全文获取类型
收费全文 | 430篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 20篇 |
废物处理 | 18篇 |
环保管理 | 122篇 |
综合类 | 46篇 |
基础理论 | 125篇 |
环境理论 | 3篇 |
污染及防治 | 66篇 |
评价与监测 | 21篇 |
社会与环境 | 17篇 |
灾害及防治 | 10篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 7篇 |
2016年 | 21篇 |
2015年 | 12篇 |
2014年 | 10篇 |
2013年 | 33篇 |
2012年 | 29篇 |
2011年 | 35篇 |
2010年 | 22篇 |
2009年 | 18篇 |
2008年 | 19篇 |
2007年 | 24篇 |
2006年 | 14篇 |
2005年 | 16篇 |
2004年 | 14篇 |
2003年 | 24篇 |
2002年 | 11篇 |
2001年 | 12篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有448条查询结果,搜索用时 125 毫秒
161.
Promiscuous honeybee queens generate colonies with a critical minority of waggle-dancing foragers 总被引:1,自引:1,他引:0
Honeybees present a paradox that is unusual among the social Hymenoptera: extremely promiscuous queens generate colonies of
nonreproducing workers who cooperate to rear reproductives with whom they share limited kinship. Extreme polyandry, which
lowers relatedness but creates within-colony genetic diversity, produces substantial fitness benefits for honeybee queens
and their colonies because of increased disease resistance and workforce productivity. However, the way that these increases
are generated by individuals in genetically diverse colonies remains a mystery. We assayed the foraging and dancing performances
of workers in multiple-patriline and single-patriline colonies to discover how within-colony genetic diversity, conferred
to colonies by polyandrous queens, gives rise to a more productive foraging effort. We also determined whether the initiation
by foragers of waggle-dance signaling in response to an increasing sucrose stimulus (their dance response thresholds) was
linked to patriline membership. Per capita, foragers in multiple-patriline colonies visited a food source more often and advertised
it with more waggle-dance signals than foragers from single-patriline colonies, although there was variability among multiple-patriline
colonies in the strength of this difference. High-participation patrilines emerged within multiple-patriline colonies, but
their more numerous foragers and dancers were neither more active per capita nor lower-threshold dancers than their counterparts
from low-participation patrilines. Our results demonstrate that extreme polyandry does not enhance recruitment effort through
the introduction of low-dance-threshold, high-activity workers into a colony’s population. Rather, genetic diversity is critical
for injecting into a colony’s workforce social facilitators who are more likely to become engaged in foraging-related activities,
so boosting the production of dance signals and a colony’s responsiveness to profitable food sources. 相似文献
162.
Ruchira Sen Heather D. Ishak Trevor R. Kniffin Ulrich G. Mueller 《Behavioral ecology and sociobiology》2010,64(7):1125-1133
Interspecies or intraspecies cooperation can be stabilized evolutionarily if choosing partners favor beneficial partners and
discriminate against non-beneficial partners. We quantified such partner choice (symbiont choice) in the leafcutter ant Atta texana (Attini, Formicidae) by presenting the ants in a cafeteria-style preference assay with genotypically distinct fungal cultivars
from A. texana and Acromyrmex versicolor. Symbiont choice was measured as the ants' tendency to choose one or more cultivar(s) from several pure (axenic) cultivar
fragments and convert a given fungal fragment into a garden. Microsatellite DNA fingerprinting enabled us to identify the
cultivars chosen by the ants for their gardens. In 91% of the choice tests, A. texana workers combined multiple cultivars into a single intercropped, chimaeric garden, and the cultivars coexisted in such chimaeric
gardens for as long as 4 months. Coexistence of distinct fungal genotypes in chimaeric gardens appears to contradict a recent
model of cultivar competition postulating that each cultivar secretes incompatibility compounds harming other cultivars, which
presumably would preclude the intercropped polyculture observed in our experiments. Although we found no clear evidence of
novel, recombinant genotypes in the experimental chimaeric gardens, the intercropping of cultivar genotypes may occasionally
lead under natural conditions to exchange of genetic material between coexisting cultivars, thus introducing novel cultivar
genotypes into the leafcutter symbiosis. Symbiont choice by ants and any competition between coexisting cultivar strains in
chimaeric gardens do not appear to operate fast enough in our laboratory assay to convert chimaeric gardens into the monocultures
observed for A. texana under natural conditions. 相似文献
163.
Hong S. Moon Jason M. Abercrombie Albert P. Kausch C. Neal Stewart Jr. 《Environmental management》2010,46(4):531-538
Done correctly, cellulosic bioenergy should be both environmentally and economically beneficial. Carbon sequestration and
decreased fossil fuel use are both worthy goals in developing next-generation biofuels. We believe that biotechnology will
be needed to significantly improve yield and digestibility of dedicated perennial herbaceous biomass feedstocks, such as switchgrass
and Miscanthus, which are native to the US and China, respectively. This Forum discusses the sustainability of herbaceous feedstocks relative
to the regulation of biotechnology with regards to likely genetically engineered traits. The Forum focuses on two prominent
countries wishing to develop their bioeconomies: the US and China. These two countries also share a political desire and regulatory
frameworks to enable the commercialization and wide release of transgenic feedstocks with appropriate and safe new genetics.
