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121.
Beom Kyu Min Sangku Lee Hwa Jung Roh Ji Yeon Ryu Junseong Lee Jae Nyoung Kim 《Tetrahedron letters》2017,58(33):3251-3255
6π-Electrocyclization of conjugated trienes derived in-situ from the Morita-Baylis-Hillman carbonates of N-methylisatins afforded dispirocyclohexadiene bisoxindoles in good yields. Two stereoisomers (cis and trans) were formed in almost equal amounts. 相似文献
122.
Poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) (P(VDF‐co‐CTFE)) backbone was grafted with crosslinkable chains of poly(hydroxyl ethyl acrylate) (PHEA) and proton conducting chains of poly(styrene sulfonic acid) (PSSA) to produce amphiphilic P(VDF‐co‐CTFE)‐g‐P(HEA‐co‐SSA) graft copolymer via atom transfer radical polymerization (ATRP). Successful synthesis and microphase‐separated structure of the copolymer were confirmed by 1H NMR, FT‐IR spectroscopy, and TEM analysis. Furthermore, this graft copolymer was thermally crosslinked with sulfosuccinic acid (SA) to produce grafted/crosslinked membranes. Ion exchange capacity (IEC) increased continuously with increasing SA contents but the water uptake increased up to 6 wt% of SA concentration, above which it decreased monotonically. The membrane also exhibited a maximum proton conductivity of 0.062 S/cm at 6 wt% of SA concentration, resulting from competitive effect between the increase of ionic groups and the degree of crosslinking. XRD patterns also revealed that the crystalline structures of P(VDF‐co‐CTFE) disrupted upon graft polymerization and crosslinking. These membranes exhibited good thermal stability at least up to 250°C, as revealed by TGA. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
123.
Ki-Min Park Soo-Gyun Roh Eunsung Lee Jaheon Kim Hee-Joon Kim Jae Wook Lee 《Supramolecular chemistry》2013,25(2-3):153-158
The construction of a square-wave-shaped one-dimensional polyrotaxane using a preorganized L-shaped [3]pseudorotaxane and metal ion is reported. A phenanthroline derivative having two N -(3-pyridylmethyl)-1,4-butanediammonium "arms" was synthesized as a preorganized L-shaped ligand. This L-shaped ligand easily forms a stable [3]pseudorotaxane incorporating cucurbituril (CB[6]). The reaction of the [3]pseudorotaxane with Ni(II) or Zn(II) ion produces a square-wave-shaped one-dimensional-polyrotaxane. 相似文献
124.
Layer-by-layer (LbL) deposition of CuInS2 (CIS) thin films at room temperature (25 °C) from alkaline CuSO4 + In2(SO4)3 and Na2S precursor solutions was reported. The method allowed self-limited growth of CIS films with nanocrystalline structure and composed of densely packed nanometer-sized grains. The as-deposited CIS film was 250 nm thick and composed of closely packed particles of 20-30 nm in diameter. The alkaline cationic precursor solution was obtained by dissolving CuSO4 and InSO4 in deionized water with a appropriate amount of hydrazine monohydrate (H-H) and 2,2′,2″-nitrilotriethanol (TEA). CIS films were annealed at 200 °C for 2 h and effect of annealing on structural, optical, and surface morphological properties was thoroughly investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis spectrometer, C-V, and water contact angle techniques, respectively. 相似文献
125.
For a strong solution u(x,t) of the Navier-Stokes equations in exterior domain Ω in Rn where n=2,3, we study the time decay of ‖α|x|u(t)Lp‖ for α<n. When a domain has a boundary, pressure term makes an obstacle since we do not have enough information on the pressure term near the boundary. To overcome the difficulty, we adopt the ideas in [H.-O. Bae, B.J. Jin, Temporal and spatial decay rates of Navier-Stokes solutions in exterior domains, Bull. Korean Math. Soc. 44 (3) (2007) 547-567; H.-O. Bae, B.J. Jin, Asymptotic behavior for the Navier-Stokes solutions in 2D exterior domains, J. Funct. Anal. 240 (2006) 508-529] and we will extend Bae and Jin's results by modifying their methods. 相似文献
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R. Hartschuh Y. Ding J. H. Roh A. Kisliuk A. P. Sokolov C. L. Soles R. L. Jones T. J. Hu W. L. Wu A. P. Mahorowala 《Journal of Polymer Science.Polymer Physics》2004,42(6):1106-1113
For a range of applications, polymers are now being patterned into nanometer‐sized features. In these applications, the robust mechanical properties of the nanostructures are critical for performance and stability. Brillouin light scattering is presented as a nondestructive, noncontact tool used to quantify the elastic constants in such nanostructures. We demonstrate this through a series of thin films and parallel ridges and spacings (gratings) with ridge widths ranging from 180 to 80 nm. For the set of films and structures presented here, the room‐temperature elastic moduli did not change with decreasing film thickness or grating ridge width, and this implied that one‐dimensional and two‐dimensional confinement‐induced changes of the mechanical properties were not significant down to feature sizes of 80 nm. Additionally, Brillouin spectra of submicrometer gratings revealed new modes not present in the spectra of thin films. The origin of these new modes remains unclear. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1106–1113, 2004 相似文献
130.
Young Hae Roh Jong Woo Bae Gil Soo Nam Joong Hyup Kim Sung Hoon Kim Cheol Min Yoon 《合成通讯》2013,43(1):81-86
The reaction of 6-[1-Aza-2-(dimethylamino)prop-l-enyl]-5-iodo-1,3-dimethyluracil (3) with various olefins in the presence of a catalytic amount of Pd(OAc)2 and 1.5 equiv. of K2CO3 in DMF at 120 °C gave the pyrido[2,3-d]pyrimidine derivatives (5a-b and 7a-d) in moderate to high yield. 相似文献