排序方式: 共有108条查询结果,搜索用时 31 毫秒
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提出一种基于Agent的细胞自动机(CA)演化模型,并采用整体建模仿真的方法,对农田虫害的演化进行了模拟.它采用自底向上的建模思想,利用Agent的局部连接规则,建立复杂系统的整体模型.针对不同环境条件设定相应的仿真参数,可以得到恰当的害虫种群演化结果,有助于农田生态管理的科学决策.同时,农田虫害的管理是预测专家系统的重要应用领域,该模型与专家系统的最终集成,可以提高专家系统的预测能力. 相似文献
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Arshid Numan Navaneethan Duraisamy Fatin Saiha Omar Dhanaraj Gopi K. Ramesh S. Ramesh 《自然科学进展(英文版)》2017,27(4):416-423
A facile and fast approach for the synthesis of a nanostructured nickel hydroxide(Ni(OH)_2) via sonochemical technique is reported in the present study. The X-ray diffraction results confirmed that the synthesized Ni(OH)_2 was oriented in β-phase of hexagonal brucite structure. The nanostructured Ni(OH)_2 electrode exhibited the maximum specific capacitance of 1256 F/g at a current density of 200 mA/g in 1 M KOH_((aq)). Ni(OH)_2 electrodes exhibited the pseudocapacitive behavior due to the presence of redox reaction. It also exhibited long-term cyclic stability of 85% after 2000 cycles, suggesting that the nanostructured Ni(OH)_2 electrode will play a promising role for high performance supercapacitor application. 相似文献
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One billion people depend on seafood as their primary source of protein and 25% of the world's total animal protein comes from fisheries. Yet a third of fish stocks worldwide are overexploited or depleted. Using individual case studies, many have argued that community-based co-management should prevent the tragedy of the commons because cooperative management by fishers, managers and scientists often results in sustainable fisheries. However, general and multidisciplinary evaluations of co-management regimes and the conditions for social, economic and ecological success within such regimes are lacking. Here we examine 130 co-managed fisheries in a wide range of countries with different degrees of development, ecosystems, fishing sectors and type of resources. We identified strong leadership as the most important attribute contributing to success, followed by individual or community quotas, social cohesion and protected areas. Less important conditions included enforcement mechanisms, long-term management policies and life history of the resources. Fisheries were most successful when at least eight co-management attributes were present, showing a strong positive relationship between the number of these attributes and success, owing to redundancy in management regulations. Our results demonstrate the critical importance of prominent community leaders and robust social capital, combined with clear incentives through catch shares and conservation benefits derived from protected areas, for successfully managing aquatic resources and securing the livelihoods of communities depending on them. Our study offers hope that co-management, the only realistic solution for the majority of the world's fisheries, can solve many of the problems facing global fisheries. 相似文献
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对于工业发酵菌种肺炎克雷伯氏菌(Klebsiella pneumoniae),研究发现有两种消除其重组型质粒的有效方法,一种是连续传代培养,另一种是使用消除剂十二烷基硫酸钠(SDS)。对K.pneumoniae重组菌连续20代传代培养后,发现其质粒具有较高的消除率;而以0.2%SDS复合Ca2+处理K.pneumoniae重组菌,也能有效消除其重组型质粒,且该方法省却了反复的传代培养,能快速得到质粒消除菌,更具简便易操作性。消除了质粒的K.pneumoniae能再次接纳新的质粒,有效避免了因质粒不相容性带来的转化不成功,进而可用作宿主菌积累更多的生理性状。 相似文献
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高位钻孔瓦斯抽采参数优化设计 总被引:10,自引:0,他引:10
基于采空区覆岩裂隙分布规律、覆岩裂隙瓦斯流动规律和高位钻孔抽采技术研究现状,从覆岩"竖三带"、"O"形圈和U型通风条件下采动裂隙瓦斯流动规律出发,找出高位钻孔的理论合理布置区域,指出工作面后方50m范围内覆岩裂隙发育状况是高位钻孔层位设计的关键,针对祁南煤矿32煤层的特点,结合现场采用数值模拟方法模拟不同开采速度条件下覆岩裂隙发育规律,优化设计高位钻孔的抽采参数,在34下2工作面和3410工作面的现场试验中,高位钻孔抽采浓度和抽采率得到大大提高,取得了较好的抽采效果,验证了研究的正确性。 相似文献
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在可度量化拓扑线性空间中,讨论一些非线性映象的不动点与Mann迭代序列的收敛性问题,在一定条件下,得到了一些新的结果,推广和发展了Khan,Ghosh及Rhoades等人的工作。 相似文献
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