全文获取类型
收费全文 | 206篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 6篇 |
废物处理 | 2篇 |
环保管理 | 44篇 |
综合类 | 31篇 |
基础理论 | 77篇 |
环境理论 | 2篇 |
污染及防治 | 40篇 |
评价与监测 | 9篇 |
社会与环境 | 12篇 |
灾害及防治 | 4篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 15篇 |
2015年 | 13篇 |
2014年 | 11篇 |
2013年 | 16篇 |
2012年 | 14篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 13篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有227条查询结果,搜索用时 328 毫秒
101.
Nir Sapir Martin Wikelski Roni Avissar Ran Nathan 《Behavioral ecology and sociobiology》2011,65(7):1353-1365
Understanding departure decisions of migratory birds and the environmental factors affecting them is important for predicting
their distribution, abundance, and arrival times to breeding and wintering areas. In the past, methodological difficulties
to obtain fine-scale bird departure and meteorological data have limited testing the multi-scale effects of meteorology on
bird departure during migration. We investigated departure timing of European bee-eaters (Merops apiaster) staging in southern Israel, identified their departure flight mode (flapping or soaring) using radio telemetry, and measured
local meteorological conditions to study if bird departure was affected by these. Departure timing was examined using a timescale
analysis design. The conditions before, during, and after the time of departure were compared using timescales of 24 h, 6 h,
1 h, and 10 min and in relation to bird flight mode. At the between-days timescale, barometric pressure at departure time
was significantly lower compared with 2–1 day earlier, whereas temperature at departure was significantly higher compared
with 3–2 days earlier. Temperature at departure was also higher compared with 6 h and 3–2 h earlier. Tailwind assistance had
no significant effect at any timescale. Soaring birds departed at significantly higher temperature compared with flapping
birds. We suggest that bee-eater departure is tuned to the infrequent passage of warm atmospheric depressions at the between-days
timescale and with an increasing temperature trend within these days enabling the birds to use energetically cheap soaring
flight. We thus suggest that energetic considerations dictate the departure decisions of migrating European bee-eaters. 相似文献
102.
Jesús M. Avilés Juan J. Soler Nathan S. Hart 《Behavioral ecology and sociobiology》2011,65(9):1721-1730
It has been proposed that the blue-green bird egg colourations of many avian species may constitute a sexually selected female
signal that males can use to modulate their parental investment. A fundamental untested assumption for the validation of this
hypothesis is that males can accurately assess differences in the colour of eggs. A recent review suggests that this could
be particularly problematic when egg clutches were located within a dimly lit nest cavity, due to limitations of the visual
system in low light conditions. Here, we first used a photoreceptor noise-limited model of colour discrimination ability that
accounts for visual performance under low light conditions to study whether a typical cavity-nesting passerine, the spotless
starling Sturnus unicolor, can discriminate their eggs under the ambient illumination in their nest-holes. Secondly, we tested the validity of model
predictions with behavioural data collected in two egg discrimination experiments performed in this species. Estimated egg
detectability depended entirely on model assumptions about visual limitations linked to light intensity. Starlings would not
be able to discriminate egg differences in their nests if the model was based on the assumption that light intensity limited
detectability, whereas they could potentially perceive as different many possible pairwise clutch comparisons if the model
assumption was that light intensity did not limit detectability. Results of behavioural experiments fitted the prediction
of the visual model where light intensity did not limit detectability. Our results suggest that photoreceptor noise-limited
colour models based on stimulation of single photoreceptors cannot, at present, be used to predict egg discrimination ability
in spotless starlings under low light conditions. Future studies aiming to test egg discrimination constraints in the frame
of the sexual selection hypothesis should therefore combine both modelling and behavioural experiments to determine which
are the components of the models that produce the mismatch with the behavioural conditions. 相似文献
103.
William H. Richards ‡ David O. Wallin Nathan H. Schumaker† 《Conservation biology》2002,16(5):1409-1421
104.
John A. Simon Stew Abrams Tim Bradburne Dan Bryant Matthew Burns Daniel Cassidy John Cherry Sheau‐Yun Chiang Douglas Cox Michelle Crimi Elizabeth Denly Bill DiGuiseppi Jim Fenstermacher Stephanie Fiorenza Joseph Guarnaccia Nathan Hagelin Linda Hall John Hesemann Erika Houtz Stephen S. Koenigsberg Francois Lauzon Jeffrey Longsworth Tom Maher Angus McGrath Ravi Naidu Charles J. Newell Beth L. Parker Tadbir Singh Paul Tomiczek Rick Wice 《补救:环境净化治理成本、技术与工艺杂志》2019,29(4):31-48
Sixty leading members of the scientific, engineering, regulatory, and legal communities assembled for the PFAS Experts Symposium in Arlington, Virginia on May 20 and 21, 2019 to discuss issues related to per‐ and polyfluoroalkyl substances (PFAS) based on the quickly evolving developments of PFAS regulations, chemistry and analytics, transport and fate concepts, toxicology, and remediation technologies. The Symposium created a venue for experts with various specialized skills to provide opinions and trade perspectives on existing and new approaches to PFAS assessment and remediation in light of lessons learned managing other contaminants encountered over the past four decades. The following summarizes several consensus points developed as an outcome of the Symposium:
- Regulatory and policy issues: The response by many states and the US Environmental Protection Agency (USEPA) to media exposure and public pressure related to PFAS contamination is to relatively quickly initiate programs to regulate PFAS sites. This includes the USEPA establishing relatively low lifetime health advisory levels for PFAS in drinking water and even more stringent guidance and standards in several states. In addition, if PFAS are designated as hazardous substances at the federal level, as proposed by several Congressional bills, there could be wide‐reaching effects including listing of new Superfund sites solely for PFAS, application of stringent state standards, additional characterization and remediation at existing sites, reopening of closed sites, and cost renegotiation among PRPs.
