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排序方式: 共有267条查询结果,搜索用时 15 毫秒
91.
P. Tim Prins Johanna C. van der Bok Thomas P. van Swieten Stijn O. M. Hinterding Andy J. Smith Andrei V. Petukhov Andries Meijerink Freddy T. Rabouw 《Angewandte Chemie (International ed. in English)》2023,62(28):e202305086
β-NaYF4 nanocrystals are a popular class of optical materials. They can be doped with optically active lanthanide ions and shaped into core-multi-shell geometries with controlled dopant distributions. Here, we follow the synthesis of β-NaYF4 nanocrystals from α-NaYF4 precursor particles using in situ small-angle and wide-angle X-ray scattering and ex situ electron microscopy. We observe an evolution from a unimodal particle size distribution to bimodal, and eventually back to unimodal. The final size distribution is narrower in absolute numbers than the initial distribution. These peculiar growth dynamics happen in large part before the α-to-β phase transformation. We propose that the splitting of the size distribution is caused by variations in the reactivity of α-NaYF4 precursor particles, potentially due to inter-particle differences in stoichiometry. Rate equation modeling confirms that a continuous distribution of reactivities can result in the observed particle growth dynamics. 相似文献
92.
Florin Panaite Freddy Van Oystaeyen 《Proceedings of the American Mathematical Society》2007,135(6):1669-1677
If is a quasi-Hopf algebra and is a right -comodule algebra such that there exists a morphism of right -comodule algebras, we prove that there exists a left -module algebra such that . The main difference when comparing to the Hopf case is that, from the multiplication of , which is associative, we have to obtain the multiplication of , which in general is not; for this we use a canonical projection arising from the fact that becomes a quasi-Hopf -bimodule.
93.
Synthesis and Analysis of the Structure,Diffusion and Cytotoxicity of Heterocyclic Platinum(IV) Complexes 下载免费PDF全文
Freddy J. Macias Krishant M. Deo Benjamin J. Pages Prof. Paul Wormell Dr. Jack K. Clegg Dr. Yingjie Zhang Dr. Feng Li Dr. Gang Zheng Dr. Jennette Sakoff Dr. Jayne Gilbert Prof. Janice R. Aldrich‐Wright 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16990-17001
We have developed six dihydroxidoplatinum(IV) compounds with cytotoxic potential. Each derived from active platinum(II) species, these complexes consist of a heterocyclic ligand (HL) and ancillary ligand (AL) in the form [Pt(HL)(AL)(OH)2]2+, where HL is a methyl‐functionalised variant of 1,10‐phenanthroline and AL is the S,S or R,R isomer of 1,2‐diaminocyclohexane. NMR characterisation and X‐ray diffraction studies clearly confirmed the coordination geometry of the octahedral platinum(IV) complexes. The self‐stacking of these complexes was determined using pulsed gradient stimulated echo nuclear magnetic resonance. The self‐association behaviour of square planar platinum(II) complexes is largely dependent on concentration, whereas platinum(IV) complexes do not aggregate under the same conditions, possibly due to the presence of axial ligands. The cytotoxicity of the most active complex, exhibited in several cell lines, has been retained in the platinum(IV) form. 相似文献
94.
Back Cover: Multi‐frequency (S,X, Q and W‐band) EPR and ENDOR Study of Vanadium(IV) Incorporation in the Aluminium Metal–Organic Framework MIL‐53 (ChemPhysChem 14/2015) 下载免费PDF全文
95.
Xiao J Yang B Wong JI Liu Y Wei F Tan KJ Teng X Wu Y Huang L Kloc C Boey F Ma J Zhang H Yang HY Zhang Q 《Organic letters》2011,13(12):3004-3007
Synthesis, structure, and physical properties of a novel 11-methylbenzo[d]pyreno[4,5-b]furan (BPF) and its self-assembly in water have been reported. The performance of nanowire-based films in organic light-emitting diodes is much better than that of the thin film deposited by directly drop-coating BPF molecules in THF solution. SEM study indicates that the well-organized structure (nanowires) is an important factor in enhancing the performance of OLED devices. 相似文献
96.
97.
Single-walled carbon nanotubes (SWCNTs) have attracted great interest in the last two decades because of their unique electrical, optical, thermal, mechanical properties, etc. One major research field of SWCNTs is the controlled growth of them from the patterned catalysts on substrates, since the integration of SWCNTs into nanoelectronics and other devices requires well-organized SWCNT arrays. This tutorial review describes the commonly used lithographic techniques to pattern catalysts used for controlled growth of SWCNTs, specifically confined to the horizontal direction. Advantages and disadvantages of each method will be briefly discussed. Applications of the SWCNT arrays grown from the catalyst patterns will also be introduced. 相似文献
98.
99.
Nilsson M Lätt J Nordh E Wirestam R Ståhlberg F Brockstedt S 《Magnetic resonance imaging》2009,27(2):176-187
The aim of this work was to study the diffusion-related signal attenuation curves (signal-vs.-b curves) measured perpendicular and parallel to the neuronal fibers of the corticospinal tract in vivo and to determine whether effects of restricted diffusion could be observed when varying the diffusion time (TD). A biexponential model and a two-compartment model including exchange according to the Kärger formalism were employed to analyze the signal-vs.-b curves. To validate the two-compartment model, restricted diffusion with exchange was simulated for uniformly sized cylinders, using different diameters and exchange times. The model was shown to retrieve the simulated parameters well, also when the short gradient pulse approximation was not met. The in vivo measurements performed perpendicular to the tracts, using b values up to 28000 s/mm2 and TD values between 64 and 256 ms, did not show the effects of restricted diffusion as expected from previous ex vivo studies. The applied two-compartment model yielded an average axonal diameter of about 4 μm and an intracellular exchange time of about 300 ms, but did not fit statistically well to the data. In conclusion, this study indicates that if the diffusion is modeled as two compartments, of which one is restricted, exchange must be included in the model. 相似文献
100.
We consider some aspects of the curved BPS domain walls and their supersymmetric Lorentz invariant vacua of the four dimensional N = 1 supergravity coupled to a chiral multiplet. In particular, the scalar manifold can be viewed as a two dimensional Kähler-Ricci soliton generating a one-parameter family of Kähler manifolds evolved with respect to a real parameter, τ. This implies that all quantities describing the walls and their vacua indeed evolve with respect to τ. Then, the analysis on the eigenvalues of the first order expansion of BPS equations shows that in general the vacua related to the field theory on a curved background do not always exist. In order to verify their existence in the ultraviolet or infrared regions one has to perform the renormalization group analysis. Finally, we discuss in detail a simple model with a linear superpotential and the Kähler-Ricci soliton considered as the Rosenau solution. 相似文献