首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
从农用地价值的综合分析出发,提出了农用地转用的景观生态补偿价格结构。为实现农用地景观生态价值的货币化,建立了以条件价值法为核心的农用地转用的景观生态补偿价格评估模型,并以重庆市北碚区为例进行了实证研究。研究表明,开展农用地转用的环境影响评价是十分必要的,运用景观生态补偿价格评估模型估算农用地转用的景观生态补偿价格是可行的。  相似文献   

2.
高校档案具有类型多、范围广、数量大等特点。随着教育事业的发展,高校的管理方式、培养模式发生了改变,高校的档案产生途径和利用范围也随之发生了变化。因此,必须实现档案信息数字化管理,建立专项数据库。建库要有专业人员,依据国标或行业标准,要注重实效性和安全性。专项数据库建设和信息资源建设是数字化档案馆建设的基础和必由之路。  相似文献   

3.
The Household Responsibility System initiated in the late 1970s in China has brought a profound change to its rural economy. The shift from the collective farming system to individual family farms has changed land management. The change, including fertilization and crop systems, may have significant effects on soil quality and agro-environmental sustainability. However, very little research is being carried out on the impact of reformed land tenure systems on the spatial variability of soil nutrients. In this study, geostatistics was applied to analyze changes in the spatial variability of soil organic matter and nutrients in paddy fields in Pinghu County, China after 20 years of land management change. In 1984 and 2002, 617 and 131 locations were selected, respectively, for collecting surface soil samples to analyze soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK). From 1984 to 2002, variability of the SOM and TN changed from strongly to moderately spatial-dependent, and the variability of AP remained weakly dependent on space, but that of the AK changed from moderately to weakly spatial-dependent. That the trend of the variability of four soil properties in 2002 became weaker than that in 1984 showed that the extrinsic factors (soil management practices, such as fertilization) weakened the effect by intrinsic factors (soil formation factors, such as soil parent materials) owing to a long period of land management change. The temporal geographic maps of the SOM and nutrients spatial distributions suggested that the concentrations of the SOM and nutrients had been changed to different extents during the period. Significant increase in AP and decrease in AK were noted. The changes were likely due to the imbalance between N, P, and K fertilizers and increased grain yield.  相似文献   

4.
水利工程一般表现为多种功能,但其原生功能因不同时代的需求变化而各异,总体经历了从农业时代的“兴农水利”,到工业时代的“能源水利”,再到后工业时代“民生水利”的转变.随着休闲旅游市场的日益兴旺,水利工程因其独特的景观价值和科学价值而被开发成为水利旅游风景区.系统分析了水利工程的原生功能及其变迁规律,指出水利旅游是其重要的拓展功能,因此要利用和挖掘好古代水利工程文化遗产价值,对现代水利工程进行未来遗产式开发,对水利工程赋存的非物质文化遗产进行活态开发,整体提升水利旅游发展的品位和质量.  相似文献   

5.
本文讨论了克黄灵注射液和颗颗灵栓剂配合施用问题,两者配合施用有助于颗颗灵的溶解,叶片转缓时间比单施颗颗灵提前且维持时间更长.  相似文献   

6.
In this paper, we estimate the cost-effectiveness of tillage methods as a measure to reduce phosphorus loss. The study was based on real-world information on costs. Data on phosphorus loss for different soil tillage methods were modelled. The cost-effectiveness of various soil tillage methods were related to autumn ploughing. The results showed large variation in cost-effectiveness related to erosion risk. Furthermore, spring harrowing was the most cost-effective method to reduce phosphorus loss, followed by autumn harrowing and spring ploughing in spring cereals. Implementation of changed tillage methods showed lower costs for spring cereals compared to winter wheat. The differences in costs between areas were most evident for spring tillage due to differences in yields and agronomic management. Cost-effectiveness is an important criterion in selecting mitigation methods, but due to large variations in the effect of changed tillage, these should be locally adapted to the high risk areas of erosion.  相似文献   

7.
随着我国油田相继进入开发后期,传统的滤料及设备过滤精度已不能满足注水的要求。因此,研究并开发了具有一定抗油污能力的新型过滤材料,设计了新型的超精细过滤器系列产品。对滤料进行的室内实验结果表明,在开始过滤的近10h内,过滤后的水中含油量基本上满足注水的水质要求。在开始过滤的近20h内,滤层的水头损失随时间的变化较为平缓;随着过滤时间的延长,水头损失变化加剧。从现场实验可以看出,所设计的过滤器有良好的过滤性能和抗冲击能力。新型过滤材料的研究成功解决了油田含油污水精细过滤的问题,新型过滤器也是含油污水超精细过滤的理想产品。  相似文献   

8.
会计电算化的普及与深入,使会计档案管理工作发生了重要变化。本文从保密性管理,使用权限管理,存储管理和网络化管理等方面,论述了电算化条件下如何做好会计档案管理工作。  相似文献   

9.
本文指出,把旅游资源优势转化为经济优势是河南旅游业发展的关键,转化的方式是将旅游资源变为旅游产品,转化的原则是市场的需求,转化的步骤是根据市场需求,对旅游资源进行筛选,加工成适销对路的产品再推向旅游市场.  相似文献   

