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排序方式: 共有372条查询结果,搜索用时 15 毫秒
41.
42.
RA Toth 《Canadian Metallurgical Quarterly》1997,186(2):276-292
Fourier transform spectrometer data of heavy water vapor were obtained at resolutions of 0.01 and 0.02 cm-1. The spectra were analyzed to obtain line center frequencies and line strengths of HD16O from 4719 to 5843 cm-1. The analysis included 1700 assigned lines of the (011)-(000), (200)-(000), (120)-(000), and (021)-(010) bands. This is the first report of assignments in the weak (120)-(000) band which borrows much of its strength from the (200)-(000) band. The measurements provided in this work are a marked improvement over the HDO listing presently available on the HITRAN database in the spectral region. Copyright 1997 Academic Press. Copyright 1997Academic Press 相似文献
43.
A local circuit approach to understanding integration of long-range inputs in primary visual cortex 总被引:1,自引:0,他引:1
DC Somers EV Todorov AG Siapas LJ Toth DS Kim M Sur 《Canadian Metallurgical Quarterly》1998,8(3):204-217
Integration of inputs by cortical neurons provides the basis for the complex information processing performed in the cerebral cortex. Here, we have examined how primary visual cortical neurons integrate classical and nonclassical receptive field inputs. The effect of nonclassical receptive field stimuli and, correspondingly, of long-range intracortical inputs is known to be context-dependent: the same long-range stimulus can either facilitate or suppress responses, depending on the level of local activation. By constructing a large-scale model of primary visual cortex, we demonstrate that this effect can be understood in terms of the local cortical circuitry. Each receptive field position contributes both excitatory and inhibitory inputs; however, the inhibitory inputs have greater influence when overall receptive field drive is greater. This mechanism also explains contrast-dependent modulations within the classical receptive field, which similarly switch between excitatory and inhibitory. In order to simplify analysis and to explain the fundamental mechanisms of the model, self-contained modules that capture nonlinear local circuit interactions are constructed. This work supports the notion that receptive field integration is the result of local processing within small groups of neurons rather than in single neurons. 相似文献
44.
No evidence for a higher resting metabolic rate in noninstitutionalized Alzheimer's disease patients
KE Donaldson WH Carpenter MJ Toth MI Goran P Newhouse ET Poehlman 《Canadian Metallurgical Quarterly》1996,44(10):1232-1234
OBJECTIVE: It has previously been suggested that Alzheimer's disease patients have higher resting energy requirements than healthy individuals, which may contribute to their unexplained weight loss. We examined whether resting metabolic rate, the largest component of daily energy expenditure, is elevated in Alzheimer's patients compared with healthy older controls. DESIGN: Cross-sectional. SETTING: General Clinical Research Center and Baltimore VA Medical Center. PATIENTS: Twenty-five noninstitutionalized demented patients (74 +/- 8 years; mean +/- SD) with a wide range of Mini-Mental Examination scores (1 to 20) and 73 healthy older individuals (69 +/- 7 years). MEASUREMENTS: Resting metabolic rate was measured by indirect calorimetry, fat-free mass and fat mass by dual energy X-ray absorptiometry, and daily energy intake by food diaries. RESULTS: No differences in fat-free mass and fat mass were noted between Alzheimer's disease patients and healthy older controls. Resting metabolic rate was similar in Alzheimer's disease patients (5446 +/- 962 kJ/day) and healthy older individuals (5647 +/- 887 kJ/day). These results persisted when resting metabolic rate was statistically adjusted for differences in body composition and age. CONCLUSION: These results provide no evidence for an elevation in resting energy requirements in noninstitutionalized demented patients. 相似文献
45.
