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排序方式: 共有102条查询结果,搜索用时 15 毫秒
91.
用静电音频内耗仪测试了Fe-Mn-Si-Cr形状记忆合金在-100 ̄300℃温度范围内耗及模量变化,研究了γ→ε马氏体相变及其逆相变的内耗特征。结果表明,γ→ε马氏体相变及其逆相变具有不同的机制,在相变过程中未出现软模现象,可见该合金的层错形核可能无需点阵软化。相变过程中的模量变化归因子于ε相模量高于γ相的模量。  相似文献   
92.
用X衍射线形分析法测定了Fe-30.3%Mn-6.1%Si(质量分数)形状记忆合金经不同温度淬火和经退火后的层错几率Psf.研究了淬火空位、层错几率与马氏体相变点Ms的关系.结果表明,增加淬火空位将促进层错的形成,使Ms提高;且Ms与1/Psf呈线性关系.对可能的机理进行了讨论.  相似文献   
93.
本文研究了间羧基偶氮氯膦(CPAmK)在树脂相中与钪的显色条件。在盐酸介质中,以阴离子交换树脂吸附Sc-CPAmK络阴离子。钪与试剂在0.06mol/L盐酸介质中生成1:2的螯合物,在波长675nm处有最大吸收,表观摩尔吸光系数ε=140×105L·mol-1·cm-1。在50ml溶液中,1-7μgSc/50ml符合比耳定律,应用于合金中钪的直接测定,结果良好。  相似文献   
94.
Tuberculoma of the lung is one of manifestations in tuberculosis and usually presents as a solitary pulmonary nodule (SPN). It is difficult to differentiate tuberculoma from SPN by other benign or malignant diseases. At present, the crucial role of video-assisted thoracoscopic surgery (VATS) in diagnosis and treatment of pulmonary diseases has been well acknowledged. Here, we reported 53 patients undergoing VATS resection for tuberculomas in our series. No postoperative mortality was found and only two patients experienced prolonged air-leakage (>7 d) and two had minor wound infections that were recovered after anti-tuberculosis or antibiotic treatment. Anti-tuberculosis chemotherapy from 6 to 12 months was routinely used postoperatively. We conclude that VATS is a satisfactory tool for the diagnosis and treatment of tuberculoma and can also establish a reliable diagnosis for all patients with SPNs.  相似文献   
95.
Toll-like receptors (TLRs) are activated by pathogen-associated molecular patterns to induce innate immune responses and production of pro-inflammatory cytokines, interferons and anti-inflammatory cytokines. TLRs activate downstream effectors through adaptors that contain Toll/interleukin-1 receptor (TIR) domains, but the mechanisms accounting for diversification of TLR effector functions are unclear. To dissect biochemically TLR signalling, we established a system for isolating signalling complexes assembled by dimerized adaptors. Using MyD88 as a prototypical adaptor, we identified TNF receptor-associated factor 3 (TRAF3) as a new component of TIR signalling complexes that is recruited along with TRAF6. Using myeloid cells from TRAF3- and TRAF6-deficient mice, we show that TRAF3 is essential for the induction of type I interferons (IFN) and the anti-inflammatory cytokine interleukin-10 (IL-10), but is dispensable for expression of pro-inflammatory cytokines. In fact, TRAF3-deficient cells overproduce pro-inflammatory cytokines owing to defective IL-10 production. Despite their structural similarity, the functions of TRAF3 and TRAF6 are largely distinct. TRAF3 is also recruited to the adaptor TRIF (Toll/IL-1 receptor domain-containing adaptor-inducing IFN-beta) and is required for marshalling the protein kinase TBK1 (also called NAK) into TIR signalling complexes, thereby explaining its unique role in activation of the IFN response.  相似文献   
96.
台湾可持续能源发展指标建构与耦合性分析   总被引:1,自引:0,他引:1  
为应对全球气候变迁之冲击,以及迈向低碳社会,推动可持续能源发展,已成为本世纪各国政府施政的重点.依据国际可持续能源指标架构,建立"台湾可持续能源指标系统",并以Eview计量软件进行指标项目与架构之"单根"(unit root)、"共整合"(integration)、与"因果"(causality)检定,并据此建构的长期稳定关系与各方面耦合性(coupling)的可持续能源发展指标"压力-状态-响应"(Pressure,State,Response,PSR)架构系统.回顾了台湾近18年(1990-2007)来可持续能源发展绩效,获得结论如下:1)台湾能源发展已朝向可持续性,其中以环境保护方面绩效最佳,而能源安全与经济竞争力仍需改善;2)整体指标架构的状态与响应指标耦合度相当高,惟压力指标则呈现脱钩(decoupling)现象;3)权重模拟分析发现,适当调整权重,可以大幅提高经济竞争力与环境保障方面指标耦合性,显示权重具敏感性;惟能源安全指标方面的权重较不具敏感性.  相似文献   
97.
98.
Als TD  Vila R  Kandul NP  Nash DR  Yen SH  Hsu YF  Mignault AA  Boomsma JJ  Pierce NE 《Nature》2004,432(7015):386-390
Large blue (Maculinea) butterflies are highly endangered throughout the Palaearctic region, and have been the focus of intense conservation research. In addition, their extraordinary parasitic lifestyles make them ideal for studies of life history evolution. Early instars consume flower buds of specific host plants, but later instars live in ant nests where they either devour the brood (predators), or are fed mouth-to-mouth by the adult ants (cuckoos). Here we present the phylogeny for the group, which shows that it is a monophyletic clade nested within Phengaris, a rare Oriental genus whose species have similar life histories. Cuckoo species are likely to have evolved from predatory ancestors. As early as five million years ago, two Maculinea clades diverged, leading to the different parasitic strategies seen in the genus today. Contrary to current belief, the two recognized cuckoo species show little genetic divergence and are probably a single ecologically differentiated species. On the other hand, some of the predatory morphospecies exhibit considerable genetic divergence and may contain cryptic species. These findings have important implications for conservation and reintroduction efforts.  相似文献   
99.
Hsu LC  Park JM  Zhang K  Luo JL  Maeda S  Kaufman RJ  Eckmann L  Guiney DG  Karin M 《Nature》2004,428(6980):341-345
Macrophages are pivotal constituents of the innate immune system, vital for recognition and elimination of microbial pathogens. Macrophages use Toll-like receptors (TLRs) to detect pathogen-associated molecular patterns--including bacterial cell wall components, such as lipopolysaccharide or lipoteichoic acid, and viral nucleic acids, such as double-stranded (ds)RNA--and in turn activate effector functions, including anti-apoptotic signalling pathways. Certain pathogens, however, such as Salmonella spp., Shigellae spp. and Yersiniae spp., use specialized virulence factors to overcome these protective responses and induce macrophage apoptosis. We found that the anthrax bacterium, Bacillus anthracis, selectively induces apoptosis of activated macrophages through its lethal toxin, which prevents activation of the anti-apoptotic p38 mitogen-activated protein kinase. We now demonstrate that macrophage apoptosis by three different bacterial pathogens depends on activation of TLR4. Dissection of anti- and pro-apoptotic signalling events triggered by TLR4 identified the dsRNA responsive protein kinase PKR as a critical mediator of pathogen-induced macrophage apoptosis. The pro-apoptotic actions of PKR are mediated both through inhibition of protein synthesis and activation of interferon response factor 3.  相似文献   
100.
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