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排序方式: 共有2247条查询结果,搜索用时 15 毫秒
141.
We present a detailed theoretical heat transfer model for the entire rotational molding process (including heating and cooling stages) and identify the key dimensionless groups affecting the process cycle time. This theoretical model is employed to generate numerical results that are in very good agreement with the experimental data available in the literature. The effects of variations in the dimensionless groups on the cycle time are evaluated. In addition, part shrinkage has been incorporated in the models, and its effect on the process cycle time has been studied extensively. 相似文献
142.
OBJECTIVE: To systematically review the effects of isotonic crystalloids compared with colloids in fluid resuscitation. DATA SOURCES: Computerized bibliographic search of published research and citation review of relevant articles. STUDY SELECTION: All randomized clinical trials of adult patients requiring fluid resuscitation comparing isotonic crystalloids vs. colloids were included. Pulmonary edema, mortality, and length of stay were evaluated. Independent review of 105 articles identified 17 relevant primary studies of 814 patients. Weighted c about article inclusion was high (0.76). DATA EXTRACTION: Data on population, interventions, outcomes, and methodologic quality of the studies were obtained by duplicate independent review with differences resolved by consensus. Weighted ic on the validity assessment was moderate (0.54). DATA SYNTHESIS: No difference was observed overall between crystalloid and colloid resuscitation with respect to mortality and pulmonary edema; however, the power of the aggregated data was insufficient to detect small but potentially clinically important differences. Subgroup analysis suggested a statistically significant difference in mortality in trauma in favor of crystalloid resuscitation (relative risk 0.39, 95% confidence intervals: 0.17 to 0.89). Several methodologic issues are noteworthy regarding the primary studies, including lack of blinding (except in three studies). The type, dose, and duration of fluid administration and outcomes measured were different across these trials. CONCLUSIONS: Overall, there is no apparent difference in pulmonary edema, mortality, or length of stay between isotonic crystalloid and colloid resuscitation. Crystalloid resuscitation is associated with a lower mortality in trauma patients. Methodologic limitations preclude any evidence-based clinical recommendations. Larger well-designed randomized trials are needed to achieve sufficient power to detect potentially small differences in treatment effects if they truly exist. 相似文献
143.
Volatile Profiles of Raw and Cooked Turkey Thigh as Affected by Purge Temperature and Holding Time Before Purge 总被引:1,自引:0,他引:1
Effects of purge temperature and sample holding time on volatile profiles were determined using a purge-and-trap/gas chromatography unit with autosampler. Purge temperature and sample holding time before purge influenced the profile of volatiles in raw and cooked meat. The most notable changes were observed when the purge temperature was increased from 60°C to 80°C. Many of the changes in volatiles were related to oxidation of lipids. We recommend that meat should be purged at 40°C or 50°C (temperature at sensory analysis) to minimize heat-induced production of volatiles and sample purge should be done within 3h after sampling to reduce oxidative changes during sample holding time. 相似文献
144.
The formation and growth of crystal nuclei of zeolite A from clear solutions at room temperature were studied with low-dose, high-resolution transmission electron microscopy in field emission mode and with in situ dynamic light scattering. Single zeolite A crystals nucleated in amorphous gel particles of 40 to 80 nanometers within 3 days at room temperature. The resulting nanoscale single crystals (10 to 30 nanometers) were embedded in the amorphous gel particles. The gel particles were consumed during further crystal growth at room temperature, forming a colloidal suspension of zeolite A nanocrystals of 40 to 80 nanometers. On heating this suspension at 80 degrees C, solution-mediated transport resulted in additional substantial crystal growth. 相似文献
145.
Object-oriented analysis (OOA), a powerful methodology for understanding and documenting complex software applications, is discussed. The methodology supports and promotes the fullest possible understanding of the integrated network management problem domain. These benefits of OOA are attributable to its ability to support integrated and consistent analysis of software systems containing informational, behavioral, and computational complexities. The authors explain how to use OOA, discuss the relationship of OOA to industry standards, and summarize its pros and cons 相似文献
146.
Memorializes R. Case, a developmental theorist who was among the first to transform Piaget's theory of intellectual growth into the more precise terms of information processing theory. Case was also the first to document the marked social class differences that are present at school entry in children's general sense of numbers. He attacked the problem with an innovative program in early mathematics education that concentrates on teaching number sense rather than formal computational mathematics in early grades. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
147.
148.
SK Shapira C McCaskill H Northrup AS Spikes FF Elder VR Sutton JR Korenberg F Greenberg LG Shaffer 《Canadian Metallurgical Quarterly》1997,61(3):642-650
Deletions of the distal short arm of chromosome 1 (1p36) represent a common, newly delineated deletion syndrome, characterized by moderate to severe psychomotor retardation, seizures, growth delay, and dysmorphic features. Previous cytogenetic underascertainment of this chromosomal deletion has made it difficult to characterize the clinical and molecular aspects of the syndrome. Recent advances in cytogenetic technology, particularly FISH, have greatly improved the ability to identify 1p36 deletions and have allowed a clearer definition of the clinical phenotype and molecular characteristics of this syndrome. We have identified 14 patients with chromosome 1p36 deletions and have assessed the frequency of each phenotypic feature and clinical manifestation in the 13 patients with pure 1p36 deletions. The physical extent and parental origin of each deletion were determined by use of FISH probes on cytogenetic preparations and by analysis of polymorphic DNA markers in the patients and their available parents. Clinical examinations revealed that the most common features and medical problems in patients with this deletion syndrome include large anterior fontanelle (100%), motor delay/hypotonia (92%), moderate to severe mental retardation (92%), growth delay (85%), pointed chin (80%), eye/vision problems (75%), seizures (72%), flat nasal bridge (65%), clinodactyly and/or short fifth finger(s) (64%), low-set ear(s) (59%), ear asymmetry (57%), hearing deficits (56%), abusive behavior (56%), thickened ear helices (53%), and deep-set eyes (50%). FISH and DNA polymorphism analysis showed that there is no uniform region of deletion but, rather, a spectrum of different deletion sizes with a common minimal region of deletion overlap. 相似文献
149.
LG Shakhlina 《Canadian Metallurgical Quarterly》1997,19(5):23-27
Elderly cataract patients frequently have comorbid multisystem disease. Local or regional anesthesia is provided to reduce complications of retrobulbar infiltration. Performing painless eye blocks without sedation is probably the safest route. 相似文献
150.
Eric R. Marsh David A. Arneson Melvin J. Liebers Mike W. Olson 《Precision Engineering》2008,32(2):143-147
Stable, externally pressurized aerostatic spindles exhibit picometer-level vibration as a result of the interaction of the high-pressure working fluid and its path through a spindle's compensation features (e.g., grooves, orifices, pockets, etc.). This vibration presents a challenge as end users seek the lowest possible asynchronous error motion in manufacturing, metrology and data storage applications. This technical brief describes experimental testing to quantify this low-level vibration and its significant variation with both supply gas composition and pressure. Of the gases tested, helium and neon generate the lowest vibration while other gases including air lead to an order of magnitude higher vibration. Vibration levels with carbon dioxide and nitrous oxide are an additional order of magnitude higher. At present, the root cause of the vibration amplitude dependence on supply gas composition is unknown although kinematic viscosity and mean free path length correlate well with the results presented here. 相似文献