全文获取类型
收费全文 | 251篇 |
免费 | 121篇 |
国内免费 | 22篇 |
专业分类
安全科学 | 10篇 |
废物处理 | 1篇 |
环保管理 | 3篇 |
综合类 | 66篇 |
基础理论 | 292篇 |
污染及防治 | 11篇 |
评价与监测 | 3篇 |
社会与环境 | 3篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 47篇 |
2017年 | 25篇 |
2016年 | 26篇 |
2015年 | 30篇 |
2014年 | 39篇 |
2013年 | 40篇 |
2012年 | 21篇 |
2011年 | 34篇 |
2010年 | 27篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 14篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1995年 | 2篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有394条查询结果,搜索用时 15 毫秒
151.
Atlantic sturgeon (Acipenser oxyrhynchus) populations have been declared either endangered or threatened under the U.S. Endangered Species Act. Effective measures to repel sturgeon from fishing gear would be beneficial to both fish and fishers because they could reduce both fishery‐associated mortality and the need for seasonal and area closures of specific fisheries. Some chondrostean fishes (e.g., sturgeons and paddlefishes) can detect weak electric field gradients (possibly as low as 5 Μv/cm) due to arrays of electroreceptors (ampullae of Lorenzini) on their snout and gill covers. Weak electric fields, such as those produced by electropositive metals (typically mixtures of the lanthanide elements), could therefore potentially be used as a deterrent. To test this idea, we recorded the behavioral responses of juvenile Atlantic sturgeon (31–43 cm fork length) to electropositive metal (primarily a mixture of the lanthanide elements neodymium and praseodymium) both in the presence and absence of food stimuli. Trials were conducted in an approximately 2.5 m diameter × 0.3 m deep tank, and fish behaviors were recorded with an overhead digital video camera. Video records were subsequently digitized (x, y coordinate system), the distance between the fish and the electropositive metal calculated, and data summarized by compiling frequency distributions with 5‐cm bins. Juvenile sturgeon showed clear avoidance of electropositive metal but only when food was present. On the basis of our results, we conclude that the electropositive metals, or other sources of weak electric fields, may eventually be used to reduce the interactions of Atlantic sturgeon with fishing gear, but further investigation is needed. El Potencial del Metal Electropositivo para Reducir las Interacciones del Esturión Atlántico con Instrumentos de Pesca Bouyoucos, Bushnell & Brill 13–003 相似文献
152.
T. H. Galligan M. A. Taggart R. J. Cuthbert D. Svobodova J. Chipangura D. Alderson V. M. Prakash V. Naidoo 《Conservation biology》2016,30(5):1122-1127
The nonsteroidal anti‐inflammatory drug (NSAID) diclofenac is highly toxic to Gyps vultures, and its recent widespread use in South Asia caused catastrophic declines in at least 3 scavenging raptors. The manufacture of veterinary formulations of diclofenac has since been banned across the region with mixed success. However, at least 12 other NSAIDs are available for veterinary use in South Asia. Aceclofenac is one of these compounds, and it is known to metabolize into diclofenac in some mammal species. The metabolic pathway of aceclofenac in cattle, the primary food of vultures in South Asia, is unknown. We gave 6 cattle the recommended dose of aceclofenac (2 mg/kg), collected blood thereafter at intervals for up to 12 h, and used liquid chromatography with mass spectrometry in a pharmacokinetic analysis of aceclofenac and diclofenac in the plasma. Nearly all the aceclofenac administered to the cattle was very rapidly metabolized into diclofenac. At 2 h, half the aceclofenac had been converted into diclofenac, and at 12 h four‐fifths of the aceclofenac had been converted into diclofenac. Therefore, administering aceclofenac to livestock poses the same risk to vultures as administering diclofenac to livestock. This, coupled with the risk that aceclofenac may replace diclofenac in the veterinary market, points to the need for an immediate ban on all aceclofenac formulations that can be used to treat livestock. Without such a ban, the recovery of vultures across South Asia will not be successful. 相似文献
153.
154.
