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121.
H. Neumann B. Perlt N.A.K. Abdul-Hussein R.D. Tomlinson A.E. Hill 《Crystal Research and Technology》1982,17(4):469-474
The optical absorption of r.f. sputtered CuInSe2 thin films was studied in the photon energy range from 1 to 3 eV. The gap energy and the spin-orbit splitting are found to be (1.01 ± 0.01) eV and (0.24 ± 0.02) eV, respectively. From the photon energy dependence of the absorption coefficient it is concluded that the heavy and light hole bands are parabolic whilst the split-off band contains terms linear in the wavevector. The optical transition probability for valence band- to- conduction band transitions is estimated to be (10.8 ± 1.0) eV which yields an admixture of copper d states to the valence band of (30 ± 8) %. 相似文献
122.
Alexandros P. SiskosAlison M. Hill 《Tetrahedron letters》2003,44(4):789-792
Labeled glycerol is a widely used biochemical probe to investigate biosynthetic pathways. A highly efficient synthesis of [1-13C, 18O]- and [1-13C, 2H2]-glycerol is described in which the 13C label is introduced using cyanide. The 18O label was introduced by a Pinner synthesis and reduction of the ester 5 allowed incorporation of the 2H labels. 相似文献
123.
We present a finite-difference based solver for hyper-elastic and viscoplastic systems using a hybrid of the weighted essentially non-oscillatory (WENO) schemes combined with explicit centered difference to solve the equations of motion expressed in an Eulerian formulation. By construction our approach minimizes both numerical dissipation errors and the creation of curl-constraint violating errors away from discontinuities while avoiding the calculation of hyperbolic characteristics often needed in general finite-volume schemes. As a result of the latter feature, the formulation allows for a wide range of constitutive relations and only an upper-bound on the speed of sound at each time is required to ensure a stable timestep is chosen. Several one- and two-dimensional examples are presented using a range of constitutive laws with and without additional plastic modeling. In addition we extend the reflection technique combined with ghost-cells to enforce fixed boundaries with a zero tangential stress condition (i.e. free-slip). 相似文献
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125.
Power grids have been studied as a typical example of real-world complex networks. Different from previous methods, this paper proposes a hybrid approach for structural vulnerability analysis of power transmission networks, in which a DC power flow model with hidden failures is embedded into the traditional error and attack tolerance methodology to form a new scheme for power grids vulnerability assessment and modeling. The new approach embodies some important characteristics of power transmission networks. Furthermore, the simulation on the standard IEEE 118 bus system demonstrates that a critical region might exist and when the power grid operates in the region, it is vulnerable to both random and intentional attacks. Finally, a brief theoretical analysis is presented to explain the new phenomena. 相似文献
126.
Eric James Davis Brian H. Clowers William F. Siems Herbert H. Hill Jr. 《International Journal for Ion Mobility Spectrometry》2011,14(2-3):117-124
Scientific applications of Ion Mobility Spectrometry require the ability to easily compare data between different laboratories. Reduced mobility values attempt to provide this functionality, but no standard exists for the collection and manipulation of the raw data obtained during an IMS experiment. We have created a comprehensive software suite based on the LabVIEW programming language that can be used to collect and interpret IMS data. The software may be used to collect data from a stand-alone IMS cell, a voltage sweep IMS cell, or a coupled chromatography-IMS system, and this framework may be adapted to incorporate mass spectral data analysis as well. This software is provided under an open source license for the benefit of the IMS community. 相似文献
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128.
This review covers the isolation and structure determination of triterpenoids including squalene derivatives, lanostanes, cycloartanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, isomalabicanes and saponins. The literature from January to December 2000 is reviewed and 277 references are cited. 相似文献
129.
Synthesis of a new fluorescent probe specific for catechols 总被引:1,自引:0,他引:1
[reaction: see text] The synthesis of a new fluorescent probe, specific for the catechol moiety, has been conducted by preparation of alpha,alpha-dibromomalonamides containing an appropriate fluorophore. N,N'-Bis-anthracen-9-ylmethyl-2,2-dibromomalonamide reacted with various catechols in the presence of cesium carbonate to generate highly fluorescent derivatives. 相似文献
130.
Li WS Li Y Hill CM Lum KT Raushel FM 《Journal of the American Chemical Society》2002,124(14):3498-3499
The phosphotriesterase from Pseudomonas diminuta has been shown to selectively cleave the pro-R p-nitrophenolate substituent from bis-p-nitrophenyl alkyl phosphothioate esters. When the alkyl substituent is methyl, ethyl, or isopropyl the enantiomeric excess of the product is >/=99%. Manipulation of the active site through mutagenesis has enabled the preparation of protein variants that preferentially hydrolyze the pro-S substituent of the target substrates. This methodology thus permits the preparation of chiral products from prochiral precursors. 相似文献