排序方式: 共有46条查询结果,搜索用时 15 毫秒
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Lewis HD Leveridge M Strack PR Haldon CD O'neil J Kim H Madin A Hannam JC Look AT Kohl N Draetta G Harrison T Kerby JA Shearman MS Beher D 《Chemistry & biology》2007,14(2):209-219
In this report, inhibitors of the gamma-secretase enzyme have been exploited to characterize the antiproliferative relationship between target inhibition and cellular responses in Notch-dependent human T cell acute lymphoblastic leukemia (T-ALL) cell lines. Inhibition of gamma-secretase led to decreased Notch signaling, measured by endogenous NOTCH intracellular domain (NICD) formation, and was associated with decreased cell viability. Flow cytometry revealed that decreased cell viability resulted from a G(0)/G(1) cell cycle block, which correlated strongly to the induction of apoptosis. These effects associated with inhibitor treatment were rescued by exogenous expression of NICD and were not mirrored when a markedly less active enantiomer was used, demonstrating the gamma-secretase dependency and specificity of these responses. Together, these data strengthen the rationale for using gamma-secretase inhibitors therapeutically and suggest that programmed cell death may contribute to reduction of tumor burden in the clinic. 相似文献
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E H Jansen D van den Bosch R W Stephany L J van Look C van Peteghem 《Journal of chromatography. A》1989,489(1):205-212
A new detection system is introduced for the quantitative analysis of thin-layer chromatographic plates, which is based on a relatively simple, cheap but advanced image analysis system. Both one- and two-dimensional plates can be analysed. Recording and analysis can also be performed from photographs or even slides. Applications are shown for a number of samples containing anabolic compounds. 相似文献
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L. J. Brillson S. T. Bradley S. H. Goss X. Sun M. J. Murphy W. J. Schaff L. F. Eastman D. C. Look R. J. Molnar F. A. Ponce N. Ikeo Y. Sakai 《Applied Surface Science》2002,190(1-4):498-507
We have used low-energy electron-excited nanoluminescence (LEEN) spectroscopy combined with ultrahigh vacuum surface analysis techniques to obtain electronic bandgap, confined state and deep-level trap information from III nitride compound semiconductor surfaces and their buried interfaces on a nanometer scale. Localized states are evident at GaN/InGaN quantum wells, GaN ultrathin films, AlGaN/GaN pseudomorphic heterostructures, and GaN/Al2O3 interfaces that are sensitive to the chemical composition, bonding and atomic structure near interfaces, and in turn to the specifics of the epitaxial growth process. Identification of electrically active defects in these multilayer nanostructures provides information to optimize interface growth and control local electronic properties. 相似文献
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Debin Mao Richard Lookman Hendrik Van De Weghe Dirk Van Look Guido Vanermen Nicole De Brucker Ludo Diels 《Journal of chromatography. A》2009,1216(9):1524-1527
Enhanced bioremediation of petroleum hydrocarbons in two biopiles was quantified by high-performance liquid chromatography (HPLC) followed by comprehensive two-dimensional gas chromatography (GCXGC). The attenuation of 34 defined hydrocarbon classes was calculated by HPLC–GCXGC analysis of representative biopile samples at start-up and after 18 weeks of biopile operation. In general, a-cyclic alkanes were most efficiently removed from the biopiles, followed by monoaromatic hydrocarbons. Cycloalkanes and polycyclic aromatic hydrocarbons (PAHs) were more resistant to degradation. A-cyclic biomarkers farnesane, trimethyl-C13, norpristane, pristane and phytane dropped to only about 10% of their initial concentrations. On the other hand, C29–C31 hopane concentrations remained almost unaltered after 18 weeks of biopile operation, confirming their resistance to biodegradation. They are thus reliable indicators to estimate attenuation potential of petroleum hydrocarbons in biopile processed soils. 相似文献
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Jianjun Gao Choi Look Law Hong Wang Sheel Aditya 《International Journal of Infrared and Millimeter Waves》2002,23(11):1611-1626
An improved equivalent circuit model under pinchoff condition for extracting parasitic model parameters for Double Heterojunction -doped PHEMTs is presented. Good prediction for S parameters and noise performance are obtained up to 40GHz. A modified parameter extraction technique based on this new model was use to determine a PHEMT equivalent circuit model. Signification improvements of the accuracy of S parameters are obtained by using the new pinchoff model. 相似文献
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Unusual electrical properties of hydrothermally grown ZnO 总被引:1,自引:0,他引:1
Bulk ZnO of high structural and optical quality can be grown by the hydrothermal method. An X-ray rocking-curve linewidth of 18 arcsec has been measured for the (002) reflection, and a photoluminescence linewidth of 0.3 meV has been found for one of the donor–bound exciton lines. However, the electrical properties are unusual in that shallow donors are not dominant, as is the case for vapor-phase-grown and melt-grown bulk crystals. This situation can be greatly modified by annealing in forming gas (5% H2 in N2) at , with bulk shallow donors then becoming completely dominant for , and near-surface donors at lower temperatures. As TA is varied from 100–650 C, both the mobility and carrier concentration vary in nonmonotonic fashion, due to changes in the relative strengths of the bulk and surface components of conduction. 相似文献
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Look DC Farlow GC Reunchan P Limpijumnong S Zhang SB Nordlund K 《Physical review letters》2005,95(22):225502
Recent theory has found that native defects such as the O vacancy V(O) and Zn interstitial Zn(I) have high formation energies in n-type ZnO and, thus, are not important donors, especially in comparison to impurities such as H. In contrast, we use both theory and experiment to show that, under N ambient, the complex Zn(I)-N(O) is a stronger candidate than H or any other known impurity for a 30 meV donor commonly found in bulk ZnO grown from the vapor phase. Since the Zn vacancy is also the dominant acceptor in such material, we must conclude that native defects are important donors and acceptors in ZnO. 相似文献