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排序方式: 共有887条查询结果,搜索用时 15 毫秒
101.
OBJECTIVE: Evaluate wound healing of incisions created by the scalpel, electrocautery, CO2 laser, and potassium titanyl phosphate (KTP) laser in the upper aerodigestive tract in an animal model. STUDY DESIGN: Prospective randomized study in an animal model. METHODS: Postoperative oral intake, histologic depth of injury, and tensile mechanical strength were measured in rat tongues after creating incisions using a scalpel, electrocautery, CO2 laser, and KTP laser. An unpaired, two-tailed Student's t-test was used to compare results between the experimental groups. RESULTS: Oral intake, indirectly assessed by postoperative weight loss, by the third postoperative day was significantly decreased in the electrocautery (P = 0.004), CO2 laser (P = 0.001), and KTP laser (P = 0.0001) groups as compared with the scalpel group. The depth of the wound healing, as assessed by histologic examination, was successively greater for the scalpel (75 +/- 13 microm), electrocautery (110 +/- 10 microm), CO2 laser (145 +/- 10 microm), and KTP laser (195 +/- 23 microm) groups. However, this difference was only statistically significant for the CO2 laser (P = 0.006) and KTP laser (P = 0.01) groups relative to the scalpel group. Wounds created by the KTP laser had the lowest strength (76.5 +/- 6.9 kPa) as compared with the CO2 laser (156 +/- 28.4 kPa), electrocautery (153 +/- 15.7 kPa), and scalpel groups (249 +/- 61.8 kPa). This difference was only statistically significant for the KTP laser group (P = 0.02) when compared with the scalpel group. CONCLUSIONS: Wounds created in the upper aerodigestive tract of rats by scalpels result in the least postoperative weight loss, tissue destruction, and decrease in tensile strength, whereas wounds created by the KTP laser demonstrated a significantly greater postoperative weight loss, depth of wounding, and decrease in tensile strength. 相似文献
102.
Thermodynamically consistent description of heat conduction with finite speed of heat propagation 总被引:1,自引:0,他引:1
Isaac Shnaid 《International Journal of Heat and Mass Transfer》2003,46(20):3853-3863
In this work, governing equations for heat conduction with finite speed of heat propagation are derived directly from classical thermodynamics. For a one-dimensional flow of heat, the developed governing equation is linear and of parabolic type. In a three dimensional case, the system of nonlinear equations is formulated.Analytical solutions of the equations for one-dimensional flow of heat are obtained, and their analysis shows characteristic features of heat propagation with finite speed, being fully consistent with classical thermodynamics. 相似文献
103.
The mechanical properties and failure behavior of single tire belts with different cord angles were investigated. The cords consisted of two pairs of twisted steel wires. Geometric moiré and the grid method were used to measure small and large deformations, respectively. The stress–strain curves of all samples tested display three typical deformation stages, initial nonlinear deformation, followed by an intermediate stage of approximately linear deformation and a final stage of approximately linear deformation with increased modulus. The transition strain from the first to the second stage increases linearly with cord angle and the ultimate strength is found to follow the Tsai–Hill failure criterion. Failure mechanisms varied with cord angle. They are classified into four modes including failure within the cord, shear failure at the interface between cord and rubber, a combination of the above two modes and cord breakage. In-plane shear properties were obtained using both the Arcan pure shear and the 22° off-axis tests. They were found to be in good agreement. A nonlinear micromechanics model was proposed to predict the properties of single belts with different cord orientations by taking into consideration both the material and geometric nonlinearities. 相似文献
104.
Zygmunt Pizlo Azriel Rosenfeld Isaac Weiss 《Computer Vision and Image Understanding》1997,65(3):425-433
We address the problem of a geometrical model of vision. This problem is interesting for at least two reasons. First, any theory of vision (human or computer) must decide which geometry should be used to represent perceived objects (e.g., Euclidean vs projective). We believe that this representation should be compatible with geometrical properties of the imaging device (eye or camera). Second, the analysis of geometrical properties of vision will examine the usefulness of standard geometries and can lead to progress in mathematics itself. We analyze the geometry of image formation and show that human vision appears to involve a new branch of geometry whose properties are quite different from the properties of traditional geometries. We formulate these properties and use them to derive models of shape perception. Finally, we provide perceptual interpretations for our theoretical analyses. 相似文献
105.
