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701.
本文对浙江省第四纪古红土的分布、形态特征和理化性质作了分析研究,并就古红土农业利用的有利和不利条件作了探讨.  相似文献   
702.
本文研究了湖北省武当山风景区石英云母片岩发育的7个土样的粘土矿物组成、粘粒氧化物含量。土壤电荷量及电荷零点.结果表明:(1)供试土壤粘土矿物均以2∶1型矿物占优势,在海拔440m以下的土壤中主要是水云母和蛭石,在海拔670m以上的土壤中主要是1.4nm过渡矿物、绿泥石和水云母;(2)土液粘粘中氧化铁和氧化铝的含量、粘粒硅铝率及氧化铁的游离度随海拔的变化而变化的趋势不甚明显,但非晶形铝铁氧化物的含量及氧化铝和铁的活化度随海拔升高而趋于增加;(3)土壤可变负电荷量、阴离子吸附量和电荷零点随海拔升高而趋于增加。  相似文献   
703.
福建集体林权制度改革热潮后的冷思考   总被引:4,自引:0,他引:4  
通过对福建集体林权制度改革完成后必须面临和亟待解决的政府职能转变、林业税费征收和使用的合理性、生态公益林补偿机制、林权流转的监督等问题的讨论与分析,提出了相应的改革建议.  相似文献   
704.
Abstract:  Customary forms of resource management, such as taboos, have received considerable attention as a potential basis for conservation initiatives in the Indo-Pacific. Yet little is known about how socioeconomic factors influence the ability of communities to use customary management practices and whether socioeconomic transformations within communities will weaken conservation initiatives with a customary foundation. We used a comparative approach to examine how socioeconomic factors may influence whether communities use customary fisheries management in Papua New Guinea. We examined levels of material wealth (modernization), dependence on marine resources, population, and distance to market in 15 coastal communities. We compared these socioeconomic conditions in 5 communities that used a customary method of closing their fishing ground with 10 communities that did not use this type of management. There were apparent threshold levels of dependence on marine resources, modernization, distance to markets (<16.5 km), and population (>600 people) beyond which communities did not use customary fisheries closures. Nevertheless, economic inequality, rather than mean modernization levels seemed to influence the use of closures. Our results suggest that customary management institutions are not resilient to factors such as population growth and economic modernization. If customary management is to be used as a basis for modern conservation initiatives, cross-scale institutional arrangements such as networks and bridging organizations may be required to help filter the impacts of socioeconomic transformations.  相似文献   
705.
应用定量结构-性质相关法预测有机物的亨利常数   总被引:3,自引:0,他引:3  
建立了预测有机物亨利常数的定量结构-性质相关方程,回归分析结果表明,此方程可以解释206种有机物98%的实验数据变异,标准偏差为0.25个对数单位,应用该方程能很好地预测许多有机化合物的亨利常数值。  相似文献   
706.
以硝酸钙、磷酸氢二铵和腐殖酸为原料,制备了腐殖酸负载羟基磷灰石(HA/HAP)复合吸附剂.同时,利用SEM、BET、FT-IR、XRD对复合吸附剂结构和形貌进行表征,研究了HA/HAP对废水中Cd~(2+)的吸附工艺.结果表明,腐殖酸使羟基磷灰石孔容和孔径增大、比表面积减小,从而提高了羟基磷灰石的吸附性能.在pH=6、吸附剂投加量为800 mg、接触时间为180 min时吸附率最佳,为98.3%.HA/HAP对废水中Cd~(2+)的吸附是自发的、吸热的、可持续的化学吸附,反应前120 min适合采用准一级动力学伴随着内扩散模型描述,后120 min适合采用准二级动力学伴随着内扩散模型描述,Dubinin-Radushkevich(D-R)等温线模型拟合的吸附数据在不同温度下效果最好(R~20.98),吸附量分别为259.15、266.05和264.66 mg·g~(-1).研究表明,静电吸附到腐殖酸活性位点后Cd~(2+)主要以络合反应被吸附到羟基磷灰石的表面和两个羟基中间.  相似文献   
707.
淀粉改性阳离子絮凝剂的制备及其絮凝性能研究   总被引:51,自引:1,他引:51  
以淀粉─丙烯酰胺接枝共聚物为母体.加入阳离子化试剂,合成了阳离子型改性高分子絮凝剂FNQE。以高岭土悬浊液为处理体系,探讨了FNQE的絮凝性能,结果表明FNQE投加量4mg/L时即有理想的絮凝除浊效果,处理水上清液剩余浊度可降至3.ZNTU.其性能明显优于均聚型丙烯酰胺。对城市污水及饮食业污水的絮凝实验表明.投加量6~10mg/L时.FNQE对浊度、色度的去除率均在90%以上,COD去除率也在75%~80%以上。  相似文献   
708.
The inexplicit efficiency of environmental property rights lies in its fuzziness. Based on the character of environmental property rights discussed, unit environment shows intra relationship between efficiency and duty of environmental property rights, and constructs a symmetrical system arrangement. Through analyzing the possibility and feasibility of unit environmental property rights, the significance of symmetrical system arrangement to avoid the inexplicit efficiency of environmental property rights is discussed in this dissertation from the aspect of the validity of offering and implementing system.  相似文献   
709.
In China, farmland property rights characterized by the household-responsibility system (HRS) have been improved since the reform and opening-up. The rights of use, transfer and gain become more stable, authorized and complete. This paper firstly analyzes the impact on farmland productivity, which comes from the improvement of farmland property rights. Then, an economet-ric model is built to test the above analysis. It concludes that changes of property rights will affect farmland performance in China. In the end, some policy implications are explored for fur-ther reforms.  相似文献   
710.
ABSTRACT: Water policy problems are wicked, not in an ethically deplorable sense, but in the sense that they present us with especially difficult challenges of becoming more effective in our interdisciplinary collaboration, of integrating two very different types of knowledge, of working across several socio‐political units of analysis simultaneously, and of better organizing water as a common property resource. Sociology, as a discipline, does not have a particularly rich history of successful interdisciplinary collaboration on water resources research and teaching, but it potentially has a most useful contribution to make by focusing on the analysis of local common property resource organizations that operate in the interface between individual resource users and State‐Federal entities. These organizations (e.g., water user associations, mutual companies, irrigation districts, acequias, conservancy districts) have been the orphans of water policy discourse but their operations are critical to undertaking more effective 21st century social analysis, research work, and action programs. Sociologists who work to better comprehend the operations of, and constraints upon, these organizations build a sociology that can better collaborate with other water‐related disciplines in addressing the challenges posed by the wickedness of our water problems.  相似文献   
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