- Chemistry and analytics: PFAS analysis is confounded by the lack of regulatory‐approved methods for most PFAS in water and all PFAS in solid media and air, interference with current water‐based analytical methods if samples contain high levels of suspended solids, and sample collection and analytical interference due to the presence of PFAS in common consumer products, sampling equipment, and laboratory materials.
- Toxicology and risk: Uncertainties remain related to human health and ecological effects for most PFAS; however, regulatory standards and guidance are being established incorporating safety factors that result in part per trillion (ppt) cleanup objectives. Given the thousands of PFAS that may be present in the environment, a more appropriate paradigm may be to develop toxicity criteria for groups of PFAS rather than individual PFAS.
- Transport and fate: The recalcitrance of many perfluoroalkyl compounds and the capability of some fluorotelomers to transform into perfluoroalkyl compounds complicate conceptual site models at many PFAS sites, particularly those involving complex mixtures, such as firefighting foams. Research is warranted to better understand the physicochemical properties and corresponding transport and fate of most PFAS, of branched and linear isomers of the same compounds, and of the interactions of PFAS with other co‐contaminants such as nonaqueous phase liquids. Many PFAS exhibit complex transport mechanisms, particularly at the air/water interface, and it is uncertain whether traditional transport principles apply to the ppt levels important to PFAS projects. Existing analytical methods are sufficient when combined with the many advances in site characterization techniques to move rapidly forward at selected sites to develop and test process‐based conceptual site models.
- Existing remediation technologies and research: Current technologies largely focus on separation (sorption, ion exchange, or sequestration). Due to diversity in PFAS properties, effective treatment will likely require treatment trains. Monitored natural attenuation will not likely involve destructive reactions, but be driven by processes such as matrix diffusion, sorption, dispersion, and dilution.
105.
A multispecies test of source–sink indicators to prioritize habitat for declining populations
下载免费PDF全文
![点击此处可从《Conservation biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Julie A. Heinrichs Joshua J. Lawler Nathan H. Schumaker Chad B. Wilsey Kira C. Monroe Cameron L. Aldridge 《Conservation biology》2018,32(3):648-659
For species at risk of decline or extinction in source–sink systems, sources are an obvious target for habitat protection actions. However, the way in which source habitats are identified and prioritized can reduce the effectiveness of conservation actions. Although sources and sinks are conceptually defined using both demographic and movement criteria, simplifications are often required in systems with limited data. To assess the conservation outcomes of alternative source metrics and resulting prioritizations, we simulated population dynamics and extinction risk for 3 endangered species. Using empirically based habitat population models, we linked habitat maps with measured site‐ or habitat‐specific demographic conditions, movement abilities, and behaviors. We calculated source–sink metrics over a range of periods of data collection and prioritized consistently high‐output sources for conservation. We then tested whether prioritized patches identified the habitats that most affected persistence by removing them and measuring the population response. Conservation decisions based on different source–sink metrics and durations of data collection affected species persistence. Shorter time series obscured the ability of metrics to identify influential habitats, particularly in temporally variable and slowly declining populations. Data‐rich source–sink metrics that included both demography and movement information did not always identify the habitats with the greatest influence on extinction risk. In some declining populations, patch abundance better predicted influential habitats for short‐term regional persistence. Because source–sink metrics (i.e., births minus deaths; births and immigrations minus deaths and emigration) describe net population conditions and cancel out gross population counts, they may not adequately identify influential habitats in declining populations. For many nonequilibrium populations, new metrics that maintain the counts of individual births, deaths, and movement may provide additional insight into habitats that most influence persistence. 相似文献
106.
