文献
992.
Shuliang Yang Cunqi WuMingbo Ruan Yanqin Yang Yongxia Zhao Jiajia NiuWei Yang Jingwei Xu 《Tetrahedron letters》2012,53(33):4288-4292
A simple, metal- and ligand-free procedure for the Ullmann-type C-O coupling reactions has been achieved by allowing aryl bromides to react with a variety of phenols in the presence of t-BuOK. Moderate to excellent yields of O-arylation products are obtained under mild conditions in a short time. In addition, two examples of C-N coupling reactions are also reported. A benzyne mechanism is proposed according to the experiment data. 相似文献
993.
Lin H Long J Gu Q Zhang W Ruan R Li Z Wang X 《Physical chemistry chemical physics : PCCP》2012,14(26):9468-9474
The surface species on P25-TiO(2) were characterized by FTIR after evacuation at 50-550 °C. The functions of OH groups on P25-TiO(2) catalysts have been tested by the adsorption and photooxidation of toluene in an in situ IR cell. FTIR studies show that the hydroxyl species on P25-TiO(2) are clearly temperature-dependent and P25-TiO(2) has six isolated hydroxyls with bands at 3734, 3715, 3688, 3671, 3658 and 3640 cm(-1). The OH groups on P25 play different roles in the photo-oxidation process: surface hydroxyls with bands at 3688, 3671, 3658 and 3640 cm(-1) act as adsorption sites while surface hydroxyls with bands at 3734 and 3715 cm(-1) act as sources of the ˙OH radical. 相似文献
994.
Cytokinins (CTKs) are a class of growth-regulating hormones involved in various physiological and developmental processes. More novel analytical methods for the accurate identification and quantitative determination of trace CTKs in plants have been desired to better elucidate the roles of CTKs. In this work, a novel method based on monolithic molecularly imprinted solid-phase extraction followed by liquid chromatography–electrospray tandem mass spectrometry (mMI-SPE-LC-MS/MS) was developed for accurate determination of four CTKs in plant samples. The molecularly imprinted polymer monolith was prepared by using kinetin as the template in syringes and exhibited specific recognition ability for the four CTKs in comparison with that of non-imprinted polymer monolith. Several factors affecting the extraction performance of mMI-SPE, including the pH of loading sample solution, the nature and volume of elution solvent, the flow rate of sample loading, and sample volume, were investigated, respectively. Under the optimized conditions, the proposed mMI-SPE-LC-MS/MS method was successfully applied in the selective extraction and determination of four CTKs in plant tissues, and it offers detection limits (S/N?=?3) of 104, 113, 130, and 89 pg/mL and mean recoveries of 85.9%, 79.3%, 73.5%, and 70.1% for kinetin, kinetin glucoside, trans-zeatin, and meta-topolin (mT), respectively, with the corresponding RSDs less than 15%. Figure
Trace determination of cytokinins in different plant samples by monolithic molecularly imprinted solid-phase extraction and liquid chromatography–mass spectrometry 相似文献
995.
本文在多通道量子数亏损理论(MQDT)框架下,利用相对论多通道理论(RMCT),分别在冻结实近似、 考虑Δl=-1的偶极极化效应、Δl=+1的偶极极化效应、Δl=± 1的偶极极化效应、伸缩模效应以及同时考虑偶极极化效应和伸缩模效应等不同层次近似下,系统地计算了碱金属Li, Na, K, Rb, Cs和Fr七个里德伯系列的能级,即ns2S1/2, np2P1/2, np2P3/2, nd2D3/2, nd2D5/2, nf2F5/2 和nf2F7/2.计算结果表明,电子关联效应对碱金属原子的里德伯能级的影响很大.总的来说,偶极极化效应比伸缩模效应重要,而在偶极极化效应中, Δl = + 1的偶极极化效应比Δl = - 1的偶极极化效应重要.但对于Na的ns2S1/2,(nd2D3/2,nd2D5/2)里德伯系列的能级,和Li的(np2P1/2,np2P3/2)里德伯系列的能级,是伸缩模效应比较重要. 相似文献
996.
997.
Xue-Zhi Li Xi-Chao Duan Mini Ghosh Xiu-Ying Ruan 《Nonlinear Analysis: Real World Applications》2009,10(5):3298-3311
In this paper, a two-strain epidemic model with saturating contact rates is considered. It is shown that if the social activity of infected individuals does not vary with strains, then the competitive exclusion principle holds; if the social activity of infected individuals varies with different strains, the coexistence of pathogens is possible under a certain condition which involves the invasion reproduction numbers. The stability of the dominance equilibria and coexistence equilibrium is also examined. Numerical simulations are presented to illustrate the results. 相似文献
998.
Rao M Li Q Feng L Xia X Ruan L Sheng X Ge M 《Analytical and bioanalytical chemistry》2011,401(2):699-706
The diversity of microbial metabolites has been of interest and concern for a long time, yet a suitable method for discovering
these is still unavailable. In the work discussed in this report, ultra-performance liquid chromatography coupled with tandem
quadrupole and time of flight high-resolution mass spectrometry (UPLC–Q–TOF-HRMS), with MS data analysis, was set up to study
the metabolites of Streptomyces strain HCCB10043. It was found that besides antibacterial substances (A21978C complex) and two anti-aminopeptidase compounds
(valistatin and bestatin), this strain can produce a new aminopeptidase inhibitor, identified as 3-amino-2-hydroxy-4-phenylbutanoylvalylisoleucine.
This new compound had greater activity than valistatin or bestatin in aminopeptidase N (APN) inhibition assay. The results
proved that combination of UPLC–Q–TOF-MS analysis and classic purification and identification steps as complementary strategies
can provide a method with high reliability for research on microbial secondary metabolites. Furthermore, it has shown that
the study of secondary metabolic profiling might be the key to discovering new drugs. 相似文献
999.
Asymmetric vinylogous Mannich reaction (VMR) of 2-(tert-butyldimethylsilyloxy)furan (TBSOF, 1) with (R(S))- or (S(S))-t-BS-imines (3) furnished 5-aminoalkylbutenolides 7a-k in 75-87% yields with anti/syn ratios ranging from 75:25 to 97:3. Butenolides 7a-f,k were readily converted into substituted lactones 8 and 5 and 6-substituted 5-hydroxypiperidin-2-ones 11a-g, which are, in turn, key intermediates for the synthesis of many bioactive compounds. 相似文献
1000.
Li DH Shen JS Chen N Ruan YB Jiang YB 《Chemical communications (Cambridge, England)》2011,47(20):5900-5902
A ratiometric luminescent sensing of Ag(+) ion is developed via the Ag(I)-NCys coordination polymeric luminophore in situ formed in aqueous solution upon mixing Ag(+) ion with the designed fluorescent thiol ligand NCys. 相似文献