首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   60篇
  免费   0篇
  国内免费   5篇
安全科学   2篇
废物处理   12篇
环保管理   1篇
综合类   15篇
基础理论   13篇
污染及防治   13篇
评价与监测   1篇
社会与环境   7篇
灾害及防治   1篇
  2023年   1篇
  2022年   1篇
  2021年   2篇
  2020年   1篇
  2017年   1篇
  2016年   4篇
  2015年   1篇
  2014年   6篇
  2013年   3篇
  2012年   6篇
  2011年   2篇
  2010年   2篇
  2009年   2篇
  2008年   1篇
  2007年   9篇
  2006年   6篇
  2005年   3篇
  2004年   3篇
  2003年   1篇
  2002年   5篇
  2000年   1篇
  1999年   1篇
  1993年   1篇
  1983年   2篇
排序方式: 共有65条查询结果,搜索用时 31 毫秒
21.
22.
In the intertidal limpet Patelloida pygmaea, two distinctive morphs, the forms pygmaea and conulus, have been recorded. The former possesses a flat elongated shell, and the latter has an extremely high round shell. It has been observed in the field that pygmaea is found on oyster shells Crassostrea gigas. The form conulus uses an unusual substrate for attachment. It is found on the living shells of the intertidal gastropod Batillaria cumingi. Although conulus is normally found only on shells of Batillaria, it can also be found on oyster shells when pygmaea and Batillaria shells are not present in nature. An electrophoretic analysis of allozymes showed that these two forms are reproductively isolated from each other and coexist without gene exchange on the same mudflat. Laboratory experiments showed that pygmaea prefers oyster shells and conulus prefers Batillaria shells as substrates for attachment when both oyster and Batillaria shells are present. The form pygmaea did not attach to Batillaria shells, even when only Batillaria shells were available. However, conulus also attached to oyster shells when Batillaria shells were not available. The proportion of individuals of conulus that attached to oyster shells decreased significantly when pygmaea was attaching to the oyster shells. These results suggest that pygmaea is ecologically more specialized to living on oyster shells than conulus.  相似文献   
23.
24.
A Chinese praying mantis, Tenodera sinensis, was observed feeding on a living red-spotted newt, Notophthalmus viridescens. Specimens of that newt’s population are known to contain high concentrations of tetrodotoxin (TTX), a specific blocker of voltage-gated sodium channels. After experimental oral administration of a TTX-solution (1 mg/ml) to adult specimens of four mantis species, all survived high TTX concentrations (up to 30.8 μg/g body mass) as revealed by analysis of their body extracts, but they are rapidly killed by intra-abdominal injection of 1 μg TTX. The toxin was found to be gradually excreted with faeces. As demonstrated by monoclonal antibody-based immunohistochemical technique, TTX does not penetrate the mid-gut membrane, since it was localized only in the gut lumen, but not in the epithelial cells. This prevents the toxin to reach its target, the sodium channels of the insect’s nervous system, and enables the mantids to feed on toxic prey without risking poisoning.  相似文献   
25.
Intertidal organisms commonly form zonation bands along the shore. Environmental stressors often determine the vertical position of each zonation band. These stressors may similarly affect the distribution pattern of endogenous species in their intertidal hosts. To evaluate this possibility, we investigated the distribution pattern of endosymbiotic zooxanthellae in the genus Symbiodinium in a population of the intertidal sea anemone Anthopleura uchidai. We used molecular genetics to identify the Symbiodinium clades and found that A. uchidai has two clades of Symbiodinium, clades A and F. These Symbiodinium clades were disproportionally distributed along the vertical gradient of the intertidal shore. Anemones on the upper shore exclusively possessed clade F Symbiodinium while clade A Symbiodinium became dominant in the sea anemones on the lower shore. Photosynthesis activity assays showed that these Symbiodinium clades had similar net productivities at 23.3 and 31.8 °C at all irradiance levels. At 35 °C, however, clade A Symbiodinium exhibited substantially lower net productivities than clade F Symbiodinium, demonstrating that these Symbiodinium clades have distinct tolerances to thermal stress. These results suggest that the thermal gradient across tidal height is a major factor shaping the zonation pattern of Symbiodinium clades in A. uchidai.  相似文献   
26.
一种基于小样本数据信息扩散的重大火灾频度估算方法   总被引:3,自引:0,他引:3  
重大火灾的发生是小概率事件,其历史数据属于小样本统计数据。在应用频率直方图法对小样本数据进行处理时,分析结果对直方图的起点、区间步长以及样本中的奇异数据十分敏感。采用信息扩散方法,对日本1995-2008年各年重大火灾次数统计样本进行分析,对比了不同扩散条件下的扩散结果,结果表明信息扩散方法具有很好的稳定性和一致性。基于信息扩散的结果,计算了以年为周期的重大火灾发生次数的超越概率分布,建立了一种重大火灾频度估算方法。  相似文献   
27.
