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21.
The collapse of the World Trade Center (WTC) on September 11, 2001, generated large amounts of dust and smoke that settled in the surrounding indoor and outdoor environments in southern Manhattan. Sixteen dust samples were collected from undisturbed locations inside two uncleaned buildings that were adjacent to Ground Zero. These samples were analyzed for morphology, metals, and organic compounds, and the results were compared with the previously reported outdoor WTC dust/smoke results. We also analyzed seven additional dust samples provided by residents in the local neighborhoods. The morphologic analyses showed that the indoor WTC dust/smoke samples were similar to the outdoor WTC dust/smoke samples in composition and characteristics but with more than 50% mass in the <53-microm size fraction. This was in contrast to the outdoor samples that contained >50% of mass above >53 microm. Elemental analyses also showed the similarities, but at lower concentrations. Organic compounds present in the outdoor samples were also detected in the indoor samples. Conversely, the resident-provided convenience dust samples were different from either the WTC indoor or outdoor samples in composition and pH, indicating that they were not WTC-affected locations. In summary, the indoor dust/smoke was similar in concentration to the outdoor dust/smoke but had a greater percentage of mass <53 microm in diameter.  相似文献   
22.
Barks of six species of trees were sampled at thirty-nine different locations in Ibadan, Nigeria and were analysed for the trace metals lead, cadmium, cobalt, copper, zinc, manganese, and iron. Lead levels in barks from areas with relatively high traffic density were generally higher than lead levels in barks from areas with low traffic density. The lead level recorded in the high traffic density areas, 40–140 μg/g, is low compared to values reported for barks of trees along busy roads in developed countries. For the other metals, no correlation with traffic density was observed.  相似文献   
23.
The Miombo, the most extensive tropical woodland formation of Africa directly supports the livelihoods of over 100 million people through the provision of many tree products and ecosystem services essential to both the rural and urban communities. While the destruction of the Miombo has often been blamed on the rural communities dwelling near the forest resources, many urban dwellers depend heavily on the various products derived from the woodlands. This paper highlights the importance of the Miombo in the livelihoods of rural people, the potential threats to this ecosystem and opportunities for its sustainable management. About 70% of energy consumed in southern Africa is in the form of fuelwood or charcoal. The economic importance of the Miombo especially from non-timber forest products (NTFPs) is usually understated due to their perceived non-economic value yet they play an important role in sustaining livelihoods of forest dependent people in the miombo ecoregion. The Miombo also contributes to health services through the use of medicinal plant and products, in some cases, contributing up to 80% to rural health, including helping in coping with effects of HIV/AIDS, malaria and several diseases. The possibility of developing payment for environmental services schemes through public–private partnerships, and community-based sustainable management models are proposed. Through conservation and commercialization of some of the products and services, there is a potential to provide income and improve the livelihood of people involved in the trade along the value chain.  相似文献   
24.
In most of sub‐Saharan Africa, where the agricultural sector experiences dismal performance and is characterized by a gloomy picture, the cotton sub‐sector in Côte d’Ivoire is often mentioned as a “success story” given the spectacular rise in the quantity of cotton production and the profile of the crop within the farming system. What are the historical and political antecedents of the development of cotton and the factors responsible for the feat accomplished in the midst of general failures in the same continent? To what extent can cotton be regarded as a “success story” and, what lessons can be drawn for agricultural development strategies based on the Ivorian case study? This paper traces the historical and socio‐political background of cotton development in Côte d’Ivoire and identifies key policy and institutional interventions that have influenced the rise of cotton production and its emergence as the dominant crop in the farming systems of the country. Four stages in Ivorian cotton development are identified: planning, take off, crisis and the renaissance phases. The study demonstrates how a combination of good planning, technological advancement and appropriate policy and institutional conditions have contributed significantly to the rise of cotton production and its influence on the agricultural economy of northern Côte d’Ivoire. The study also highlights how the sustainability of agricultural development has been impacted by domestic and international policies and political events over which smallholder farm families have little control, and can at best only respond to. Important questions about cotton development in Côte d'Ivoire are raised that need to be answered before the program can be categorized conclusively as a success story. The study shows that there are no quick fixes to agricultural development in the sub‐region. Rather, good planning and putting the necessary building blocks in place are important prerequisites. It is recommended that agricultural development efforts in the continent take cognizance of the complexity of the sector and address the inter‐relationships that exist among the technical, policy, market and institutional factors that combine individually and collectively to influence African agriculture.  相似文献   
25.