C.R.M. Attard L.M. Möller M. Sasaki M.P. Hammer C.M. Bice C.J. Brauer D.C. Carvalho J.O. Harris L.B. Beheregaray 《Conservation biology》2016,30(5):1060-1069
Research in reintroduction biology has provided a greater understanding of the often limited success of species reintroductions and highlighted the need for scientifically rigorous approaches in reintroduction programs. We examined the recent genetic‐based captive‐breeding and reintroduction literature to showcase the underuse of the genetic data gathered. We devised a framework that takes full advantage of the genetic data through assessment of the genetic makeup of populations before (past component of the framework), during (present component), and after (future component) captive‐breeding and reintroduction events to understand their conservation potential and maximize their success. We empirically applied our framework to two small fishes: Yarra pygmy perch (Nannoperca obscura) and southern pygmy perch (Nannoperca australis). Each of these species has a locally adapted and geographically isolated lineage that is endemic to the highly threatened lower Murray–Darling Basin in Australia. These two populations were rescued during Australia's recent decade‐long Millennium Drought, when their persistence became entirely dependent on captive‐breeding and subsequent reintroduction efforts. Using historical demographic analyses, we found differences and similarities between the species in the genetic impacts of past natural and anthropogenic events that occurred in situ, such as European settlement (past component). Subsequently, successful maintenance of genetic diversity in captivity—despite skewed brooder contribution to offspring—was achieved through carefully managed genetic‐based breeding (present component). Finally, genetic monitoring revealed the survival and recruitment of released captive‐bred offspring in the wild (future component). Our holistic framework often requires no additional data collection to that typically gathered in genetic‐based breeding programs, is applicable to a wide range of species, advances the genetic considerations of reintroduction programs, and is expected to improve with the use of next‐generation sequencing technology. 相似文献
155.
MARTIN DALLIMER DUGALD TINCH NICK HANLEY KATHERINE N. IRVINE JAMES R. ROUQUETTE PHILIP H. WARREN LORRAINE MALTBY KEVIN J. GASTON PAUL R. ARMSWORTH 《Conservation biology》2014,28(2):404-413
Given that funds for biodiversity conservation are limited, there is a need to understand people's preferences for its different components. To date, such preferences have largely been measured in monetary terms. However, how people value biodiversity may differ from economic theory, and there is little consensus over whether monetary metrics are always appropriate or the degree to which other methods offer alternative and complementary perspectives on value. We used a choice experiment to compare monetary amounts recreational visitors to urban green spaces were willing to pay for biodiversity enhancement (increases in species richness for birds, plants, and aquatic macroinvertebrates) with self‐reported psychological gains in well‐being derived from visiting the same sites. Willingness‐to‐pay (WTP) estimates were significant and positive, and respondents reported high gains in well‐being across 3 axes derived from environmental psychology theories (reflection, attachment, continuity with past). The 2 metrics were broadly congruent. Participants with above‐median self‐reported well‐being scores were willing to pay significantly higher amounts for enhancing species richness than those with below‐median scores, regardless of taxon. The socio‐economic and demographic background of participants played little role in determining either their well‐being or the probability of choosing a paying option within the choice experiment. Site‐level environmental characteristics were only somewhat related to WTP, but showed strong associations with self‐reported well‐being. Both approaches are likely to reflect a combination of the environmental properties of a site and unobserved individual preference heterogeneity for the natural world. Our results suggest that either metric will deliver mutually consistent results in an assessment of environmental preferences, although which approach is preferable depends on why one wishes to measure values for the natural world. Preferencias de Cuantificación para el Mundo Natural Usando Estudios de Valor Monetario y No Monetario. 相似文献
156.
T. R. McClanahan N. A. J. Graham M. A. MacNeil J. E. Cinner 《Conservation biology》2015,29(2):409-417
The failure of fisheries management among multispecies coral reef fisheries is well documented and has dire implications for the 100 million people engaged in these small‐scale operations. Weak or missing management institutions, a lack of research capacity, and the complex nature of these ecosystems have heralded a call for ecosystem‐based management approaches. However, ecosystem‐based management of coral reef fisheries has proved challenging due to the multispecies nature of catches and the diversity of fish functional roles. We used data on fish communities collected from 233 individual sites in 9 western Indian Ocean countries to evaluate changes in the site's functional composition and associated life‐history characteristics along a large range of fish biomass. As biomass increased along this range, fish were larger and grew and matured more slowly while the abundance of scraping and predatory species increased. The greatest changes in functional composition occurred below relatively low standing stock biomass (<600 kg/ha); abundances of piscivores, apex predators, and scraping herbivores were low at very light levels of fishing. This suggests potential trade‐offs in ecosystem function and estimated yields for different management systems. Current fishing gear and area restrictions are not achieving conservation targets (proposed here as standing stock biomass of 1150 kg/ha) and result in losses of life history and ecological functions. Fish in reefs where destructive gears were restricted typically had very similar biomass and functions to young and low compliance closures. This indicates the potentially important role of fisheries restrictions in providing some gains in biomass and associated ecological functions when fully protected area enforcement potential is limited and likely to fail. Our results indicate that biomass alone can provide broad ecosystem‐based fisheries management targets that can be easily applied even where research capacity and information is limited. Of particular value, is our finding that current management tools may be used to reach key ecosystem‐based management targets, enabling ecosystem‐based management in many socioeconomic contexts. 相似文献
157.
