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Peer ratings of the quality of doctoral program faculties were obtained in a 1975 national survey of chemistry, history, and psychology programs. The ratings were then compared to those obtained 6 and 11 years earlier by the American Council on Education. In general, the rankings obtained from the ratings proved to be highly stable over the 11-year period, particularly in chemistry and history. Some ratings were also obtained for subspecialties within the three disciplines. Though it is clear that variations in quality among subspecialty faculties do exist and are important for individual program evaluations, it is unlikely that such subspecialty ratings would be feasible or useful in national surveys of the reputations of doctoral programs. The ratings were found to be highly related to a number of research-oriented variables of departments (such as size, productivity, percentage of alumni holding academic positions at Ph.D.-granting universities), but unrelated or very weakly related to such features as the student-reported quality of teaching and degree of faculty concern for students, or faculty-reported degree of departmental effort toward the career development of junior members of the faculty. 相似文献
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DH Lowndes DB Geohegan AA Puretzky DP Norton CM Rouleau 《Science (New York, N.Y.)》1996,273(5277):898-903
Pulsed laser deposition (PLD) is a conceptually and experimentally simple yet highly versatile tool for thin-film and multilayer research. Its advantages for the film growth of oxides and other chemically complex materials include stoichiometric transfer, growth from an energetic beam, reactive deposition, and inherent simplicity for the growth of multilayered structures. With the use of PLD, artificially layered materials and metastable phases have been created and their properties varied by control of the layer thicknesses. In situ monitoring techniques have provided information about the role of energetic species in the formation of ultrahard phases and in the doping of semiconductors. Cluster-assembled nanocrystalline and composite films offer opportunities to control and produce new combinations of properties with PLD. 相似文献
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Extensive large colon resection in the pony. II. Digestibility studies and postmortem findings. 总被引:1,自引:0,他引:1
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N G Ducharme J H Burton A A van Dreumel F D Horney J D Baird M Arighi 《Canadian journal of veterinary research》1987,51(1):76-82
The nutritional implications and adaptive processes resulting from resection of 75% of the length of the large colon in ponies were investigated. Ten ponies in good physical condition were divided into two groups: six in the experimental group and four in the control group. During the sixth postoperative month, two digestibility studies were conducted, and phosphate fractional renal excretion and serum biochemical profiles were determined in both groups. The ponies (N = 10) were euthanized six months postoperatively, and gross and histopathological examinations were performed. Results of the serum biochemical profiles, phosphate fractional renal extraction and digestibility studies showed no statistically significant difference between groups except for the serum phosphate concentration. However, large colon resection was associated with hypophosphatemia in three of the six ponies and produced an overall significantly lower phosphate concentration in the experimental ponies. This hypophosphatemia suggests that some dietary modifications may be needed postoperatively in ponies or horses undergoing this surgical procedure. Postmortem examination and histopathological examination failed to demonstrate differences between groups. Adaptive mechanisms, specifically mucosal hypertrophy or hyperplasia, were not observed. 相似文献
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Evaluation of renal gentamicin depletion kinetic properties in sheep, using serial percutaneous biopsies 总被引:1,自引:0,他引:1
Tissue drug residue research often involves the killing of an animal every time tissue concentrations are determined. To decrease the number of animals required to perform tissue depletion studies and to circumvent the statistical problems associated with determining tissue depletion kinetic properties, using multiple animals, the renal depletion profile of gentamicin from individual sheep was studied, using a bilateral renal translocation technique. Seven ewes were surgically altered, allowed to stabilize, and then allocated into 2 groups; group-1 sheep (n = 4) were given 3 mg of gentamicin/kg, IM, q 12 h for 10 days, and group-2 sheep (n = 3) were not given gentamicin. The kidneys from all ewes were biopsied 9 times over 74 days after the termination of gentamicin treatment. The renal concentrations of gentamicin were measured by use of a validated tissue digestion procedure coupled with a liquid-phase fluorescence polarization immunoassay. On days 75 and 77 after the end of gentamicin treatment, all ewes were euthanatized and necropsied. The concentrations of gentamicin in the biopsy specimens ranged from 71.9 to 183 micrograms/g on days 1 and 2 after dosing, and decreased to concentrations ranging from 3.99 to 7.35 micrograms/g on days 73 and 74 after the end of dosing. The decrease in renal gentamicin concentrations was best described by a biexponential equation. The early phase half-life was 2.8 days, whereas the terminal phase half-life was 59 days (harmonic means). There was no difference in the appearance or histologic features of the kidneys from groups 1 and 2. The only lesions noticed were linear fibroses that were attributed to the biopsy procedure. 相似文献