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排序方式: 共有698条查询结果,搜索用时 15 毫秒
91.
We investigate the evolution of self-guided beams in a chi((2)) medium with a fluctuating phase mismatch between the fundamental wave and its second harmonic, as may occur in particular when the quasi-phase-matching technique is applied. We show that the fluctuations reduce the phase correlation and act as an effective loss to solitary waves. 相似文献
92.
B. Neumann H. Holthöfer A. Juckenack H. Klut M. Beck J. v. Daranyi E. Zander A. Koch O. Fürth B. Schoeninger J. Formánek J. Knop O. Schumm E. Winterstein G. Trier I. Bang G. Blix Th. Paul E. Böhm K. R. Dietrich Bundesamt für Eich- und Vermessungswesen Wien 《Analytical and bioanalytical chemistry》1927,71(8):311-312
93.
94.
Lim YT Cho MY Choi BS Lee JM Chung BH 《Chemical communications (Cambridge, England)》2008,(40):4930-4932
Paramagnetic gold nanostructures were synthesized by combining the paramagnetism of gadolinium with the plasmonic properties of gold nanoparticles and used for dual modal (MRI and optical) imaging and phototherapy of breast cancer cells. 相似文献
95.
Hyunjin Bang 《Journal of solid state chemistry》2008,181(8):1798-1802
We found new synthetic routes to obtain 1-D quaternary thiophosphate compounds and a 0-D molecular complex containing a Nb2S4 core from a 2-D ternary thiophosphate, Nb4P2S21. When Nb4P2S21 was reacted with alkali metal halides (ACl; A=Na, K, Rb, Cs) or TlCl at 500-700 °C, the -S-S-S- bridges in 2-D Nb2PS10-S-S10PNb2 were excised to form a 1-D chain, and cations were inserted between the chains to form ANb2PS10 (A=Na, K, Rb, Cs, Tl). We also found that thallium chloride (TlCl) is an excellent reagent for further excision, and it substitutes chloride ligands for the sulfur ligands of 2-D Nb4P2S21 to form the molecular complex Tl5[Nb2S4Cl8]Cl. Crystal data for TlNb2PS10: monoclinic, Pn, a=6.9452(11) Å, b=7.3761(12) Å, 12.873(2) Å, β=104.472(3)°, and Z=2. Crystal data for Tl5[Nb2S4Cl8]Cl: orthorhombic, Immm, a=7.001(5) Å, b=9.509(7) Å, c=15.546(11) Å, and Z=2. 相似文献
96.
On stable cutsets in claw-free graphs and planar graphs 总被引:4,自引:0,他引:4
A stable cutset in a connected graph is a stable set whose deletion disconnects the graph. Let and (claw) denote the complete (bipartite) graph on 4 and vertices. It is NP-complete to decide whether a line graph (hence a claw-free graph) with maximum degree five or a -free graph admits a stable cutset. Here we describe algorithms deciding in polynomial time whether a claw-free graph with maximum degree at most four or whether a (claw, )-free graph admits a stable cutset. As a by-product we obtain that the stable cutset problem is polynomially solvable for claw-free planar graphs, and also for planar line graphs.Thus, the computational complexity of the stable cutset problem is completely determined for claw-free graphs with respect to degree constraint, and for claw-free planar graphs. Moreover, we prove that the stable cutset problem remains NP-complete for -free planar graphs with maximum degree five. 相似文献
97.