Brett G. Dickson Christine M. Albano Ranjan Anantharaman Paul Beier Joe Fargione Tabitha A. Graves Miranda E. Gray Kimberly R. Hall Josh J. Lawler Paul B. Leonard Caitlin E. Littlefield Meredith L. McClure John Novembre Carrie A. Schloss Nathan H. Schumaker Viral B. Shah David M. Theobald 《Conservation biology》2019,33(2):239-249
Conservation practitioners have long recognized ecological connectivity as a global priority for preserving biodiversity and ecosystem function. In the early years of conservation science, ecologists extended principles of island biogeography to assess connectivity based on source patch proximity and other metrics derived from binary maps of habitat. From 2006 to 2008, the late Brad McRae introduced circuit theory as an alternative approach to model gene flow and the dispersal or movement routes of organisms. He posited concepts and metrics from electrical circuit theory as a robust way to quantify movement across multiple possible paths in a landscape, not just a single least-cost path or corridor. Circuit theory offers many theoretical, conceptual, and practical linkages to conservation science. We reviewed 459 recent studies citing circuit theory or the open-source software Circuitscape. We focused on applications of circuit theory to the science and practice of connectivity conservation, including topics in landscape and population genetics, movement and dispersal paths of organisms, anthropogenic barriers to connectivity, fire behavior, water flow, and ecosystem services. Circuit theory is likely to have an effect on conservation science and practitioners through improved insights into landscape dynamics, animal movement, and habitat-use studies and through the development of new software tools for data analysis and visualization. The influence of circuit theory on conservation comes from the theoretical basis and elegance of the approach and the powerful collaborations and active user community that have emerged. Circuit theory provides a springboard for ecological understanding and will remain an important conservation tool for researchers and practitioners around the globe. 相似文献
107.
Ze'ev Gedalof David L. Peterson Nathan J. Mantua 《Journal of the American Water Resources Association》2004,40(6):1579-1592
ABSTRACT: A network of 32 drought sensitive tree‐ring chronologies is used to reconstruct mean water year flow on the Columbia River at The Dalles, Oregon, since 1750. The reconstruction explains 30 percent of the variability in mean water year (October to September) flow, with a large portion of unexplained variance caused by underestimates of the most severe low flow events. Residual statistics from the tree‐ring reconstruction, as well as an identically specified instrumental reconstruction, exhibit positive trends over time. This finding suggests that the relationship between drought and streamflow has changed over time, supporting results from hydrologic models, which suggest that changes in land cover over the 20th Century have had measurable impacts on runoff production. Low pass filtering the flow record suggests that persistent low flows during the 1840s were probably the most severe of the past 250 years, but that flows during the 1930s were nearly as extreme. The period from 1950 to 1987 is anomalous in the context of this record for having no notable multiyear drought events. A comparison of the flow reconstruction to paleorecords of the Pacific Decadal Oscillation (PDO) and El Nino/Southern Oscillation (ENSO) support a strong 20th Century link between large scale circulation and streamflow, but suggests that this link is very weak prior to 1900. 相似文献
108.
Nathan Buras 《Journal of the American Water Resources Association》1985,21(6):1013-1020
Designing a surface reservoir involves the concept of reservoir yield. This concept embodies three basic information items: hydrologic regime, active storage volume, and reservoir release policy. In the actual case presented below, the magnitude of the active storage was prescribed by a legal procedure, so that the planning issue became that of determining the reservoir yield given the hydrological information. A stochastic dynamic programming model was formulated to derive a schedule of seasonal optimal reservoir releases and their respective probabilities of occurrence. This schedule is the reservoir yield. The yearly cycle was divided into three seasons representing the actual climatic conditions, and conditional probabilities linking streamflows in consecutive seasons were estimated. An operating policy was postulated, based on the same set of legal decisions that prescribed the active storage volume, and target reservoir releases were assumed. Similarly, target storages at the end of each season were set up. The optimizing/ minimizing criterion in the dynamic programming formulation was the sum of squares of deviations of actual releases and final storage volumes from their respective targets. 相似文献
109.
Household evacuation characteristics in American Samoa during the 2009 Samoa Islands tsunami
下载免费PDF全文
![点击此处可从《Disasters》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tsunamis represent significant threats to human life and development in coastal communities. This quantitative study examines the influence of household characteristics on evacuation actions taken by 211 respondents in American Samoa who were at their homes during the 29 September 2009 Mw 8.1 Samoa Islands earthquake and tsunami disaster. Multiple logistic regression analysis of survey data was used to examine the association between evacuation and various household factors. Findings show that increases in distance to shoreline were associated with a slightly decreased likelihood of evacuation, whereas households reporting higher income had an increased probability of evacuation. The response in American Samoa was an effective one, with only 34 fatalities in a tsunami that reached shore in as little as 15 minutes. Consequently, future research should implement more qualitative study designs to identify event and cultural specific determinants of household evacuation behaviour to local tsunamis. 相似文献
110.
Sarah Hitchner John Schelhas J. Peter Brosius Nathan P. Nibbelink 《Environmental Communication: A Journal of Nature and Culture》2019,13(3):353-365
For cultures around the world, a journey, particularly one undertaken by foot through landscapes that are simultaneously natural and cultural, is both a metaphor for the discovery of the self and the divine and an embodied practice in the physical realm. Here we analyze twenty-six publicly available blogs of thru-hikers of the John Muir Trail in the Sierra Nevada mountains of California, U.S.A. Cognizant of the critiques of the intrusion of technology into wilderness areas, we examine how the communication medium of travel blogs becomes a vehicle for both self-reflection and for sharing spiritual experiences, and how the act of blogging merges virtual and corporeal communities formed among hikers. It is in the intersection of these social networks and mobile communication technologies that we find suggestions of changing relationships between a subculture of tech-savvy and highly connected hikers sometimes called “flashpackers” and the physical landscapes through which they travel. 相似文献