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101.
Community violence has emerged as a major risk factor for the development of mental health problems in children and adolescents. If mental health providers are to meet the needs of children and communities dealing with community violence, then they will need to integrate principles from various subdisciplines in psychology (e.g., developmental psychology, school psychology, developmental psychopathology) as well as disciplines outside of psychology (e.g., sociology, public health, medicine) to understand fully the developmental impact of exposure to community violence. The development of such a model is necessary to identify the pathways, risk, and protective factors on which prevention and intervention programs can be built. The goal of this article is to present an ecological-transactional model of community violence as a conceptual framework for understanding the existing literature and for guiding future research on community violence exposure and child development. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
102.
鲁德宏 《工业炉》2003,25(1):41-43,51
论述了燃气红外线辐射器的基本原理 ,对其节能与环保特性的分析表明 :与大气式燃烧器相比 ,红外线辐射器的燃料节约率为 15 %~ 45 % ,CO2 排放量减少率为 15 %~ 48% ,CO排放量减少率为 96.2 %~ 97.7% ,NOx 减少率为 94.9%~ 96.9% ,具有显著的节能与环保效果  相似文献   
103.
针对压气站运行优化模型,引入了两个开关型变量:压气站开关变量和压缩机开关变量:同时还引入了考虑提供单位功率所需的能耗量两个变量。其优点是考虑了压气站越站和站内压缩机停机的情形,而且还直接引入与价格相关的变量,使得模型在运行优化的结果上更能体现某种方案的经济性,这对于管道运行商来说,更具有直观性。  相似文献   
104.
景省利  羊彦  毛玉泉 《现代电子技术》2006,29(4):103-105,108
介绍一种由集成电路芯片TDA16846完成的利用电荷泵(Charge Pump)实现的有源功率因数校正(APFC)技术。这种APFC电路的突出优点就是结构简单,通过对常规缓冲电路进行合理调整,可以很容易变成具有PFC功能的高性能开关电源。分析了APFC的工作原理,应用专用芯片TDA16846设计了电路图,并阐述了主要元件的功能。经实验证明,推荐电路设计合理,应用前景广阔。  相似文献   
105.
Concrete filled grid bridge decks exhibit orthogonal elastic properties and significant two-way bending action enabling orthotropic plate theory to determine structural response for these elements. Current American Association of State Highway and Transportation Officials load and resistance factor design (LRFD) specifications employ an orthotropic plate model to predict live load moment in concrete filled grid bridge decks but provide no guidance for computing displacement, a potentially important serviceability consideration. This paper presents equations to approximate the maximum deflection in concrete filled grid bridge decks based on orthotropic plate theory, multiple patch loads, LRFD design truck and tandem load cases, the influence of multiple spans, and the two most common deck orientations.  相似文献   
106.
低渗透油田套管损坏机理分析及防治措施   总被引:1,自引:0,他引:1  
在注水开发油田,油水井套管损坏是一种极为普遍的现象,但又各具特点.通过对鄯善油田套管损坏井的自身特点进行统计、归纳,深入分析低渗透砂岩油藏套管变形影响因素和作用机理,提出了套管损坏井的预防及相应治理措施.  相似文献   
107.
We report improvement of emission efficiency in polymer light-emitting devices (PLEDs) employing phosphorescent polymers. A hole-blocking layer was inserted between the emissive layer and the cathode to enhance recombination efficiency for the injected holes and electrons. Aluminum(III)bis(2-methyl-8-quinolinato)4-phenylphenolato (BAlq) was used for the hole-blocking layer. The resultant PLEDs exhibited significant improvement of emission efficiency. The respective external quantum efficiencies for red, green and blue PLEDs were 6.6, 11 and 6.9%. These values are very high compared with those based on conventional fluorescent polymers.  相似文献   
108.
脆断事故的原因分析和预防措施   总被引:1,自引:0,他引:1  
分析高强度材料和大型工程结构元件发生低应力脆性断裂的原因及条件,指出传统强度设计理论的局限性,从设计和工艺上提出防止发生低应力脆断事故的具体措施,给使用高强度材料和设计大型工程结构元件时提供参考。  相似文献   
109.
To examine affect and cognition in differentiating anxiety and depression, 83 older participants with generalized anxiety disorder completed the Cognitive Checklist (CCL) and the Positive and Negative Affect Schedule (PANAS). A 3-factor solution was found for the PANAS: positive affect (PA), anxiety and anger (Negative Affect 1 [NA-1]), and guilt and shame (Negative Affect 2 [NA-2]). A 2-factor structure was noted for the CCL. Correlations with anxiety and depression measures suggested that the CCL Depression (CCL-D) subscale showed stronger correlations with depression, whereas the CCL Anxiety subscale did not uniquely correlate with anxiety. The NA-1 subscale correlated positively with measures of depression and anxiety, whereas the PA subscale showed negative correlations. Hierarchical regression suggested that the CCL-D subscale was a significant predictor of self-reported depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
110.
The corrosion behavior of NiCrMo Alloy 625 (UNS N06625) has been characterized in a 10,000 h test conducted in hydrogenated water at 260 °C. The corrosion kinetics were observed to be parabolic, the parabolic rate constant being determined by chemical descaling to be 0.074 mg dm−2 h−1/2. Characterizations of the corrosion oxide layer via grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy in combination with argon ion milling and target factor analysis, revealed the presence of two spinel oxide phases and significant amounts of recrystallized nickel. Based on the distribution of three oxidized alloying constituents (Ni, Cr, Fe) with respect to depth and oxidation state, it was concluded that: (a) corrosion occurs in a non-selective manner, but significant amounts of nickel(II) ions are released to the water, and (b) the spinel oxides exist as a chromite-rich inner layer (Ni0.7Fe0.3)(Cr0.8Fe0.2)2O4 underneath a coarser, ferrite-rich outer layer (Ni0.9Fe0.1)(Cr0.1Fe0.9)2O4. The trivalent cation distribution in each of these phases appears to represent a solvus in the immiscible NiCr2O4-NiFe2O4 binary.  相似文献   
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