In recent years, regulators in both countries perform regular inspections of transgenic field releases and seriously consider
compliance issues, even though the US framework is considered to be more mature and stringent. Transgene flow continues to
be a pertinent environmental and regulatory issue with regards to transgenic plants. This concern is largely driven by consumer
issues and ecological uncertainties. Regulators are concerned about large-scale releases of transgenic crops that have sexually
compatible crops or wild relatives that can stably harbor transgenes via hybridization and introgression. Therefore, prior
to the commercialization or extensive field testing of transgenic bioenergy feedstocks, we recommend that mechanisms that
ensure biocontainment of transgenes be instituted, especially for perennial grasses. A cautionary case study will be presented
in which a plant’s biology and ecology conspired against regulatory constraints in a non-biomass crop perennial grass (creeping
bentgrass, Agrostis stolonifera), in which biocontainment was not attained. Appropriate technologies that could be applied to perennial grass feedstocks
for biocontainment are discussed. 相似文献
164.
Particle-reactive, naturally occurring radionuclides are useful tracers of the sinking flux of organic matter from the surface to the deep ocean. Since the Joint Global Ocean Flux Study (JGOFS) began in 1987, the disequilibrium between 234Th and its parent 238U has become widely used as a technique to measure particle export fluxes from surface ocean waters. Another radionuclide pair, 210Po and 210Pb, can be used for the same purpose but has not been as widely adopted due to difficulty with accurately constraining the 210Po/210Pb radiochemical balance in the ocean and because of the more time-consuming radiochemical procedures. Direct comparison of particle flux estimated in different ocean regions using these short-lived radionuclides is important in evaluating their utility and accuracy as tracers of particle flux. In this paper, we present paired 234Th/238U and 210Po/210Pb data from oligotrophic surface waters of the subtropical Northwest Atlantic and discuss their advantages and limitations. Vertical profiles of total and particle size-fractionated 210Po and 234Th activities, together with particulate organic carbon (POC) concentrations, were measured during three seasons at the Bermuda Atlantic Time-series Study (BATS) site. Both 210Po and 234Th reasonably predict sinking POC flux caught in sediment traps, and each tracer provides unique information about the magnitude and efficiency of the ocean's biological pump. 相似文献
165.
Simon H Allen DT Wittig AE 《Journal of the Air & Waste Management Association (1995)》2008,58(2):320-343
Emissions inventories of fine particulate matter (PM2.5) were compared with estimates of emissions based on data emerging from U.S. Environment Protection Agency Particulate Matter Supersites and other field programs. Six source categories for PM2.5 emissions were reviewed: on-road mobile sources, nonroad mobile sources, cooking, biomass combustion, fugitive dust, and stationary sources. Ammonia emissions from all of the source categories were also examined. Regional emissions inventories of PM in the exhaust from on-road and nonroad sources were generally consistent with ambient observations, though uncertainties in some emission factors were twice as large as the emission factors. In contrast, emissions inventories of road dust were up to an order of magnitude larger than ambient observations, and estimated brake wear and tire dust emissions were half as large as ambient observations in urban areas. Although comprehensive nationwide emissions inventories of PM2.5 from cooking sources and biomass burning are not yet available, observational data in urban areas suggest that cooking sources account for approximately 5-20% of total primary emissions (excluding dust), and biomass burning sources are highly dependent on region. Finally, relatively few observational data were available to assess the accuracy of emission estimates for stationary sources. Overall, the uncertainties in primary emissions for PM2.s are substantial. Similar uncertainties exist for ammonia emissions. Because of these uncertainties, the design of PM2.5 control strategies should be based on inventories that have been refined by a combination of bottom-up and top-down methods. 相似文献
166.
Phil N. Trathan Pablo García‐Borboroglu Dee Boersma Charles‐André Bost Robert J. M. Crawford Glenn T. Crossin Richard J. Cuthbert Peter Dann Lloyd Spencer Davis Santiago De La Puente Ursula Ellenberg Heather J. Lynch Thomas Mattern Klemens Pütz Philip J. Seddon Wayne Trivelpiece Barbara Wienecke 《Conservation biology》2015,29(1):31-41
Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large‐scale conservation zones are not always practical or politically feasible and other ecosystem‐based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales. Contaminación, Pérdida de Hábitat, Pesca y Cambio Climático como Amenazas Críticas para los Pingüinos 相似文献
167.