"Six Macacus cynomolgus monkeys were trained in a shock-avoidance situation while under the influence of reserpine. Three sessions of 60 trials were given a week apart. Subsequent acquisition of the habit was retarded." (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Isaac C. Sanchez 《Polymer Engineering and Science》1984,24(2):79-86
An abbreviated review of the current state of knowledge of polymer interfacial phenomena is given. Classical thermodynamics treats the interfacial zone (the interphase) as a “black box” and yields rigorous relationships among interfacial quantities. A recent reformulation of interphase thermodynamics, which eliminates the use of a Gibbs dividing surface, is shown to be an invaluable tool for investigating interfacial properties. Microscopic theories, such as the gradient theory, yield more details about what is in the black box, but the information is only approximate. The gradient theory has been used to: (1) relate the surface tension of a polymer liquid to its isothermal compressibility, (2) develop a quantitative theory of polymer liquid surface tension, and (3) determine the interfacial tension between two immiscible polymer liquids. The gradient theory will be shown to be in harmony with the microscopic theory of Helfand and co-workers although the latter treats polymer interfaces from a completely different point of view. 相似文献
107.
We have analyzed a large set of data in the literature as well as new data of our own to provide an improved equation of state of solid para-hydrogen and ortho-deuterium, with pressures ranging from 0 to 25 kbar (at the melting line). Results, including pressure, bulk modulus, and thermal expansion, are tabulated for a dense set of molar volumes as a function of temperature.Partial financial support provided by the Stichting FOM. 相似文献
108.
A study of the transient liquid phase bonding process applied to a Ag/Cu/Ag sandwich joint 总被引:6,自引:0,他引:6
Isaac Tuah-Poku M. Dollar T.B. Massalski 《Metallurgical and Materials Transactions A》1988,19(3):675-686
Transient liquid phase (TLP) bonding is a process currently used for joining heat resistant alloys, for example nickel- and
cobalt-based superalloys. It involves the formation of a liquid layer between two adjoining pieces and the formation of a
solid bond as the liquid disappears during annealing at a suitable constant temperature. In the present study, a model Ag/Cu/Ag
sandwich joint associated with a simple eutectic phase diagram was used to study the different stages of this process. The
results confirm that the TLP bonding is a diffusional process occurring in clearly distinctive stages. The two most important
stages are the widening and homogenization of the previously dissolved liquid interlayer, and the subsequent solidification
and shrinking of the interlayer. Whereas the former stage involves diffusional processes both in the liquid phase and in the
adjoining solids, the latter is controlled mainly by the diffusion in the solid phase. A modeling approach has been explored
which shows that in most eutectic systems there exists an optimal bonding temperature corresponding to the shortest time needed
for complete solidification. The results of a study on a Ag/Ag-20 wt pct Cu/Ag sandwich joint provide evidence that the use
of an alloy close to the eutectic composition as an interlayer material shortens the TLP process substantially. 相似文献
109.
Andrew M. Bailey Laura Pajak Isaac R. Fruchey Cristopher A. Cowan Peter A. Emanuel 《Journal of The Association for Laboratory Automation》2003,8(6):113-120
The events that occurred following the mailing of Bacillus anthracis-laced envelopes through the postal system has highlighted the need to perform biological screening on large numbers of environmental samples. High-throughput screening that relies on integrated robotic systems to speed analysis has been undertaken to handle the surge in samples requiring testing in events involving weapons of mass destruction. These automated screening systems require DNA extraction methods capable of handling environmental samples that contain inhibitors and have target organisms at low concentrations. This study describes the development of a method for the detection of the biological warfare agent simulants Erwinia herbicola and Bacillus subtilis var. niger spores using paramagnetic bead-based resin with an automated liquid handler and environmental samples. 相似文献
110.
This obituary describes the professional career of Robert J. Wherry, which spanned 48 years, from 1927 to 1975. Wherry was an exceptional example of a quantitative-industrial psychologist who was able to make independent, original academic contributions, and yet have an exceptional understanding of problems of application. Throughout his career, two of Wherry's overriding interests were in the development and application of statistical models for prediction and factor analysis. In addition to his contributions to the quantitative literature, Wherry made substantial contributions to industrial psychology, publishing extensively in the industrial literature. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献