全文获取类型
收费全文 | 52篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
废物处理 | 1篇 |
环保管理 | 34篇 |
综合类 | 10篇 |
基础理论 | 3篇 |
污染及防治 | 1篇 |
评价与监测 | 3篇 |
灾害及防治 | 1篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
1997年 | 2篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有53条查询结果,搜索用时 15 毫秒
1.
我国森林环境服务市场构建与私人参与的选择 总被引:4,自引:1,他引:4
分析了我国出现森林资源环境服务市场构建态势及存在问题、对策等,回顾了现有市场构建的政策与制度,把森林资源环境服务与产品界定为公共产品,分析了私人部门参与的可能性、必要性。其次,对流域管理、生物多样性保护、景观价值、碳储存等生态服务的市场构建状况进行分析,最后分析市场创建机制所面临的主要挑战,并提出了相应的政策建议,以促进私人部门参与森林环境服务。 相似文献
2.
Hydrogeomorphic (HGM) functional assessment models were used to assess whether function in created wetlands of two ages (1 year
old and >12 years old) was equivalent to that of natural (reference) mainstem floodplain wetlands. Reference wetlands scored
higher than both created age classes for providing energy dissipation and short-term surface water storage. Reference wetlands scored higher in maintaining native plant community and structure than 1-year-old sites, and 12-year-old wetlands scored higher than reference sites for providing vertebrate habitat structure. Analysis of individual model variables showed that reference wetlands had greater vegetative biomass and higher soil organic
matter content than both created wetland age classes. Created wetlands were farther from natural wetlands and had smaller
mean forest patch sizes within a 1-km-radius circle around the site than did the reference sites, indicating less hydrologic
connectivity. Created wetlands also had less microtopographic variation than reference wetlands. The 1-year-old created sites
were placed in landscape settings with greater land use diversity and road density than reference sites. The 12-year-old sites
had a higher gradient and a higher percentage of their surrounding area in urban land use. These results show that the created
wetlands were significantly structurally different (if not functionally so) from reference wetlands even after 12 years. The
most profound differences were in hydrology and the characteristics of the surrounding landscape. More attention needs to
be focused on placing created wetlands in appropriate settings to encourage proper hydrodynamics, eliminate habitat fragmentation,
and minimize the effects of stressors to the site. 相似文献
3.
研究了湿地重建过程中植物、土壤和水质的动态变化特征.湿地重建2 a后植物种类增加了11种,芦苇、菖蒲和香蒲3种植物的高度、生物量在第2个生长季明显高于第1个生长季节,植物生物量分别增加到原来的13、1.5和1.4倍.湿地种植区土壤有机质总体上是降低的,土壤全氮含量从1?500 mg/kg降低到850 mg/kg(p<0.01),土壤全磷在试验期间略有增加.对重建湿地12种水质指标分析表明,夏季湿地出口源水溶解氧高于进口源水,出口源水总氮、叶绿素a、藻类计数3种水质指标均低于进口源水,说明重建湿地水质在夏季出口源水优于进口源水,水质得到改善.研究表明,湿地植物群落重建成功,生物多样性增加,重建湿地在改善和保持源水水质方面发挥了一定的作用. 相似文献
4.
The paper examines characteristics of science parks in the face of employment decline, raising doubts about the scale of their success. The paper re‐examines previous research on the existence and causes of long waves of economic growth and decline and concludes that if these are not generated by innovations in production, then it should not be surprising that science parks have not lived up to expectations. 相似文献
5.
Paul Lawless 《Journal of Environmental Planning and Management》1988,31(1):13-18
There has been a marked proliferation of local economic development initiatives in recent years. Enterprise Boards have proved one of the most successful of these innovations. In the early 1980s five were established. Two, the Greater London and the West Midlands Enterprise Boards, were initially designed to intervene radically within their local economies, although subsequent events moderated their activities. The remaining three in Lancashire, West Yorkshire and Merseyside, have successfully widened their operations to embrace collaborate projects with the private sector, training, boosting co‐operatives, and research. By many economic evaluations, for example, jobs supported, leverage ratios and investment per job, Enterprise Boards have performed better than other instruments of urban and regional development. Wider socio‐political objectives have proved more difficult to achieve. 相似文献
6.
