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971.
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975.
C. Zhao O. RichardE. Young H. BenderG. Roebben S. HaukkaS. De Gendt M. HoussaR. Carter W. TsaiO. Van Der Biest M. Heyns 《Journal of Non》2002,303(1):144-149
One challenge in the development of high-k dielectric films is to preserve their amorphous nature during the processing of CMOS. In this work, the feasibility of using ZrO2-Al2O3 binary alloys to obtain a stable homogeneous amorphous structure in a high-k layer is investigated. In situ high temperature X-ray diffraction tests show that the onset crystallisation temperature of the binary alloy with 42 and 61 mol% Al2O3 is 900, 400 °C higher than that of the pure ZrO2. After rapid thermal process anneals up to 900 °C, the ZrAlxOy film remains amorphous. At 1000 °C, tetragonal ZrO2 forms in the ZrAlxOy film. In addition, it is demonstrated that there is no undesirable amorphous phase separation during annealing at temperatures below and equal to 900 °C in the ZrO2-Al2O3 system. 相似文献
976.
Stereoselective synthesis of (+)-monocerin was accomplished via radical cyclization of a vinylic ether intermediate. 相似文献
977.
The conformational preferences and prolyl cis-trans isomerization of oxidized and reduced Ac-Cys-Pro-Phe-Cys-NH2 (CPFC peptides) have been carried out using the ab initio HF/6-31+G(d) and hybrid density functional B3LYP/6-311++G(d,p) levels of theory. The most preferred conformations of oxidized and reduced CPFC peptides with the trans prolyl peptide bond have a type-I beta-turn for the Pro-Phe sequence in common. In particular, the transition states for both forms are stabilized by the intramolecular hydrogen bonds between the prolyl nitrogen and the N-H group of the Phe3 residue. The rotational barrier DeltaGct to the cis-to-trans isomerization for the oxidized CPFC peptide is calculated to be 19.37 kcal/mol at the B3LYP/6-311++G(d,p)//HF/6-31+G(d) level of theory, which is lower by 0.88 kcal/mol than that of the reduced CPFC peptide. This may indicate that the rate constant kc-->t of the prolyl cis-to-trans isomerization for the oxidized form is about 4 times larger than that of the reduced form, which is reasonably consistent with the value deduced from NMR experiments. In particular, the increase in vibrational entropy for the transition state of the oxidized form over that of the reduced form contributes to enhance the rate constant for the prolyl cis-to-trans isomerization of the oxidized form. 相似文献
978.
Hydrophilic interaction LC with MS/MS (HILIC-MS/MS) was described as a rapid, sensitive, and selective method for the quantification of doxazosin in human plasma. Doxazosin and cisapride (internal standard) were extracted from human plasma with ethyl acetate at alkaline pH and analyzed on an Atlantis HILIC Silica column with the mobile phase of ACN/ammonium formate (100 mM, pH 4.5) (93:7 v/v). The analytes were detected using an ESI MS/MS in the selective-reaction-monitoring mode. The standard curve was linear (r = 0.9994) over the concentration range of 0.2-50 ng/mL. The LOQ for doxazosin was 0.2 ng/mL using 100 microL plasma sample. The CV and relative error for intra- and interassay at four QC levels were 3.7-8.7% and 0.0-9.8%, respectively. The matrix effect for doxazosin and cisapride were practically absent. The recoveries of doxazosin and cisapride were 67.4 and 61.7%, respectively. This method was successfully applied to the pharmacokinetic study of doxazosin in humans. 相似文献
979.
Mader conjectured that for all there is an integer such that every digraph of minimum outdegree at least contains a subdivision of a transitive tournament of order . In this note, we observe that if the minimum outdegree of a digraph is sufficiently large compared to its order then one can even guarantee a subdivision of a large complete digraph. More precisely, let be a digraph of order n whose minimum outdegree is at least d. Then contains a subdivision of a complete digraph of order . © 2007 Wiley Periodicals, Inc. J Graph Theory 57: 1–6, 2008 相似文献
980.
A general approach to triphenylenes and azatriphenylenes: total synthesis of dehydrotylophorine and tylophorine 总被引:1,自引:0,他引:1
A convergent and flexible synthesis of substituted triphenylenes, azatriphenylenes, and the cytotoxic alkaloids dehydrotylophorine and tylophorine has been developed. 相似文献