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排序方式: 共有167条查询结果,搜索用时 156 毫秒
71.
Nisar Ahmed Vijay Madhav Miriyala Seong-Kyoon Choi Kyeong-Min Lee Won Bae Jeon 《Supramolecular chemistry》2013,25(7-8):478-483
Fluorescent imaging probes have revolutionised cell biology by monitoring cellular objects. However, the lack of fluorescent probes with high selectivity for RNA has been a drawback. Thus, selective RNA binding for fluorescent sensors is essential. Here, we report the selective fluorescence enhancement upon addition of RNA. By exploiting a selective recognition of small tetra-cationic probe 1 for RNA, we also explain the possible binding mode for RNA. As a membrane-permeant fluorescence probe, 1 provides selective imaging of RNA not only in human neuroblastoma tumour SH-SY5Y cell line used for Parkinson's disease but also in the unicellular green alga cells. Further exploitation could open new opportunities in neurotoxin and cancer biology. 相似文献
72.
The gas phase elimination kinetics of 2‐bromopropene was studied over the temperature range of 571–654 K and pressure range of 12–46 Torr using the seasoned static reaction system. Propyne was the only olefinic product formed and accounted for >98% of the reaction. This product was formed by homogeneous, unimolecular pathways with high‐pressure first‐order rate constant k∞ given by the equation k∞ = 1013.47 ± 0.6 exp?208.2 ± 6.7 (kJ mol?1)/RT. The error limits are 95% certainty limits. The observed Arrhenius parameters are consistent with the four centered activated complex. The presence of methyl group on α‐carbon lowers the activation energy by 41 kJ mol?1. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 39: 1–5, 2007 相似文献
73.
Mercaptothiazolinyl functionalized hexapodal (L(1)) and tripodal (L(2)) receptors on the benzene platform have been synthesized easily in good yields and structurally characterized by a single-crystal X-ray crystallographic study. In the solid state, L(1) shows an orientation of six arms in 1,3,5 vs 2,4,6 facial steric gearing fashion, whereas L(2) adopted C(2v) symmetry where two of its thiazolinyl arms are oriented in one direction and the third arm in the another direction. Two silver complexes of L(1), 1 ([2(L(1))·6(AgClO(4))·2(CHCl(3))·HClO(4)]) and 2 ([2(L(1))·6(AgClO(4))]), that are suitable for single-crystal X-ray studies are isolated upon the slow diffusion of a dimethylformamide solution of AgClO(4) to the solution of L(1) in chloroform and dichloromethane, respectively. Similarly, upon the slow diffusion of an acetonitrile solution of AgClO(4) to the chloroform solution of L(2), colorless crystals of the silver complex of L(2), 3, are successfully isolated. The structural analyses of 1 and 2 show the formation of a silver ion assisted hexanuclear metallocage Ag(6)(L(1))(2) via dimeric assembly of L(1) with multiple clefts and pockets toward guests binding. In 1, two chloroform molecules sit in top and bottom pockets, whereas six perchlorate counteranions are bound in six clefts between the silver ion pillared side arms of the metallocage. Though complex 2 shows the formation of a metallocage like 1, the single crystal structural analysis depicts perchlorate counteranions bonded to the silver atoms of the metallocage. On the contrary, the silver complex of tripodal receptor L(2), 3, shows the formation of a metallo-organic polymeric network of L(2) and Ag(+). To the best of our knowledge, this work represents the first report on the formation of an M(6)L(2) type metallosupramolecular cage topology with multiple clefts for guest binding by a semirigid hexapodal receptor. 相似文献
74.
Yan Y Wang J Zhang L Yang JY Fazal IM Ahmed N Shamee B Willner AE Birnbaum K Dolinar S 《Optics letters》2011,36(21):4269-4271
We propose a fiber coupler consisting of a central ring and four external cores to generate up to ten orbital angular momentum (OAM) modes. Four coherent input lights are launched into the external cores and then coupled into the central ring waveguide to generate OAM modes. By changing the size of the external cores, one can selectively excite a high-order OAM mode. The quality of the generated OAM modes can be enhanced by adjusting the polarization state and the phase of input lights. We show the generation of OAM modes with odd charge numbers of -9 to +9 (i.e., 10 modes totally) with mode purity of >99% using <2?mm long fiber. This fiber coupler design can be extended to enable all-fiber spatial-mode (de)multiplexing. 相似文献
75.
Free space optics (FSO) technology provides a promising solution for future broadband networks, offering high data transmission compared to RF technology. This work is focused on investigating the performance of an FSO system with OFDM and QAM. A 10 Gbps data stream is transmitted using a 4-level QAM sequence through the FSO system under different atmospheric conditions. Results indicate that the integration of SOA prolongs the maximum achievable distance with acceptable SNR to 185 km under clear weather conditions whereas under atmospheric fog, the maximum distance is extended to 2.5 km. 相似文献
76.
A new synthetic receptor has selective and strong interactions with glucose, directing towards future diabetes management. These studies pave the way to design future selective receptors that can potentially be modified with combinations of urea walls having multiple H-binding sites to generate hydrophilic affinities, and the incorporation of promising aromatic systems for hydrophobic π-interactions with glucose CH. 相似文献
77.
Bushra Nisar Syeda Laila Rubab Abdul Rauf Raza Sobia Tariq Ayesha Sultan Muhammad Nawaz Tahir 《Molecular diversity》2018,22(3):709-722
Novel and highly sensitive indole-based imines have been synthesized. Their synthesis has been compared employing a variety of protocols. Ultimately, a convenient, economical and high yielding set of conditions employing green chemistry have been designed for their synthesis. 相似文献
78.
Uddin Iftikhar Ullah I. Ali Rashid Khan Ilyas Nisar K. S. 《Journal of Thermal Analysis and Calorimetry》2021,145(2):495-505
Journal of Thermal Analysis and Calorimetry - The aim of the study is to explore nonlinear mixed convection flow of nanomaterials (Prandtl–Eyring nanoliquid) with activation energy. Analysis... 相似文献
79.
Nisar M Qayum M Adhikari A Khan I Kaleem WA Ali Z Choudhary MI 《Natural product communications》2010,5(11):1727-1728
4-Deacetylbaccatin III was isolated and characterized from the bark of Taxus wallichiana Zucc. It was previously identified as an intermediate during the synthesis of paclitaxel and was proposed as a precursor for the biosynthesis of paclitaxel. Existence of 4-deacetylbaccatin III in T. wallichiana is strong evidence for the previously proposed biosynthetic pathway of paclitaxel via 4-deacetylbaccatin III. 相似文献
80.