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   280篇
  免费   11篇
  国内免费   3篇
安全科学   14篇
废物处理   4篇
环保管理   58篇
综合类   40篇
基础理论   70篇
污染及防治   68篇
评价与监测   12篇
社会与环境   19篇
灾害及防治   9篇
  2023年   4篇
  2022年   9篇
  2021年   5篇
  2020年   8篇
  2019年   6篇
  2018年   8篇
  2017年   17篇
  2016年   13篇
  2015年   15篇
  2014年   14篇
  2013年   27篇
  2012年   10篇
  2011年   24篇
  2010年   13篇
  2009年   10篇
  2008年   10篇
  2007年   6篇
  2006年   11篇
  2005年   4篇
  2004年   12篇
  2003年   12篇
  2002年   8篇
  2001年   5篇
  2000年   5篇
  1999年   4篇
  1998年   1篇
  1997年   2篇
  1995年   5篇
  1994年   2篇
  1993年   2篇
  1992年   4篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1982年   1篇
  1978年   2篇
  1972年   2篇
  1964年   1篇
  1958年   1篇
排序方式: 共有294条查询结果,搜索用时 125 毫秒
71.
Eradication and control of invasive species are often possible only if populations are detected when they are small and localized. To be efficient, detection surveys should be targeted at locations where there is the greatest risk of incursions. We examine the utility of habitat suitability index (HSI) and particle dispersion models for targeting sampling for marine pests. Habitat suitability index models are a simple way to identify suitable habitat when species distribution data are lacking. We compared the performance of HSI models with statistical models derived from independent data from New Zealand on the distribution of two nonindigenous bivalves: Theora lubrica and Musculista senhousia. Logistic regression models developed using the HSI scores as predictors of the presence/absence of Theora and Musculista explained 26.7% and 6.2% of the deviance in the data, respectively. Odds ratios for the HSI scores were greater than unity, indicating that they were genuine predictors of the presence/ absence of each species. The fit and predictive accuracy of each logistic model were improved when simulated patterns of dispersion from the nearest port were added as a predictor variable. Nevertheless, the combined model explained, at best, 46.5% of the deviance in the distribution of Theora and correctly predicted 56% of true presences and 50% of all cases. Omission errors were between 6% and 16%. Although statistical distribution models built directly from environmental predictors always outperformed the equivalent HSI models, the gain in model fit and accuracy was modest. High residual deviance in both types of model suggests that the distributions realized by Theora and Musculista in the field data were influenced by factors not explicitly modeled as explanatory variables and by error in the environmental data used to project suitable habitat for the species. Our results highlight the difficulty of accurately predicting the distribution of invasive marine species that exhibit low habitat occupancy and patchy distributions in time and space. Although the HSI and statistical models had utility as predictors of the likely distribution of nonindigenous marine species, the level of spatial accuracy achieved with them may be well below expectations for sensitive surveillance programs.  相似文献   
72.
Analysis of shoreline change is often based exclusively upon the littoral cell concept and modelling of hydrodynamic processes. The Futurecoast study has considered fresh approaches to assessing shoreline evolution, which have been used to provide an analysis of future long-term evolution for the entire shoreline of England and Wales. This has been based upon an improved understanding of coastal systems and their behavioural characteristics. The study has included a range of supporting studies, focussing upon maximizing use of existing information and experience. A number of additional data sets have also been produced. The integration of leading expertise from different areas of coastal research to collectively consider this information has been the foundation for the study. The key outputs from this research are: (1) Improved understanding of coastal behaviour; (2) Assessment of future shoreline evolution; (3) Supporting information and data; (4) Delivery of results on an interactive CD-ROM.  相似文献   
73.
74.
Phenoloxidase (PO) is a key enzyme involved in the immune response of insects. We show that egg-to-adult exposure to residues of 0.001, but not 0.0005 mg kg−1 ivermectin elevated PO activity in yellow dung flies (Scathophaga stercoraria) developing in cattle dung. Fly fat content was unaffected by the treatments. Therefore, the response of PO was a direct effect of ivermectin and not an indirect one caused by an alteration in body ‘condition’. This supports the non-intuitive conclusion that flies surviving exposure to faecal residues may have enhanced immune function. To our knowledge, this is the first study to assess the effects on PO activity of insecticidal residues in livestock dung. The non-target effects of such residues are of wide interest, given the global use of veterinary products.  相似文献   
75.
One of the most popular measures of ecological worldview, predicting environmental attitudes and behaviours, is the New Ecological Paradigm (NEP) scale. Since the adoption of the scale for the use among children by Manoli, Johnson and Dunlap in 2007, it has been applied to measure children??s environmental attitudes across cultures. There is however some controversy about the cross-cultural applicability and the relevance of the NEP scale items. The aim of this article is to contribute to the research about environmental views of children from an anthropological view. In the case study, 59 voluntarily participating students aged between ten and 12?years were interviewed in order to learn about their understanding of the NEP items for children. Group discussions were carried out to discover divergent views on the items, followed by in-depth interviews with 15 pupils. The excerpts from these discussions suggest that children experience ambiguity in interpreting the items of the NEP scale. It is concluded that the effective interpretation of scientific facts requires more nuanced and context-specific approach. The author asks for more qualitative, critical probing in addition to the application of the NEP scale in order to get a fuller response and deeper understanding of environmental attitudes of children.  相似文献   
76.
