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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
J.H Xiang 《Corrosion Science》2004,46(8):2025-2039
The oxidation of the ternary alloys Ni-45Cu-10Al and Ni-30Cu-10Al has been studied at 800-900 °C under 1 atm O2. The presence of 10 at.% Al reduces significantly the oxidation rate of the corresponding Cu-Ni alloys during the initial oxidation stages, even before the establishment of a complete Al2O3 layer. The weight of individual sample of the two ternary Ni-Cu-10Al alloys at 800 °C increases more rapidly than at 900 °C during the initial oxidation stage. As oxidation proceeds, the weight gain at 800 °C slows down to a degree that the total weight gain after 24 h oxidation at 800 °C is less than that at 900 °C. Due to a faster formation of the Al2O3 layer, which suppresses earlier the further oxidation of Cu and Ni, the external region of the scales grown on Ni-45Cu-10Al contain much less Cu and Ni oxides than those grown on Ni-30Cu-10Al. The transition from the internal oxidation to the selective external oxidation of the most reactive component Al in Ni-Cu-Al alloys is favored by higher values of the Al content, of temperature and of the Cu/Ni ratio. 相似文献
962.
D.S. Patil K. PrabhakaranRajiv Dayal C. Durga PrasadN.M. Gokhale A.B. SamuiS.C. Sharma 《Ceramics International》2008
An organic precursor-mixing route has been developed for preparation of 8 mol% yttria stabilized zirconia (8YSZ) ceramics. Polymeric salt of succinic acid with yttrium and zirconium has been prepared separately by treating sodium succinate with yttrium chloride and zirconyl chloride followed by washing with water and drying at 120 °C. Thorough mixing of the two salts in stoichiometric proportions by planetary ball milling followed by calcination at 850 °C resulted in a precursor powder containing nanocrystalline (∼40 nm) monoclinic zirconia, tetragonal YSZ, cubic YSZ and yttria. Compacts prepared after deagglomeration of powder by planetary ball milling produce 8YSZ ceramics having density 99.3% TD on sintering at 1550 °C for 2 h. 相似文献
963.
管理信息化是促进企业全面发展的重要途径 总被引:1,自引:0,他引:1
杨孝伟 《武汉工业学院学报》2004,23(2):87-90
认为进一步提高认识是搞好管理信息化的重要前提条件,并从加强规划、全面实施业务流程重组、加强人员培训等方面提出了实施管理信息化的措施。 相似文献
964.
介绍了畸形波的概念和发生的机理,及两种畸形波波形模拟的方法,以Stocks五阶波的叠加来模拟畸形波,主要用于工程计算;用NLS方程建立深水单向波模型,求出符合畸形波特性的解,对畸形波进行数值模拟,适用于动力分析。 相似文献
965.
Consumers' beliefs, attitudes and intentions towards genetically modified foods, based on the 'perceived safety vs. benefits' perspective 总被引:1,自引:0,他引:1
Ioannis S. Arvanitoyannis & Athanasios Krystallis 《International Journal of Food Science & Technology》2005,40(4):343-360
It has been repeatedly claimed that the application of genetic engineering in the field of agricultural and food production is both beneficial and advantageous. However, biotechnology is developing in an environment where public concerns about food safety and environmental protection are steadily increasing. The present study aims at gaining an insight into Greek consumers’ beliefs, attitudes and intentions towards genetically modified (GM) food products. The objectives of this study are summarized as follows (i) to provide evidence that consumer beliefs are built around the ‘safety‐benefits’ axis, and (ii) to segment the Greek market in terms of consumer beliefs about GM food products and identify a number of clusters with clear‐cut behavioural profiles. Although the overall attitude of Greek consumers towards GM food is negative, the research very interestingly concludes that there exists a market segment of substantial size, whose beliefs about GM food appears to be positive. This finding suggests that there is not a ‘consensus’ regarding the rejection of GM foods in the Greek market as one might have expected thus ‘encouraging’ the implementation of adequate marketing strategies to target this segment of ‘early adopters’ in the first place. 相似文献
966.
967.
板深51区块存在压力敏感地层,在非目的层井段存在大段高渗低压砂岩,而目的层又属于高压低渗地层,属于难采油气田。室内进行的砂床滤失量、砂床封堵带承压能力、岩心封堵带的承压能力及油气层保护效果实验表明,在超低渗钻井液中增加固相含量,能够提高超低渗透膜结构强度,提高地层承压能力,降低砂床侵入深度,增强保护油气层效果,而且有选择性地增加有用固相效果更佳。基于这一理论,研究成功了超低渗广谱屏蔽暂堵油层保护技术,并在板深51区块长22—15井和长23—17K井进行了试验应用。该技术的关键是依据地层特性确定复配暂堵剂。长22-15井和长23-17K井射孔后未经过压裂、酸化、排液处理,获自喷高产,尤其是长22-15井形成自喷油流,创油田单井试采产量最高记录。应用结果表明,超低渗广谱保护油气层钻井液技术封堵隔层的承压能力强,很大程度地提高了漏失层的承压能力和破裂压力,较好地解决了含多套压力层系长裸眼段钻井过程中发生的漏失、井喷、卡钻、油气层保护等技术难题。 相似文献
968.
Qijun Zhao 《Pattern recognition》2006,39(2):310-312
In this paper, we propose a fast Evolutionary pursuit algorithm. It searches for optimal discriminant vectors through linearly combining standard bases. Experiments on the Yale and ORL databases verify its effectiveness and enhanced efficiency. 相似文献
969.
970.
计算机分系统是光刻机整机控制和管理的中枢,直接反映和影响整机的性能和介绍了计算机硬件接口控制原理,描述了分步重复投影光刻机系统软件的主要设计思想和软件的主要功能。 相似文献