ABSTRACT

The use of both oxygenated fuels in carbon monoxide (CO) nonattainment areas and reformulated gasoline in ozone nonattainment areas has been mandated by the 1990 Clean Air Act Amendments. Methanol has been proposed as an alternative fuel for CO nonattainment areas. Its use will potentially increase indoor methanol inhalation exposure resulting from the evaporation of metha-nol vapor from methanol-fueled vehicles parked in residential garages. Indoor air concentrations of metha-nol, benzene, and toluene were measured in a residential home with an attached garage. The effects of vehicle emission control devices (charcoal canister hose connection); home heating, ventilation, and air conditioning (HVAC) fans; ambient air, garage, and fuel tank temperatures; and wind speed were examined.

The disconnection of the charcoal canister hose, which simulates a spent evaporative emission control device, resulted in elevated benzene, toluene, and metha-nol concentrations in the garage and attached home. Higher fuel tank temperatures resulted in higher benzene and toluene concentrations in the garage, but not methanol. The concentrations for all compounds in the garage and concentrations of benzene and toluene in the adjacent room were lower when the HVAC fan was on than when it was off, while the concentrations of all three compounds in the rest of the house were higher, although these differences were not statistically significant. Thus, the portion of the population that parks cars in garages attached to homes will experience increased methanol exposures if methanol is used as an automotive fuel.  相似文献   
26.
Cultural management practices that reduce the off-site transport of herbicides applied to row crops are needed to protect surface water quality. A soybean [Glycine max (L.) Merr.] field study was conducted near Stoneville, MS on Sharkey clay to evaluate row spacing (50 cm vs. 100 cm) effects on metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(methoxy-1-methylethyl) acetamide] transport. One day after the foliar application of metolachlor to 2.03 m wide by 2.43 m long plots, 60 mm h(-1) of simulated rainfall was applied until 25 min of runoff was generated per plot. The calculated mass of metolachlor intercepted by the soybean foliage was greater in narrow-row than wide-row soybean, 0.39 kg ha(-1) vs. 0.23 kg ha(-1), respectively. Field and laboratory studies indicated that less than 2% of the metolachlor intercepted by the soybean foliage was available for foliar wash-off 1 d after application. Antecedent soil water content at the start of the simulations was lower in narrow-row soybean. In turn, there was a 1.7-fold greater time to runoff on narrow-row plots. The greater time to runoff likely contributed to lower metolachlor concentration in runoff from narrow-row plots. Cumulative metolachlor losses were significantly greater in wide-row than narrow-row soybean, 3.7% vs. 2.2%, respectively. Findings indicate that narrow-row planting systems may reduce metolachlor runoff following a post-emergence application.  相似文献   
27.
Samanta G  Clifford DA 《Chemosphere》2006,65(5):847-853
Generally, H2SO4, HNO3, HCl or the combination of ethylenediaminetetraacetate with acetic acid (EDTA-HAc) have been used to preserve arsenite and arsenate species prior to analysis. When these acidic preservatives are added in sulfidic water, instantaneous precipitation of poorly crystalline orpiment, As2S3(am), occurs, thereby lowering the total arsenic, As(Tot), analysis. A new method for the determination of As(Tot) was developed in which acid-preserved sulfidic water samples were oxidized with NaOCl, converting As2S3(am) and thioarsenic species to arsenate. A new method was also developed for the separation of uncharged arsenite and charged thioarsenic species in fresh, unpreserved sulfidic water by adsorbing the charged thioarsenic species while allowing uncharged arsenite to pass through a strong-base resin unhindered. The adsorbed thioarsenic species could be eluted efficiently with 0.16 M NaOCl solution.  相似文献   
28.
