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61.
Soil erosion is a severe problem for many developing regions that lack adequate infrastructure to combat the problem. The
authors established a first-order method for prioritizing areas to be examined and remediated using preexisting data and expert
knowledge where data are lacking. The Universal Soil Loss Equation was applied to the Rio Lempa Basin in Central America using
geographic information systems and remote sensing technologies, and the estimated erosion rates were compared with sediment
delivery ratios. Spatial analysis indicates that agriculture on very steep slopes contributes only a small fraction to the
total estimated soil erosion, whereas agriculture on gentle and moderately steep slopes contributes a large fraction of the
erosion. Although much of the basin is in El Salvador, the greatest estimated amount of erosion is from Honduras. Data quality
and availability were impaired by a lack of coordination among agencies and across countries. Several avenues for improving
the authors’ methods are described. 相似文献
62.
Alexander Ziv Ruwim Berkowicz Eugene Genikhovich Finn Palmgren Ekaterina Yakovleva 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):297-310
Since October 1998 two DOAS instruments were installed at the level of the first floor and at the top of a building located in St. Petersburg at Pestelya Street. The collected datacovers the time period of December 1998–March 2001, and include concentrations of benzene, toluene, NO and NO2, ozone and SO2. There is also an additional information about the traffic intensity and meteorological conditions. The results of the analysis of this data set, using the OSPM model, are presented here with the goal to understand the features of the air pollution dispersion in this street canyon and to analyse the information about the emission factors of the vehicles. In particular, the model results are used for the solution of the inverse problem of reconstructing the emission factors from measured concentrations. The results obtained indicate that most of the concentrations are well inside the Russian standards with the only exception of NO2 (mean and 98-th percentile are equal to 57.8 and 119.2 g m-3 for the street level). The same values for benzene are 18.5 and 62.6, respectively. Emission estimates show that there is a possibility that the NOx and benzene basic emission factors recommended by the Russian national guidelines could result in overestimating the traffic emissions. These considerations are supplemented with the model sensitivity tests carried out in connection with the problem of predictability of NO2 concentrations in the street canyon. Tests indicate that NO2 concentrations are not very sensitive to NOx emissions because of the usually low urban background ozone levels. 相似文献
63.
64.
Making sense of the sensemaking perspective: Its constituents,limitations, and opportunities for further development 下载免费PDF全文
Through a wide‐ranging critical review of relevant publications, we explore and articulate what constitutes the sensemaking perspective in organization studies, as well as its range of applications and limitations. More specifically, we argue that sensemaking in organizations has been seen as consisting of specific episodes, is triggered by ambiguous events, occurs through specific processes, generates specific outcomes, and is influenced by several situational factors. Furthermore, we clarify the application range of the sensemaking perspective and identify, as well as account for, the types and aspects of organizational sensemaking that have been under‐researched. We critically discuss the criticism that the sensemaking perspective has received so far and selectively expand on it. Finally, we identify the main limitations of the sensemaking perspective, which, if tackled, will advance it: the neglect of prospective sensemaking, the exclusive focus on disruptive episodes at the expense of more mundane forms of sensemaking implicated in routine activities, the ambiguous status of enactment, the conflation of first‐order and second‐order sensemaking, and the lack of proper attention to embodied sensemaking. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
65.
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67.
D.A. Levaggi J.S. Sandberg M. Feldstein SuzAnne Twiss 《Journal of the Air & Waste Management Association (1995)》2013,63(6):554-559
Extensive chemical analysis of suspended particulate was undertaken by the Bay Area Air Pollution Control District, so that more meaningful interpretation of total mass loading data could be made and more serious problem areas detected. From high-volume samples taken with cellulose paper as the collection medium, analyses were performed for the five heavy metals and nitrate, sulfate, chloride, silicon, and total organics (loss on ignition at 550°C). Two constituents considered primarily nonanthropogenic, silicate and chloride, were evaluated from eight sampling sites. The data were derived from over 600 individual samples, one sample per week per site. The locations have diverse geographical backgrounds, although they lie in a common air basin. For example, a 21 month average for chlorides ranged from 4.2 µ/m3 at San Francisco to 1.7 µg/m3 at Livermorè some 40 miles inland. Inversely, the total silicates increased from 5.7 µg/m3 at San Francisco to 22.6 µg/m3 at Livermore. The silicate values peak strongly in the dry season, with individual 24 hr silicate component values greater than 60 µg/m3 at inland stations. Wind-generated dust from the bare hills of the Coast Range is the most probable source. Since the silicates and chlorides are primarily non-anthropogenic, they were excluded from the TSP values to give a total anthropogenic suspended particulate (TASP). The TASP values for the Bay Area show a geographic distribution in much closer conformity to visibility reduction and citizen complaint than do TSP values. 相似文献
68.
