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排序方式: 共有4704条查询结果,搜索用时 15 毫秒
1.
Recurrent erosion of the corneal epithelium has been treated successfully by phototherapeutic keratectomy when convention therapy has failed. We present a case of recurrent corneal erosion occurring 1 year after photorefractive keratectomy in a 55-year-old myopic woman. No corneal abnormalities were previously identified in either the affected or the fellow eye. This case demonstrates the potential for ineffective healing of the corneal epithelial basement membrane complex after excimer laser photorefractive keratectomy. 相似文献
2.
AS Jonason S Kunala GJ Price RJ Restifo HM Spinelli JA Persing DJ Leffell RE Tarone DE Brash 《Canadian Metallurgical Quarterly》1996,93(24):14025-14029
The multiple genetic hit model of cancer predicts that normal individuals should have stable populations of cancer-prone, but noncancerous, mutant cells awaiting further genetic hits. We report that whole-mount preparations of human skin contain clonal patches of p53-mutated keratinocytes, arising from the dermal-epidermal junction and from hair follicles. These clones, 60-3000 cells in size, are present at frequencies exceeding 40 cells per cm2 and together involve as much as 4% of the epidermis. In sun-exposed skin, clones are both more frequent and larger than in sun-shielded skin. We conclude that, in addition to being a tumorigenic mutagen, sunlight acts as a tumor promoter by favoring the clonal expansion of p53-mutated cells. These combined actions of sunlight result in normal individuals carrying a substantial burden of keratinocytes predisposed to cancer. 相似文献
3.
BA Stankiewicz JC Hutchins R Thomson DE Briggs RP Evershed 《Canadian Metallurgical Quarterly》1997,11(17):1884-1890
Flash pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) was used to assess the quality and mechanism of protein preservation in the tissue of Iron Age bog bodies from Lindow, UK, and south-eastern Drenthe, The Netherlands. Abundant pyrolysis products of the fresh skin tissue, including 2,5-diketopiperazines of Pro-Gly, Pro-Ala, Pro-Val, Pro-Pro and Hyp, were readily assigned to specific amino acid or dipeptide moieties. Comparison of the pyrolysates of the bog-body tissues with that of modern samples revealed qualitative similarities suggesting good preservation of the collagen and non-collagenous proteins in the ancient tissues. Examination of the pyrolysates of samples of fresh calf skin, which had been treated with various vegetable tanning agents, clearly revealed markers of non-hydrolysable tannins including 1,2-benzenediol, 1,3-benzenediol and 1,2,3-benzenetriol, although chromatographic quality inevitably diminished with increasing functionalization of the compounds. Such markers were not detected in the pyrolysates of the bog-body tissues. Instead 4-isopropenylphenol, a characteristic pyrolysis product of Sphagnum moss, was detected in both solvent-extracted and base-treated samples of tissue. The presence of 4-isopropenylphenol in the pyrolysates of the bog-body tissues provides evidence that their preservation involves reactions of amino acids with sphagnum acid, and possibly other agents derived from the peat. The study constitutes the first chemical characterization of the pyrolysis products of modern and ancient collagen. 相似文献
4.
DE Stewart 《Canadian Metallurgical Quarterly》2003,191(9):561-562
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DE Patterson CA Raviola EA D'Orazio C Buch KD Calligaro MJ Dougherty DA DeLaurentis 《Canadian Metallurgical Quarterly》1996,24(6):1030-1033
This case report details the multidisciplinary treatment of peripartum left iliac vein thrombosis using percutaneous catheter-directed urokinase thrombolysis and balloon thromboplasty. Enhanced chances for long-term patency and the normalization of venous function make these minimally invasive procedures accepted options for the treatment of iliofemoral deep venous thrombosis in selected peripartum patients. 相似文献
7.
SUSANNA DE CORDT MARC HENDRICKX GEERT MAESMANS PAUL TOBBACK 《International Journal of Food Science & Technology》1992,27(6):661-673
Biphasic and nth-order models were tested as to their usefulness to fit experimental inactivation data of Bacillus licheniformis α-amylase, immobilized on glass beads, and were discussed with respect to their suitability to characterize the considered enzymic system as a time—temperature integrator (TTI) to evaluate heat processes. Both isothermal and non-isothermal inactivation experiments were carried out. Model (kinetic) parameters (rate constant k, activation energy EA and reaction order n) were estimated using a non-linear regression procedure. The results obtained, especially the activation energy of about 293 kJ mole–1 , indicated a potential use of this system as a TTI for heating processes in the temperature range of 96–108°C. 相似文献
8.
Influence of electroosmotic treatment on the hydro-mechanical behaviour of clayey silts: preliminary experimental results 总被引:1,自引:0,他引:1
Laura Gabrieli Cristina Jommi Guido Musso Enrique Romero 《Journal of Applied Electrochemistry》2008,38(7):1043-1051
Preliminary results of an investigation focused on the influence of electrokinetic treatment on the mechanical and hydraulic
behaviour of clayey soils are presented. The experimental programme aims at providing a contribution to the sustainability
of contaminant extraction or containment via electroosmosis. Changes in the hydraulic and mechanical properties of two illitic
clayey soils, subjected to a DC electric field, were investigated. Samples of the two soils were subjected to electrokinetic
filtration, for different periods of time, and under different constant loads. Afterwards, they were tested under one-dimensional
compression to detect changes in stiffness and hydraulic conductivity due to the electrical treatment. After the application
of a DC field for a few hours, a small reversible increment in the average soil stiffness was observed, with respect to the
untreated soil, while the hydraulic conductivity was not affected substantially. Dramatic changes of the mechanical and hydraulic
soil properties, correlated to changes of the soil pH, were observed following non-conditioned electrokinetic treatment with
duration of the order of days. 相似文献
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