Effect of Nano-Al2O3 on the Properties of Ultra High MolecularWeight Polyethylene Engineering Material

The composite material of nano-Al 2O 3 and UHMW-PE was made by the way of pressing and agglomeration. Effect of nano-Al 2O 3 on the friction, wear characteristic of Ultra High Molecular Weight Polyethylene plastic was studied by using MPV-200 model friction and wear tester and caustic wear one. At the same time, the hardness of UHMW-PE was mensurated in sclerometer. The results showed that nano-Al 2O 3 not only decreases the friction coefficient of UHMW-PE, but also greatly reduce the wear of UHMW-PE.The hardness of UHMW-PE is improved. Which possesses important theoretic significance for optimizing of structure and property of UHMW-PE material.     

贵州习水国家级自然保护区森林土壤理化性状研究

在贵州习水国家级自然保护区内,根据不同的森林植被分布状况及相应海拔高度设置了13个具有代表性的标准调查样地,分别采集土壤测定其理化性状,结果表明:(1)自然保护区森林土壤容重为1.07～2.06g/cm3;土壤总孔隙度为34.9%～83.4%;森林土壤的最大蓄水量为1479.00 t.hm-2～5517.00 t.hm-2;土壤的平均初渗速率和稳渗速率分别为9.05mm.min-1和3.32mm.min-1。(2)自然保护区森林土壤主要为酸性土壤,pH值在3.72～5.97之间变动;土壤有机质的含量为74.83g/kg;土壤全N和有效N分别为2.01g/kg和215.09mg/kg;土壤的全P含量为0.33g/kg;土壤速效磷含量在1.10～84.92mg/kg之间波动,平均含量为8.02mg/kg;土壤的全K和有效K含量分别为11.81g/kg和64.37mg/kg。(3)习水自然保护区所分布的森林植被类型在改良其森林土壤的物理特性,提高土壤的贮水能力,丰富土壤有机质及其N、P、K的含量,增强和维护土壤肥力等方面都具有较显著的生态功能。     

农村土地国有化的产权制度创新

农村土地国有化是在我国现实基础上的最佳选择,制度转换的路径是:国家以法律形式宣布所有土地为国家所有,取消农村土地的集体所有,农民现在承包的土地使用权归农民,使用年限为40年,到期后所有土地由国家无偿收回.     

鸡腿菇中多酚氧化酶性质及其抑制剂研究

[目的]为鸡腿菇的保鲜提供理论依据。[方法]从新鲜鸡腿菇中提取多酚氧化酶(PPO)的粗酶液,研究pH值和温度对鸡腿菇PPO活性的影响,分析其热稳定性,并探讨亚硫酸氢钠、抗坏血酸和柠檬酸3种抑制剂对鸡腿菇PPO活性的抑制作用。[结果]在强酸性和强碱性环境中,PPO都会失去活性。PPO酶活性随保温时间的延长呈降低趋势,说明PPO是一种热敏感性酶。3种抑制剂对鸡腿菇PPO活性均有抑制作用,其中NaHSO3的抑制作用最强,抗坏血酸和柠檬酸次之。[结论]在鸡腿菇的加工过程中,添加NaHSO3能有效降低PPO活性和防止褐变的发生。     

Gender and property rights in the commons: Examples of water rights in South Asia

In many countries and resource sectors, the state is devolving responsibility for natural resource management responsibility to ``communities' or local user groups. However, both policymakers and researchers in this area have tended to ignore the implications of gender and other forms of intra-community power differences for the effectiveness and equity of natural resource management. In the irrigation sector, despite the rhetoric on women's participation, a review of evidence from South Asia shows that organizations often exclude women through formal or informal membership rules and practices. Women may have other ways to obtain irrigation services, but even if they are effective, these other informal ways of obtaining irrigation services are typically less secure. As resource management – and rights to resources – are transferred from the state to local organizations, ensuring women's participation is essential for gender equity in control over resources. Greater involvement of women can also strengthen the effectiveness of local organizations by improving women's compliance with rules and maintenance contributions. Further detailed and comparative research is required to identify the major factors that affect women's participation and control over resources, if devolution policies are to be both equitable and sustainable. This revised version was published online in June 2006 with corrections to the Cover Date.     

山杨小径材干燥特性的研究

本文从山杨小径材的材性与成熟材材性的差异，对干燥时易皱缩的原因作了研究和分析，并指出汽蒸两段式干燥基准可有效地减少皱缩。     

无引发剂接枝聚合对丝素蛋白纤维性能的影响

通过对不同接枝率的丝素蛋白纤维的耐水洗性、吸湿性、力学性能、热稳定性及染色性等的研究和分析 ,探讨了无引发剂条件下甲基丙烯酸甲酯 (MMA)与丝素蛋白纤维接枝聚合对丝素蛋白纤维性能的影响。结果表明 :接枝聚合后丝素蛋白纤维有良好的耐水洗性 ,力学性能、热稳定性均有提高 ,吸湿性下降不明显 ,染色性有所提高 ,接枝率 2 6 %左右吸色深度最大。     

浅谈我国植物园的现状及发展对策

随着城市化的快速发展,生态环境的日益恶化,植物园除能作为学术研究之外,对生态科学和城市环境的保护有着重大意义。人们还可借助其完善的解说系统学习植物知识,揭开自然界中千姿百态的植物奥秘。植物的特征、性质的研究为人们带来更舒适的生存环境,营造更具美感的生活空间。本文从植物园的定义、性质和功能,并对我国植物园的现状和发展趋势作了详尽的论述。以此,为合理开发利用植物园提供一定的理论参考。     

《中国农学通报》性质及学科分类

根据期刊性质和学科分类方法,以文献数量为依据对《中国农学通报》进行分类。结果发现,《中国农学通报》2010年刊登的论文以学术性为主,其中农作物类、园艺类、植物保护类、农业基础科学类、农业经济类、林业类、生物学类、环境科学与资源利用类以及农艺学类文献数都超过各自学科"20%区域"文献数均值,其余学科文献量均较少,不能划入相应学科,因此应将该刊归类为这9个学科的专业学术期刊。     

《西北植物学报》性质及学科分类

根据期刊性质和学科分类方法,以文献数量为依据对《西北植物学报》进行分类。结果发现,《西北植物学报》2010年刊登的论文全为学术性,生物学类文献占文献总量的42.09%,园艺类、农作物类文献超过各自学科"20%区域"文献数均值,其余学科文献均较少,不能划入相应学科,因此应将该刊同时归类为生物学类、园艺类、农作物类专业学术期刊。