In smelting processes, a large amount of off-gas emission is often generated, which can cause serious environmental and plant hygiene problems if not properly treated. Off-gas cleaning systems extract and treat the hazardous emissions, and ensure that the smelter operation is in accordance with environmental and industrial hygiene regulations. To this end, it is paramount that a well-designed control structure be incorporated into the system. In this work a plantwide control design procedure is applied to an industrial nickel smelter furnace off-gas cleaning system. We first approach the problem by conducting a steady-state analysis based on a nonlinear model of the process, where the objective is to determine how to achieve safe, clean and economic operation in terms of energy consumption. Results reveal that a large amount of energy can be saved by controlling the temperature in the furnace freeboard at its upper bound (active constraint). For the same reason, the temperatures in the two louvers (active constraints) should be controlled at their respective upper bounds so to minimize air intake into the system. The selection of the “unconstrained” variable to be controlled is found by applying the self-optimizing control technique, and the results indicate that a small loss is acceptable when one of the manipulated variables is fixed at its nominal optimal operating point, a highly desirable choice from an operational viewpoint. The bottleneck of the system is identified as the fans' discharge pressures when we allow the feed rate as a degree of freedom. Furthermore, a design change consisting of the installation of an auxiliary air intake in the smelter furnace shows to be a very effective economic alternative to minimize energy consumption. A control structure is then designed where the issue is to keep pressures in the system well within the negative region by determining the configuration of the regulatory and supervisory control layers such that acceptable dynamic performance in face of known, deterministic disturbance is achieved. Nonlinear dynamic simulations are performed to validate the suggested control structure for both modes of operation in the original system and in the proposed design change. The results showed that both regulatory and supervisory designs should make use of the simplicity of decentralized PI control schemes associated with some cascaded configurations so as to boost the disturbance rejection capabilities of the system.  相似文献   
77.
Human activities are accelerating global biodiversity change and have resulted in severely threatened ecosystem services. A large proportion of terrestrial biodiversity is harbored by soil, but soil biodiversity has been omitted from many global biodiversity assessments and conservation actions, and understanding of global patterns of soil biodiversity remains limited. In particular, the extent to which hotspots and coldspots of aboveground and soil biodiversity overlap is not clear. We examined global patterns of these overlaps by mapping indices of aboveground (mammals, birds, amphibians, vascular plants) and soil (bacteria, fungi, macrofauna) biodiversity that we created using previously published data on species richness. Areas of mismatch between aboveground and soil biodiversity covered 27% of Earth's terrestrial surface. The temperate broadleaf and mixed forests biome had the highest proportion of grid cells with high aboveground biodiversity but low soil biodiversity, whereas the boreal and tundra biomes had intermediate soil biodiversity but low aboveground biodiversity. While more data on soil biodiversity are needed, both to cover geographic gaps and to include additional taxa, our results suggest that protecting aboveground biodiversity may not sufficiently reduce threats to soil biodiversity. Given the functional importance of soil biodiversity and the role of soils in human well-being, soil biodiversity should be considered further in policy agendas and conservation actions by adapting management practices to sustain soil biodiversity and considering soil biodiversity when designing protected areas.  相似文献   
78.
Dynamite or "blast" fishing is one of the most immediate and destructive threats to coral reefs worldwide. However, little is known about the long-term ecosystem effects of such blasts or the dynamics of recovery. Here, we examine coral reef recovery in the simplest case of acute single blasts of known age, as well as recovery from chronic blasting over greater spatial and temporal scales. Rubble resulting from single blasts slowly stabilized, and craters filled in with surrounding coral and new colonies. After five years, coral cover within craters no longer differed significantly from control plots. In contrast, extensively bombed areas showed no significant recovery over the six years of this study, despite adequate supply of coral larvae. After extensive blasting, the resulting coral rubble shifts in ocean currents, forming unstable "killing fields" for new recruits. While recently tested rehabilitation methods might be feasible on a small scale, human intervention is unlikely to be effective on large spatial scales, highlighting the need for effective management to prevent blast fishing in the first place.  相似文献   
79.
Dead and deformed grey heron (Ardea cinerea) chicks were reported at a large heronry in North Nottinghamshire, UK between 1996 (when systematic visits to the heronry started) and 2002. Many of the birds died for no obvious reason but deformities in others included multiple fractures of the tarsus and tibia and metacarpal bones (angel wings). This study aimed to investigate possible chemical causes of these deformities. Analysis of eggs and nestling tissue for a range of metals showed no levels of concern and no significant differences between unaffected and deformed birds. However, the levels of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) detected in affected heron nestlings in 2002 and in eggs taken from nests in 2003 were sufficiently high to suggest that this may be the underlying cause of the deformities, possibly due to effects on deposition of calcium in bone. Further work is underway to identify where the parent birds of the affected nestlings are feeding and identify the possible source of the pollution.  相似文献   
80.
Measurements of pollutant gases, airborne particulate matter mass and composition, and meteorology have been made at a core site near downtown Atlanta, GA, since August 1998 in support of the Aerosol Research and Inhalation Epidemiology Study (ARIES). This site is one of eight in the Southeastern Aerosol Research and Characterization network. The measurement objective is to provide a long-term, multivariate dataset suitable for investigating statistical associations of respiratory and cardiovascular disease with airborne particulate matter composition, meteorology, and copollutant gases through epidemiologic modeling. Measurements are expected to continue through 2010. Ancillary multiyear measurements at additional sites in the Atlanta metropolitan area and in short-term exposure assessments have been used to estimate the exposure/measurement error associated with using data from a central site to approximate human exposures for the entire area. To date, 13-, 25-, and 53-month air quality datasets have been used in epidemiologic analyses.  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