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121.
122.
Agricultural activities are one of the major drivers of increased nutrient levels such as nitrogen (N) and phosphorus (P) to both terrestrial and aquatic ecosystems. Elevated nutrient concentrations are associated with degraded water quality that can result in potential impacts for human health and the environment. A recent European study has identified elevated concentrations of N and P for many European river monitoring stations. In many cases the management of N and P has been considered separately here we address the multi-dimensional issue of water quality where the simultaneous management and control of both N and P is considered desirable. Using an integrated modelling approach various nutrient management scenarios are examined. It is found that although the control of N and P involve different farm adjustments and induce different land use changes there is a certain degree of complementarity between these two nutrient controls. The policy implication of ignoring such complementarity is that the appropriate environmental taxes to control the required nutrient losses are overestimated, resulting in unnecessary welfare losses to the society.  相似文献   
123.
Amendment effects on soil test phosphorus   总被引:1,自引:0,他引:1  
Applications of animal manures have increased soil test P values in many parts of the USA and thus increased the risk that soil P will be transferred to surface water and decrease water quality. To continue farming these areas, landowners need tools to reduce the risk of P losses. A field experiment was conducted near Kurten, TX, on a Zulch fine sandy loam (thermic Udertic Paleustalfs) with Bray-1 P values exceeding 3000 mg P kg(-1) soil (dry wt.) in the A(p) horizon to evaluate the effectiveness of soil amendments for reducing soil test P values. Soils were amended annually from 1999 to 2001 with 1.5 and 5.0 Mg gypsum ha(-1), 1.4 Mg alum ha(-1), or 24.4 Mg ha(-1) of waste paper product high in Al alone or in combination with 1.5 Mg gypsum ha(-1) and/or 1.4 Mg alum ha(-1). These treatments supplied a maximum of 225 and 1163 kg ha(-1) yr(-1) of Al and Ca, respectively. Soil Bray-1 P and dissolved reactive P levels were monitored from 1999 to 2004. None of the soil amendment treatments affected Bray-1 P values. Only annual additions of 5.0 Mg gypsum ha(-1) from 1999 to 2001 significantly reduced soil dissolved reactive P. Dissolved reactive P levels reached minimal levels after two applications of 5.0 Mg gypsum ha(-1) but increased in 2003 and 2004. These results indicate that soil dissolved reactive P levels can be reduced if sufficient amounts of gypsum were added to supply Ca in amounts similar to the soil test P values.  相似文献   
124.
With more and more organizations seeking opportunities to generate benefits beyond compliance from environmental management activities, the challenges for environmental directors today is to develop and implement an environmental strategy that links environmental performance with the overarching strategic business goals of the organization. Organizations today are looking for opportunities to develop environmental management solutions that not only address the concerns of regulatory stakeholders, but also provide opportunities to improve operating efficiency and financial performance, enhance customer satisfaction, sustain market growth, and enhance goodwill, to satisfy the demands of a broader set of stakeholder groups including customers, investors, and employees. To achieve broader benefits from environmental management investments, this article shows how organizations must first develop a methodology for aligning their environmental management activities with the organization's strategic business goals and create a plan for systematically managing continuous improvement to achieve these goals. The second challenge is to implement this strategy at the business unit and facility level in a manner which integrates environmental management activities with an organization's core business processes to achieve improved product and service performance.  相似文献   
125.
Recycling policy, insofar as it exists, tends to be heavily weighted towards price manipulation. However, it is by now fairly well established that the supply of secondary materials is in most cases quite unresponsive to price changes, so that price-based policies are very unlikely to be effective. This view is further borne out by an attempt to consider explicitly the sort of adjustment processes which must necessarily occur in the generally volatile markets for waste materials. It is suggested that price-oriented policies must first influence the expectations of potential suppliers before any response is forthcoming When this is considered along with the evidently small reaction to those expectations, an even more pessimistic conclusion about the suitability of standard measures to encourage recycling is reached.  相似文献   
126.
Risk analysis is being used to evaluate and manage the potential of unwanted events in the chemical processing industry. The risk in this study is the risk posed by chemical plant accidents and it is presented in a simple quantitative form. A safety risk index is formulated that represents the maximum number of people that might be affected if an accident occurred that caused the release of all the plant inventory of a chemical. The index has four terms: frequency of accidents; hazardous effect of the chemical; inventory of the chemical released; size of the plant. The overall unit of the index is expressed as the number of people affected per year from the plant operation and is formed in a particularly simple manner so as to be suitable for the comparison of safety risk within a model for planning the development of the petrochemical industry.  相似文献   
127.
