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101.
The US economy annually needs over 4 billion tons of new mineral supplies. The value of domestically produced energy and processed materials of mineral origin exceeds $175 billion annually, but domestic production of both raw and processed minerals is not keeping pace with demand.  相似文献   
102.
The solution with the aid of the hybrid computer of the partial and total differential equations for an integrated surface water groundwater system is described. A versatile computing technique has been developed to make a rapid and accurate study of the groundwater response due to varying inputs (deep percolation) or outputs (evapotranspiration) from the groundwater system. Spatial variations in basic vegetation phenomena, such as pattern, and hydrological parameters, are represented by means of a grid network which also allows the input of variable boundary conditions. The model is applied to an area in Columbia, South America which is subject to high water-table conditions. Various reclamation schemes and management practices under conditions of irrigated agriculture are assessed.  相似文献   
103.
70 beaches in Wales, UK, were investigated with regard to the quality of beach scenery using video panoramas. Beaches were given a score from zero to 20 by a panel of 24 coastal managers (National Park and Heritage Coast Wardens, etc.) and 42 final year Degree or Master of Science students specializing in environmental sciences. Mean scores of coastal managers ranged from 16.1 (Broadhaven, S. Pembrokeshire; 80%) to 3.8 (Prestatyn, North Wales; 19%), while scores of students ranged from 16.0 (Barafundle, S. Pembrokeshire; 80%) to 6.1 (Trecco Bay, Porthcawl; 31%). Wave height, number of people present on the beach and position on the final videotape did not have significant effects on mean scores generated by either group. With both groups a strong preference was observed for undeveloped beaches over those where anthropogenic structures were prominent (p=0.00), but beach commercialization level had an independent effect only on scores from the student group (p=0.02). Cloud cover at time of filming had a significant effect (p=0.00) on scoring, so a correction was applied for final score calculation and ranking. The findings contribute to management of coastal aesthetic resources by providing a quantitative evaluation scheme. It is proposed to use these scores for beach scenery/aesthetic quality in a novel, comprehensive beach rating system.  相似文献   
104.
Summary In all the species of theCataglyphis bicolor group examined yet, i.e.C. bicolor, C. diehli, C. isis, C. nodus, andC. viaticus, 2-methyl-1-hexanol is the characteristic substance and almost the only substance found in the mandibular glands. Its chirality has been determined inC. bicolor and shown to be exclusively (S)-2-methyl-1-hexanol.  相似文献   
105.
This study examined the role of place attachment in determining visitors’ willingness to engage in climate friendly behavior in parks and support for management actions to minimize climate-change impacts. The sample consisted of visitors to Missouri State Parks (n = 1775). Place attachment was measured using 12 items of place identity, place dependence, and social bonding. Exploratory factor analysis of climate friendly behavior items revealed two dimensions: Visit based (i.e., short-term, immediate actions individuals could take during their visit) and Big Picture (i.e., advocacy actions that suggest a long-term engagement with parks). A path analysis demonstrated that the dimensions of place attachment predict climate friendly behavior and support for climate friendly management action in different ways. Specifically, place identity increased climate friendly behavior (big picture) and place dependence increased both climate friendly behavior (visit based) and support for climate friendly management action. Findings from this study provided evidence for the importance of place attachment as a means for engaging visitors in climate-related actions both in and beyond the park setting.  相似文献   
106.
A better understanding of the controls on algae and dissolved O2 in agricultural streams of Illinois is needed to aid in development of nutrient standards. We investigated the relationships between dissolved nutrients, algal abundance, and dissolved O2 in five streams in east-central Illinois from March through November 2004. The streams drained watersheds from 25 to 777 km2 that were dominated by row crop agriculture. Three sites had open canopies and two were bordered by a narrow forest of deciduous trees. Algal abundance was measured as chlorophyll-a (chl-a) concentration in the water column (sestonic) and on the streambed (periphytic). Mean NO3-N concentrations ranged from 5.5 to 8.8 mg N L(-1) and did not relate to algal abundance. Sestonic chl-a values ranged from nearly zero to >15 mg m(-3) with no differences between open and shaded streams and only a weak correlation with dissolved reactive P (mean concentrations were 44-479 microg L(-1)). The results suggest that sestonic chl-a is a poor criterion for assessing nutrient-related problems in these streams. Greatest periphytic chl-a occurred during low flow from August through October, but periphyton occurred consistently in only two of the five streams. The abundance of filamentous algae explained 64% of the variation in diel O2 saturation, but was not correlated with nutrients. Currently it appears that hydrology and light, rather than nutrients, control algal abundance in these streams, and in the agricultural landscape of east-central Illinois, it may not be possible to reduce nutrient concentrations sufficiently to limit filamentous algal blooms.  相似文献   
107.
