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1.
多孔性青铜含油轴承是全世界都在生产的,最早与最无处不用的现代粉末冶金产品。然而,各地区产品之间仍存在着明显差异。近期发布的粉末冶金材料的全球标准ISO5755,其中有2个描述轴承材料性能的数据表。其中列举的几项关键性轴承特性和MPIF标准35或相应的ASTM标准中列出的轴承性能有所不同。因此,MPIF标准委员会进行一项小型试验,对标准90%(质量分数)Cu-10%(质量分数)Sn轴承的关键特性进行了对比。这项研究的样品零件来自欧洲与北美的大批量生产厂家。数据证实孔隙度与径向压溃强度不同,这种差异是原料粉与制造工艺的微妙差异所致。最终用户应该了解这些差异,和确认IS05755中列举的特性能满足他们对轴承的要求。  相似文献   

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Sustainable design should be applied in all phases of the life cycle of a building, including programming, design, building construction, building operation, and finally demolition. This paper compares and contrasts sustainable design programs based on the life cycle of a building in North America, Europe, and Asia. Tables comparing programs from these three regions are provided for each phase in the life cycle of a building. These tables can be used by building design professionals as a reference guide to sustainable design around the world. The tables also highlight specific requirements or concerns that are applicable in a particular region. The similarities between different programs and regions can be taken into consideration during the planning of sustainable design work, regardless of the region of construction. Finally, references to more detailed program documents are provided so that interested readers can determine specific requirements that apply in a region of interest.  相似文献   

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Data for 2,069 managers from 4 regions (9 countries) taken from the International Research Groups on Management data bank and dealing with a simulation of negotiations, were contrasted with known industrial conflict patterns in the 4 regions. The importance of individual commitment to group strategy in affecting the simulation results regarding the time of negotiation and the bargaining issues was related to cultural differences. Possible implications of cultural differences to the study of managerial behavior in resolving industrial disputes are discussed. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

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一行六人南美、北欧之行收益不浅 ,小组有一个“考察报告”可供参阅。时隔几月余 ,一些感受和联想总在脑海萦环 ,不由寄笔于下 :1 南美、北欧国际矿业公司基本特征南美、北欧国际矿业公司之基本特征是 :拥有较为雄厚的矿产资源。如果只有冶炼没有矿山 ,那你只能算一个冶炼公司。单纯的冶炼厂 (公司 )多两大风险 :一是原料来源风险 ,二是原料价格风险。如果有了较好的自己开采的资源 ,这两大风险就可以自行消失 ,这对一个矿业公司持续稳定发展是至关重要的。作为一个完整矿业公司形象应包括勘探、采矿、选矿和冶炼。从这个意义上讲 ,我们江…  相似文献   

6.
This study examined whether universality of the 5-factor model (FFM) of personality operationalized by the Revised NEO Personality Inventory is due to genetic influences that are invariant across diverse nations. Factor analyses were conducted on matrices of phenotypic, genetic, and environmental correlations estimated in a sample of 1,209 monozygotic and 701 dizygotic twin pairs from Canada, Germany, and Japan. Five genetic and environmental factors were extracted for each sample. High congruence coefficients were observed when phenotypic, genetic, and environmental factors were compared in each sample as well as when each factor was compared across samples. These results suggest that the FFM has a solid biological basis and may represent a common heritage of the human species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

7.
Aboriginal communities and their health services should prepare together and in advance for caring for an HIV-infected person. Good social support will be the keystone to successful clinical management. Health care workers must look to Aboriginal people for the lead in developing appropriate responses.  相似文献   

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Negative pressure transients (NPT) recorded in a single closing event of mechanical valves in the mitral position in an in vitro setup are compared with data recorded in the left atrium in vivo with the valves implanted in the mitral position in an animal model. The loading at valve closure (dP/dtCL) computed from the in vivo ventricular pressure recording (ranging from 700 to 2300 mm Hg/s) agreed with the magnitudes predicted in our earlier in vitro experiments (750-3000 mm Hg/s). The NPT signals and the corresponding power spectral density plots from the in vivo data were in qualitative agreement with those recorded in vitro. The NPT magnitudes were found to be below the vapor pressure for blood in mechanical valves with rigid occluders suggesting a potential for the valve to cavitate in vivo. Our in vivo results also suggest that the valves with flexible occluders are less likely to cavitate. The correlation of the in vitro and in vivo data also suggests that the flexibility of valve housing used in the in vitro studies is not an important factor in the dynamics of mechanical valve closure in vivo.  相似文献   

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Informed by a new theoretical framework that assigns a key role to cultural tasks (culturally prescribed means to achieve cultural mandates such as independence and interdependence) in mediating the mutual influences between culture and psychological processes, the authors predicted and found that North Americans are more likely than Western Europeans (British and Germans) to (a) exhibit focused (vs. holistic) attention, (b) experience emotions associated with independence (vs. interdependence), (c) associate happiness with personal achievement (vs. communal harmony), and (d) show an inflated symbolic self. In no cases were the 2 Western European groups significantly different from one another. All Western groups showed (e) an equally strong dispositional bias in attribution. Across all of the implicit indicators of independence, Japanese were substantially less independent (or more interdependent) than the three Western groups. An explicit self-belief measure of independence and interdependence showed an anomalous pattern. These data were interpreted to suggest that the contemporary American ethos has a significant root in both Western cultural heritage and a history of voluntary settlement. Further analysis offered unique support for the cultural task analysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

