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排序方式: 共有269条查询结果,搜索用时 15 毫秒
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Qiu B.C. Bryce A.C. de la Rue R.M. Marsh J.H. 《Photonics Technology Letters, IEEE》1998,10(6):769-771
We report the use of a laser irradiation process, which combines irradiation by continuous wave and Q-switched pulsed Nd:YAG lasers, to promote quantum-well intermixing. Differential shifts up to 70 meV have been obtained in GaInAsP structures. Extended cavity-ridge lasers with 800-μm-long active sections and 1000-μm-long passive sections, were fabricated. The slope efficiency of the extended cavity lasers is very close to that of 800-μm-long all-active lasers, and the threshold current is 10 mA higher than for an 800-μm-long all-active device. The loss in the intermixed single-mode waveguide is 2.1 cm-1 相似文献
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H.Y. Wong M. Sorel A.C. Bryce J.H. Marsh J.M. Arnold 《Photonics Technology Letters, IEEE》2005,17(4):783-785
A highly efficient monolithically integrated Mach-Zehnder interferometer (MZI) optical switch based on a 1.5-/spl mu/m InGaAs-AlGaInAs multiple-quantum-well structure is reported. The device was fabricated by integrating phase shifter sections with bandgap-shifted low-loss waveguides obtained by a single step sputtered SiO/sub 2/-annealing quantum-well intermixing technique. Evaluation of the refractive index change induced by current injection (plasma, band-filling, band-shrinkage effects) and applied electric field (quantum confined Stark effect) based on the MZI was investigated. A device with an active length of 400 /spl mu/m in one of the MZI arms had an extinction ratio /spl ges/20 dB with a half-wavelength current (I/sub /spl pi//) and half-wavelength voltage V/sub /spl pi// as low as 3.2 mA and 3.5 V (1.9 V in push-pull configuration), respectively. 相似文献
186.
Light metal hydrides represent a promising class of materials for hydrogen storage. However, there are several technical challenges to overcome before their potential can be realized. Key among these is the often adverse absorption and desorption kinetics, which are a function of intrinsic reaction rates and practical operating temperatures. Modifying and controlling these kinetics require a thorough understanding of the hydrogen absorption and desorption processes. In this study, we have investigated the thermal decomposition of aluminum hydride, AlH3, with Magnetic Resonance Imaging in order to visualize spatially the progress and extent of the reaction. 相似文献
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L.S. Boeira J.H. Bryce G.G. Stewart B. Flannigan 《Journal of the Institute of Brewing》1999,105(6):376-381
The effect of the trichothecene mycotoxins deoxynivalenol (DON) and nivalenol (NIV) on growth of Saccharomyces cerevisiae lager and ale strains has been studied. The toxins were added into the growth medium in low and high concentrations. Yeast growth was assessed by measurement of dry weight or relative growth, cell number, viability and conductance change of the growth medium using direct and indirect methods. The inhibitory effect of both DON and NIV on yeast growth was dependent on toxin concentration. Additionally, when the extent of inhibition of yeast growth caused by high concentrations of both toxins was observed, it was subject to yeast strain, length of incubation and method used to assess yeast growth. The lowest concentrations of mycotoxin causing significant inhibition on growth of brewing yeasts were: 100 μg/ml DON for the lager strain and 50 μg/ml for the ale strain, and 50 μg/ml NIV for the ale strain. 相似文献
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IA Olivotto JS Jackson D Mates S Andersen W Davidson CJ Bryce J Ragaz 《Canadian Metallurgical Quarterly》1998,83(5):948-955
BACKGROUND: The increasing use of systemic therapy for women with lymph node negative breast carcinoma and earlier stage of disease at mammographic detection raises questions regarding the need for routine axillary lymph node dissection. Predictive modeling for lymph node involvement may be one way to reduce the need for axillary lymph node dissection and its morbidity. METHODS: A multivariate analysis of 12 factors predictive of axillary lymph node involvement was conducted in a population-based cohort of 4312 women with invasive breast carcinoma diagnosed between January 1, 1993 and December 31, 1996. RESULTS: Clinical palpability, lymphatic or vascular invasion, lesion size, margin status, histology, and patient age were independent predictors of axillary lymph node involvement. The model correctly identified lymph node status in 76.6% of cases. Model accuracy and fit were equally high when applied to randomly selected halves of the study subjects. Approximately 32.0% of the patients in the study sample (1363/4312) were identified as having an extremely high (91%; n = 1102) or low (10%; n = 261) risk of lymph node involvement. In a second analysis, a clinically useable, three-variable model identified a very low risk group of patients (n = 147) with a 4.8% risk of lymph node metastasis and a high risk group of patients (n = 1008) with a 74.2% risk of lymph node metastasis. Greater than 90% of subjects in the high risk group received adjuvant systemic therapy even if they were lymph node negative pathologically. CONCLUSIONS: A clinically useable, three-variable model employing tumor and lymph node palpability, size, and lymphatic or vascular invasion can identify women with invasive breast carcinoma in whom axillary lymph node dissection is very unlikely to alter recommendations regarding adjuvant systemic therapy. 相似文献