Robert F. Herrick James H. Stewart Joseph G. Allen 《Environmental science and pollution research international》2016,23(3):1975-1985
PCBs in building materials such as caulks and sealants are a largely unrecognized source of contamination in the building environment. Schools are of particular interest, as the period of extensive school construction (about 1950 to 1980) coincides with the time of greatest use of PCBs as plasticizers in building materials. In the USA, we estimate that the number of schools with PCB in building caulk ranges from 12,960 to 25,920 based upon the number of schools built in the time of PCB use and the proportion of buildings found to contain PCB caulk and sealants. Field and laboratory studies have demonstrated that PCBs from both interior and exterior caulking can be the source of elevated PCB air concentrations in these buildings, at levels that exceed health-based PCB exposure guidelines for building occupants. Air sampling in buildings containing PCB caulk has shown that the airborne PCB concentrations can be highly variable, even in repeat samples collected within a room. Sampling and data analysis strategies that recognize this variability can provide the basis for informed decision making about compliance with health-based exposure limits, even in cases where small numbers of samples are taken. The health risks posed by PCB exposures, particularly among children, mandate precautionary approaches to managing PCBs in building materials. 相似文献
168.
Artificial intelligence modeling to evaluate field performance of photocatalytic asphalt pavement for ambient air purification 总被引:2,自引:0,他引:2
Somayeh Asadi Marwa Hassan Ataallah Nadiri Heather Dylla 《Environmental science and pollution research international》2014,21(14):8847-8857
In recent years, the application of titanium dioxide (TiO2) as a photocatalyst in asphalt pavement has received considerable attention for purifying ambient air from traffic-emitted pollutants via photocatalytic processes. In order to control the increasing deterioration of ambient air quality, urgent and proper risk assessment tools are deemed necessary. However, in practice, monitoring all process parameters for various operating conditions is difficult due to the complex and non-linear nature of air pollution-based problems. Therefore, the development of models to predict air pollutant concentrations is very useful because it can provide early warnings to the population and also reduce the number of measuring sites. This study used artificial neural network (ANN) and neuro-fuzzy (NF) models to predict NOx concentration in the air as a function of traffic count (Tr) and climatic conditions including humidity (H), temperature (T), solar radiation (S), and wind speed (W) before and after the application of TiO2 on the pavement surface. These models are useful for modeling because of their ability to be trained using historical data and because of their capability for modeling highly non-linear relationships. To build these models, data were collected from a field study where an aqueous nano TiO2 solution was sprayed on a 0.2-mile of asphalt pavement in Baton Rouge, LA. Results of this study showed that the NF model provided a better fitting to NOx measurements than the ANN model in the training, validation, and test steps. Results of a parametric study indicated that traffic level, relative humidity, and solar radiation had the most influence on photocatalytic efficiency. 相似文献
169.
Heather J. Shipley Diana Sokoly Drew W. Johnson 《Environmental monitoring and assessment》2017,189(2):75
PCBs have been banned since the late 1970s, but concentrations still exist in sediments and riverine fish and continue to exceed regulatory limits which can result in negative health effects. This study looks at historical records of PCB and Arochlor concentrations in surface water, sediments, and fish tissue for the Lower Leon Creek, Bexar County in Texas. Temporal analysis on the concentrations of PCBs and Arochlors was conducted for detection and exceedance of selected screening criteria. In addition, the half-lives of select PCB congeners were calculated for 2007–2012 data to ascertain differences in PCB concentrations with their hydrophobicity. Source analysis was conducted to determine the potential contributing sources of PCB contamination using source data (landfills, outfalls, etc.) and the PCB exceedance data. For sediment and fish tissue sampling results, historic data shows high concentrations of PCB/Arochlors over the course of several decades. The historical data is characterized as being widely variable for detections in Arochlors and concentrations between years, with a dramatic drop in concentrations detected starting in 2009. Overall, the sampling locations adjacent to and downstream from the former Kelly Air Force Base have the highest concentrations of PCB/Arochlors over the longest period of time. The results of this work will aid regulatory agencies in addressing impairment. 相似文献
170.
The intracellular concentrations of low-molecular weight carbohydrates and quaternary ammonium compounds present in 26 axenic isolates of unicellular cyanobacteria have been studied over a range of external salinity from freshwater up to 300% seawater (100%=35 S). In all cases, a single carbohydrate, either sucrose or glucosylglycerol, was identified as the principal organic osmoticum, showing major variation in response to the external salt concentration; quaternary ammonium compounds were present in osmotically insignificant amounts. Glucosylglycerol was accumulated as primary osmoticum by nine of the isolates from saline habitats and by five of the freshwater isolates; trace amounts of sucrose were also prsent. The remaining twelve freshwater strains accumulated sucrose as sole osmoticum. Glucosylglycerol-accumulating strains grew over the widest salinity range (up to 200 to 250% seawater), whether isolated from saline or non-saline habitats. Sucrose-accumulating strains were more stenohaline, growing only in up to 50 to 100% seawater and showing no sustained growth in hypersaline media (>100% seawater). The data suggest that (1) glycosylglycerol accumulation is not unique to marine cyanobacteria, and (2) the upper salinity limit for growth may be linked to organic solute accumulation, rather than habitat, with glucosylglycerol-accumulating isolates having a greater potential for growth in salt-stressed conditions than sucrose accumulators. 相似文献