10.
以彩叶草(ColeusblumeiBenth.)为材料,用营养液培养方法,研究了不同浓度硒(se)处理对浓度为1.0mmol·L-1Pb2+胁迫下彩叶草根、叶的形貌变化及其组分形态等变化,从光谱学角度初步探讨了硒对重金属铅毒害的缓解机制。结果表明:铅胁迫下的彩叶草根系c、K、ca含量减少,O、Mg、Al、Si、Fe、Pb含量增加,叶片中的C、Mg、Al、si、K、Ca、Fe含量减少,O、Cl含量增加。铅胁迫下硒处理的彩叶草根元素种类及其元素含量均发生了明显变化;根中晶体情况及其晶相也发生了相应变化。  相似文献   

11.
ABSTRACT: The fish communities in three sewage receiving Illinois streams were monitored by electrofishing as treatment changed from secondary with chlorination to secondary without chlorination to tertiary without chlorination over a 40-month period. Degradation of the fish communities was severe during the secondary treatment/chlorination period. When treatment was changed to secondary without chlorination, strong improvements occurred in the fish communities of all streams, and degradation could no longer be demonstrated on the basis of species number. The onset of tertiary treatment resulted in few additional changes in the fish communities, with the possible exception of increased abundance of several species of minnows. Tertiary treatment consisted of nitrification, sand filtration, and, in two streams, phosphorus removal.  相似文献   

12.
张健  陈凤  濮励杰 《资源开发与市场》2007,23(12):1057-1060,1095
选取经济发达区原锡山市作为研究区域,以1982年和2005年土壤速效钾作为研究对象,分析探讨不同时空状态下区域土地利用变化对土壤钾含量的影响,以期获得较长时空条件下土壤质量对土地利用变化的响应。20年来,通过统计分析和独立样本t检验表明,原锡山市土壤速效钾含量增加了36.9mg/kg。变异函数分析表明,土壤速效钾的变异函数理论模型呈指数型,块金方差与基台值的比值、自相关阀值发生较大变化。kriging插值分析结果表明,土壤速效钾空间分布较简单,但空间变异明显。  相似文献   

13.
area cells (the areas between the tracks) increased geometrically in the unprotected area, while the increase in the protected area was linear; and (3) most area cells (50%–70%) in the protected area in each of the years analyzed (except 1944) were smaller than 10 ha in size. However, an area cell greater than 100 ha has always been observed. In contrast, in the unprotected site the number of area cells increased with time while their area size decreased. Twenty-seven percent of the unprotected area is composed at present of area cells smaller in size than 1 ha. The development of a track system in the protected site changed moderately with a few peaks during the past 50 years. This trend is a result of land management policies that actively promote sustainable ecotourism. However, in the unprotected open area, the track system has changed continuously and drastically due to a lack of land conservation management.  相似文献   

14.
古代雕塑具有记录历史、纪念人物形象、宣传、装饰环境的作用。现代雕塑的表现形式由写实到抽象,材料更轻便、廉价,在环境中存在的时间越来越短了。雕塑本身具有的永恒性已经逐渐地退化了,这种退化源自于社会的更替、人文环境的变化和新材料的出现。  相似文献   

15.
随着人们对铁细菌认识的突破,其应用也发生了巨大的变化。本文主要介绍了铁细菌在水处理方面的两个主要应用方向——酸性矿山废水的处理和城市用水的处理。同时综述了影响铁细菌生长的几个主要因素。  相似文献   

16.
长期以来,我国对排污或超标排污实行征收排污费制度。九届人大常委会第13次会议修订通过的《海洋环境保护法》对此进行了改革。本文对此进行了深入分析。  相似文献   

17.
In this paper, we investigate whether people's knowledge of the past influences their preferences and values towards future landscape change. "Knowledge of the past" is one aspect of the information set held by individuals, and a well-established finding in economics is that changes in information can change preferences and values. The particular aspects of knowledge of the past we work with here are: (i) awareness of past landuse, as represented by woodland cover and (ii) awareness of differing and sometimes contradictory literary impressions of this past landscape. The case studies used here relate to prospective changes in woodland cover in two UK national parks, the Lake District and the Trossachs. We find that people who are made aware that the landscape has changed over time, or that perceptions of the landscape have changed over time, are more likely to favour changes to the current landscape (are less likely to favour the status quo). Knowledge of the past therefore seems to have an impact on preferences for future landscapes. We also investigate the impacts on preferences of how "special", how "wild" and how "worked in" people perceive the landscapes of these two national parks to be.  相似文献   

18.
实施可持续发展的前提是保持人类的生存环境。经济的“量”增长应向“质”的发展转化,而经济发展也需要不断地协调完善。科学技术是第一生产力,但盲目用科学手段也可能带来负面影响。可持续发展应是经济、社会、环境协调统一的新文明。  相似文献   

19.
高校内部审计存在的问题与对策的初步探讨   总被引:1,自引:0,他引:1  
目前高校内部经济活动发生了很大变化,内部的经济管理也变得更加复杂。如何有效的保证教育资金合理运用,保证内部经济活动健康、有序的开展,教育审计有着举足轻重的作用。本文分析了高校内部审计存在的问题,初步探讨解决的对策。  相似文献   

20.
袋装控释铁肥压根法矫治桃树黄叶病的效果   总被引:1,自引:1,他引:0  
本文介绍了袋装控释铁肥压根法矫治桃树缺铁黄叶病的效果。该法具有大幅度增加叶绿素含量.提高果实产量,改善果实品质,降低矫治成本,安全可靠,效果好的特点。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号