Bang MH Han MW Song MC Cho JG Chung HG Jeong TS Lee KT Choi MS Kim SY Baek NI 《Chemical & pharmaceutical bulletin》2008,56(8):1168-1172
Repeated silica gel and octadecyl silica gel (ODS) column chromatography of the aerial parts of Artemisia princeps PAMPANINI (Sajabalssuk) led to the isolation of a new sesquiterpenoid, 3-((S)-2-methylbutyryloxy)-costu-1(10),4(5)-dien-12,6 alpha-olide (2), along with two previously reported sesquiterpenoids: 8 alpha-angeloyloxy-3beta,4 beta-epoxy-6 beta H,7 alpha H,8 beta H-guaia-1(10),11(13)-dien-12,6 alpha-olide (1, carlaolide B) and 3beta,4 beta-epoxy-8 alpha-isobutyryloxy-6 beta H,7 alpha H,8 beta H-guaia-1(10),11(13)-dien-12,6 alpha-olide (3, carlaolide A). The structure of compound 2 was elucidated by spectroscopic data analysis, including one dimensional (1D) and two dimensional (2D) nuclear magnetic resonance (NMR) experiments. Of the isolates, compound 2 exhibited potent cytotoxicity against human cervix adenocarcinoma cells and induced apoptosis. 相似文献
98.
Hong SS Lee SA Han XH Lee MH Hwang JS Park JS Oh KW Han K Lee MK Lee H Kim W Lee D Hwang BY 《Chemical & pharmaceutical bulletin》2008,56(2):199-202
Two new melampolide-type sesquiterpene lactones, 8beta-epoxyangeloyloxy-9alpha-ethoxy-14-oxo-acanthospermolide (1) and 8beta-angeloyloxy-9alpha-ethoxy-14-oxo-acanthospermolide (2), were isolated from the leaves of yacon [Smallanthus sonchifolia (POEPP. et ENDL.) H. Robinson] along with eleven known melampolides, allo-schkuhriolide (3), enhydrin (4), polymatin A (5), fluctuanin (6), 8beta-angeloyloxy-9alpha-acetoxy-14-oxo-acanthospermolide (7), 8beta-angeloyloxy-14-oxo-acanthospermolide (8), 8beta-methacryloyloxymelampolid-14-oic acid methyl ester (9), uvedalin (10), polymatin B (11), 8beta-tigloyloxymelampolid-14-oic acid methyl ester (12), and sonchifolin (13). Their structures were established on the basis of spectroscopic evidence including 1D- and 2D-NMR experiments. All isolates were evaluated for inhibition of LPS-induced nitric oxide production in murine macrophage RAW 264.7 cells. 相似文献
99.
Dr. Jong Wook Hong Yena Kim Dae Han Wi Seunghoon Lee Su‐Un Lee Young Wook Lee Prof. Sang‐Il Choi Prof. Sang Woo Han 《Angewandte Chemie (International ed. in English)》2016,55(8):2753-2758
A synthesis strategy for the preparation of ultrathin free‐standing ternary‐alloy nanosheets is reported. Ultrathin Pd‐Pt‐Ag nanosheets with a thickness of approximately 3 nm were successfully prepared by co‐reduction of the metal precursors in an appropriate molar ratio in the presence of CO. Both the presence of CO and the interplay between the constituent metals provide fine control over the anisotropic two‐dimensional growth of the ternary‐alloy nanostructure. The prepared Pd‐Pt‐Ag nanosheets were superior catalysts of ethanol electrooxidation owing to their specific structural and compositional characteristics. This approach will pave the way for the design of multicomponent 2D nanomaterials with unprecedented functions. 相似文献
100.
6‐TIPS‐β‐Cyclodextrin‐Modified Fe3O4 for Facile Enantioseparation of 1‐(1‐Naphthyl)ethylamine
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Lu Wang Xiang‐Yong Liang Prof. Dr. Li‐Sheng Ding Prof. Dr. Sheng Zhang Prof. Dr. Bang‐Jing Li 《化学:亚洲杂志》2016,11(24):3513-3519
A new type of chiral magnetic nanoparticle was prepared from covalently linked magnetic nanoparticles (Fe3O4) and heptakis‐(6‐O‐triisopropylsilyl)‐β‐cyclodextrin (6‐TIPS‐β‐CD). The resulting selectors (TIPS‐β‐CD‐MNPs) combined the good magnetic properties Fe3O4 and efficient chiral recognition ability of 6‐TIPS‐β‐CD. The enantioselectivity of TIPS‐β‐CD‐MNPs towards 1‐(1‐naphthyl)ethylamine was six times higher than that of the parent β‐CD modified Fe3O4 particles. 相似文献