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排序方式: 共有749条查询结果,搜索用时 15 毫秒
91.
92.
Investigated the relationship of child abuse and neglect to academic achievement and discipline problems in a school-age population. A representative community sample of 420 maltreated children in kindergarten through Grade 12 were matched with 420 nonmaltreated children in the same community. Using social service and school records as the sources of data, the authors found maltreated children performed significantly below their nonmaltreated peers in standardized tests and grades and were more likely to repeat a grade. Maltreated children also had significantly more discipline referrals and suspensions. Of the maltreated children, neglected children showed the poorest outcomes on academic performance, and physically abused children showed the most discipline problems. Variations in maltreatment effects by grade level, public assistance status, and gender are also described. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
93.
Eckenrode John; Powers Jane; Doris John; Munsch Joyce; Bolger Niall 《Canadian Metallurgical Quarterly》1988,56(1):9
A representative sample of 796 sexual abuse, 198 physical abuse, and 880 child neglect reports in New York State in 1985 was examined to identify case factors that predict the substantiation of the reports following an investigation by child protective services. This issue has taken on added significance as the number of child maltreatment reports continues to rise, whereas the percentage of those being substantiated declines. Regression analyses revealed that reports from professionals were substantiated at a significantly higher rate than reports from nonprofessionals for all types of maltreatment. These analyses further revealed that part of the effect of source of report was due to differences between professional and nonprofessional reports in the types of actions taken after the report was received. The most important predictors of substantiation, after source of report, were the variables that reflected the case investigatory process. The data also showed that background characteristics, such as the child's ethnicity or the number of children in the household, had some impact on the outcome of the investigation and that this varied as a function of the type of maltreatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
94.
The dimensions of discrete passives, passive integrated components (arrays, networks) and embedded integral ones should be reduced significantly in the nearest future. Therefore the relations between technological accuracy and limitations, minimal geometrical dimensions and electrical as well as stability properties become more and more important. This paper presents systematic studies of thick-film or LTCC microresistors made with the aid of laser shaping. The investigations are concerned with miniaturization of two resistor dimensions, namely length (down to 30 μm) and width (also down to 30 μm). The sheet resistance, hot temperature coefficient of resistance (HTCR) as well as long-term stability and durability of test structures to various short electrical pulses were related to geometrical properties of microresistors. Such investigations proved that combining of current materials and fabrication methods used in modern thick-film and LTCC technologies with laser shaping made possible fabrication of 30 × 30 μm2 microresistors with satisfactory electrical properties and can serve as interesting alternative for thick-film and LTCC resistors miniaturization. 相似文献
95.
96.
This study investigates the effectiveness of night ventilation technique for residential buildings in hot-humid climate of Malaysia. This paper firstly presents the results of a survey on usage patterns of windows and air-conditioners in typical Malaysian residential areas. Secondly, the effects of different natural ventilation strategies on indoor thermal environment for Malaysian terraced houses are evaluated based on the results of a full-scale field experiment. The results show that the majority of occupants tend to apply not night ventilation but daytime ventilation in Malaysian residential areas. It can be seen from the field experiment that night ventilation would provide better thermal comfort for occupants in Malaysian terraced houses compared with the other ventilation strategies in terms of operative temperature. However, when the evaporative heat loss of occupants is taken into account by using SET*, the night ventilation would not be the superior technique to the others in providing daytime thermal comfort mainly due to the high humidity conditions. Therefore, the indoor humidity control during the daytime such as by dehumidification would be needed when the night ventilation technique is applied to Malaysian terraced houses. Otherwise, full-day ventilation would be a better option compared with night ventilation. 相似文献
97.
98.
