首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   130篇
  免费   2篇
安全科学   5篇
废物处理   9篇
环保管理   12篇
综合类   33篇
基础理论   27篇
污染及防治   28篇
评价与监测   9篇
社会与环境   9篇
  2023年   1篇
  2022年   3篇
  2021年   3篇
  2020年   2篇
  2019年   2篇
  2018年   5篇
  2017年   10篇
  2016年   7篇
  2015年   11篇
  2014年   12篇
  2013年   5篇
  2012年   7篇
  2011年   8篇
  2010年   6篇
  2009年   9篇
  2008年   6篇
  2007年   6篇
  2006年   2篇
  2005年   7篇
  2004年   5篇
  2003年   3篇
  2002年   2篇
  2001年   2篇
  1997年   1篇
  1992年   2篇
  1986年   2篇
  1983年   1篇
  1979年   1篇
  1971年   1篇
排序方式: 共有132条查询结果,搜索用时 15 毫秒
101.
Several studies on individual physiological traits assume that past records may predict future performance. Marine mollusks, as other animals, show a wide range of between- and within-individual variation of physiological traits. However, in this group, almost nothing is known about the relative influence of genetic factors on that variation. Repeatability (R) is a measure of the consistency of the variation of a trait, which includes its genetic variance and represents the maximum potential value of its heritability (h 2). Traits that show high inter-individual variation and high repeatability levels could potentially evolve through selection (natural or artificial). We estimated the repeatability [using intra-class (τ) and Pearson-moment (r) correlation coefficients] of several physiological traits related to energy acquisition and allocation in juvenile Pacific abalone Haliotis discus hannai, maintained under controlled environment growing systems. In order to estimate the range of the R values and the effect of the time elapsed between measurements on these estimates, we measured these traits monthly during 6 months for each individual. Among the physiological traits, those related to energy allocation like oxygen consumption (standard metabolic rate, SMR) and ammonium excretion rates, and oxygen/nitrogen ratio (O/N), showed intermediate levels of repeatability (0.48, 0.55 and 0.39, respectively), when this was estimated by τ coefficient. However, the r estimation showed that SMR and O/N repeatability were significant and high (0.6–0.7 and 0.5–0.7, respectively) during the first 5 consecutive measurements, decreasing strongly (0.3 and 0.2, respectively) during the last measurement. For ammonia excretion, although repeatability (r) decreased from 0.8 to 0.5 during the 6 consecutive measurements, they remain significant during the experimental period. Therefore, our results indicate that for H. discus hannai juveniles, physiological traits like SMR, ammonia excretion and O/N are significantly repeatable (i.e. good predictors of future measurements) during a period of 4–5 months. These significant repeatability values suggest an important genetic control upon the phenotypic variation of these physiological traits, and could potentially respond to natural or artificial selection, and be used in genetic improvement programs. By contrast, those traits related to energy acquisition (i.e. ingestion, absorption and assimilation) and physiological efficiencies (i.e. net growth and scope for growth) showed very low levels of repeatability (0–0.07). This indicates that the phenotypic variation of these traits would be more influenced by environment rather than by genetic factors.  相似文献   
102.
103.
Human–wildlife conflicts are commonly addressed by excluding, relocating, or lethally controlling animals with the goal of preserving public health and safety, protecting property, or conserving other valued wildlife. However, declining wildlife populations, a lack of efficacy of control methods in achieving desired outcomes, and changes in how people value animals have triggered widespread acknowledgment of the need for ethical and evidence‐based approaches to managing such conflicts. We explored international perspectives on and experiences with human–wildlife conflicts to develop principles for ethical wildlife control. A diverse panel of 20 experts convened at a 2‐day workshop and developed the principles through a facilitated engagement process and discussion. They determined that efforts to control wildlife should begin wherever possible by altering the human practices that cause human–wildlife conflict and by developing a culture of coexistence; be justified by evidence that significant harms are being caused to people, property, livelihoods, ecosystems, and/or other animals; have measurable outcome‐based objectives that are clear, achievable, monitored, and adaptive; predictably minimize animal welfare harms to the fewest number of animals; be informed by community values as well as scientific, technical, and practical information; be integrated into plans for systematic long‐term management; and be based on the specifics of the situation rather than negative labels (pest, overabundant) applied to the target species. We recommend that these principles guide development of international, national, and local standards and control decisions and implementation.  相似文献   
104.