First, this paper evaluates the current building material stock and future demolition waste for urban residential buildings in the cities of Jakarta and Bandung using a material-flow analysis. The actual on-site building measurements were conducted in Jakarta (2012) and Bandung (2011), focusing particularly on unplanned houses, to obtain building material inventory data. A total of 297 houses were investigated in Jakarta, whereas 247 houses were measured in Bandung. Second, this paper analyses the embodied energy and CO2 emissions of building materials through an input–output analysis. The results show that, overall, the total material input intensity for the houses is 2.67 ton/m2 in Jakarta and 2.54 ton/m2 in Bandung. Two scenarios with zero and maximum reuse/recycling rates were designed to predict future demolition waste and the embodied energy/CO2 emissions of building materials in Jakarta. Closed- and open-loop material flows were applied. If the maximum reuse/recycling rates are applied to the closed- and open-loop material flows in Jakarta, then it would become possible to not only decrease the final disposal waste (from 123.9 to 2.1 million ton) but also reduce the corresponding embodied energy (from 247.8 to 192.1 PJ) and CO2 emissions (from 24.3 to 19.2 million ton CO2-eq) compared with the zero reuse/recycling scenario from 2012 to 2020.  相似文献   
28.
In sustainability science (SS), it is difficult to identify what needs to be solved, and it is also not clear how to solve the problems that are identified. There has been no consensus on the underlying question of “What is structuring knowledge in SS?” This paper focuses on knowledge structuring accompanied by supporting of thinking. It addresses the key challenges associated with knowledge structuring in SS, identifies the requirements for the structuring of knowledge, proposes a reference model, and develops an ontology-based mapping tool as a solution to one layer of the reference model. First, we identify the important requirements for SS knowledge structuring. Second, we develop a reference model composed of five layers based on three of the requirements. Third, we develop an ontology-based mapping tool at Layer 2 of the reference model for meeting the two major challenges for SS, namely, identifying what problems should be addressed in SS itself and proposing solutions for those problems. The tool is designed to store and retrieve information regarding SS, to provide access to a prototype ontology for SS, and to create multiple maps of conceptual chains depending on a user’s interests and perspectives. Finally, we assess whether the developed tool successfully realizes the targeted part of the reference model for SS by examining the tool’s conformity to the reference model, as well as its usability, effectiveness, and constraints. Although several issues were identified in the prototype ontology and the mapping tool, the study concluded that the mapping tool is useful enough to facilitate the function of Layer 2. In particular, the mapping tool can support thinking about SS from the viewpoint of: (a) finding new potentials and risks of technological countermeasures studied in SS; (b) helping users to get a more comprehensive picture of problems and their potential solutions; and (c) providing an effective opportunity to come up with new ideas that might not be thought of without such a tool.  相似文献   
29.
Sri Lanka being an agrarian country, the role of water is important for agricultural production. In Sri Lanka, various tank cascade systems, earthen dams and distribution canals have been accepted as few of the most complex ancient traditional water systems of the world. Rainfall, surface water, groundwater and runoff are linked with each other, they have close interactions to land cover classes such as forests and agriculture. The monitoring of vegetation conditions can show subsurface manifestations of groundwater. In this study, an effort to understand the role of traditional water reservoirs and groundwater recharge was made using remote sensing techniques. We have analyzed various vegetation indices such as Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI-2), Soil-Adjusted Vegetation Index (SAVI), tasselled cap transformation analysis (TCA brightness, greenness and wetness) and their relations with the existence of soil, vegetation and water. Result shows that EVI, SAVI, and TCA-based Greenness Index indicates good relationship with the vegetation conditions as compared to other indices. Therefore, these indices could play a crucial role in depicting the interaction between soil, vegetation, and water. However, multi-temporal observations can provide significant results about these interactions more accurately.  相似文献   
30.
Mercury (Hg), cadmium (Cd), iron (Fe) manganese (Mn), zinc (Zn) and copper (Cu) concentrations in the liver, kidney and muscle of nine killer whales (including three calves) that stranded together in the northern area of Japan were determined. The Hg and Cd concentrations were found at trace levels in the calf organs, and increased with age. The Fe concentration in the muscle was significantly lower in the calves than in the mature whales and also increased with age. In contrast, Mn and Cu concentrations in the muscle were significantly higher in the calves than in the mature whales, and changes in the Zn concentration relative to age were unclear. These results suggest minimal mother-to-calf transfer of the toxic metals Hg and Cd and accumulation of these metals in the organs with age, while the essential metals Mn and Cu were found at higher concentrations in the muscle of calves than in mature whales.  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