全文获取类型
收费全文 | 248篇 |
免费 | 0篇 |
专业分类
安全科学 | 5篇 |
废物处理 | 3篇 |
环保管理 | 8篇 |
综合类 | 149篇 |
基础理论 | 22篇 |
污染及防治 | 51篇 |
评价与监测 | 6篇 |
社会与环境 | 4篇 |
出版年
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 7篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1984年 | 2篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1976年 | 2篇 |
1969年 | 3篇 |
1966年 | 7篇 |
1965年 | 3篇 |
1964年 | 8篇 |
1963年 | 8篇 |
1962年 | 4篇 |
1961年 | 9篇 |
1960年 | 3篇 |
1959年 | 3篇 |
1958年 | 6篇 |
1957年 | 6篇 |
1956年 | 9篇 |
1955年 | 4篇 |
1954年 | 7篇 |
1953年 | 6篇 |
1952年 | 4篇 |
1951年 | 3篇 |
1950年 | 2篇 |
1947年 | 3篇 |
1941年 | 2篇 |
1939年 | 2篇 |
1932年 | 2篇 |
1931年 | 3篇 |
1930年 | 2篇 |
1926年 | 2篇 |
1922年 | 2篇 |
1917年 | 2篇 |
1914年 | 4篇 |
1913年 | 3篇 |
排序方式: 共有248条查询结果,搜索用时 156 毫秒
161.
162.
163.
164.
Summary Harsh physico-chemical conditions during early development may select for parental care. However, no study on the evolution of parental care has focused on the physico-chemical conditions in the environment, the physiological needs of early life stages and the significance of parental care. Early development of the bromeliad crab is completed in small rainwater reservoirs in bromeliad leaf axils. Axils not cared for by mother crabs are acidic, hypoxic and contain very little Ca2+. Maternal care buffers axil water and increases oxygen and Ca2+ availability. Our results show that (a) bromeliad crab larvae die at pH levels usually found in unattended axils, but develop successfully into the first crab stage at the pH typical of cared-for axils; (b) oxygen concentration in unattended axils is below the critical concentration for larvae, but is high enough for normal respiration in cared-for axils; (c) the calcium demand of larvae for moulting and development cannot be satisfied in unattended axils, but is met by the higher calcium content of cared-for axils. Therefore, physicochemical conditions in the bromeliad axil habitat exert strong selection for the maintenance of parental care in the bromeliad crab.
Correspondence to: R. Diesel 相似文献
165.
166.
Rudolf Huth Rainer Hartmann Michaela Kiesel Wilhelm Pyka Annette Stallauer 《Environmental Sciences Europe》2004,16(4):239-244
Goal and Scope
The goal of this study is the investigation and the grafic presentation of the characteristic redox zonation in a mineral oil contaminated aquifer which will be formed in the plume downstream of the contamination source. Methanogenic conditions, sulfate-reduction, Fe(III)-reduction, Mn(IV)-reduction, nitrate-reduction, aerobic conditions. By that indications type and degree of microbial degradation which is the most important part in Natural Attenuation (NA) processes can be obtained easily.Methods
Changes of the groundwater parameters Eh, O2, NO 3 ? , SO4 2?, Fe2+, Mn2+, HCO3 ?, Ca2+ will be measured upstream, downstream and also in the centre of the plume. The results will be presented in a sequence of special diagrams.Results and Conclusion
When microbial degradation of hydrocarbons takes place, a microbial community will always use that electron acceptor from which it will gain a maximum of energy by the corresponding redox-reactions. This means as long as oxygen is available this will be used. After its depletion nitrate serves as electron acceptor leading via nitrite to the formation of nitrogen or ammonia. Manganese (IV) and Iron (III) species which are rather insoluble are mainly available from the soil-phase, can act as electron acceptor as next, leading to soluble Manganese (II) and Iron (II) compounds in groundwater. Finally before methanogenic conditions occur sulphate will become a suitable electron acceptor leading to the formation of hydrogen sulphide. All these processes of mineralization of the hydrocarbons will lead to the production of CO2 and as consequence to an increase of HCO3 ? in groundwater changing the calcareous/carbonic acid-equilibrium. By that more soluble Ca(HCO3)2 is formed from insoluble CaCO3, so the concentration from Ca2+ will also inerease. Thus, by the action of microorganisms, a typical redox-zonation and changes of other parameters will occur.Recommendations and Perspective
To follow the changes in time and space of some characteristic groundwater parameters is a simple way to estimate the potential of microbial degradation in a contaminated aquifer considering Natural Attenuation (NA)-processes. 相似文献167.
Jaffé R Gardinali PR Cai Y Sudburry A Fernandez A Hay BJ 《Environmental pollution (Barking, Essex : 1987)》2003,123(2):291-299
Surface sediments throughout Montego Bay, Jamaica were collected in 1995 and analyzed for their trace metal and trace organic contaminant content. A variety of trace metals, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, coprostanol as well as chlorinated hydrocarbons such as pesticides and polychlorinated biphenyls were detected and provide evidence for several anthropogenic inputs to the bay. Two main sources of these chemicals are the Montego River and the North Gully, the latter being more significant. Particle-associated pollutants were found to be distributed along the Montego River plume, as well as being transported by the prevailing water currents to the South-Western sections of the bay, probably through re-suspension of enriched fine sediments from the North Gully outfall area. 相似文献
168.
Industrial tree plantations in the tropics usually follow short rotations and intensive site management including slash and burn, and the use of heavy machinery. We attempt to quantify the implied nutrient losses (harvest export, erosion, slash and burn, leaching) in order to give plantation managers a chance to understand the significance of their planning and decisions. We used the scarce globally available information and a case study plantation in East Kalimantan, Indonesia (Acacia mangium and Eucalyptus deglupta). Adaptation involves problems and is discussed in some detail. Results are approximate only. Assuming a harvest volume of 200 m3 ha(-1), we assessed a loss of 427-680 kg ha(-1) N, 12-13 kg ha(-1) P, 178-252 kg ha(-1) Ca, 276-370 kg ha(-1) K, and 45-57 kg ha(-1) Mg per rotation. Of this overall loss, stand harvest accounted for 18-29% (N), 21-30% (P), 56-26% (K), 48-64% (Ca) and 22-37% (Mg). This means that the cumulative loss by erosion, slash and burn, and leaching exceeds that of the harvest. These losses can be influenced by management. 相似文献
169.
The eutrophication status of rivers is changed to a large degree by discharge of waste waters containing high amounts of phosphates from use of detergents. Sediments from the river Elbe in the port of Hamburg, and upstream from this town, and from some parts of the rivers Trave, Eider, and Schwentine are highly enriched with phosphorus. The phosphorus contents of up to 8300 ppm are about five to tenfold higher than the phosphorus contents of intensively fertilized soils. Phosphates accumulated in sediments are mainly bound as iron phosphates of different composition in a relatively labile binding form from which considerable amounts may be released to the water by various mobilization processes. 相似文献
170.