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排序方式: 共有2318条查询结果,搜索用时 15 毫秒
1.
Verbovitskii Yu. V. Denis R. V. Shtender V. V. Zavalii I. Yu. 《Powder Metallurgy and Metal Ceramics》2015,54(3-4):220-226
Powder Metallurgy and Metal Ceramics - Multiphase La 2 MgNi 9 alloys are synthesized by induction melting. The crystalline structures of all phases in the alloys are determined with X-ray... 相似文献
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The extinction coefficient ? at 2.9 μm for OH in fluoride glasses is measured by determining the amount of HF evolved during heating of the glass under steam and the corresponding intensity of the OH absorption band. This coefficient is respectively equal to 31 litre mole?1 cm?1 for BTYbZ glass (15 BaF2 - 29 ThF4 - 28 YbF3 - 28 ZnF2) and 19.5 litre mole?1 cm?1 for BALLA glass (34 BaF2 - 57 ZrF4 - 4 AlF3 - 5 LaF3). 相似文献
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Rothschild M. Forte A.R. Horn M.W. Kunz R.R. Palmateer S.C. Sedlacek J.H.C. 《IEEE journal of selected topics in quantum electronics》1995,1(3):916-923
The trend in microelectronics toward printing features 0.25 μm and below has motivated the development of lithography at the 193-nm wavelength of argon fluoride excimer lasers. This technology is in its early stages, but a picture is emerging of its strengths and limitations. The change in wavelength from 248 to 193 nm will require parallel progress in projection systems, optical materials, and photo-resist chemistries and processes. This paper reviews the current status of these various topics as they have been engineered under a multiyear program at MIT Lincoln Laboratory 相似文献
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C Tribouilloy V Ruiz R Roudaut JC Eicher B Denis JR Lusson JL Rey JL Schmit JP Lesbre 《Canadian Metallurgical Quarterly》1996,25(28):1276-1280
OBJECTIVES: Identify factors predicting favorable outcome after medical management of valve ring abscesses in order to propose a surveillance schedule for conservative treatment. METHODS: A multicentric study conducted from July 1989 to February 1996 included 28 patients (mean age 64 +/- 16 years, range 26-83) hospitalized for active endocarditis and valve ring abscesses diagnosed at transthoracic or transesophageal echography. Conservative medical therapy was given because of a decision of the medico-surgical team (n = 9), high surgical risk (n = 12), or patient refusal of surgery (n = 7). Outcome was favourable in 18 patients (Group I) and unfavorable in 10 (Group II) due to death (n = 9) or subsequent surgery (n = 1). Univariate and multivariate analysis were used to determine differences between the groups in terms of clinical and laboratory data. RESULTS: Mean follow-up in Group I was 33 +/- 18 months and 15 +/- 10 months in Group II. Univariate analysis showed significant differences between Group I and II respectively for age (59 +/- 18 yr vs 72 +/- 10, p = 0.04), delay to apyrexia after antibiotics (4.3 +/- 2.8 vs 8.3 +/- 2.4 days, p < 0.0008), heart failure (5% vs 70%, p = 0.003), grade III or IV valvular regurgitation (5% vs 60%, p < 0.04), and mean surface area of the abscess (1.5 +/- 1.2 vs 5.4 +/- 6.4 cm2, p < 0.03). Independent factors at multivariate analysis were by decreasing order: lack of heart failure at admission, delay to apyrexia, abscess surface area, and age. Outcome was favorable (mean follow-up 33 +/- 10 months) in all patients with an abscess surface area < 1.5 cm2, no signs of heart failure, no grade III or IV valvular regurgitation, apyrexia after less than 8 days on antibiotics and no staphylococcus positive blood culture. CONCLUSION: Medical management of valve ring abscesses may be indicated in selected patients in care units with rigorous surveillance facilities. Further studies are needed to precisely identify surveillance and treatment criteria. 相似文献
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Robert H. Doremus Denis Murphy Narottam P. Bansal William A. Lanford Chandra Burman 《Journal of Materials Science》1985,20(12):4445-4453
When liquid water contacts a zirconium-barium-lanthanum fluoride glass, at least three different processes occur. Barium and zirconium fluoride dissolve into the water, water penetrates into the glass, and zirconium fluoride crystals grow on the glass surface, in static solution. The rate of dissolution, as measured by solution analysis, is possibly controlled by diffusion in the solid surface; surface blockage and surface reactions are other possible kinetic steps involved. Diffusion in solution is not the controlling mechanism. Hydrogen profiles in the glass surface suggest that the penetration rate of water into the glass is controlled by diffusion and a surface reaction. 相似文献
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Collage grammars are context-free devices which generate picture languages consisting of collages—sets of parts, where a part is a set of points in a given space. In order to show that certain collage languages cannot be generated, the well-known pumping technique turns out to be rather useless. To circumvent this difficulty, other necessary criteria for context-freeness are established in this paper. Roughly speaking, these criteria reveal that (1) the collages in a context-free collage language can be deflated stepwise in such a manner that the difference between subsequent collages in the resulting chain is small and (2) the volume of parts can grow or shrink only exponentially. 相似文献
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Bandura Albert; O'Leary Ann; Taylor C. Barr; Gauthier Janel; Gossard Denis 《Canadian Metallurgical Quarterly》1987,53(3):563
In this experiment, we tested for opioid and nonopioid mechanisms of pain control through cognitive means and the relation of opioid involvement to perceived coping efficacy. Subjects were taught cognitive methods of pain control, were administered a placebo, or received no intervention. Their pain tolerance was then measured at periodic intervals after they were administered either a saline solution or naloxone, an opiate antagonist that blocks the effects of endogenous opiates. Training in cognitive control strengthened perceived self-efficacy both to withstand and to reduce pain; placebo medication enhanced perceived efficacy to withstand pain but not reductive efficacy; and neither form of perceived self-efficacy changed without any intervention. Regardless of condition, the stronger the perceived self-efficacy to withstand pain, the longer subjects endured mounting pain stimulation. The findings provide evidence that attenuation of the impact of pain stimulation through cognitive control is mediated by both opioid and nonopioid mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献