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Flowers sensu lato are short, specialized axes bearing closely aggregated sporophylls. They are typical for seed plants (spermatophytes) and are prominent in flowering plants sensu stricto (angiosperms), where they often comprise an attractive perianth. There is evidence that spermatophytes evolved from gymnosperm-like plants with a fern-like mode of reproduction called progymnosperms. It seems plausible, therefore, that the stamens/carpels and pollen sacs/nucelli of spermatophytes are homologous to fern sporophylls and sporangia, respectively. However, the exact mode and molecular basis of early seed and flower evolution is not yet known. Comparing flower developmental control genes to their homologs from lower plants that do not flower may help to clarify the issue. We have isolated and characterized MADS-box genes expressed in gametophytes and sporophytes of the fern Ceratopteris. The data indicate that at least two different MADS-box genes homologous to floral homeotic genes existed in the last common ancestor of contemporary vascular plants, some descendants of which underwent multiple duplications and diversifications and were recruited into novel developmental networks during the evolution of floral organs.  相似文献   

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North American literature provides interesting ideas about the nature of specialist and advanced practice which are useful in informing British thinking on these subjects. However, the two roles do not have the same meanings as their British counterparts. Clarification of the terminology used and the roles described are essential if we are to understand the concepts. This article presents an overview of the literature about clinical nurse specialist and advanced practitioner roles within North America and identifies differences and similarities between the two.  相似文献   

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为满足先进航空发动机高压涡轮盘等热端部件的使用要求,需要研制更高性能的第四代粉末高温合金,其标志是最高使用温度要达到815℃。概述了最近10年来美国和英国第四代粉末高温合金的研究进展情况。重点介绍了美国高Ta含Hf的ME501合金和高W高Ta含Hf的TSNA-1合金,英国的高Co高Ta合金、高Ta低成本合金和高Nb的RRHT系合金的成分设计特点、组织及其稳定性、力学性能及抗氧化性。  相似文献   

16.
Human coenurosis in North America: case reports and review   总被引:1,自引:0,他引:1  
To validate the use of mood induction with older adults, 22 older participants receiving a depressed mood induction were compared with 20 controls and 17 older persons with high Center for Epidemiologic Studies-Depression Scale (CES-D) scores. The mood induction procedure, using self-referent statements and music, changed Depressive Adjective Checklist and CES-D scores in each of 2 sessions 1 week apart. Findings indicated that the use of mood induction procedures with older adults can provide experimental control of mood.  相似文献   

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A group of flavi-like GB viruses (GBV-A, -B, and -C) has been discovered and partially characterized. Only GBV-C is found in humans. Nucleotide sequences of the putative helicase gene of the GBV-C genome were determined in 21 Taiwanese patients and compared with isolates from Africa and North America by phylogenetic analysis. The average similarities of Taiwanese isolates to those from West Africa, East Africa, Canada, and United States were 83%, 85%, 78%, and 82%, respectively. Phylogenetic analysis of the NS3 region showed that 81% of the Taiwanese isolates were more closely related to the East African isolate. GBV-C isolates from Taiwan could be classified into at least 3 groups. These data suggest that GBV-C isolates cloned from different geographic areas have genetic heterogeneity.  相似文献   

19.
Two different yeast genes were identified that when overexpressed suppressed the low iron growth defect of a mutation in the endoplasmic reticulum iron binding enzyme methyl sterol oxidase. These genes were determined to be novel and highly related. The deduced amino acid sequences indicated that both were membrane proteins having two identical histidine-rich motifs. The predicted proteins, while not ABC transporters, are homologous to a widely distributed family of transition metal transporters present in all kingdoms. Subcellular fractionation and fluorescence microscopy localized these gene products to mitochondria. Based on this result we term these genes Mitochondrial Fe Transporters (MFT). Cells with disruptions in both genes show a growth defect on low iron medium, suggesting that these genes have redundant function and can affect cytosolic iron levels. Measurement of mitochondrial iron in cells grown in iron-rich medium overexpressing MFT1 or MFT2 show a 2-5-fold increase in iron compared with mitochondria from control cells. These results suggest that the mitochondria may act as a reservoir for iron that can be mobilized and used for cytosolic purposes.  相似文献   

20.
Generation of a recombinant adenovirus (Adv) that induces the constitutive expression of an apoptotic gene has been extremely difficult owing to severe apoptotic damage to the host cell. In this study, 293 cells were transduced with the caspase-inhibiting CrmA gene (293-CrmA cells), and used as host cells to generate Adv carrying apoptosis-inducing genes (proapoptotic genes). The 293-CrmA cells proved to be highly efficient for the construction of recombinant Adv carrying genes encoding Fas and Fas ligand. Moreover, the 293-CrmA line produced an ample quantity of these recombinant viruses. Because the conventional 293 plaque formation assay did not reflect the actual number of cells infected with the Adv carrying the proapoptotic gene, a determination of the Adv DNA copy number introduced into target cells was necessary to evaluate the quantity of infective virus. The techniques described here should be widely applicable for the construction of a recombinant Adv, in ample quantity, and for the estimation of the quantity of recombinant Adv produced.  相似文献   

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