广州市建设无公害蔬菜城市的决策分析

从广州市无公害蔬菜生产销售入手，进行了广泛深入的调查研究，运用层次分析法，找出无公害蔬菜生产销售中存在的问题，提出建设无公害蔬菜城市的指导思想，目标，准则和对策措施。     

茶多糖提取工艺条件的正交试验研究

从料液比、提取时间、温度及酒精浓度4个因素对茶多糖的提取工艺进行研究,结果表明,浸提时间、温度对茶多糖的提取率的影响最为显著,而乙醇浓度、料液比的影响则不明显。最佳提取条件为：料液比11∶0,浸提时间为60 min,浸提温度为100℃,沉淀时所用的乙醇浓度为75%。     

图像增强模糊算法的协同进化优化

协同进化遗传算法(CGA)比简单的遗传算法具有更快的收敛速度和更好的寻优效果,将其应用于图像增强的模糊算法优化,以达到最佳的模糊逻辑处理效果。遗传进化中,同时优化了模糊逻辑规则、选择了最优隶属度函数和隶属度函数参数。通过具体图像处理试验,在主观和客观评价上都证明了该方案的有效性。     

克乌成品油管道首站工艺技术

通过对克乌成品油管道工艺流程的分析，详细讨论了管道首站的泵机组组合方式，站区管网设计，油品切换以及压力调节的工艺设计特点，总结了首站关键环节的工艺设备和技术要点，对其它成品油管道的建设具有一定的借鉴作用。     

Changes in chemical composition of Phoenix canariensis Hort. Ex Chabaud palm seed oil during the ripening process

The aim of this investigation is to compare the physicochemical properties and chemical composition of Phoenix canariensis seed oil at different stages of seed date ripening. It was demonstrated that the saponification number of the oil increases during the maturation from 179.24 to 191.28 (mg KOH/g of oil), whereas the seed oil yield, the iodine number, the p-anisidine value, the peroxide value, the acidity and the unsaponifiable matter decrease from 14.73% to 10.36%, from 89.37 to 76.66 (g/100 g of oil), from 5.51 to 3.67, from 17.66 to 3.62 (mequiv. O₂/kg of oil), from 1.49% to 0.59% and from 2.72% to 1.77%, respectively. The tocol content increases as the maturity advanced. The percentages of sterols show continuous changes during ripening. The saturated fatty acid content increases throughout the ripening process. The oleic fatty acid content decreases during the seeds maturation, but increases at the end, whereas linoleic acid content initially shows an increase, and then a decrease. The total phosphorus content decreases during the period of ripening. The three samples of the seed oil show a high kinetic stability during the heating and cooling, as characterised by the differential scanning calorimetry (DSC). The DSC curves reveal an increase in the melting point from −7.73 °C to 3.71 °C but the melting enthalpy remains the same, 62.06 J/g, during the ripening of the dates.     

Elephant-induced structural changes in the vegetation and habitat selection by large herbivores in an African savanna

African elephants can affect the quality of the habitat of other species by breaking or uprooting trees and shrubs in savannas. Their effect on vegetation has been widely studied but less is known about the effects of such vegetation changes on other animals. We studied how changes in the vegetation caused by elephants influence the selection of microhabitats by five African herbivore species (giraffe, kudu, steenbok, impala, and zebra) in Hwange National Park, Zimbabwe. There was no clear significant effect of overall elephant-induced vegetation changes on microhabitat selection except for the small species (steenbok and impala) that used vegetation modified by elephants preferentially. This is consistent with a medium-term browsing facilitation hypothesis. More subtle possible effects were detected for larger browsers (giraffe and kudu). They selected areas with broken and uprooted plants and avoided coppiced areas. All of the browsers selected sites characterized by plants uprooted and broken by elephants, which were associated with a higher visibility, and ultimately a better probability of detecting an approaching predator, suggesting that perceived predation risk plays an important role in microhabitat selection. These results illustrate how elephants can initiate indirect effects that influence microhabitat selection by other herbivores. Understanding the indirect effects of elephants through changes in food availability and predation risk thus needs further investigation. The results of this study do not provide support for the hypothesis that elephant-induced changes in the structure of habitats have caused the declines in the populations of the other herbivores in the study area.     

