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排序方式: 共有648条查询结果,搜索用时 15 毫秒
641.
642.
Li Y Jones W Rasti F Blaga I Bogdan G Eberhart D Kobrin B Lee D Nielsen B van Gelder E Jovanovich S Stern S 《Lab on a chip》2011,11(15):2541-2550
We describe a programmable microfluidic system with onboard pumps and valves that has the ability to process reaction volumes in the sub-microlitre to hundred microlitre range. The flexibility of the architecture is demonstrated with a commercial molecular biology protocol for mRNA amplification, implemented without significant modification. The performance of the microchip system is compared to conventional bench processing at each stage of the multistep protocol, and DNA microarrays are used to assess the quality and performance of bench- and microchip-amplified RNA. The results show that the microchip system reactions are similar to bench control reactions at each step, and that the microchip- and bench-derived amplified RNAs are virtually indistinguishable in differential microarray analyses. 相似文献
643.
Wei Yue Adam Bange Bill L. Riehl Jay M. Johnson Ian Papautsky William R. Heineman 《Electroanalysis》2013,25(10):2259-2267
Metal catalyst free carbon nanotube (MCFCNT) whiskers were first used as an electrode modification material on a gold electrode surface for zinc voltammetric measurements. A composite film of Nafion and MCFCNT whiskers was applied to a gold electrode surface to form a mechanically stable sensor. The sensor was then used for zinc detection in both acetate buffer solution and extracted bovine serum solution. A limit of detection of 53 nM was achieved for a 120 s deposition time. The zinc in bovine serum was extracted via a double extraction procedure using dithizone in chloroform as a zinc chelating ligand. The modified electrode was found to be both reliable and sensitive for zinc measurements in both matrices. 相似文献
644.
The dipalladium compound [{(adt)Pd}(2)(μ-tpbz)] (1) (adt = bis(p-anisyl)-1,2-ethylenedithiolate, tpbz = 1,2,4,5-tetrakis(diphenylphosphino)benzene) has been synthesized from [{Cl(2)Pd}(2)(μ-tpbz)] by transmetalation employing (adt)SnMe(2). The cyclic voltammogram (CV) of 1 reveals reversible oxidation waves at 0.00 V and +0.50 V (vs [Fc](+)/Fc) with current amplitude twice that for identical processes in the monopalladium compound [(adt)Pd(dppb)] (2) (dppb = 1,2-bis(diphenylphosphino)benzene), an observation indicating each wave involves simultaneous one-electron oxidations at each metallodithiolene fragment. This assignment is affirmed by density functional theory (DFT) calculations that show the redox-active molecular orbital (MO) is principally composed of the dithiolene S(2)C(2) π-system, and by spectroelectrochemical UV-vis of [1](2+), which displays hallmark low energy charge transfer (CT) bands. Dication [1](2+) is a diradical with a near degenerate singlet-triplet ground state; fluid solution electron paramagnetic resonance (EPR) spectra validate the DFT-derived isotropic exchange coupling, J' = -6.3 cm(-1). The frozen solution X-band EPR spectrum of [1](2+) is consistent with a spin-triplet bearing a very faint half-field ("ΔM(S) = 2") signal. It is successfully simulated with an amazingly small zero field splitting, D = -15 × 10(-4) cm(-1) and negligible rhombicity (E/D = 0.008). These zero-field splitting parameters, which stem from the long-range dipolar spin coupling, are very accurately reproduced using a multipoint dipole model with an optimized interspin distance of 12.434 ?. With the framework reported herein for understanding how the weak interaction of two spins is mediated by tpbz, this bridging ligand can now be incorporated into extended systems with tailored chemical and physical properties for use in a variety of molecular-based electronic and magnetic devices. 相似文献
645.
Marius D. R. Lutz Hongyu Zhong Nils Trapp Bill Morandi 《Helvetica chimica acta》2023,106(4):e202200199
We report the synthesis of coordinatively unsaturated cationic rhodium complexes bearing the sterically encumbered electron-rich NHC ligand IPr*OMe. The COD (1,5-cyclooctadiene) complex [Rh(IPr*OMe)(COD)]BF4 adopts a tilted, pseudo-square planar coordination geometry, where bonding to the ipso-carbon of the NHC aryl substituent was observed in the solid state. Hydrogenation of this complex afforded a metastable dihydride complex [Rh(IPr*OMe)(H)2]BF4 with an unusual internal coordination to an arene of the ligand. In the absence of a hydrogen atmosphere, spontaneous reductive elimination of H2 afforded a rhodium complex [Rh(IPr*OMe)]BF4 with a single chelating ligand that stabilizes the highly unsaturated metal by two-fold π-face donation as suggested by NMR spectroscopy and computational studies. This unusual complex might serve as a versatile precatalyst for a variety of transformations. 相似文献
646.
647.
Ezio Rizzardo John Chiefari Bill Y.K. Chong Frances Ercole Julia Krstina Justine Jeffery Tam P.T. Le Roshan T.A. Mayadunne Gordon F. Meijs Catherine L. Moad Graeme Moad San H. Thang 《Macromolecular Symposia》1999,143(1):291-307
This paper describes a versatile and effective method for the control of free radical polymerization and its use in the preparation of narrow polydispersity polymers of various architectures. Living character is conferred to conventional free radical polymerization by the addition of a thiocarbonylthio compound of general structure S=C(Z)SR, for example, S=C(Ph)SC(CH3)2Ph. The mechanism involves Reversible Addition-Fragmentation chain Transfer and, for convenience of referral, we have designated it the RAFT polymerization. The process is compatible with a very wide range of monomers including functional monomers such as acrylic acid, hydroxyethyl methacrylate, and dimethylaminoethyl methacrylate. Examples of narrow polydispersity (≤1.2) homopolymers, copolymers, gradient copolymers, end-functional polymers, star polymers, A-B diblock and A-B-A triblock copolymers are presented. 相似文献
648.
New cyclic imino ether monomers, functionalized with acetylacetoxy, acetylacetamide, or acetylacetanilide moieties are described for the first time. These monomers readily form metal complexes. Also, it is shown that these monomers may be cationically homo‐ or copolymerized with other cyclic imino ethers, to provide polymers having metal complexing ability. The monomers have potential applications in a wide variety of applications. 相似文献