Experimental investigations were conducted to quantify the volatilization dynamics of blowing agent loss and to examine innovative means to maintain safe worker conditions while simultaneously recovering the auxiliary blowing agent. Methylene chloride-blown polyurethane foams with representative formulations were prepared to determine overall weight loss, auxiliary blowing agent weight loss and foam temperature profiles versus time. Approximately 60 percent of the methylene chloride is lost within the first ten minutes of the process; the residual 40 percent is lost slowly by diffusion over 24 hours. Based on the collected data, a model was developed which predicts tunnel concentrations of methylene chloride as a function of formulation, tunnel length, conveyor speed and air flow. Retrofit of a foam line to isolate the tunnel and drastically reduce exhaust flows will eliminate worker exposure to isocyanates and significantly increase tunnel concentrations of the auxiliary blowing agent. This increase in ambient blowing agent concentration should allow for recovery by conventional means. A project to demonstrate this isolation/concentration/ recovery/recycle strategy is currently underway at a North Carolina foamer.  相似文献   
29.
Almost everyone who has been involved in a site remediation project has seen schedules slip and costs escalate due to political pressure from the public or the press. While focusing on remediation technologies and containment techniques to control costs, many organizations have neglected a major cost driver—public opinion. This article examines community relations from the perspective of an organization trying to control costs during a site remediation project. It details the strong correlation between the cost of a site cleanup and the level of public dissatisfaction and provides an organization with specific strategies on how to use proven communications techniques to lower costs. Examination of several case studies is provided, including a study involving a site in which community representatives actively worked to reduce project costs. It is clear that any responsible cleanup must be protective of public health and the environment. But it is becoming increasingly apparent that wise allocation of available resources has a profound effect on the program's ability to ensure public and environmental safety. In many cases, it has been proven that some costly cleanups—for example, involving excavation—sometimes actually increase risk by creating an exposure pathway where none existed before. In turn, such cleanups waste resources that are needed elsewhere. The challenge in dealing with this complicated issue is to help stakeholders understand the true ramifications of the choices that are faced at each site. If these stakeholders feel uninformed, powerless, or excluded from the process, it is likely that they will be unable to enter a productive discussion. The community relations programs outlined in documents such as a Superfund guidance can be helpful in familiarizing the community with site-related issues and with gathering public input. These activities act as a baseline for the programs discussed in this article. However, existing programs are not focused on providing a strategic advantage in reaching cleanup solutions and balancing health and environmental considerations with economic considerations.  相似文献   
30.
The water from 34 strip mine and 9 livestock water impoundments on the Northern Great Plains was analyzed. In all areas the water was classified as slightly brackish or saline. The dominant ion sequence for the study ponds was Na>Ca>Mg>K and SO4HCO3CO3Cl, which differs from most freshwater by the transposition of Na and SO4. Even though mean concentrations of total filterable residue were consistently greater in strip mine ponds, statistically significant differences were not found at the p ≤ 0.05 level between strip ponds and livestock ponds. The macronutrients of nitrogen and phosphorus found in the ponds were neither limiting to primary productivity nor excessive for fresh water. Many ponds contain turbid water. Turbidity restricts light penetration and limits photosynthesis besides making the ponds visually unattractive. The source of water for the pond, whether surface runoff or groundwater, seems to have important bearing on turbidity. The most appropriate use of these strip mine ponds is for waterfowl, warm-water fisheries, and other wildlife associated with prairie wetlands. However, even these uses are jeopardized by detrimental concentrations of trace elements in the water (Anderson and Hawkes, 1984).  相似文献   
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