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1.
Pedro lvarez‐Boo Jos Sergio Casas Alfonso Castieiras María Delfina Couce Eduardo Freijanes Eva Novoa Jos Sordo 《应用有机金属化学》2003,17(9):725-729
Reaction of dichloro‐ and dibromodimethyltin(IV) with 2‐(pyrazol‐1‐ylmethyl)pyridine (PMP) afforded [SnMe2Cl2(PMP)] and [SnMe2Br2(PMP)] respectively. The new complexes were characterized by elemental analysis and mass spectrometry and by IR, Raman and NMR (1H, 13C) spectroscopies. Structural studies by X‐ray diffraction techniques show that the compounds consist of discrete units with the tin atom octahedrally coordinated to the carbon atoms of the two methyl groups in a trans disposition (Sn? C = 2.097(5), 2.120(5) Å and 2.110(6), 2.121(6) Å in the chloro and in the bromo compounds respectively), two cis halogen atoms (Sn? Cl = 2.4908(16), 2.5447(17) Å; Sn? Br = 2.6875(11), 2.7464(9) Å) and the two donor atoms of the ligand (Sn? N = 2.407(4), 2.471(4) Å and 2.360(5), 2.455(5) Å). In both cases, the Sn? N(pyridine) bond length is markedly longer than the Sn? N(pyrazole) distance. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
On the harmonic Bergman space of the half-space, we give characterizations for an arbitrary positive Toeplitz operator to
be a Schatten (or Schatten-Herz) class operator in terms of averaging functions and Berezin transforms. Examples are provided
to show that various results are sharp.
This research was supported by KOSEF(R01-2003-000-10243-0). 相似文献
3.
We show that Poisson integrals belonging to certain weighted harmonic Bergman spaces bδp on the upper half-space must have the moment vanishing properties. As an application, we show that b0p, p?1, contains a dense subspace whose members have the horizontal moment vanishing properties. Also, we derive related weighted norm inequalities for Poisson integrals. As a consequence, we obtain a characterization for Poisson integrals of continuous functions with compact support in order to belong to bδp. 相似文献
4.
Binyuan Liu Yang Li Boo‐Gyo Shin Do Yeung Yoon IL Kim Li Zhang Weidong Yan 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3391-3399
Three novel functionalized polynorbornenes (PNB) with pendant dimethyl carboxylate group (carboxylates—acetate, propionate, and butyrate) are synthesized as a vinyl‐type with a palladium (II) catalyst in high yield. The effects of size of substitutents, molar ratio of monomer to catalyst, solvent polarity, reaction time, and temperature on the polymerization of exo‐norbornene dimethyl propionate were systematically investigated. The low molar ratio and temperature, as well as high polarity of solvent, and long reaction time, are favorable for the enhancement of the monomer conversion, especially, the solvent have an obvious effect on the catalyst activity. The resulting poly(cis‐norbornene‐exo‐2,3‐dimethyl carboxylates) (PNB‐dimethyl carboxylates) show good solubility in common organic solvent and high thermal stability up to 360 °C. The glass transition temperature was detected by DMA at 331, 324, and 318 °C for acetate, propionate, and butyrate, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3391–3399, 2007 相似文献
5.
Sommermann T Kim BG Peters K Peters EM Linker T 《Chemical communications (Cambridge, England)》2004,(22):2624-2625
Only three steps are required for the convenient synthesis of 2-C-branched glyco-amino acids from glycals with good yields and stereoselectivities. 相似文献
6.
M. H. Lee C. W. Lee K. H. Hong Y. H. Choi B. H. Boo 《Journal of Radioanalytical and Nuclear Chemistry》1996,204(1):135-144
Depth distribution of239,240Pu and137Cs in the soils of South Korea have been studied. The average accumulated depositions were estimated roughly to be 54.8±32.1 Bq·m–2 for239,240Pu, 1.6±1.0 Bq· ·m–2 for238Pu and 1982.8±929.1 Bq·m–2 for137Cs. The activity ratios of239,240Pu/137Cs in soils were found to be in the narrow range of 0.0153 to 0.0364 with a mean value of 0.0230±0.006. The concentrations of239,240Pu and137Cs in soils decrease exponentially with increasing the soil depth. A significant correlation was found between the concentration of239,240Pu and that of137Cs. The activity ratios of239,240Pu/137Cs tend to increase slightly with increasing soil depth. 相似文献
7.
We study the commuting problem for Toeplitz operators on the harmonic Bergman space of the unit disk. We show that an analytic Toeplitz operator and a co-analytic Toeplitz operator with certain noncyclicity hypothesis can commute only when one of their symbols is constant. We also obtain analogous results for semi-commutants. 相似文献
8.
A collapsing bubble-induced microinjector: an experimental study 总被引:1,自引:0,他引:1
Abdolrahman Dadvand Boo Cheong Khoo Mohammad T. Shervani-Tabar 《Experiments in fluids》2009,46(3):419-434
In this study, a new drop-on-demand actuation mechanism, which uses an oscillating bubble as actuator is proposed and its
feasibility is investigated via the consideration of two important design parameters, namely, bubble distance to free surface
and nozzle dimension. The droplet ejection process captured using high-speed photography technique shows that such an actuation
mechanism has interesting features and perhaps some advantages over the conventional ones (thermal bubble, piezoelectric,
etc.) employed in inkjet printers such as the ejection of a droplet free of satellite droplets and others. 相似文献
9.
Phase averaged velocity fields in the near wake region behind a square cylinder have been successfully obtained using randomly sampled PIV data sets. The Reynolds number based on the flow velocity and the model height was 3,900. To identify the phase information, we examined the magnitude of circulation and the center of peak vorticity. The center of vorticity was estimated from lowpass filtered vorticity contours adopting a sub-pixel searching algorithm. Due to the sinusoidal nature of circulation which is closely related to the instantaneous vorticity, the location of peak vorticity fits well with a sine curve of the circulation magnitude. Conditionally averaged velocity fields represent the Karman Vortex shedding phenomenon quite successfully within ±5° phase uncertainty. The oscillating nature of the separated shear layers and the separation bubble at the upper and lower surfaces are clearly observed. With the hot-wire measurement of Strouhal frequency, we found that the convection velocity changes its magnitude very rapidly from 25 to 75 percent of the free stream velocity along the streamwise direction when the flow passes the recirculation region. 相似文献
10.
This paper presents a study to describe the behaviour of a non-equilibrium bubble in a fluid (Fluid 1) that is in contact with another fluid (Fluid 2). Fluid 2 is assumed to incorporate some elastic properties, which are modelled through a pressure term at the fluid–fluid interface. The Laplace equation is assumed to be valid in both fluids and the boundary integral method is employed to simulate the dynamics of the bubble and the fluid–fluid interface. Interesting characteristic phenomena concerning bubble oscillations and the deformation of the fluid–fluid interface are studied for a range of parameters (distance from the fluid–fluid interface, density ratios of the two fluids and elastic properties of Fluid 2). Some of the phenomena observed are jet formation in the bubble, bubble splitting, a ring bubble separating from the main bubble, mushroom-shaped bubbles and the dynamic elevation of the elastic interface. Most of these phenomena are only observed when Fluid 2 possesses some elastic properties (besides the usual formation of a high speed liquid jet). Comparisons with experimental observations confirm the validity of our simulations. 相似文献