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排序方式: 共有117条查询结果,搜索用时 31 毫秒
11.
Lanthanide complexes with benzothiazole derivatives (Btz-R, R = OCH(3) and OH) and terpyridine (tpy) ligands were synthesized, and their photophysical properties were precisely investigated. The free Btz-OCH(3) ligand in toluene, excited with UV light, produced the normal emission bands around 410 nm, whereas Btz-OH produced a strong excited-state intramolecular proton transfer (ESIPT) band at 510 nm. The Ln(III) complexes (Ln = Nd, Er, and Yb) exhibited sensitized near-IR luminescence when the Btz-R ligands were excited. The sensitized luminescence quantum yields (Phi(Ln)) of the lanthanide complexes were markedly enhanced by ESIPT: for [Nd(Btz-R)(tpy)] in toluene solution, Phi(Ln) = 0.04% for Btz-OCH(3) and 0.39% for Btz-OH. The sensitized luminescence of the Er(III) complexes (Phi(Ln) = 0.002% for Btz-OCH(3) and 0.009% for Btz-OH) was less efficient than that of the Nd(III) complexes. This difference is due to the smaller energy gap between the emitting and ground levels of the Er(III) ion. The rate constants for the energy transfer from Btz-R to Ln(III) were about approximately 10(9) s(-1), as evaluated by the F?rster resonance energy transfer mechanism. 相似文献
12.
Li4Ti5O12 thin films for rechargeable lithium batteries were prepared by a sol-gel method with poly(vinylpyrrolidone). Interfacial properties of lithium insertion into Li4Ti5O12 thin film were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and potentiostatic intermittent titration technique (PITT). Redox peaks in CV were very sharp even at a fast scan rate of 50 mV s−1, indicating that Li4Ti5O12 thin film had a fast electrochemical response, and that an apparent chemical diffusion coefficient of Li+ ion was estimated to be 6.8×10−11 cm2 s−1 from a dependence of peak current on sweep rates. From EIS, it can be seen that Li+ ions become more mobile at 1.55 V vs. Li/Li+, corresponding to a two-phase region, and the chemical diffusion coefficients of Li+ ion ranged from 10−10 to 10−12 cm2 s−1 at various potentials. The chemical diffusion coefficients of Li+ ion in Li4Ti5O12 were also estimated from PITT. They were in a range of 10−11-10−12 cm2 s−1. 相似文献
13.
Let D be a digraph. The competition-common enemy graph (CCE graph) of D has the same set of vertices as D and an edge between vertices u and v if and only if there are vertices w and x in D such that (w,u), (w,v), (u,x), and (v,x) are arcs of D. We call a graph a CCE graph if it is the CCE graph of some digraph. In this paper, we show that if the CCE graph of a doubly partial order does not contain C4 as an induced subgraph, it is an interval graph. We also show that any interval graph together with enough isolated vertices is the CCE graph of some doubly partial order. 相似文献
14.
Rho HS Oh SH Lee JW Lee JY Chin J Song CE 《Chemical communications (Cambridge, England)》2008,(10):1208-1210
Highly enantioselective methanolysis of meso-cyclic anhydride was achieved with bifunctional organocatalyst containing a quinine-thiourea moiety; unusual concentration, temperature and solvent effects on the enantioselectivity can be explained in terms of a mechanism involving monomer-dimer equilibration of the catalyst. 相似文献
15.
16.
The problem of pion condensation in isospin symmetric nuclear matter is investigated in the framework of the σ-model with a residual nucleon-nucleon interaction (g′σ1 · σ2τ1 · τ2δ(x)) and Δ-isobars. The equation of state for the pion condensed phase is calculated and applied to a low-energy heavy-ion collision in the TDHF approximation. The effective particle-hole interaction and the response to spin-isospin excitation are used to determine the magnitude of the Landau-Migdal parameter g′. For a reasonable range of g′(0.5 < g′ ≦ in units of g2/4m2N = 410 MeV · fm3) pion condensation occurs at densities above normal nuclear matter density and leads to an equation of state with no stable density isomer. 相似文献
17.
It is demonstrated that when quantum correlations are added, chiral Lagrangians need not generate strong many-body forces as they do in tree approximation. We suggest that a physically reasonable procedure is to adjust the σ-model parameters so as not to conflict with the current status of nuclear theory. As a consequence, the equilibrium density of abnormal states could be pushed up further, and the binding energy be considerably reduced. 相似文献
18.
19.
Kim CS Kim M Furdyna JK Dobrowolska M Lee S Rho H Smith LM Jackson HE James EM Xin Y Browning ND 《Physical review letters》2000,85(5):1124-1127
The evolution of self-assembled CdSe quantum dots deposited on (and subsequently capped by) ZnSe was investigated on a series of samples grown by molecular beam epitaxy, with CdSe coverages from 0.5 to 2.6 monolayers. The samples were investigated by cross-sectional scanning transmission electron microscopy, as well as macro- and microphotoluminescence. The results clearly indicated a coexistence of 2D ZnCdSe platelets and 3D islands, showing clearly that the platelets act as precursors for the formation of the 3D islands. 相似文献
20.
A starter culture ofTrichoderma reesei (Rut-C30) prepared in a liquid fluidized bed reactor (LFBR) gave better growth and greater cellulase production in submerged
fermentation than a conventional shake flask inoculum. The LFBR starter was prepared by first coatingT. reesei spores to 0.25 mm size corncob (1.0x108g-1) in a medium containing 1.0% corncob, 0.5 gL-1 xylose and 0.1 gL-1 lactose in a balanced salt solution, then fluidizing the particles in the LFBR for 36 h to allow germination of the spores,
and covering the particles with an approx 30 μm thick biofilm. This biofilm that developed in constant adherence to the lignocellulosic
carrier, apparently became well adapted to grow rapidly on insoluble cellulose substrates (Solca Floc), and had the enzymes
of the cellulase complex induced for increased cellulase production.
The LFBR starter used in a stirred tank reactor (STR) gave 15 gL-1 biomass production and 6.5 IU mL-1 overall cellulase activity with a volumetric productivity of 64 IU L-1h-1 in a 5 d fermentation, compared with a 7 d shake flask inoculum that gave 11 gL-1 biomass and 3.2 IU mL-1 cellulase activity, with a volumetric productivity of 31IU L-1h-1. The LFBR starter culture retained its viability in dry storage for 6–9 mo. 相似文献