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排序方式: 共有294条查询结果,搜索用时 46 毫秒
161.
Yearin Byun Lilia S. Xie Patrick Fritz Timur Ashirov Mircea Dinc Ali Coskun 《Angewandte Chemie (International ed. in English)》2020,59(35):15166-15170
Dimensionality plays an important role in the charge transport properties of organic semiconductors. Although three‐dimensional semiconductors, such as Si, are common in inorganic materials, imparting electrical conductivity to covalent three‐dimensional organic polymers is challenging. Now, the synthesis of a three‐dimensional π‐conjugated porous organic polymer (3D p‐POP) using catalyst‐free Diels–Alder cycloaddition polymerization followed by acid‐promoted aromatization is presented. With a surface area of 801 m2 g?1, full conjugation throughout the carbon backbone, and an electrical conductivity of 6(2)×10?4 S cm?1 upon treatment with I2 vapor, the 3D p‐POP is the first member of a new class of permanently porous 3D organic semiconductors. 相似文献
162.
Hyoung Moon Kim Seyeon Oh Kyung-A Byun Jin Young Yang Hye Jin Sun Donghwan Kang Kuk Hui Son Kyunghee Byun 《Molecules (Basel, Switzerland)》2022,27(2)
Dermal macrophages containing melanin increase skin pigmentation since dermal melanin removal is slower than epidermal melanin removal. Lymphatic vessels are also involved in melanin clearance. We evaluated whether radiofrequency (RF) irradiation induced an increase in HSP90, which promotes lymphangiogenesis by activating the BRAF/MEK/ERK pathway and decreasing tyrosinase activity, in the UV-B exposed animal model. The HSP90/BRAF/MEK/ERK pathway was upregulated by RF. Tyrosinase activity and the VEGF-C/VEGFR 3/PI3K/pAKT1/2/pERK1/2 pathway, which increase lymphangiogenesis, as well as the expression of the lymphatic endothelial marker LYVE-1, were increased by RF. Additionally, the number of melanin-containing dermal macrophages, the melanin content in the lymph nodes, and melanin deposition in the skin were decreased by RF. In conclusion, RF increased HSP90/BRAF/MEK/ERK expression, which decreased tyrosinase activity and increased lymphangiogenesis to eventually promote the clearance of dermal melanin-containing macrophages, thereby decreasing skin pigmentation. 相似文献
163.
164.
Low-temperature growth of GaN by atomic nitrogen based on a dielectric barrier discharge 总被引:1,自引:0,他引:1
GaN films were deposited on sapphire(0 0 0 1) and Si(1 0 0) substrates by MOCVD using an atomic nitrogen source based on a dielectric barrier discharge (DBD) method. Molecule nitrogen and trimethylgallium (TMG) were separately delivered to the substrates. Wurtzite GaN films, with no trace of cubic GaN, were successfully grown on -Al2O3 substrates even at relatively low temperatures (<800°C). Sapphire substrate RMS roughness was 5.01 and 4.93 Å before and after the exposure to DBD N-source, respectively. This shows negligible irradiation damage of accelerated N2+ ion as well as the effect of smoothening the substrate surfaces with DBD N-source. The PL results exhibited small luminescence at the spectral region of blue and UV but a luminescence around the yellow region (2.5 eV) was detected. This is caused by oxygen impurity from AES analysis. 相似文献
165.
166.
Young Hoon Lee Mihyun Kim A Rim Woo Ji Young Choi Jong Chul Byun Jack M. Harrowfield Woo Taik Lim Pierre Thu��ry Yang Kim 《Journal of inclusion phenomena and macrocyclic chemistry》2011,71(3-4):395-407
Structural studies of seven complexes of ligands derived from various azetidine- and oxetane-containing ligands characterise the difference in reactivity of both free and bound forms of these two four-membered heterocycles. The relatively unreactive azetidine ring is preserved in a variety of transformations, whereas facile opening of the oxetane ring provides a convenient pathway to complexes with pendent functionality. 相似文献
167.
Sun-Sig?Byun Dian?K.?PalagachevEmail author Pilsoo?Shin 《Calculus of Variations and Partial Differential Equations》2018,57(5):135
We derive global gradient estimates for \(W^{1,p}_0(\Omega )\)-weak solutions to quasilinear elliptic equations of the form over n-dimensional Reifenberg flat domains. The nonlinear term of the elliptic differential operator is supposed to be small-BMO with respect to x and merely continuous in u. Our result highly improves the known regularity results available in the literature. Actually, we are able not only to weaken the Lipschitz continuity with respect to u of the nonlinearity to only uniform continuity, but we also find a very lower level of geometric assumption on the boundary of the domain to ensure a global character of the gradient estimates obtained.
相似文献
$$\begin{aligned} \mathrm {div\,}\mathbf {a}(x,u,Du)=\mathrm {div\,}(|F|^{p-2}F) \end{aligned}$$
168.
We treat fourth order parabolic systems in divergence form with bounded measurable coefficients. We establish Hessian estimates for such parabolic systems by proving that the L p -regularity of the inhomogeneous terms exactly reflects in the regularity of the Hessian of the solutions for every ${p \in (1, \infty)}$ . The assumptions are that the coefficients are allowed to be merely measurable in one of spatial variables, but averaged in the other spatial variables and time variable. 相似文献
169.
Shanglong Peng Na Feng Duokai Hu Deyan He Chang-Woo Byun Yong Woo Lee Seung-Ki Joo 《Current Applied Physics》2012,12(6):1470-1475
Intrinsic and doped polycrystalline silicon thin films were grown by the Ni silicide seeds induced crystallization. The Ni first reacted to Si forming a silicide seeds, then these seeds act as nuclei, from which the grains start to grow laterally. Compared with traditional Ni induced lateral crystallization, polycrystalline silicon thin film was grown by Ni silicide induced crystallization with low Ni contamination and large grain sizes. It can be found that the Ni silicide induced crystallization rate is accelerated by p-type doping and is decelerated by n-type doping. And the slightly and strongly phosphorous-doped polycrystalline silicon can be obtained with different grain shapes. Also, the sheet resistance of doped polycrystalline silicon decreases with the increasing of the doping atoms. A reasonable explanation is presented for the dopant effects on the growth rate, microstructure and electronic properties of the samples. 相似文献
170.
We consider higher order parabolic equations in divergence form with measurable coefficients to find optimal regularity in
Orlicz spaces of the maximum order derivatives of the weak solutions. The relevant minimal regularity requirement on the tensor
matrix coefficients is of small BMO in the spatial variable and is measurable in the time variable. As a consequence we prove
the classical W
m,p
regularity, m = 1, 2, . . . , 1 < p < ∞, for such higher order equations. In the same spirit the results easily extend to higher order parabolic systems as well
as up to the boundary. 相似文献