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81.
Abstract: Local cerebral glucose utilization was measured by the [14C]2-deoxy- d -glucose method in conscious control and hyperketonemic rats. Hyperketonemia was induced by 3 days of starvation or by infusion of 3- hydroxybutyrate in fed rats. These treatments produced combined blood ketone body concentrations (acetoacetate + 3-hydroxybutyrate) of from 1.2 to 2.4 mM. Neither treatment significantly affected glucose utilization in any of the 15 brain regions studied. These observations indicate that hyperketonemia in resting, conscious rats does not interfere with brain uptake and phosphorylation of glucose.  相似文献   
82.
In Pseudomonas acidovorans, the pathways of 4-hydroxybenzoate and vanillate metabolism converge on the early intermediate, protocatechuate, which undergoes meta-cleavage. The methoxyl group of vanillate is almost completely oxidized, as shown by an experiment with (14C-methoxyl) vanillate. In batch cultures, 4-hydroxybenzoate and vanillate are simultaneously oxidized. Simultaneous oxidation was explained above all by the fact that both substrates mutually repress the ability of the cells to utilize the partner substrate.If P. acidovorans is growing in a turbidostat on one of the two substrates and is suddenly exposed to an equimolar mixture of both substrates, the respiration rates for the two substrates reciprocate, the for the substrate utilized first passing through a transient minimum, that for the added substrate passing through a transient maximum. Finally, a balance appears to be established, the for 4-hydroxybenzoate being slightly above that for vanillate. Transient phenomena also occur if a chemostat culture with both substrates is suddenly operated as a turbidostat culture or if cells not adapted to either substrate are suddenly exposed to a mixture of both substrates in the turbidostat.If a chemostat culture of P. acidovorans, growing at the expense of an equimolar mixture of 4-hydroxybenzoate and vanillate, is operated under conditions of increasing oxygen deficiency, the utilization ratio of the two substrates increases in favour of 4-hydroxybenzoate. However, if the culture is operated under conditions of increasing nitrogen deficiency, the utilization ratio increases in favour of vanillate.Abbreviations 4HB 4-hydroxybenzoate - VA vanillate - OD optical density  相似文献   
83.
With 0.5% substrate present in mineral medium, cells of Alcaligenes eutrophus H 16 were able to grow heterotrophically at the expense of guanine, hypoxanthine and xanthine, but not of adenine as sole sources of carbon and nitrogen. An increase in cell counts, however, was observed at lower adenine concentrations (0.1%). Similarly, adenine was only respired if present at low concentrations. Higher amounts of adenine were inhibitory to the utilization of adenine, guanine, hypoxanthine, xanthine, allantoin and glyoxylate, but not to that of fructose or glycerate. The adenine-dependent inhibition of adenine utilization was not overcome by the addition of thiamine, uridine or cytidine. The enzyme glyoxylate carboligase, usually formed in presence of metabolisable purines and of allantoin, was synthesized only at low adenine concentrations. Higher amounts were inhibitory even with allantoin present as additional substrate. According to these resutls, the utilization of purine derivatives and of allantoin as sources of carbon and energy is repressed by adenine in cells of A. eutrophus H 16.  相似文献   
84.
In axenic Chlorella pyrenoidosa Chick cultures, extracellular release was linear with time, but plateau-type curves were obtained in cultures with added bacteria. Initial rates of excretion were identical in both, systems. Kinetics of extracellular release in axenic Anabaena flos-aquae (Lyng.) Bréb. cultures were more complex than in Chlorella but the initial excretion rates were identical in axenic and mixed algal-bacterial cultures. In lakewater, extracellular release kinetics resemble the pattern in mixed Chlorella-bacteria cultures. An explanation is an initial lag in bacterial utilization of algal extracellular products. As a result, both in situ and in the laboratory, consecutive short, experiments give higher excretion rates than single long incubations. It is suggested that the former are close to total or gross extracellular release rates whereas the latter give net values, detecting only substances not, removed by heterotrophs.  相似文献   
85.
Von Hippel and colleagues have highlighted the crucial role of users in innovation in different industries and types of products. They describe the innovation process in terms of the distinct domains of knowledge that producers and users possess. Producers have knowledge about technical solutions and users about their needs, the context of use, and their own capabilities as users. Both sets of knowledge are characterized by "stickiness": They move relatively freely within their own domain but are difficult to transfer outside of it.
In the case of radical innovations for sustainable consumption, the problem of "sticky information" is compounded. Both producers and consumers need to reach out of their conventional competencies and search for new solutions. "Societal actors," such as government bodies or environmental experts, can show the way to such solutions, but this new knowledge needs to be integrated with the "sticky" knowledge about everyday practices in production and consumption.
In the present article we attempt to conceptualize the role and interaction of user and producer knowledge with the knowledge of environmental experts in housing energy innovations. We do so by applying the user−producer interaction framework to a case study on the introduction of low-energy housing concepts in Finland. On the basis of this analysis, we draw conclusions on the potential and limitations of today's practices in the field. For example, we suggest that user involvement can help to enhance the acceptance of low-energy solutions but that the methods for involving users need to be adapted to the particular circumstances in each industry.  相似文献   
86.