The vagus nerve appears to serve a role in mediating peripheral immunologic influences on CNS processes. Previous work demonstrates that subdiaphragmatic vagotomy prevents or attenuates many of the behavioral and physiological responses to exogenous interleukin-1 (IL-1) or lipopolysaccharide (LPS). We determined whether the somnogenic effects of IL-1 and LPS were altered in vagotomized rats, and whether the effects of vagotomy on IL-1- and LPS-induced alterations in sleep would vary as a function of circadian phase. The data indicate that vagotomy does not influence the normal circadian patterns of sleep and wakefulness in untreated rats, or modify the pyrogenic or somnogenic effects of intracerebroventricular administration of IL-1. However, in unchallenged animals vagotomy reduces basal brain temperatures, increases delta wave amplitudes during slow-wave sleep (SWS), and induces a reduced rate of weight gain, gastric distension, and adrenal hypoplasia. Vagotomy attenuates the febrile effects of IL-1 during both light and dark phases, attenuated IL-1-induced sleep enhancement during the dark phase, and attenuated IL-1-induced increases in delta wave amplitudes within SWS during the light period. In LPS-treated rats, vagotomy attenuates the febrile and SWS responses to LPS after administration at light onset, but not after administration at dark onset. These results indicate that subdiaphragmatic vagotomy attenuates several of the somnogenic and pyrogenic effects of IL-1beta and LPS, although the effectiveness of the vagal transection in modulating these responses is influenced by circadian factors. 相似文献
46.
TL Toth SG Baka LL Veeck HW Jones S Muasher SE Lanzendorf 《Canadian Metallurgical Quarterly》1994,61(5):891-894
OBJECTIVE: To determine the potential for in vitro maturation, fertilization, and cleavage after cryopreservation of immature, prophase I human oocytes. DESIGN: Immature oocytes obtained in excess of the number required by the patient were randomized and cryopreserved at the prophase I stage or cultured as control. After thawing and maturation in vitro, test and control oocytes were inseminated with husband's sperm and evaluated for fertilization and cleavage in vitro. SETTING: In vitro fertilization program. PATIENTS: Consenting patients undergoing controlled ovarian hyperstimulation for the purposes of IVF. MAIN OUTCOME MEASURES: Rates of maturation to metaphase II, fertilization, and cleavage were compared between control and cryopreserved oocytes. RESULTS: Upon thaw, 58.5% (72/123) of prophase I oocytes were viable. Control oocytes demonstrated a 74.8% (98/131) maturation rate to metaphase II, a 56.5% (52/92) fertilization rate, and an 11.5% (6/52) blastocyst rate. Cryopreserved oocytes showed a 83.3% (60/72) rate of maturation, a 57.7% (30/52) fertilization rate, and a 3.3% (1/30) blastocyst rate. No significant differences were noted between any of these parameters. CONCLUSIONS: These results demonstrate that prophase I oocytes from stimulated IVF cycles are able to survive cryopreservation and resume meiosis to achieve full nuclear maturation post-thaw. In addition, cryopreserved oocytes retain the same capacity for fertilization and development as control oocytes. 相似文献
47.
L Pal L Leykin JL Schifren KB Isaacson YC Chang N Nikruil Z Chen TL Toth 《Canadian Metallurgical Quarterly》1998,13(7):1837-1840
A case series of eight cycles of in-vitro fertilization (IVF) in five women diagnosed with malignant disorders is presented. These patients chose to defer definitive treatment for a chance for preservation of potential fertility. The response of these patients to ovarian stimulation, and the outcome, was compared with 17 IVF cycles in 12 age-matched patients with isolated tubal infertility. An apparent adverse influence of malignant disease on the quality and behaviour of oocytes was observed. Despite a comparable total number of oocytes per cycle in the two groups, a significantly reduced percentage of mature oocytes was retrieved per cycle from patients with malignant diseases. The oocytes from patients with malignant disorders were of a poorer quality and exhibited a significantly impaired fertilization rate compared to the controls. We propose that neoplastic processes, irrespective of the site or cell of origin, may have a detrimental impact on the biology of oocytes, an effect akin to that seen on spermatozoa in men with certain malignancies. 相似文献
48.
A Slater Pauling type magnetization curve has been found for transition metal phosphides. The curve suggests a transfer of
2.4 electrons from each phosphorus atom to the metal d-bands. The curve is independent of crystal structure. Some deviations
from the Slater Pauling curve exist which may be due to antiferromagnetic coupling or due to the formation of virtual bound
states.
Research supported by a grant from the National Science Foundation 相似文献
49.
K.S. Toth 《Nuclear Data Sheets》1977,20(2):119-137
Nuclear structure information for all nuclei with mass number A = 226 is evaluated. The results from various decay experiments are compared. Adopted data, levels, and spin and parity assignments are given. 相似文献
50.