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251.
Understanding interactions between large ships and large whales is important to estimate risks posed to whales by ships. The coastal waters of Alaska are a summer feeding area for humpback whales (Megaptera novaeangliae) as well as a prominent destination for large cruise ships. Lethal collisions between cruise ships and humpback whales have occurred throughout Alaska, including in Glacier Bay National Park (GBNP). Although the National Park Service (NPS) establishes quotas and operating requirements for cruise ships within GBNP in part to minimize ship–whale collisions, no study has quantified ship–whale interactions in the park or in state waters where ship traffic is unregulated. In 2008 and 2009, an observer was placed on ships during 49 different cruises that included entry into GBNP to record distance and bearing of whales that surfaced within 1 km of the ship’s bow. A relative coordinate system was developed in ArcGIS to model the frequency of whale surface events using kernel density. A total of 514 whale surface events were recorded. Although ship–whale interactions were common within GBNP, whales frequently surfaced in front of the bow in waters immediately adjacent to the park (west Icy Strait) where cruise ship traffic is not regulated by the NPS. When ships transited at speeds >13 knots, whales frequently surfaced closer to the ship’s midline and ship’s bow in contrast to speeds slower than 13 knots. Our findings confirm that ship speed is an effective mitigation measure for protecting whales and should be applied to other areas where ship–whale interactions are common.  相似文献   
252.
Under the Canadian Species at Risk Act (SARA), Garry oak (Quercus garryana) ecosystems are listed as “at-risk” and act as an umbrella for over one hundred species that are endangered to some degree. Understanding Garry oak responses to future climate scenarios at scales relevant to protected area managers is essential to effectively manage existing protected area networks and to guide the selection of temporally connected migration corridors, additional protected areas, and to maintain Garry oak populations over the next century. We present Garry oak distribution scenarios using two random forest models calibrated with down-scaled bioclimatic data for British Columbia, Washington, and Oregon based on 1961–1990 climate normals. The suitability models are calibrated using either both precipitation and temperature variables or using only temperature variables. We compare suitability predictions from four General Circulation Models (GCMs) and present CGCM2 model results under two emissions scenarios. For each GCM and emissions scenario we apply the two Garry oak suitability models and use the suitability models to determine the extent and temporal connectivity of climatically suitable Garry oak habitat within protected areas from 2010 to 2099. The suitability models indicate that while 164 km2 of the total protected area network in the region (47,990 km2) contains recorded Garry oak presence, 1635 and 1680 km2 of climatically suitable Garry oak habitat is currently under some form of protection. Of this suitable protected area, only between 6.6 and 7.3% will be “temporally connected” between 2010 and 2099 based on the CGCM2 model. These results highlight the need for public and private protected area organizations to work cooperatively in the development of corridors to maintain temporal connectivity in climatically suitable areas for the future of Garry oak ecosystems.  相似文献   
253.
254.
A screening life cycle assessment (LCA) of tomato ketchup has been carried out. The purpose was to identify ‘hot-spots', that is parts of the life-cycle that are important to the total environmental impact. The system investigated includes agricultural production, industrial refining, packaging, transportation, consumption and waste management. Energy use and emissions were quantified and some of the potential environmental effects assessed. Packaging and food processing were found to be hot-spots for many, but not all, of the impact categories investigated. For primary energy use, the storage time in a refrigerator (household phase) was found to be a critical parameter.  相似文献   
255.
In anaerobic digestion, the production of short-chain fatty acids (SCFAs) can be beneficial or harmful to the overall process, depending on the concentration of accumulated acids. Therefore, the accurate determination of the SCFA concentration in both fresh and stored sludge hydrolysates is important. To select a suitable method for monitoring SCFAs during the anaerobic digestion of sewage sludge, the accuracy of three available analytical methods, including 5 pH point acid titration (TITRA5), gas chromatography (GC), and spectrophotometry, were compared in the present study. The results revealed that TITRA5 and GC displayed better agreement in the achieved measurements and higher precision and accuracy than the spectrophotometric assay, as supported by the application of different statistical models. TITRA5 excelled in titrating unfiltered hydrolysate while simultaneously measuring the alkalinity, whereas the GC method provided detailed information on the contribution of different fatty acids to the total acidity. In contrast, the spectrophotometric assay suffered from many forms of interference, depending on the sample's matrix. SCFA production followed the pattern of enzymatic reactions and fitted the Michaelis-Menten model. In addition to promoting TITRA5 as an accurate and robust analytical tool for routine SCFA analyses, this comparative study also demonstrated the possibility of storing hydrolysate samples at different temperatures and durations without altering the SCFA measurements.  相似文献   
256.
257.
