排序方式: 共有47条查询结果,搜索用时 15 毫秒
11.
Sandee AJ van Der Veen LA Reek JN Kamer PC Lutz M Spek AL van Leeuwen PW 《Angewandte Chemie (International ed. in English)》1999,38(21):3231-3235
By a sol-gel process a rhodium complex containing a diphosphane with a large natural P-Rh-P bite angle is covalently anchored in a silica matrix (see picture). The immobilized catalyst is a very selective hydroformylation catalyst that is completely and conveniently separated from the product and can be reused in numerous cycles. 相似文献
12.
13.
Perry Skeath I. Lindau P. Pianetta P.W. Chye C.Y. Su W.E. Spicer 《Journal of Electron Spectroscopy and Related Phenomena》1979,17(4):259-265
A room-temperature reaction between Al adsorbate atoms and a GaAs (110) surface is observed by means of soft X-ray photoemission techniques. Evidence of two states of Al which are distinct from the bulk Al metal is seen at submonolayer coverages. The sequential appearance of these states suggest that both Al chemisorbed on the surface and Al replacing Ga in the surface lattice are present. The possible influence of surface lattice reconstruction and Al proximity effects on the replacement reaction is discussed. The replacement reaction is important in the context of metal contacts to GaAs (both ohmic and Schottky barriers) as well as for GaAs—AlGaAs heterojunctions. 相似文献
14.
A. Kahn D. Kanani P. Mark P.W. Chye C.Y. Su I. Lindau W.E. Spicer 《Surface science》1979,87(2):325-332
Cleaved GaAs(110) surfaces were exposed to oxygen (106 ? 5 × 1010 L) and analysed by LEED and UPS. Very important changes in the electron diffraction occur at 108 L and the analysis of the LEED pattern shows a bulk-like diffraction superposed on a high background, implying that a thin layer (1–3 Å) disordered by the oxidation covers the GaAs lattice relaxted to its bulk structure. 相似文献
15.
Mutation and polymorphism detection is of increasing importance for a variety of medical applications, including identification of cancer biomarkers and genotyping for inherited genetic disorders. Among various mutation-screening technologies, enzyme mismatch cleavage (EMC) represents a great potential as an ideal scanning method for its simplicity and high efficiency, where the heteroduplex DNAs are recognized and cleaved into DNA fragments by mismatch-recognizing nucleases. Thereby, the enzymatic cleavage activities of the resolving nucleases play a critical role for the EMC sensitivity. In this study, we utilized the unique features of microfluidic capillary electrophoresis and de novo gene synthesis to explore the enzymatic properties of T7 endonuclease I and Surveyor nuclease for EMC. Homoduplex and HE DNAs with specific mismatches at desired positions were synthesized using PCR (polymerase chain reaction) gene synthesis. The effects of nonspecific cleavage, preference of mismatches, exonuclease activity, incubation time, and DNA loading capability were systematically examined. In addition, the utilization of a thermostable DNA ligase for real-time ligase mediation was investigated. Analysis of the experimental results has led to new insights into the enzymatic cleavage activities of T7 endonuclease I and Surveyor nuclease, and aided in optimizing EMC conditions, which enhance the sensitivity and efficiency in screening of unknown DNA variations. 相似文献
16.
PD Tran L Xi SK Batabyal LH Wong J Barber JS Chye Loo 《Physical chemistry chemical physics : PCCP》2012,14(33):11596-11599
Co and Ni-nanoclusters are attractive alternatives to Pt catalysts for hydrogen generation. These earth abundant elements when loaded onto the TiO(2) nanopowders surface act as efficient co-catalysts. Co, Ni-decorated TiO(2) photocatalysts display only three (3) times lower catalytic activities for H(2) evolution under UV illumination compared with Pt-decorated TiO(2) photocatalysts. 相似文献
17.
Jian-Feng ZhaoYi Liu Jiayun Bethia SohYong-Xin Li Rakesh GangulyKai-Qi Ye Fengwei HuoLing Huang Alfred Iing Yoong TokJoachim Say Chye Loo Qichun Zhang 《Tetrahedron letters》2012,53(45):6044-6047
A novel diazaperinone 12H-pyrazino[2′,3′:3,4]pyrrolo[1,2-a]perimidin-12-one has been successfully synthesized through a one-step condensation. Single crystal X-ray analysis shows that the product is of planar structure with strong π?π interactions and H-bonding. Interestingly, the 12H-pyrazino[2′,3′:3,4]pyrrolo[1,2-a]perimidin-12-one can recognize three different metal cations Cu2+, Ag+ and Hg2+ via naked eye visualization, and shows turn-on fluorescence for Fe3+ and Ag+ among the 22 metal cations. 相似文献
18.
Li Y Chye Y Chiang YF Pi K Wang WH Stephens JM Mack S Awschalom DD Kawakami RK 《Physical review letters》2008,100(23):237205
We investigate the spin-dependent reflection properties in Fe/MgO/GaAs heterostructures by optical pump-probe measurement of the ferromagnetic proximity polarization (FPP). As a function of MgO thickness, the FPP is initially enhanced (<2.0 A) and then exhibits an unexpected sign reversal at approximately 5.0 A. The identification of two competing thresholds in the intensity dependence of FPP and the observation of FPP sign reversal in Fe/Mg/GaAs suggest that the inversion of FPP is related to an interfacial bonding effect. 相似文献
19.
20.
C.Y. Su I. Lindau P.W. Chye S.-J. Oh W.E. Spicer 《Journal of Electron Spectroscopy and Related Phenomena》1983,31(3):221-259
Photoemission studies of the oxidation of Cs at ~ 140 K have been carried out. Four different states of oxygen were observed. Definitive identification of three of the four states has been achieved in two steps: (1) comparison of the multiplet structure of free oxygen ions and the multiplet structure in the photoemission spectra of oxygen sorbed in Cs (i.e., comparison of the energy separations of the various oxygen levels involved); and (2) comparison of experimentally measured binding energies of various states of oxygen with calculated binding energies of known oxygen species inserted in Cs. The oxygen species identified are O2?, O22? and O2?. The multiplet structure of O22? in Cs is identical to that expected for free O22? with no differential relaxation of orbital energies. In contrast, significant differential relaxation in orbital energies is observed for O2? in Cs. This difference is attributed to the closed-shell and open-shell configurations of O22? and O2?, respectively. The oxidation-induced changes in the Cs 4d, 5s and 5p core levels and the NOO and OVV Auger transitions have also been studied in detail. A discussion of the oxidation of Cs, based on the oxygen species identified definitively, is also given. 相似文献