The effect of nitrogen deposition on the species richness of acid grasslands in Denmark: a comparison with a study performed on a European scale 总被引:1,自引:0,他引:1
Damgaard C Jensen L Frohn LM Borchsenius F Nielsen KE Ejrnæs R Stevens CJ 《Environmental pollution (Barking, Essex : 1987)》2011,159(7):1778-1782
The effect of atmospheric nitrogen deposition on the species richness of acid grasslands was investigated by combining data from a large Danish monitoring program with a large European data set, where a significant non-linear negative effect of nitrogen deposition had been demonstrated (Stevens et al., 2010). The nitrogen deposition range in Denmark is relatively small and when only considering the Danish data a non-significant decrease in the species richness with nitrogen deposition was observed. However, when both data sets were combined, then the conclusion of the European survey was further corroborated by the results of the Danish monitoring. Furthermore, by combining the two data sets a more comprehensive picture of the threats to the biodiversity of acid grasslands emerge; i.e., species richness in remnant patches of acid grassland in intensively cultivated agricultural landscapes is under influence not only from nitrogen deposition, but also from current and historical land use. 相似文献
69.
Victoria Hemming Abbey E. Camaclang Megan S. Adams Mark Burgman Katherine Carbeck Josie Carwardine Iadine Chadès Lia Chalifour Sarah J. Converse Lindsay N. K. Davidson Georgia E. Garrard Riley Finn Jesse R. Fleri Jacqueline Huard Helen J. Mayfield Eve McDonald Madden Ilona Naujokaitis-Lewis Hugh P. Possingham Libby Rumpff Michael C. Runge Daniel Stewart Vivitskaia J. D. Tulloch Terry Walshe Tara G. Martin 《Conservation biology》2022,36(1):e13868
Biodiversity conservation decisions are difficult, especially when they involve differing values, complex multidimensional objectives, scarce resources, urgency, and considerable uncertainty. Decision science embodies a theory about how to make difficult decisions and an extensive array of frameworks and tools that make that theory practical. We sought to improve conceptual clarity and practical application of decision science to help decision makers apply decision science to conservation problems. We addressed barriers to the uptake of decision science, including a lack of training and awareness of decision science; confusion over common terminology and which tools and frameworks to apply; and the mistaken impression that applying decision science must be time consuming, expensive, and complex. To aid in navigating the extensive and disparate decision science literature, we clarify meaning of common terms: decision science, decision theory, decision analysis, structured decision-making, and decision-support tools. Applying decision science does not have to be complex or time consuming; rather, it begins with knowing how to think through the components of a decision utilizing decision analysis (i.e., define the problem, elicit objectives, develop alternatives, estimate consequences, and perform trade-offs). This is best achieved by applying a rapid-prototyping approach. At each step, decision-support tools can provide additional insight and clarity, whereas decision-support frameworks (e.g., priority threat management and systematic conservation planning) can aid navigation of multiple steps of a decision analysis for particular contexts. We summarize key decision-support frameworks and tools and describe to which step of a decision analysis, and to which contexts, each is most useful to apply. Our introduction to decision science will aid in contextualizing current approaches and new developments, and help decision makers begin to apply decision science to conservation problems. 相似文献
70.
Zea mays was grown in nutrient solution with different concentrations of sulphite and sulphate (0, 5, and 10 mM) at pH 5 or 7, with or without aeration, for five days. Sulphite injured the plants, especially at low pH. Lack of aeration increased the sulphite injury of the plants at the high pH. in the aerated solutions, sulphite concentrations approached zero after five hours, while the unaerated solutions still contained sulphite after four days. Very little sulphite was found in the plants. The results indicate that the toxicity to the plants of the different chemical species of the sulphite in the solution decreases in the following order: SO2 (aq) > HSO3
– > SO3
2–. 相似文献