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111.
Upon irradiation with 300-nm UV light, the photolysis of diazomalonates in benzene unexpectedly affords 2,6-dicarboxylate bicyclo[3.2.0]hepta-2,6-dienes in low yields. These products are proven to be derived from cyclohepta-1,3,5-triene intermediates presumably via a tandem 1,5-carboxylate migration/[2+2] cycloaddition sequence. 相似文献
112.
Chiang C. Mei 《Transport in Porous Media》1992,9(3):261-274
The theory of homogenization which is a rigorous method of averaging by multiple scale expansions, is applied here to the transport of a solute in a porous medium. The main assumption is that the matrix has a periodic pore structure on the local scale. Starting from the pores with the Navier-Stokes equations for the fluid motion and the usual convective-diffusion equation for the solute, we give an alternative derivation of the three-dimensional macroscale dispersion tensor for solute concentration. The original result was first found by Brenner by extending Brownian motion theory. The method of homogenization is an expedient approach based on conventional continuum equations and the technique of multiple-scale expansions, and can be extended to more complex media involving three or more contrasting scales with periodicity in every but the largest scale. 相似文献
113.
Two new cobalt phosphites, (H3NC6H4NH3)Co(HPO3)2 (1) and (NH4)2Co2(HPO3)3 (2), have been synthesized and characterized by single-crystal X-ray diffraction. All the cobalt atoms of 1 are in tetrahedral CoO4 coordination. The structure of 1 comprises twisted square chains of four-rings, which contain alternating vertex-shared CoO4 tetrahedra and HPO3 groups. These chains are interlinked with trans-1,4-diaminocyclohexane cations by hydrogen bonds. The 2-D structure of 2 comprises anionic complex sheets with ammonium cations present between them. An anionic complex sheet contains three-deck phosphite units, which are interconnected by Co2O9 to form complex layers. Magnetic susceptibility measurements of 1 and 2 showed that they have a weak antiferromagnetic interaction. 相似文献
114.
Cheng-Kang Chiang Mi-Chen Chiang Zong-Hong Lin Guo-Yu Lan Yang-Wei Lin Huan-Tsung Chang 《Journal of the American Society for Mass Spectrometry》2010,21(7):1204-1207
We have investigated six nanomaterials for their applicability as surfaces for the analyses of peptides and proteins using
surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Gold nanoparticles (NPs) were useful nanomateriais
for small analytes (e.g., glutathione); Pt nanosponges and Fe3O4 NPs were efficient nanomaterials for proteins, with an upper detectable mass limit of ca. 25 kDa. Nanomateriais have several
advantages over organic matrices, including lower limits of detection for small analytes and lower batch-to-batch variations
(fewer problems associated with “sweet spois”), when used in laser desorption/ionization mass spectrometry. 相似文献
115.
Li‐Chai Chen I‐Li Chen Chih‐Chiang Huang Chang‐Hui Liao Jhy‐Yih Chen Tai‐Chi Wang 《中国化学会会志》2010,57(6):1331-1340
Some oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were synthesized and evaluated for their antiplatelet and antiproliferative activities. These compounds were synthesized via alkylation of hydroxyl precursors followed by the reaction with NH2OH. The preliminary assays indicated that (Z)‐7‐[2‐(4‐fluorophenyl)‐2‐(hydroxyimino)ethoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (13c) is the most active against U46619 induced platelet aggregation with an IC50 value of 3.51 μM. For the inhibition of AA‐induced aggregation, (E)‐6‐[2‐(hydroxyimino)propoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (15 ) is the most potent with an IC50 value of 1.85 μM. These oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were inactive against thrombin induced platelet aggregation with an IC50 value of greater than 26.78 μM. For the antiproliferative activity, most of these oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were inactive while (Z)‐7‐[2‐(hydroxyimino)‐2‐(naphthalen‐2‐yl)ethoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (13a) exhibited only marginal activities with GI50 value of 7.63, 7.34 and 6.36 μM against the growth of NPC‐TW01, NCI‐H661, and Jurkat respectively. 相似文献
116.
We demonstrate that the simultaneous self-mode-locking of TEM0,0 and TEM1,0 modes can be achieved in a standard end-pumped Nd:YVO4 laser. With this simultaneous self-mode-locking, the transverse beat frequency can be accurately measured as a function of
the absorbed power. We employ the measured beat frequency and the cavity theory to precisely determine the effective focal
length of the thermal lens in the gain medium. 相似文献
117.
Chih-Wei Chiang Subrata Kumar Das Huang-Shih Liao 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(2):197-203
We report the first inter-comparison of vertical profiles of aerosols and clouds derived from space (CALIPSO) and ground based lidar over Chung-Li, Taiwan. Results show that inter-comparison is closer in case of aerosols than clouds. The strength/shortcoming of the comparison has been also discussed. An iterative calculation to retrieve extinction-to-backscatter ratio (lidar ratio) by using sun-photometer and CALIPSO data is also documented. By using the mentioned method, a mean lidar ratio of 23.5±8.2 sr was found. The derived lidar ratios are lower than former studies. The possible reasons for the difference have been discussed in this paper. The discussed methodology will be helpful to reduce the uncertainty of optical parameters derived from lidar data especially near the surface where the atmosphere is inhomogeneous. 相似文献
118.
Electronic chirality near the Dirac point is a key property of graphene systems, which is revealed by the spectral intensity patterns as measured by angle-resolved photoemission spectroscopy under various polarization conditions. Specifically, the strongly modulated circular patterns for monolayer (bilayer) graphene rotate by ±90° (±45°) in changing from linearly to circularly polarized light; these angles are directly related to the phases of the wave functions and thus visually confirm the Berry's phase of π (2π) around the Dirac point. The details are verified by calculations. 相似文献
119.
Y. F. Chen Y. J. Huang P. Y. Chiang Y. C. Lin H. C. Liang 《Applied physics. B, Lasers and optics》2011,103(4):841-846
A short-cavity Nd:YVO4 laser is employed to confirm that a spontaneous mode locking (SML) typically occurs without employing an extra nonlinearity.
We further experimentally demonstrate that reducing the number of longitudinal lasing modes can diminish the phase fluctuation
and effectively improve the SML pulse stability. Considering the spatial hole-burning (SHB) effect, an analytical expression
is derived to accurately estimate the number of longitudinal lasing modes for a practical design guideline. 相似文献
120.
A method, novel to our knowledge, for effective mirror image suppression in Fourier-domain optical coherence tomography based on a phase shift between neighboring A-mode scans is demonstrated. By realizing that the phase shifts of the real and mirror images are mutually reversed and assuming that the real image intensities of the two successive A-mode scans are the same, we can solve a set of two coupled equations to obtain the real image signals. The images based on the scanning of a high-resolution spectral-domain optical coherence tomography system are processed to show effective mirror image suppression results. Compared with a similar method of broad application, our approach has the advantages of shorter process time and higher flexibility in selecting the concerned image portions for processing. 相似文献