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Richard L. Lehman 《Journal of the American Ceramic Society》1992,75(8):2194-2199
Sodium-calcium-lead silicate glass compositions were prepared over a wide compositional range by conventional glass-melting methods. The acid chemical stability of the glass structure was studied by corroding samples of glass in 4% acetic acid solution at 22°C for periods up to 24 h. Lead corrosion stability was evaluated by measuring lead concentrations in the corrosion solution. At short times, parabolic time dependence was observed and the parabolic time coefficients were regressed against composition, yielding a simple additive relationship. A similar model was fitted to 24-h release data, which showed compositional effects similar to the 2-h data. Of the oxides studied, sodium was the most detrimental to durability, and the coefficients of the oxides decreased in the series: Na2 O, PbO, CaO, SiO2 . The effects of the oxides could be partially explained by the number of nonbridging oxygens expected in the glass structure, and the residual effect was attributed to cation characteristics. Small phosphate additions to the glass greatly increased the lead-ion stability under nearly all experimental conditions examined. 相似文献
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Avants S. Kelly; Margolin Arthur; Kosten Thomas R.; Rounsaville Bruce J.; Schottenfeld Richard S. 《Canadian Metallurgical Quarterly》1998,66(6):924
In response to a need to match drug users to the most appropriate and cost-effective level of care, it was hypothesized that socially anxious methadone-maintained patients would attain greater benefit from coping skills training provided in the context of a low-intensity enhanced standard methadone maintenance intervention (E-STD) than in the context of a high-intensity, socially demanding day treatment program (DTP). Social anxiety was assessed in 307 methadone-maintained patients using the Social Anxiety and Distress Scale prior to randomization to either E-STD or DTP. The hypothesis was supported: Socially anxious patients were drug free longer during treatment, were more likely to be abstinent at treatment completion, and had greater reductions in HIV risk behaviors if assigned to the lower intensity intervention, which was provided at ? the cost of the DTP. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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A group's staffing level can play an important role in its socialization practices. For example, a group that is understaffed should be more open than an overstaffed group to both prospective and new members. To test this prediction, the leaders of nearly 100 student groups on a college campus were interviewed. These interviews yielded qualitative and quantitative data about the staffing levels in the groups and the methods that they used for recruiting prospective members and assimilating new ones. Analyses of the qualitative data clarified issues such as when understaffing and overstaffing are likely to occur, what kinds of problems they produce in groups, and how groups try to solve those problems. Analyses of the quantitative data revealed that our prediction was correct: As their staffing levels decrease, most groups become more open to prospective and new members. Implications of the results are discussed, and some suggestions for future research are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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This study examined the efficacy of task analysis training for case managers helping seriously mentally ill patients find roommates and housing. Behavioral objectives and task analysis were used to develop the task-oriented behavioral training program. Case managers were trained to use a checklist for every session with patients, which included the goal of the session, tasks required to accomplish that goal and lists of all the sub-tasks. The results of this study suggest that this methodology: (1) reduced the time required for patients to find roommates and housing; (2) increased the percentage of patients finding housing; and (3) decreased hospitalization rates occurring during the process of looking for roommates and housing. 相似文献
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Jarrett Robin B.; Basco Monica R.; Risser Richard; Ramanan Janaki; Marwill Maria; Kraft Dolores; Rush A. John 《Canadian Metallurgical Quarterly》1998,66(6):1036
Two pilot studies evaluated the rate of relapse or recurrence (i.e., major depressive disorder) after cognitive therapy (CT). Two sequential cohorts included outpatients who responded to acute phase CT (A-CT) and who agreed to monthly, treatment-free follow-up. In Study 1, the Kaplan-Meier technique estimated relapse and recurrence rates of 40% at 6 months, 45% at 8 months, 50% at 12 months, 67% at 18 months, and 74% at 24 months. In Study 2, responders to A-CT received 8 months (10 sessions) of continuation phase CT (C-CT). In Study 2, relapse or recurrence was 20% at 6 and 8 months, 27% at 12 months, and 36% at 18 and 24 months after A-CT. An exploratory log-rank test showed that relapse or recurrence-free survival was greater in Study 2 than in Study 1. If replicated, this result suggests that C-CT can reduce depressive relapse or recurrence. Alternative explanations are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献