This article presents the results of the first critical examination of time series of riverine nutrient-load data for the entire Baltic Sea drainage area. Water quality data collected by or for the different national environmental agencies were compiled and analysed statistically to identify and remove inconsistent or obviously incorrect observations. Moreover, sampling tours were undertaken to acquire additional information about the present nutrient concentrations in the largest rivers in the study area. Gaps in the time series of approved data were then filled in by employing statistical interpolation and extrapolation methods. Thereafter, the concentration and runoff data were combined to obtain estimates of monthly nutrient loads for the time period 1970–93. The results of the calculations showed that although there had been substantial changes in land use, atmospheric deposition and wastewater treatment in many parts of the study area, the total riverine loads of nitrogen (N) and phosphorus (P) to the Baltic Sea have been fairly constant since 1980, and most likely also since 1970. Moreover, the interannual variation was clearly correlated to the runoff. The mean annual loads for the time period 1980–93 were found to be about 825 000 tonnes N and 41 000 tonnes P, respectively. This implies that (i) several other investigators have strongly underestimated the riverine loads of nutrients, especially the nitrogen, and that (ii) the riverine loads by far exceed the input to the Baltic Sea from other sources, {i.e.} atmospheric deposition, direct emissions from cities and industries along the Baltic Sea coast and nitrogen fixation by marine algae.  相似文献   
258.
Females across many taxa commonly use multiple or complex traits to choose mates. However, the functional significance of multiple or complex signals remains controversial and largely unknown. Different elements of multiple or complex signals may convey independent pieces of information about different aspects of a prospective mate (the “multiple messages” hypothesis). Alternatively, multiple or complex signals could provide redundant information about the same aspect of a prospective mate (the “redundant” or “back-up” signal hypothesis). We investigated these alternatives using spadefoot toads, Scaphiopus couchii. Spadefoot toads primarily use calls to attract their mates, but males also exhibit sexually dimorphic coloration. We investigated whether male coloration is indicative of male size, condition, or infection status by a socially transmitted monogenean flatworm. We found that male coloration and dorsal patterning predicts male size and condition but not infection status. Moreover, when we presented females with a choice between a bright male model and a dark male model, we found that females preferred the bright model. Because aspects of males’ calls are also associated with male size and condition, we conclude that coloration is a potentially redundant indicator of male phenotype. We suggest that coloration could enhance mate choice in conjunction with male calling behavior by providing females with a long distance cue that could enable them to identify prospective mates in a noisy chorus environment where the discrimination of individual calls is often difficult. Generally, such redundant signals may facilitate mate choice by enhancing the quality and accuracy of information females receive regarding prospective mates.  相似文献   
259.
Voluntary corporate environmental initiatives and shareholder wealth   总被引:1,自引:0,他引:1  
Researchers debate whether environmental investments reduce firm value or actually improve financial performance. We provide some compelling evidence on shareholder wealth effects of membership in voluntary environmental programs (VEPs). Companies announcing membership in EPA's Climate Leaders, a program targeting reductions in greenhouse gas emissions, experience significantly negative abnormal stock returns. The price decline is larger in firms with poor corporate governance structures, and for high market-to-book (i.e., high growth) firms. However, firms joining Ceres, a program involving more general environmental commitments, have insignificant announcement returns, as do portfolios of industry rivals. Overall, corporate commitments to reduce greenhouse gas emissions appear to conflict with firm value maximization. This has important implications for policies that rely on voluntary initiatives to address climate change. Further, we find that firms facing climate-related shareholder resolutions or firms with weak corporate governance standards – giving managers the discretion to make such voluntary environmentally responsible investment decisions – are more likely to join Climate Leaders; decisions that may result in lower firm value.  相似文献   
260.
Extensive aquatic or semi-aquatic production of water spinach (Ipomoea aquatica Forssk.) for human consumption takes place in Southeast Asia. The aim of this study was to assess the concentrations of 38 elements in soil and water spinach cultivated under different degrees of wastewater exposure in Hanoi, Vietnam. The results showed no effect of wastewater use on the overall element concentrations in soil and water spinach. Mean soil concentrations for selected potentially toxic elements at the studied field sites had the following ranges 9.11–18.7 As, 0.333–0.667 Cd, 10.8–14.5 Co, 68–122 Cr, 34.0–62.1 Cu, 29.9–52.8 Ni, 32.5–67.4 Pb, 0.578–0.765 Tl and 99–189 Zn mg kg−1 dry weight (d.w.). In all samples Cd, Pb and Zn soil concentrations were below the Vietnamese Guideline Values (TCVN 7209-2002) for agricultural soils whereas As and Cu exceeded the guideline values. Maximum site element concentrations in water spinach were 0.139 As, 0.032 Cd, 0.135 Cr, 2.01 Cu, 39.1 Fe, 57.3 Mn, 0.16 Ni, 0.189 Pb and 6.01 Zn mg kg−1 fresh weight (f.w.). The site and soil content of organic carbon were found to have high influence on the water spinach element concentrations whereas soil pH and the total soil element concentrations were of less importance. The estimated average daily intake of As, Cd, Cu, Fe, Pb and Zn for adult Vietnamese consumers amounts to <11% of the maximum tolerable intake proposed by FAO/WHO for each element. It is assessed that the occurrence of the investigated elements in water spinach will pose low health risk for the consumers.  相似文献   
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