In an ongoing effort to propose biologically protective nutrient criteria, we examined how total nitrogen (TN) and its forms were associated with macroinvertebrate communities in wadeable streams of Maryland. Taxonomic and functional metrics of an index of biological integrity (IBI) were significantly associated with multiple nutrient measures; however, the highest correlations with nutrients were for ammonia-N and nitrite-N and among macroinvertebrate measures were for Beck’s Biotic Index and its metrics. Since IBI metrics showed comparatively less association, we evaluated how macroinvertebrate taxa related to proposed nutrient criteria previously derived for those same streams instead of developing nutrient–biology thresholds. We identified one tolerant and three intolerant taxa whose occurrence appeared related to a TN benchmark. Individually, these taxa poorly indicated whether streams exceeded the benchmark, but combining taxa notably improved classification rates. We then extracted major physiochemical gradients using principal components analysis to develop models that assessed their influence on nutrient indicator taxa. The response of intolerant taxa was predominantly influenced by a nutrient-forest cover gradient. In contrast, habitat quality had a greater effect on tolerant taxa. When taxa were aggregated into a nutrient sensitive index, the response was primarily influenced by the nutrient-forest gradient. Multiple lines of evidence highlight the effects of excessive nutrients in streams on macroinvertebrate communities and taxa in Maryland, whose loss may not be reflected in metrics that form the basis of biological criteria. Refinement of indicator taxa and a nutrient-sensitive index is warranted before thresholds in aquatic life to water quality are quantified.  相似文献   
108.
Most agricultural information is reported by government sources on a state or county basis. The purpose of this study was to demonstrate use of geospatial data, the 2002 Agricultural Cropland Data Layer (CDL) for the mid-Atlantic region, to characterize agricultural, environmental, and other scientific parameters for the Chincoteague Bay subbasin using geographic information systems. This study demonstrated that agriculture can be characterized accurately on subbasin and subwatershed bases, thus complimenting various assessment technologies. Approximately 28% of the dry land of the subbasin was cropland. Field corn was the largest crop. Soybeans, either singly or double-cropped with wheat, were the second most predominant crop. Although the subbasin is relatively small, cropping practices in the northern part were different from those in the southern portion. Other crops, such as fresh vegetables and vegetables grown for processing, were less than 10% of the total cropland. A conservative approximation of the total pesticide usage in the subbasin in 2002 was over 277,000 lbs of active ingredients. Herbicides represented the most frequently used pesticides in the subbasin, both in number (17) and in total active ingredients (over 261,000 lbs). Ten insecticides predominated in the watershed, while only small quantities of three fungicides were used. Total pesticide usage and intensity were estimated using the CDL. Nutrient inputs to cropland from animal manure, chemical fertilizer, and atmospheric deposition were modeled at over 30 million pounds of nitrogen and over 7 million pounds of phosphorous. Crops under conservation tillage had the largest input of both nutrients.  相似文献   
109.
The issue of planning for sustainability is becoming more established within Canadian municipal planning. As municipalities begin to align their planning policy to reflect a more sustainable approach, there is an increased interest in how sustainability is being operationalised within municipal documents. This research aims to better understand how principles of sustainability are imbedded within Ontario municipal documents, with a specific focus on the Integrated Sustainability Community Planning approach that has emerged in Canada. Drawing on a nested comparative case study of four mid-sized municipalities, we uncover the language and strategies employed by the municipalities as they relate to the principles of sustainability developed by Gibson [2006a. Sustainability assessment: basic components of a practical approach. Impact Assessment and Project Appraisal, 24 (3), 170–182]. The findings suggest that current policy-based approaches to sustainability are considering more socially oriented strategies focused on promoting community involvement, inclusive decision-making, equity, socio-ecological civility, long-term integrative planning, and responsibility through stewardship. However, there are potential limitations that will require future research to examine policy outcomes associated with sustainability uptake. The ICSP approach must still overcome the issues relating to lack of regulatory authority and the incorporation of policies based on popular trends rather than empirical evidence.  相似文献   
110.
Development policy increasingly focuses on building capacities to respond to change (adaptation), and to drive change (innovation). Few studies, however, focus specifically on the social and gender differentiation of capacities to adapt and innovate. We address this gap using a qualitative study in three communities in Solomon Islands; a developing country, where rural livelihoods and well-being are tightly tied to agriculture and fisheries. We find the five dimensions of capacity to adapt and to innovate (i.e. assets, flexibility, learning, social organisation, agency) to be mutually dependant. For example, limits to education, physical mobility and agency meant that women and youth, particularly, felt it was difficult to establish relations with external agencies to access technical support or new information important for innovating or adapting. Willingness to bear risk and to challenge social norms hindered both women’s and men’s capacity to innovate, albeit to differing degrees. Our findings are of value to those aspiring for equitable improvements to well-being within dynamic and diverse social–ecological systems.  相似文献   
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