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131.
Leitenberg Harold; Yost Leonard W.; Carroll-Wilson Marilyn 《Canadian Metallurgical Quarterly》1986,54(4):528
Constructed a self-report questionnaire, Children's Negative Cognitive Error Questionnaire (CNCEQ), to measure in children 4 types of negative cognitive errors derived from A. T. Beck's (1967, 1976) cognitive theory of adult depression: (a) overgeneralized predictions of negative outcomes, (b) catastrophizing the consequences of negative events, (c) incorrectly taking personal responsibility for negative outcomes, and (d) selectively attending to negative features of an event. Results from administration of the CNCEQ to a normative sample of 637 4th-, 6th-, and 8th-grade children showed that in general these Ss did not endorse any of the 4 types of negative thoughts to any large extent. However, 3 subsequent studies, using 201 of the Ss in the normative sample and 211 other 4th–8th grade children, indicated that Ss with self-reported symptoms of depression, low self-esteem, and evaluation anxiety (according to a children's depression inventory, the Piers-Harris Children's Self-Concept Scale, and a test anxiety scale) endorsed each type of negative cognitive error significantly more than did their nondepressed, high self-esteem, and non-evaluation-anxious counterparts. (55 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
132.
This paper deals with lateral-torsional buckling of beams which have already buckled locally before the occurrence of overall buckling. Due to the weakening effects of local buckling, the stiffness of the beam is reduced. As a result, overall lateral buckling takes place at a lower load than the member would carry in the absence of local buckling. The effective width concept is used in this investigation to account for the post-buckling strength in the buckled compression plate elements of the beam section. A finite element formulation in conjunction with effective width concept is presented. Due to the nonlinearity involved because of local buckling, an iterative procedure is necessary. Search techniques are used to find the load factor. The method combined with an analysis on nonlinear bending moment distribution can be used to analyze the lateral stability problem of locally buckled continuous structure. In this case, both elastic stiffness matrix and geometric stiffness matrix must be revised at each load level. A computer program has been prepared for an IBM 370/165 computer. 相似文献
133.
F. G. Yost 《Journal of Electronic Materials》1974,3(2):353-369
Eutectic bonding is a technique commonly used in the electronics industry to fasten silicon chips to substrates coated with
gold. The reverse process of bonding small gold tabs to large semiconductor substrates is also possible. Gold plated Kovar
tabs have been bonded to a hot pressed silicon-germanium alloy (80 wt % Si) and to single crystals of silicon and germanium.
The joining alloys used were gold-silicon (2 wt % Si) and gold-germanium (22 wt % Ge) which melt at 370‡C and 356‡C, respectively.
Ultimate tensile loads have been measured and found to range from approximately 7.5 to l8 kilograms. Low tensile loads were
associated with semiconductor surfaces which showed little evidence of dissolution, apparently protected by a surface oxide.
A preliminary etch in 10% HF increased failure load considerably. Fracture then took place within the semiconductor material.
Low strength bonds exhibit a lamellar eutectic structure, while high strength bonds exhibit lace-like grain boundary penetration
of gold. Bonds on single crystals have considerable microstructural detail. Some show evidence of dendritic solidification,
while others show evidence of eutectic solidification. 相似文献
134.
Volatile compounds emanated from human skin were studied by gas chromatography/mass spectrometry (GC/MS). The purpose of this study was to identify compounds that may be human-produced kairomones which are used for host location by the mosquito, Aedes aegypti (L.). The procedure used to collect volatiles was chosen because of prior knowledge that attractive substances can be transferred from skin to glass by handling. Laboratory bioassays have shown that the residuum on the glass remains attractive to mosquitoes until the compounds of importance evaporate. The sampling and analytical procedures modeled the above-cited process as closely as possible except that the evaporation of compounds from the glass surface was accomplished by thermal desorption from glass beads in a heated GC injection port. This made possible the solventless injection of volatiles onto the column. The compounds were cryofocused on the head of the column with liquid nitrogen prior to GC separation. A single stage of mass spectrometry on a triple quadrupole instrument was used for mass analysis. A combination of electron ionization and pulsed positive ion/negative ion chemical ionization modes on two different GC columns (one polar, one relatively nonpolar) was used to identify most of the 346 compound peaks detected by this technique. 相似文献
135.
Experiments are performed to observe capillary flow in grooves cut into copper surfaces. Flow kinetics of two liquids, 1-heptanol and eutectic SnPb solder, are modeled with modified Washburn kinetics and compared to flow data. It is shown that both liquids flow parabolically in narrow V-grooves, and the data scale as predicted by the modified Washburn model. The early portions of the flow kinetics are characterized by curvature in the length vs time relationship which is not accounted for in the modified Washburn model. This effect is interpreted in terms of a dynamic contact angle. It is concluded that under conditions of rapid flow, solder spreading can be understood as a simple fluid flow process. Slower kinetics, e.g. solder droplet spreading on flat surfaces, may be affected by subsidiary chemical processes such as reaction. 相似文献
136.
Computer-based technologies are becoming increasingly important in translating the wealth of agricultural research information into forms that can be used by extension workers. The Acidity Decision Support System (ADSS) is a computer-based expert system that diagnoses and corrects Al-toxicity problems on highly-weathered mineral soils. The objectives of this work were to use published data to evaluate and provide recommendations to improve the ADSS knowledge base. The relative yield-Al saturation curves used by ADSS satisfactorily predict the results of field experiments for maize and soybean, but needs to be improved for rice and cassava. Curves used by ADSS for all four crops should, however, be updated to represent the research data better. Insufficient data were obtained to evaluate other crops satisfactorily. ADSS predicted that more lime would be needed to reduce soil Al saturation than was actually needed. This can be corrected by changing the value of the liming factor (LF) constant in ADSS to better represent the capability of liming materials to neutralize soil Al in the field. ADSS also predicted more response of rice and soybean to lime in on-farm experiments than occurred in practice, although there was a correlation between predicted and actual relative yield for soybean. ADSS should indicate the chances that the predicted relative yield response will not occur because of factors other than liming, under normal farming conditions. The Smyth and Cravo equation provides a reasonable estimate, in lieu of alternatives, of the change in soil Al saturation for up to five years after liming. 相似文献