Incentivizing biodiversity conservation in artisanal fishing communities through territorial user rights and business model innovation 下载免费PDF全文
C. Josh Donlan 《Conservation biology》2015,29(4):1076-1085
Territorial user rights for fisheries are being promoted to enhance the sustainability of small‐scale fisheries. Using Chile as a case study, we designed a market‐based program aimed at improving fishers’ livelihoods while incentivizing the establishment and enforcement of no‐take areas within areas managed with territorial user right regimes. Building on explicit enabling conditions (i.e., high levels of governance, participation, and empowerment), we used a place‐based, human‐centered approach to design a program that will have the necessary support and buy‐in from local fishers to result in landscape‐scale biodiversity benefits. Transactional infrastructure must be complex enough to capture the biodiversity benefits being created, but simple enough so that the program can be scaled up and is attractive to potential financiers. Biodiversity benefits created must be commoditized, and desired behavioral changes must be verified within a transactional context. Demand must be generated for fisher‐created biodiversity benefits in order to attract financing and to scale the market model. Important design decisions around these 3 components—supply, transactional infrastructure, and demand—must be made based on local social‐ecological conditions. Our market model, which is being piloted in Chile, is a flexible foundation on which to base scalable opportunities to operationalize a scheme that incentivizes local, verifiable biodiversity benefits via conservation behaviors by fishers that could likely result in significant marine conservation gains and novel cross‐sector alliances. Incentivar la Conservación de la Biodiversidad con Comunidades de Pesca Artesanal por medio de Derechos de Uso Territorial y la Innovación de Modelos de Negocio 相似文献
158.
KATHARINE R. E. SIMS JENNIFER M. ALIX‐GARCIA ELIZABETH SHAPIRO‐GARZA LEAH R. FINE VOLKER C. RADELOFF GLEN ARONSON SELENE CASTILLO CARLOS RAMIREZ‐REYES PATRICIA YAÑEZ‐PAGANS 《Conservation biology》2014,28(5):1151-1159
Natural resource managers are often expected to achieve both environmental protection and economic development even when there are fundamental trade‐offs between these goals. Adaptive management provides a theoretical structure for program administrators to balance social priorities in the presence of trade‐offs and to improve conservation targeting. We used the case of Mexico's federal Payments for Hydrological Services program (PSAH) to illustrate the importance of adaptive management for improving program targeting. We documented adaptive elements of PSAH and corresponding changes in program eligibility and selection criteria. To evaluate whether these changes resulted in enrollment of lands of high environmental and social priority, we compared the environmental and social characteristics of the areas enrolled in the program with the characteristics of all forested areas in Mexico, all areas eligible for the program, and all areas submitted for application to the program. The program successfully enrolled areas of both high ecological and social priority, and over time, adaptive changes in the program's criteria for eligibility and selection led to increased enrollment of land scoring high on both dimensions. Three factors facilitated adaptive management in Mexico and are likely to be generally important for conservation managers: a supportive political environment, including financial backing and encouragement to experiment from the federal government; availability of relatively good social and environmental data; and active participation in the review process by stakeholders and outside evaluators. Mejorando los Objetivos Ambiental y Social Mediante el Manejo Adaptativo en el Programa de Pagos por Servicios Hidrológicos en México 相似文献
159.
Two cases of amniotic fluid cell cultures are reported, where a familial, non-heterochromatic 9p+ variant has been found. 相似文献
160.
Trisomy 9 syndrome is a rare chromosomal anomaly associated with specific patterns of multisystem dysmorphism and occasional central nervous system (CNS) malformations, the most common being the Dandy-Walker malformation. Milder anomalies are usually seen with trisomy 9 mosaicism. We report what we believe to be the first case of a baby with an isolated Dandy-Walker malformation which was diagnosed prenatally and was subsequently found to have a trisomy 9 mosaic syndrome. 相似文献