农业机械管理过程中存在的问题及解决策略

随着我国经济快速发展,农业机械化进程不断加快,农业机械被越来越多的应用到农业生产活动中,文章主要讨论了现阶段农业机械管理过程中存在的问题,并提出了相应的改进措施,希望可以促进农业快速发展.     

广东沿岸牡蛎体内总汞含量变动趋势及其健康风险评价

为保障水产品质量安全和保护广东近岸海洋生态环境,于2004—2010年对广东沿岸17个主要港湾的海水养殖牡蛎进行了采样,运用原子荧光光谱法监测其总汞含量,并结合1989—1993年的历史监测数据分析了广东近岸海域总体及粤东、珠江口和粤西三大主要海区牡蛎体内汞的时空分布规律,应用单因子指数法和人体暴露风险系数法（HQ）评价了牡蛎体汞含量对人体暴露的健康风险。结果表明,1989—2010年广东沿海牡蛎体内汞含量的检出率为100%,变化范围为（0.080±0.114）mg·kg-（1湿重,下同）。单因子指数评价结果与风险系数（HQ）评价结果一致。上世纪80年代末（1989年）广东海域牡蛎体内汞含量处于污染水平,健康风险系数较大（HQ=3.39×10-2）;90年代（1991—1993年）牡蛎体内汞含量逐年降低,健康风险显著降低（HQ=2.23×10-2,P〈0.05）;2004年以来,全海域的牡蛎体内汞含量一直稳定地维持在较低水平（[0.012±0.006）mg·kg-1];粤东、珠江口海域牡蛎体内含量稳定下降,粤西海域降幅有所减小。2006—2010年,人均摄取牡蛎软组织20g·d-1,每年食用200d,食用20a后,在人均寿命70岁的时间内,其健康风险系数HQ为0.13×10-2,食用安全,不存在潜在的危害性,食用广东沿海牡蛎对人体日均总汞允许摄入限量的贡献率仅为0.13%。     

工业区河涌污染与生态危害评价——以佛山三水大塱涡涌为例

在对工业区大塱涡涌水质及底泥重金属进行调查与分析的基础上,评价了底泥重金属潜在生态危害。结果表明,大塱涡涌水体COD、氨氮、总磷、DO与重金属Cr均超过地表水Ⅴ类水体标准,属于劣Ⅴ类水体;底泥重金属Cu、Zn与Cd平均含量超出土壤环境质量三级标准,且重金属Cu、Zn、Pb平均含量超过农用污泥污染物控制标准,该河段疏浚底泥不宜作为肥料直接施用于农田;大塱涡涌表层底泥重金属的潜在生态危害程度总体为强,几种重金属潜在生态危害平均程度从大到小为：Cd〉Cu〉Pb〉Zn〉Cr。     

Precipitation or water capacity indices? An analysis of the benefits of alternative underlyings for index insurance

Eastern Germany is often hit by drought causing income risk for crop farmers. Index-based risk management instruments could help crop farmers to reduce their farm income risk. Such instruments have some important advantages over damage-based insurance, like e.g. less moral hazard and adverse selection. At the same time they typically have a high level of basis risk. Up to now, mainly precipitation-based weather derivatives have been discussed as an appropriate risk management instrument for farmers in Germany. As a potentially more effective alternative, we propose water capacity-based index insurance. In order to show the benefits of a precipitation-based and water capacity-based index insurance, several contract designs are compared. Using a whole farm risk program planning approach, we show that for an average agricultural producer in Eastern Germany water capacity-based index insurance offers greater benefits than precipitation-based index insurance.