The paper describes the fieldwork at the Italian test site of the abandoned mine of sphalerite and galena in Ingurtosu (Sardinia), with the aim to assess the applicability of a “toolbox” to establish the optimized techniques for remediation of soils contaminated by mining activities. A preliminary characterization—including (hydro)geochemistry, heavy metal concentration and their mobility in soil, bioprospecting for microbiology and botany—provided a data set for the development of a toolbox to deliver a microbially assisted phytoremediation process. Euphorbia pithyusa was selected as an endemic pioneer plant to be associated with a bacterial consortium, established with ten selected native strains, including metal-tolerant bacteria and producers of plant growth factors. The toolbox was firstly assessed in a greenhouse pot experiment. A positive effect of bacterial inoculum on E. pithyusa germination and total plant survival was observed. E. pithyusa showed to be a well-performing metallophyte species, and only inoculated soil retained a microbial activity with a high functional diversity, expanding metabolic affinity also towards root exudates. These results supported the decision to proceed with a field trial, investigating different treatments used singly or in combination: bioaugmentation with bacterial consortia, mycorrhizal fungi and a commercial mineral amendment. Microbial activity in soil, plant physiological parameters and heavy metal content in plants and in soil were monitored. Five months after the beginning, an early assessment of the toolbox under field conditions was carried out. Despite the cold season (October–March), results suggested the following: (1) the field setup as well as the experimental design proved to be effective; (2) plant survival was satisfactory; (3) soil quality was increased and bioaugmentation improved microbial activity, expanding the metabolic competences towards plant interaction (root exudates); and (4) multivariate analysis supported the data provided that the proposed toolbox can be established and the field trial can be carried forward.  相似文献   
105.
Fascination with animals and their behaviour is one the most prominent patterns persisting in all human cultures. During the last decades, however, technological development and public access to the Internet have increased the speed and the extent of information sharing at an unprecedented rate, in some cases even challenging the traditional methods used in science. In order to understand the extent of this influence, we focused on the behaviour of shrikes. Shrikes are an enigmatic group of songbirds with a unique behaviour of impaling prey. We employed an extensive Internet search on YouTube (YT), a very popular and increasingly important source of information worldwide, for videos recording shrikes. Our analyses revealed that the number of shrike videos on YT is strongly positively correlated with classical knowledge on shrikes from books and scientific articles. Our results also suggest that in some cases YT may provide an alternative source of information on shrike ecology and behaviour. YT videos may thus provide new insights into the study of certain species or subjects and help identify gaps in ecological studies, especially in poorly studied species.  相似文献   
106.
The fossil record of Late Cretaceous–Paleogene modern birds in the Southern Hemisphere includes the Maastrichtian Neogaeornis wetzeli from Chile, Polarornis gregorii and Vegavis iaai from Antarctica, and Australornis lovei from the Paleogene of New Zealand. The recent finding of a new and nearly complete Vegavis skeleton constitutes the most informative source for anatomical comparisons among Australornis, Polarornis, and Vegavis. The present contribution includes, for the first time, Vegavis, Polarornis, and Australornis in a comprehensive phylogenetic analysis. This analysis resulted in the recognition of these taxa as a clade of basal Anseriformes that we call Vegaviidae. Vegaviids share a combination of characters related to diving adaptations, including compact and thickened cortex of hindlimb bones, femur with anteroposteriorly compressed and bowed shaft, deep and wide popliteal fossa delimited by a medial ridge, tibiotarsus showing notably proximally expanded cnemial crests, expanded fibular crest, anteroposterior compression of the tibial shaft, and a tarsometatarsus with a strong transverse compression of the shaft. Isolated bones coming from the Cretaceous and Paleogene of South America, Antarctica, and New Zealand are also referred to here to Vegaviidae and support the view that these basal anseriforms were abundant and diverse at high southern latitudes. Moreover, vegaviids represent the first avian lineage to have definitely crossed the K–Pg boundary, supporting the idea that some avian clades were not affected by the end Mesozoic mass extinction event, countering previous interpretations. Recognition of Vegaviidae indicates that modern birds were diversified in southern continents by the Cretaceous and reinforces the hypothesis indicating the important role of Gondwana for the evolutionary history of Anseriformes and Neornithes as a whole.  相似文献   
107.