冯思远  赵文武  华廷  王涵 《生态学报》2021,41(20):7955-7964
“SDGs加速行动”是国际组织、政府部门、私营机构和其他利益攸关方为加快落实2030年可持续发展议程采取的全球行动。2019年联合国可持续发展目标峰会后,政府、国际组织、私营部门等提出了214项SDGs加速行动。2019年爆发的新型冠状病毒肺炎(Corona Virus Disease 2019,COVID-19)对实现可持续发展目标带来了系列影响,后疫情时代如何推动全球SDGs加速行动的实施成为重要的问题。对可持续发展评估报告(2019)和可持续发展目标加速行动等政策文件进行信息提取,建立加速行动匹配性指数模型和各国应对新冠疫情的恢复力指数模型,根据匹配性-恢复力分类体系将各国按照17项可持续发展目标分为9类,为推动后疫情时代全球可持续发展目标加速行动提供支撑。研究发现:(1)现有可持续发展目标加速行动的实施与区域需求不匹配,且这种不匹配的情况在COVID-19爆发前已经出现;(2)加速行动的实施受限于现有可持续发展水平和国家经济基础,区域关注的可持续发展目标与其自然地理位置和社会发展水平有着密切的关系,多边组织机构和其他利益攸关方需要在发展中国家大力推动可持续发展加速行动;(3)下一步实施加速行动需要加强国际间的合作,根据分类框架和可持续发展目标的关联关系,分重点推进加速行动的实施,完善可持续发展指标监测体系,分类设立后疫情时代不同时期的阶段目标,分阶段循序渐进,定期反馈追踪,以在2030年促进17项可持续目标的实现。  相似文献   
87.
《Mammalian Biology》2014,79(3):176-182
Rapid changes in agricultural landscape structure and composition affect many different farmland biotas, including carnivores, which are a key element of ecosystem stability, yet little is known about their distribution and habitat use. In this study, we evaluated how habitat characteristics on two different spatial scales (local and landscape scale) affected the forest-edge utilization by small and medium-sized carnivores in fragmented central European farmland. Based on an indirect method for detecting carnivores (scent stations), we sampled 212 forest fragments of different sizes (1–7864 ha) during April to May from 2006 to 2009. Our results indicate that carnivore utilization of forest-edge habitats was driven by landscape rather than local characteristics even though the overall extent of explained variation was small. The most important factors that determined response of the carnivore community were the area of farmland and that of urban land on a landscape scale. The corridor connectivity between small forest fragments and other spatial elements played a crucial role in the occurrence of red fox. Our results suggest that comprehensive studies on multi-species carnivore assemblage using scent station might be useful in evaluating species-specific response to habitat characteristics, especially if large numbers of stations visited by carnivores are available.  相似文献   
88.
城市公园是城市生态系统的重要组成部分和城市生物多样性热点地区,具有丰富的声景观资源。由于声景观及声学方法具有信息量大,成本低,低侵入的特点,因此其研究和应用对生态系统健康及监测具有较高价值。声景观研究通过总结生物声的活动或多样性来衡量生物多样性。记录了北京20个城市公园的春季声景观,使用定量方法描述了声景观特征与变化;测试三种了已被证明与生物多样性相关并被广泛使用的声学指数(BIO、ADI、NDSI)与植被群落关系,完成了城市环境中声景观与环境关系的初步探究。研究结果表明:(1)声学指数能够有效表征城市公园声景观信息,具有显著的时间动态特性,能准确反映鸟类黎明合唱等重要生物生态活动;(2)声学强度指数也具有显著的时间动态变化和沿频率梯度的变化,不同的频率区间反映了不同声学群落的活动信息;(3)植被结构尤其是垂直结构对声景观起着重要作用,垂直异质性越大,声学多样性越高。发现支持声景观作为公园植被状况的度量,强调了其作为生物多样性和生态系统健康状况监测方法,用于城市管理和可持续发展的巨大潜力。  相似文献   
89.
90.
烟梗是烟草工业的重要副产物,也是宝贵的自然资源。本研究首先利用白腐菌漆酶对烟梗丝进行预处理,提升了添加烟梗丝的卷烟品质;然后分别以木质素、纤维素、半纤维素和果胶的降解率为响应值,采用Box-Behnken设计建立方程模型,对漆酶、纤维素酶、半纤维素酶和果胶酶组成的复合酶预处理烟梗丝条件进行了优化。结果表明:每100g烟梗丝加入30U漆酶,在料液比为35%、温度为30℃、酶解pH为5处理48h的条件下预处理的烟梗丝对提升卷烟品吸效果最佳,烟梗丝中木质素、纤维素、半纤维素和果胶的降解率分别为20.16%、15.10%、7.20%和12.40%;为获得与之相同的各组分降解率,响应面法优化漆酶复合酶最佳处理条件为:每100g烟梗丝加入漆酶14.72U、纤维素酶1.00U、半纤维素酶1.00U、果胶酶8.45U。验证发现烟梗丝各组分降解率实测值与理论值无显著性差异,且显微结构观察显示复合酶处理后的烟梗丝表面致密结构被破坏,孔洞数量明显增加。本研究获得的白腐菌漆酶预处理后的烟梗丝在卷烟中的添加能有效改善卷烟品质,且漆酶复合酶的使用大幅减少了漆酶的用量,降低了漆酶预处理烟梗丝的成本,为废弃烟梗生物质的资源化利用提供了重要依据。  相似文献   
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