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101.
陶瓷增强金属基复合材料(MMCs)因其优异的耐磨性、韧性、高温蠕变性能和疲劳强度,已被广泛应用于生物医学、航空航天、电子等高端工程行业。激光熔覆是在基体表面,利用激光束使陶瓷及其他特殊粉末与基体表层融化,并自激冷却形成冶金结合涂层的环保新技术,具有沉积效率高、厚度可控、热变形小、冷却快、稀释率小以及冶金结合等优点。本文介绍了激光熔覆陶瓷颗粒的形成方式对MMCs性能的影响,随后讨论了激光熔覆辅助能场及高速激光熔覆技术对MMCs的界面强化效应,并分析了陶瓷颗粒的强化机制和激光辅助能场的作用机制。最后,对目前激光熔覆陶瓷颗粒增强基金属复合材料研究的发展进行了展望。 相似文献
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多目标粒子群优化(multi-objective particle swarm optimization,MOPSO)算法在维护收敛性的同时搜索分布良好的最优解集较为费力.为此,提出一种基于双重距离的MOPSO,由种群的平均距离定义粒子的邻域空间,邻域粒子数为粒子的等级,数量越多,粒子的等级越大.当等级相同时,算法结合粒子的拥挤距离选择最优粒子,并更新外部归档集.此外,算法结合粒子的变异行为避免陷入局部最优.在对比实验中,该算法在收敛性和多样性上可取得较优结果.最后,将该算法应用到电力系统的环境/经济调度模型(environmental/economic dispatch,EED),也可获得性能较好的解集. 相似文献
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为防止品种混杂,筛选药用或茶用菊花的专用品种,以不同产地来源的8个药用菊花品种16个样品为试材,采用超高效液相色谱法和比色法测定不同产地药用菊花的品质成分含量;并基于主成分分析和聚类分析,对不同产地药用菊花品种产量与品质进行综合评价。结果表明,不同产地药用菊花品种单株花头数变异系数(39.03%)最大,是构成药用菊花单株花头干重的主要因素(
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AA Guglielmone CI Lugaresi MM Volpogni OS Anziani VR Vanzini 《Canadian Metallurgical Quarterly》1997,70(1-3):33-39
The efficacy of vaccination of Argentinean cattle against babesiosis and anaplasmosis using live immunogens was tested to detect specific antibodies in samples obtained about 60 days after vaccination. Under these conditions a higher than expected proportion of cattle failed to show antibodies against Babesia bigemina. Therefore, a study was designed to evaluate if this failure was due to insensitivity of the routine test to detect antibodies to B. bigemina or to lack of infectivity of the live vaccine. Four groups (G) of cattle were each inoculated subcutaneously with 10 million Babesia bovis (vaccinal strain R1A), 10 million B. bigemina (vaccinal strain S1A) and 10 million Anaplasma centrale (strain M1). G1 and G2 consisted of ten Angus bulls 20-24 months old and ten Angus bulls 15-18 months old, respectively; G3 and G4 consisted of ten and 16 Holstein 1-month-old male calves, respectively. Blood samples were obtained on days 0, 10, 20, 30, 40, 50 and 60 after vaccination and the sera were analysed with an indirect immunofluorescent (IFA) test to detect antibodies to B. bovis (baseline dilution for a positive result 1:60) and B. bigemina (baseline dilution 1:120). Positive IFA titres were considered as evidence of the infectivity of the Babesia vaccinal strains contained in the vaccine. All Angus bulls were found positive to antibodies against both Babesia species, by day 20 (B. bovis) and day 30 (B. bigemina), whereas 10-25% of Holstein calves were negative throughout. The partial lack of vaccine infectivity in the calves was considered to be a consequence of innate resistance of young calves to Babesia. Antibody titres to B. bovis and B. bigemina declined by day 60 after vaccination. However, all cattle that were positive to B. bovis antibodies on day 50 were still positive to the IFA test 10 days later while 10%, 30% and 12% of cattle of G1, G2 and G3 that were positive to B. bigemina antibodies on day 50 after vaccination were found negative to the IFA test on day 60. In future, samples taken on days 40-50 will be used for detection of B. bigemina antibodies in vaccinated cattle, on day 60 for A. centrale and on either occasion for B. bovis. The reaction to the inoculation of B. bigemina S1A strain appears to lag behind the reaction to B. bovis R1A strain. It is not certain if this is a normal reaction to this B. bigemina strain or the result of interaction with the B. bovis strain. 相似文献
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AD Dwarakanath LG Yu C Brookes D Pryce JM Rhodes 《Canadian Metallurgical Quarterly》1995,37(4):585-588
Pyoderma gangrenosum is strongly associated with inflammatory bowel disease and exhibits pathergy, occurring at sites of previous minor trauma. A patient is presented with a 21 year history of extensive ulcerative colitis, who developed pyoderma gangrenosum and arthralgia while receiving high dose corticosteroids for active ulcerative colitis. The arthralgia exhibited pathergy affecting particularly the left temporomandibular joint, which was stressed by an asymmetric bite, and the left elbow, which had been fractured many years previously. This prompted the hypothesis that neutrophils in this condition may be marginated, as a result of increased stickiness of either the neutrophil or the vascular endothelium. The introduction of heparin therapy was associated with rapid resolution of the arthralgia, pyoderma gangrenosum, and ulcerative colitis. 相似文献
110.
S Knapp PT Mattson P Christova KD Berndt A Karshikoff M Vihinen CI Smith R Ladenstein 《Canadian Metallurgical Quarterly》1998,31(3):309-319
We have generated two conditionally immortalized neuronal cell lines from primary cultures of embryonic day 13 (E13) and postmitotic (postnatal day 0; P0) cortical neurons transformed with the temperature-sensitive SV-40 large-T antigen. Two clonal cell lines (CN1.4 from E13 cultures and SJ3.6 from P0 cultures) were isolated and stable maintained in vitro. Both cell lines expressed a number of neuronal markers such as the neurofilaments, glutamic acid decarboxylase 67, neuron-specific enolase, and the BG21 isoform of the myelin basic protein gene. At 34 degrees C, the CN1.4 cell line had elaborated short processes, whereas the SJ3.6 cell line produced long processes that formed a delicate network. When these cell lines were cultured at 39 degrees C, some of the cellular processes grew longer, adopting a more mature neuronal morphology. Interestingly, at 39 degrees C, the in vitro survival of these cell lines differed significantly. Whereas the survival of CN1.4 cell line was greatly unaffected, SJ3.6 cells died soon after they were cultured at 39 degrees C. The cell death of SJ3.6 cells was accompanied by fragmentation and condensation of DNA in their nuclei, indicative of an apoptotic event. Under these conditions, SJ3.6 showed an upregulation of the p75 receptor. When this cell line was cocultured with oligodendrocytes, astrocytes, or glial conditioned media (GCM), there was a marked increase in survival. In contrast, little effect of glial cells or GCM was observed on the CN1.4 cell line. These lines appear to be useful models to study neuronal-glial interactions in addition to neuronal cell death and the effects of glial factors that promote the survival of neurons. 相似文献