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131.
132.
以乙二胺为溶剂,以介孔分子筛SBA-15为载体,采用低温溶剂热法成功地合成出V和N元素共修饰的V-TiO2-xNx/SBA-15整体式可见光催化剂.将其用于光催化降解亚甲基兰的反应,较单一V或N改性的催化剂具有更强的可见光吸收能力,表现出更好的催化降解亚甲基兰的性能.结果也表明,采用金属、非金属双元素改性及"一锅法"整体合成方法是提高二氧化钛催化活性和实用性的有效方法. 相似文献
133.
文中介绍了超声通过界面时的折射规律,说明凹声透镜和凸声透镜超声聚焦的原理,提出了可以舴怕透镜扩大井下超声换能器的作用范围,从理论上设计了井下亏声聚焦系统。 相似文献
134.
终端在G*DAPS—4设备检修中的开发应用 总被引:2,自引:0,他引:2
地震仪器设备的计算机化,单纯依靠线路分析检修二分困难。文章提出了一套利用终端检修G*DAPS-4地震仪地面设备的方法。通过终端读取地面设备的状态信息,以信息提示为依据进行检修,同时文章还介绍了利用终端重写设备内部参数以及作为信号源检修设备通讯故障的方法。 相似文献
135.
HDY- 12 5型恒电位仪利用逆变技术研制而成。主电路采用半桥式结构 ,场效应管作为功率开关元件 ,集成芯片 TL 494作为其控制电路的核心。该仪器质量小、效率高、噪音低 ,在外加电流的阴极保护领域具有良好的应用前景 相似文献
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DD Baird AJ Wilcox CR Weinberg F Kamel DR McConnaughey PI Musey DC Collins 《Canadian Metallurgical Quarterly》1997,12(12):2607-2613
We compared daily urinary concentrations of oestrogen and progesterone metabolites in paired menstrual cycles (conception and non-conception) from 32 women. Volunteers with no known fertility problems were enrolled in the study at the time they began trying to become pregnant. They collected first-morning urine specimens and kept daily records of menstrual bleeding and sexual intercourse for 6 months or until they became clinically pregnant. Intercourse in non-conception cycles was close to the time of ovulation so that failure to conceive was caused by factors other than poorly timed intercourse. Compared with non-conception cycles, conception cycles had a steeper early luteal rise in progesterone and higher mid-luteal oestrogen and progesterone concentrations. These hormonal characteristics may be markers of better quality cycles, but because all these differences were in the luteal phase, we cannot rule out the possibility that the preimplantation embryo had stimulated early increases in steroid production. We propose an analysis strategy that could help support or refute the importance of preimplantation embryonic signalling, but our small sample size limits our own conclusions about this mechanism. 相似文献
138.
PI Spuls PM Bossuyt JJ van Everdingen L Witkamp JD Bos 《Canadian Metallurgical Quarterly》1998,134(12):1591-1596
OBJECTIVE: To develop and introduce evidence-based guidelines for the selection of 5 commonly used treatment modalities--UV-B, photochemotherapy, methotrexate, acitretin, and cyclosporine--for adult patients with severe plaque form psoriasis. PATIENTS AND SETTING: Patients, residents, and dermatologists from the Department of Dermatology of the Academic Medical Center of the University of Amsterdam, Amsterdam, the Netherlands, were involved in this process. DESIGN: The development process started with a questionnaire to evaluate how patients with severe psoriasis were treated. A systematic literature review was set up to provide evidence-based estimates of effectiveness, adverse effects, and dropout rates. In 2 meetings, the opinion leaders and intended users discussed the results of the questionnaire and systematic review as well as the clinical considerations in the treatment choices. Guidelines were then made regarding the sequence of selection of 5 modalities in the concept of rotational therapy. These guidelines were introduced. Their use was analyzed for 6 months. RESULTS: Before the guidelines, there was no uniform approach. In the systematic review, 665 studies concerning the treatments were found. Exclusion rates were high. No studies of methotrexate therapy could be included. Photochemotherapy showed the highest average proportion of patients with clearance (70% [6947/9925]) and good response (83% [8238/9925]), followed by UV-B (67.9% [620/913]) and cyclosporine (64% [1030/1609]) therapy. In the second internal meeting, the following sequence for the treatments was defined: UV-B, photochemotherapy, methotrexate, acitretin, and cyclosporine. In 78% (69/88) of patients treated after the introduction, the guidelines were followed to determine the treatment choice. CONCLUSIONS: Guidelines for treating severe plaque form psoriasis can be successfully developed, introduced, and implemented and were considered to improve clinical care. 相似文献
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针对影响PLC控制系统可靠性和安全性的主要因素,从硬件电路设计和软件编程两方面提出了提高系统可靠性和安全性的几种措施。 相似文献