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阐述了时空效应规律在软土深基坑工程中的运用情况,实践证明,运用时空效应规律,能可靠而合理地利用土体自身在基坑开挖过程中控制土体位移的潜力而达到保护环境的目的。 相似文献
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Koenen Karestan C.; Stellman Jeanne Mager; Stellman Steven D.; Sommer John F. Jr. 《Canadian Metallurgical Quarterly》2003,71(6):980
Risk factors affecting the course of posttraumatic stress disorder (PTSD) are poorly understood. As part of a larger study on characterizing exposure to herbicides in Vietnam, the authors investigated this issue in a random sample of 1,377 American Legionnaires who had served in Southeast Asia during the Vietnam War and were followed over a 14-year period. High combat exposure, perceived negative community attitudes at homecoming, minority race, depression symptoms at Time 1, and more anger at Time 1 predicted a more chronic course. Community involvement at Time 1 was protective and associated with decreased risk at Time 2. Discomfort in disclosing Vietnam experiences was associated with an increased risk for developing PTSD but did not predict its course. Combat exposure predicted PTSD course more strongly than any other risk factor. Findings suggest recovery from PTSD is significantly influenced by perceived social support. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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This research focuses on the spatial economics of geothermal district energy (DE) systems that distribute hot fluids through a pipeline network to multiple thermal customers. We argue here that DE is held back by uncertainty about its economic feasibility when implemented in real places. DE works best with high urban densities, but in the US the best geothermal resources are in the less-populated west. Economic geography theory suggests that the optimal size of a DE firm's service area should depend on the trade-off between the economies of scale inherent in a large service area and the greater network development costs and heat loss involved in serving a large area. The HEATMAP© software program developed by Washington State University was used to study the feasibility of numerous scenarios for a proposed DE system in Mammoth Lakes, California. Results indicate that the core area of the town is large enough, dense enough, and in close enough proximity to the resource for profitable DE development. Proposed ski village developments would increase the thermal load density and significantly enhance its ability to remain competitive with other fuels, even in pessimistic sensitivity analyses regarding geothermal heat input costs, public participation, and retro-fitting costs. 相似文献
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柴油机针阀体的乙炔低压渗碳 总被引:2,自引:0,他引:2
乙炔低压渗碳可以有效地避免在真空渗碳过程中产生炭黑和焦油,同时由于乙炔具有较高的供碳能力,使这一技术尤其适用于针阀体这样的小直径深盲孔零件。 相似文献
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JU Bowie 《Canadian Metallurgical Quarterly》1997,272(5):780-789
A survey of 45 transmembrane (TM) helices and 88 helix packing interactions in three independent transmembrane protein structures reveals the following features. (1) Helix lengths range from 14 to 36 residues with an average length of 26.4 residues. There is a preference for lengths greater than 20 residues. (2) The helices are tilted with respect to the bilayer normal by an average of 21 degrees, but there is a decided preference for smaller tilt angles. (3) The distribution of helix packing angles is very different than for soluble proteins. The most common packing angles for TM helices are centered around +20 degrees while for soluble proteins packing angles of around -35 degrees are the most prevalent. (4) The average distance of closest approach is 9.6 A, which is the same as soluble proteins. (5) There is no preference for the positioning of the point of closest approach along the length of the helices. (6) It is almost a rule that TM helices pack against neighbors in the sequence. Of the 37 helices that have a sequence neighbor, 36 of them are in significant contact with a neighbor. (7) An antiparallel orientation is more prevalent than a parallel orientation and antiparallel interactions are more intimate on average. The general features of helix bundle membrane protein architecture described in this survey should prove useful in the modeling of helix bundle transmembrane proteins. 相似文献