Vernal pools are vulnerable to loss through development and agricultural and forestry practices owing to their isolation from open water bodies and their small size. Some vernal pool-dependent species are already listed in New England as Endangered, Threatened, or Species of Special Concern. Vernal pool creation is becoming more common in compensatory mitigation as open water ponds, in general, may be easier to create than wooded wetlands. However, research on vernal pool creation is limited. A recent National Research Council study (2001) cites vernal pools as challenging to recreate. We reviewed documentation on 15 vernal pool creation projects in New England that were required by federal regulatory action. Our purpose was to determine whether vernal pool creation for compensatory mitigation in New England replaced key vernal pool functions by assessing project goals and documentation (including mitigation plans, pool design criteria, monitoring protocols, and performance standards). Our results indicate that creation attempts often fail to replicate lost pool functions. Pool design specifications are often based on conjecture rather than on reference wetlands or created pools that function successfully. Project monitoring lacks consistency and reliability, and record keeping by regulatory agencies is inadequate. Strengthening of protection of isolated wetlands in general, and standardization across all aspects of vernal pool creation, is needed to ensure success and to promote conservation of the long-term landscape functions of vernal pools. 相似文献
7.
A study was carried out in Nova Scotia, Canada, to experimentally assess the effect of snowmobiles on old field and marsh vegetation. Snowmobile treatments ranging from a single pass to 25 passes (five passes on five separate days) were administered. The first pass by a snowmobile caused the greatest increase in snow compaction-roughly 75% of that observed after five sequential passes. Snowmobile treatment resulted in highly significant increases in snow retention in spring. Frequency was more important than intensity in this regard.Standing crop and species composition were measured the following summer. Standing crop in the field showed a significant reduction with increasing snowmobile use; frequency of treatment (p < 0.01) was more important than intensity (p = 0.125).Stellaria graminea, Aster cordifolius, Ranunculus repens, andEquisetum arvense all showed significant (p < 0.05) differences in percent cover resulting from the treatment. Marginally significant changes were observed inAgrostis tenuis andPhleum pratense Marsh vegetation showed no significant effects of snowmobile treatment. This may have been because of solid ice cover during the winter.The literature is critically reviewed. It is concluded that snowmobile use can have a highly significant effect upon natural vegetation. Management suggestions are made. 相似文献
8.
从废弃资源特点和价值来源出发,分析了废弃资源正负价值来源,建立基于微观经济基础的循环经济分析框架,分析影响循环经济的近因和远因,并根据系统论及自组织理论,对远因进行分类,提出了影响循环经济的主导因素和次要因素等。 相似文献
9.
Zhalong National Nature Reserve in the northeast of China is a large wetland and a habitat of hundreds species of fauna and
flora. The rare red-crowned crane is one kind of endangered birds in it. Recently, Zhalong wetland is shrinking and it encounters
many problems including occasional fires, bad water quality, human activities, etc. In order to find out a proper way to protect
and restore the wetland, this study, using a geographic information system, the global positioning system and remote sensing
techniques, analyses the spatial characteristics of the changes in marsh landscape pattern and examines the driving factors
for these changes. Data sources include 8 Landsat Thematic Mapper satellite images of Zhalong area in the period of 1986–2002
and the investigation information on site. Based on the analysis of changes of marsh area and annual precipitation during
the 16 years, it is found that there is a close correlation between annual precipitation and marsh area. It means that climate
is one of driving factors of marsh pattern changes. To understand influences of other kinds of land uses on marsh spatial
distribution in Zhalong wetland, this paper analyses the relationship between marsh and different kinds of land uses, such
as water surface, residential area, farmland, salina land and grass land, respectively. According to the patch analysis theory,
a fragmental index and a fractal dimension of the marsh are calculated with perimeter-area method. The results indicate that
the marsh pattern is affected by human activities significantly. In addition, the location alteration of marsh centroid point
over the 16 years is studied. The movement trace of marsh centroid point is concerned with different hydrological situation
in different areas of the wetland. In summary the characteristics of the marsh landscape pattern evolution during the 16 years
are affected by multiple driving factors. The main driving factors are climate, human activities, distribution of other kinds
of land uses and hydrological situation in different areas. 相似文献
10.
Spartina alterniflora was transplanted into dieback areas of a salt marsh in southeast Louisiana at two elevations (ambient and +30 cm) with and
without macro- (N, P, and K) and micronutrient (Fe, Mn, Cu, and Zn) additions to determine if transplant success is dependent
on increasing elevation or nutrients.Spartina alterniflora transplanted into elevated plots had more than twice the above- and belowground biomass as compared to nonelevated plots
after three months of growth. Additionally, there was significantly more vegetative reproduction (greater culm density and
number of newly produced culms) in elevated plots as compared to plots at ambient elevation. Macronutrient additions increased
culm densities only in elevated plots.Spartina alterniflora transplanted into nonelevated plots had lower survival rates even when transplants received nutrient additions. These results
suggest thatS. alterniflora may be transplanted successfully into degraded salt-marsh areas if elevation is increased. The addition of nutrients without
a concomitant increase in elevation is not sufficient for transplant success. 相似文献