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The new C7N aminocyclitol kirkamide ( 1 ) was isolated from leaf nodules of the plant Psychotria kirkii by using a genome‐driven 1H NMR‐guided fractionation approach. The structure and absolute configuration were elucidated by HRMS, NMR, and single‐crystal X‐ray crystallography. An enantioselective total synthesis was developed, which delivered kirkamide ( 1 ) on a gram scale in 11 steps and features a Ferrier carbocyclization and a Pd‐mediated hydroxymethylation. We propose that kirkamide is synthesized by Candidatus Burkholderia kirkii, the obligate leaf symbiont of Psychotria kirkii. Kirkamide ( 1 ) was shown to be toxic to aquatic arthropods and insects, thus suggesting that bacterial secondary metabolites play a protective role in the Psychotria/Burkholderia leaf nodule symbiosis.  相似文献   
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应急物资实物代储方式是有效降低应急物流成本和实现应急物资快速筹集的重要举措。针对政府直接储备应急物资所带来的采购和管理成本过高、巨额资金占用、物资性能降低以及因管理不善造成的应急物资浪费等问题,本文本着互利合作的原则,借助种群共生理论构建政府与应急物资代储企业之间的合作共生关系,并通过构建数学模型分析了政府与实物代储企业满足共生平衡点的稳定性条件,以解决政府在限制支付条件下如何选择应急物资代储企业的问题,为政府制定应急物资储备策略提供决策依据。  相似文献   
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以变分不等式为基础提出生态工业链网络均衡模型。生态工业链是通过仿照自然生态系统中的物质循环方式与生物群体之间的竞争与共生模式,使不同企业之间形成共享资源和互换副产品从而实现园区各企业经济与环境效益的最大化。针对生态工业链网络的多产品(主副产品和废弃物)多层次的网络结构,模仿自然生态系统中的生产者、消费者和分解者,分别对各层决策者的独立优化决策行为及其相互作用进行分析,利用变分不等式分析各层均衡条件进而构建生态工业链网络均衡模型,得到系统达到均衡的条件并给出相应的经济解释。在证明系统变分不等式的解存在的基础上,通过数值算例验证模型的合理性与有效性。  相似文献   
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史欢  李洪波 《运筹与管理》2022,31(6):233-239
共生机制是推进众创空间创业生态系统螺旋式上升发展的关键,基于共生理论构建了以创业企业、利益相关者和政府为主体的众创空间创业生态系统三方共生行为策略演化博弈模型,并通过数值模拟分析探究了各主体不同行为策略的影响因素及演化路径。研究结果表明:创业企业、利益相关者以及政府选择合作的初始意愿对彼此行为的影响程度有所差异;相较于利益相关者,创业企业对政府的补贴政策和惩罚力度更为敏感;制定合理的收益分配机制能够促进系统向互利共生方向演化。  相似文献   
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《Physics letters. A》2020,384(36):126915
The complex symbiotic relationship in the industrial symbiosis network (ISN) may cause new risks for firms. In view of this problem, previous studies mainly regard the ISN as a static system, without considering the adaptive behavior of firms. This paper establishes a risk propagation model of the ISN based on the change of firm state, proposes four kinds of reconnection strategies to model the adaptive behavior, and uses numerical simulation to investigate the effect of adaptive behavior on risk propagation. The results demonstrate that all the reconnection strategies play an inhibitory role in the risk propagation. Therein, the effectiveness of PP strategy is the best, followed by RR strategy, and DP (SP) strategy. In any case, the effect of reconnection strategies on risk propagation will improve with the increase of the disconnection probability and network resilience. Additionally, the more decentralized weight distribution will weaken the inhibition of adaptive behavior on risk propagation.  相似文献   
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Tissue sections have long been the subject matter for the application of imaging mass spectrometry, but recently the technique has been adapted for many other purposes including bacterial colonies and 3D cell culture. Here, we present a simple preparation method for unsectioned invertebrate tissue without the need for fixing, embedding, or slicing. The protocol was used to successfully prepare a Hawaiian bobtail squid hatchling for analysis, and the resulting data detected ions that correspond to compounds present in the host only during its symbiotic colonization by Vibrio fischeri.  相似文献   
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Sugar coat: The nitrogen-fixing soil bacterium Bradyrhizobium sp. BTAi1 is coated with a unique lipopolysaccharide that does not induce innate immune responses in its host plant Aeschynomene indica or in different plant families. The chemical nature of the monosaccharide forming the polymer (see picture) is unprecedented in nature, which helps to avoid "harmful" recognition by its symbiotic host.  相似文献   
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Soil application of cement kiln exhausts (electrostatic precipitator dust) at both lower and higher concentrations did not inhibit growth, nodule formation, and productivity inCajanus cajan, vigna radiata, andVigna mungo. In fact, growth was promoted, possibly because of the dust containing most of the elements, such as N, Ca, Fe, Mg, Mn, K, Zn, P, S, and Cu, which are needed for plant growth and root nodulation. Foliar application of the dust did not affect chlorophylls and carotenoids. The rate of photosynthesis as measured by CO2 uptake and stomatal diffusive resistance of all legumes were not affected. There was a biomagnification of Mg and K in leaves and seeds. Addition of the ESP dust did not affect either the soil or nodule rhizobial population. It is evident that the dust did not act as a phytotoxicant but as an elixir of plant life.  相似文献   
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