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排序方式: 共有620条查询结果,搜索用时 15 毫秒
71.
Increasingly, health care professionals and the public are asking questions about the role of the hospital in meeting community need including its not-for-profit tax status. This article reviews the community benefit literature, provides a framework for understanding how a hospital community benefit program was developed, and delineates through a structured case study the lessons learned from this experience. It provides the practitioner with a context in which other hospitals may replicate the program and gives researchers a substantive case study that may be used as the basis for the empirical testing of community benefit models. The authors also outline the many difficult issues faced by a typical community hospital as it attempted to examine and develop additional responses to community need. 相似文献
72.
Demonstration of low voltage field emission 总被引:1,自引:0,他引:1
Adler E.A. Bardai Z. Forman R. Goebel D.M. Longo R.T. Sokolich M. 《Electron Devices, IEEE Transactions on》1991,38(10):2304-2308
The authors describe field emission from a thin-film field emitter array. The process used to fabricate the field emitters is based on the mold technique described by H.F. Gray and R.F. Greene (US patent 4,307,507). Each emitter chip consists of a 10×10 square array of field emitter tips and associated lead bonding pads. There is a 10-μm spacing between emitter tips. The bare chips were packaged by mounting to an alumina substrate, four to eight chips per substrate. The chips were tested in a demountable vacuum system equipped with a movable anode. The testing apparatus makes it possible to accurately measure currents as low as 100 nA at low duty. Fowler-Nordhein-like current-voltage characteristics were measured for most of the chips tested, indicating field emission. Substantial emission currents were observed at less than 20 V. The emitted current was collected almost entirely at the anode: the measured gate current was 1 to 5% of the emitted current 相似文献
73.
C.C. Wang M.H. Kalisher J.M. Tracy J.E. Clarke J.T. Longo 《Solid-state electronics》1978,21(4):625-632
The results of a study of the overall electrical characteristics of PbSnTe diodes are presented and interpreted on the basis of a simple p-n junction model. These diodes are made from a PbSnTe epilayer grown by a liquid-phase epitaxy technique on a PbTe wafer substrate. The diodes have a 50% spectral cutoff at 11.5 μm when operated at 85K, which shifts to 14.5 μm at T = 15K. Major contributions to the bulk current are diffusion current at T > 80K, and generation-recombination current for 80 >T ? 30K. Surface related leakage is predominant at T < 30 K for small area diodes (A < 1 × 10?4 cm2) at low bias voltage. Bulk defect related leakage contributes heavily the large area diodes (A > 1 × 10?3 cm2) at T ? 60K. 相似文献
74.
Lateral diffusion in planar lipid bilayers 总被引:1,自引:0,他引:1
PF Fahey DE Koppel LS Barak DE Wolf EL Elson WW Webb 《Canadian Metallurgical Quarterly》1977,195(4275):305-306
Direct measurements by fluorescence correlation spectroscopy of lateral diffusion coefficients of fluorescent lipid analogs in lipid bilaryer membranes indicate self-diffusion coefficients D greater than 10(-7) square centimeters per second for various lipid systems above their reported transition temperatures. Cholesterol in egg lecithin at mole ratio of 1 : 2 reduces D by about twofold, while retained hydrocarbon solvent can increase it by two- to threefold. 相似文献
75.
D Gouveia N Cardim S Longo J Carranca C Ferreira J Cunha R de Almeida A Pereira N Lousada T Ferreira T Pereira M Correia 《Canadian Metallurgical Quarterly》1998,11(5):503-506
OBJECTIVE: Techniques for in vitro culturing and autotransplantation have been developed for a variety of human cells and are used today in several fields of medicine. In reconstructive surgery within the genitourinary tract, autologous urothelial cells cultured in vitro could be of considerable value but have not yet been used clinically. The aim of this study was to facilitate transplantation of cultured urothelium by establishing a reliable method for culturing urothel on an immunologically inert and biodegradable structure. METHODS: Normal human urothelial cells were cultured in vitro using a feeder-cell system. To achieve an optimal carrier structure, cells were removed enzymatically from a split thickness skin graft. Human urothelial cells were then seeded on the cell-free dermis and incubated in vitro. The seeded dermis samples were investigated histologically and with immunohistochemical methods at days 7, 14 and 21. RESULTS: The human urothelial cells incubated in vitro reached confluence after 7-10 days and the cells could be cultured through 9 passages with preserved proliferative potential. When the cells were seeded on a cell-free dermis they attached, formed colonies and became confluent and stratified up to three cell layers after 21 days of incubation. The urothelial origin of the cells was confirmed by immunohistochemical staining against cytokeratin. CONCLUSION: The advantages of culturing the urothelial cells on a cell-free dermis include a short time lag until grafts are available, probably facilitated transplantation procedure, transplantation of undifferentiated cells and the formation of a vascularised base under the new urothelium. The method described in this study may be of great value in providing autologous urothelium for reconstructive surgery in the genitourinary tract. 相似文献
76.
77.
RR Brodie LF Chasseaud FF Elson ER Franklin T Taylor 《Canadian Metallurgical Quarterly》1976,26(5):896-901
The excretion and plasma concentrations of radioactivity and chromatographic patterns of radioactive components in plasma and excreta have been compared in rats, dogs and man after oral doses of the hypolipidemic agent isopropyl-[4'-(p-chlorobenzoyl)-2-phenoxy-2-methyl]-propionate (LF 178; procetofene; Lipanthyl?). 2. In rats, 48.1% of a single dose of 25 mg/kg was excreted in the urine, and 48.6% in the faeces. In dogs, 23.1% of a single dose at the same level was excreted in the urine, and 71.8% in the faeces, but 88.1% of a dose of 300 mg to man was excreted in the urine, and only 5.1% in the faeces. Peak levels of radioactivity in the plasma of all three species studied were similar (20--30 mug/ml) after doses at these levels and concentrations declined thereafter with half-lives of 7--24 h in rats and dogs, and 7 h in man. The half-life of radioactivity concentrations in rat plasma was not altered by repeated daily doses for 7 days. 3. Whole-body autoradiography of rats showed that radioactivity was largely associated with the liver, kidneys and gut, which are the organs of biotransformation and excretion, although relatively high levels were present in lungs and blood, and small amounts of radioactivity had a widespread distribution into some peripheral tissues during 2--7 h after dosing. 4. The available chromatographic evidence indicated that the most important biotransformation pathway appeared to be ester hydrolysis to LF 178 acid and formation of water soluble conjugates of this acid. This pathway appeared similar to that of the related drug clofibrate (ethyl p-chlorophenoxyisobutyrate). 相似文献
78.
79.
Richard Sasin Frederick R. Longo Francis A. Carey Charles M. Paulson Jr. George S. Sasin 《Journal of the American Oil Chemists' Society》1960,37(3):152-153
Summary
p-Bromo-,m-nitro-,p-nitrobenzenesulfonamides,p-toluenesulfonamides,p-tolyl-, anda-naphthylureas, and 3-nitrophthalimide derivatives of pentyl-, hexyl-, heptyl-, octyl-, and decylamines were prepared.m-Nitrobenzenesulfonamides,p-nitrobenzensulfonamides, andp-tolylureas appear to be the most satisfactory derivatives for the identification of these amines.
Taken from senior theses submitted by Francis A. Carey and Charles M. Paulson. 相似文献
80.