In the current EU risk assessment for pesticide registration, the European Community requires prediction of the concentration of each pesticide in air. A number of mathematical models are used to assess the fate of pesticides in groundwater, surface water and soil. PELMO 3.20 calculates the volatilization fluxes from bare soil and was improved in the new version PELMO 3.31 to include the effect of temperature and sorption in dry soil. The objective of this study was to evaluate the new version of PELMO 3.31 in predicting the pesticide volatilization under field conditions. Procymidone, malathion, and ethoprophos were the test compounds in two different seasons (autumn and winter). Comparing simulation results obtained with PELMO 3.31, after calibration, with the previous version PELMO 3.20 shows that the estimated volatilization results seems improved for malathion, similar or slightly overestimating in the warmer season for ethoprophos, and similar or slightly underestimating in the colder season for procymidone. The new release of PELMO allows a more accurate estimation of pesticides volatilization from soil as function of meteorological factors, especially for medium or low volatility pesticides. Some difficulties remain, such as the determination of the active air layer and the sorption increment with the soil drying.  相似文献   
108.
ABSTRACT

Aurelia is a jellyfish genus common in coastal and estuarine habitats, that are typically affected by human pressures such as heavy metals contamination. Mercury is one of the most dangerous due to its high toxicity, persistence and bioaccumulation. In this paper, we tested for the first time the independent and combined effects of a level of mercury allowable by European regulation in force and hyposalinity on the asexual reproduction of Aurelia sp. polyps, mirroring a realistic scenario. Both mercury (0.07?µg/L, Maximum Allowable Concentration) and salinity (18 and 23 PSU) and the combination of the two factors stimulated the asexual reproduction increasing the number of polyps and buds during the 41 days of experiments. The increment of the asexual reproduction and the absence of suffering and mortality suggest that levels of mercury below the concentration fixed by the law and hyposalinity conditions could promote jellyfish proliferations, according to the hormesis hypothesis.  相似文献   
109.
110.
The Topolobampo coastal lagoon system, located on the eastern side of the Gulf of California, is a marine zone of considerable economic importance with vessel traffic, dredging operations and aquaculture development. Despite its relevance as a conservation site, this ecosystem has been poorly studied. Since life in marine substrates is abundant, we investigated the capability of tidal hydrodynamics in the lagoon to erode and to accumulate sediment. We calculated the morphodynamics caused by bed load sediment transport applying a two dimensional non-linear hydrodynamic finite difference model. Bed erosion and accretion patterns of sediment (for specific grain size: 170 μm) were determined from the divergence of sediment transport. After a year of numerical simulation of sediment transport the areas of noticeable changes on the bottom of the lagoon have been revealed. Most of sediment accretion took place in the narrow steeped channel connecting the Topolobampo and Ohuira sections. This area appears characterized by the presence of high tidal velocity gradients. Another finding was that accretion areas were coupled with erosion zones in an alternating form. This outcome suggests that sediment do not travel long distances but is deposited nearby the erosion sites. The results are strong evidence of the influence of tidal hydrodynamics on the sediments distribution in the Topolobampo coastal lagoon system and on the generation of substrates where marine life may find protection.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号