ABSTRACT: Grazed pastures represent a potential source of non‐point pollution. In comparison to other nonpoint sources (e.g., row‐cropped lands), relatively little information exists regarding possible magnitudes of nutrient losses from grazed pasture, how those losses are affected by management variables, and how the losses can be minimized. The objective of this study was to measure concentrations of nitrogen (N), phosphorus (P), and solids in runoff from fescue plots and relate those measurements to simulated forage management strategy. The study was conducted at the University of Kentucky Maine Chance Agricultural Experiment Station north of Lexington. Plots (2.4 m wide by 6.1 m long) were constructed and established in Kentucky 31 fescue (Festuca arundinacea Schreb.) to represent pasture. The experimental treatments applied to the plots varied in terms of forage height and material applied (none, manure, or manure and urine). Runoff was sampled for six simulated rainfall events applied over the summer of 1997 and analyzed for nitrate N (NO3‐N), ammonia N (NH3‐N), total Kjeldahl N (TKN), ortho‐P (PO4‐P), total P (TP), and total suspended solids (TSS). All runoff constituents exhibited dependence on the date of simulated rainfall with generally higher concentrations measured when simulated rainfall followed relatively dry periods. The effects of forage height and manure addition were mixed. Highest runoff N concentrations were associated with the greatest forage heights, whereas highest P concentrations occurred for the least forage heights. Manure/urine addition increased runoff P concentrations relative to controls (no manure/urine) for both the greatest and least forage heights, but runoff N concentrations were increased only for the greatest forage heights. These findings indicate that runoff of N and P is at least as sensitive to amount and proximity of preceding rainfall and suggest that managing forage to stimulate growth and plant uptake can reduce runoff of N.  相似文献   
128.
ABSTRACT: Grazed pastures represent a potential source of non‐point pollution. In comparison to other nonpoint sources (e.g., row‐cropped lands), relatively little information exists regarding possible magnitudes of pollution from grazed pasture; how that pollution is affected by weather, soil, management and other variables; and how the pollution can be minimized. The objective of this study was to assess how the quality of runoff from fescue plots is influenced by duration of cattle manure application (4–12 weeks) and manure application strategy (none, weekly application of 1.4 kg/plot, and monthly application at 5.6 kg/plot). Additional analyses were performed to relate runoff quality to the timing of sample collection. The study was conducted at the University of Kentucky Maine Chance Agricultural Experiment Station north of Lexington. Plots (2.4 m wide by 6.1 m long) were constructed and established in Kentucky 31 fescue (Festuca arundinacea Schreb.) to represent pasture. Grazing was simulated by application of beef cattle manure to the plots. Runoff was generated by applying simulated rainfall approximately 4, S and 12 weeks following initiation of manure application. Runoff samples were collected and analyzed according to standard methods for nitrogen (N), phosphorus (P) and fecal coliforms (FC). Runoff concentrations of N and P from manure‐treated plots were low and generally not consistently different from control plot concentrations or related to manure application strategy. Runoff FC concentrations from manure‐treated plots were higher than from control plot concentrations. Runoff concentrations of ammonia N, total Kjeldahl N, ortho‐P and FC decreased approximately exponentially in response to increasing time of sample collection. These findings suggest that manure deposition on well‐managed pasture at the rates used in this study might have a negligible impact on nutrient content of runoff.  相似文献   
129.
Reproduction in the sea pen Pennatula phosphorea Linnaeus 1758 was investigated in a population located in southern Loch Linnhe, west Scotland. This was accomplished through analysis of trends in oocyte size-frequency distribution and fecundity over a 12-month period. Pennatula phosphorea is dioecious and the study population exhibited a sex ratio of 1:1. Oogenesis in female P. phosphorea is characterised by the maintenance of a large pool of small oocytes throughout the year of which a small proportion (<30%) mature synchronously and are broadcast-spawned during the summer months of July and/or August. Although spawning occurs annually, the duration of oogenesis exceeds 12 months. Initial oocyte generation is best described as ‘quasi-continuous’ as it may be suppressed during winter. The timing and periodicity of oogenesis and spawning may be related to seasonal environmental cues and it is proposed that annual spawning constitutes a brief and synchronous event. Fecundity is high in P. phosphorea, typically up to 50 oocytes per polyp and 40,000 oocytes per colony in medium to large colonies. Although mean polyp fecundity increased with colony size (axial rod length) there was no seasonal fluctuation in this measure of relative fecundity. Since only a small proportion of oocytes present are spawned each year, the present study advises caution when making inferences regarding the seasonal output of viable oocytes, especially on occasions where the definition of fecundity or the details of the oogenic cycle of a species are unclear. Pennatula phosphorea produces large oocytes (>500 μm), indicative of the production of lecithotrophic larvae; this may confer certain advantages with respect to larval longevity and survival.  相似文献   
130.
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