Side‐Directed Transfer and Presystemic Metabolism of Selenoneine in a Human Intestinal Barrier Model
Isabelle Rohn Nina Kroepfl Julia Bornhorst Doris Kuehnelt Tanja Schwerdtle 《Molecular nutrition & food research》2019,63(12)
Scope : Selenoneine, a recently discovered selenium (Se) species mainly present in marine fish, is the Se analogue of ergothioneine, a sulfur‐containing purported antioxidant. Although similar properties have been proposed for selenoneine, data on its relevance to human health are yet scarce. Here, the transfer and presystemic metabolism of selenoneine in an in vitro model of the human intestinal barrier are investigated. Methods and results : Selenoneine and the reference species Se‐methylselenocysteine (MeSeCys) and selenite are applied to the Caco‐2 intestinal barrier model. Selenoneine is transferred in higher amounts, but with similar kinetics as selenite, while MeSeCys shows the highest permeability. In contrast to the reference species, transfer of selenoneine is directed toward the blood side. Cellular Se contents demonstrate that selenoneine is efficiently taken up by Caco‐2 cells. Moreover, HPLC/MS‐based Se speciation studies reveal a partial metabolism to Se‐methylselenoneine, a metabolite previously detected in human blood and urine. Conclusions : Selenoneine is likely to pass the intestinal barrier via transcellular, carrier‐mediated transport, is highly bioavailable to Caco‐2 cells and undergoes metabolic transformations. Therefore, further studies are needed to elucidate its possible health effects and to characterize the metabolism of selenoneine in humans. 相似文献
99.
Doris Pospiech Andreas Korwitz Kathrin Eckstein Hartmut Komber Dieter Jehnichen Marcus Suckow Albena Lederer Kerstin Arnhold Michael Göbel Martina Bremer Anton Hoffmann Steffen Fischer Anett Werner Thomas Walther Harald Brünig Brigitte Voit 《应用聚合物科学杂志》2019,136(46):48257
Thermotropic liquid crystalline polyesters with varied chemical structure are synthesized by melt transesterification polycondensation. They are employed as matrix for blends with lignin materials to obtain melt-spinnable precursors for carbon fibers. The lignin samples are carefully purified by fractionation, enzymatic removal of reducing sugars, and subsequent modification of the terminal OH groups. Effective melt blending is achieved with liquid-crystalline aromatic–aliphatic polyesters having melting ranges that match the softening temperature of the lignin fractions, which is necessary to prevent thermal decomposition of the lignin. Polyester/lignin blends are partially compatibilized, phase-separated materials. The polyester/lignin materials are melt-spun successfully. The fiber properties depend on the lignin purification process. X-ray scattering reveals that orientation in lignin-containing fibers is maintained. First experiments show that the fibers can be converted successfully to carbon fibers by thermal annealing procedures. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48257. 相似文献
100.
Sahir Naqash Doris Sebold Frank Tietz Olivier Guillon 《Journal of the American Ceramic Society》2019,102(3):1057-1070
The ionic conductivity of solid electrolytes is dependent on synthesis and processing conditions, ie, powder properties, shaping parameters, sintering time (ts), and sintering temperature (Ts). In this study, Na3Zr2(SiO4)2(PO4) was sintered at 1200 and 1250°C for 0-10 hours and its microstructure and electrical performance were investigated by means of scanning electron microscopy and impedance spectroscopy. After sintering under all conditions, the sodium super-ionic conductor-type structure was formed along with ZrO2 as a secondary phase. The microstructure investigation revealed a bimodal particle size distribution and grain growth at both Ts. The density of samples increased from 60% at 1200°C for 0 hours to 93% at 1250°C for 10 hours. The ionic conductivity of the samples increased with ts due to densification and grain growth, ranging from 0.13 to 0.71 mS/cm, respectively. The corresponding equivalent circuit fitting for the impedance spectra revealed that grain boundary resistance is the prime factor contributing to the changing conductivity after sintering. The activation energy of the bulk conductivity (Ea,bulk) remained almost constant (0.26 eV) whereas the activation energy of the total conductivity (Ea) exhibited a decreasing trend from 0.37 to 0.30 eV for the samples with ts = 0 and 10 hours, respectively—both sintered at 1250°C. In this study, the control of the grain boundaries improved the electrical conductivity by a factor of 6. 相似文献