全文获取类型
收费全文 | 15942篇 |
免费 | 199篇 |
国内免费 | 134篇 |
专业分类
安全科学 | 451篇 |
废物处理 | 584篇 |
环保管理 | 2189篇 |
综合类 | 3088篇 |
基础理论 | 4002篇 |
环境理论 | 10篇 |
污染及防治 | 3917篇 |
评价与监测 | 970篇 |
社会与环境 | 939篇 |
灾害及防治 | 125篇 |
出版年
2022年 | 122篇 |
2021年 | 126篇 |
2020年 | 110篇 |
2019年 | 135篇 |
2018年 | 200篇 |
2017年 | 240篇 |
2016年 | 331篇 |
2015年 | 282篇 |
2014年 | 371篇 |
2013年 | 1335篇 |
2012年 | 476篇 |
2011年 | 632篇 |
2010年 | 506篇 |
2009年 | 569篇 |
2008年 | 636篇 |
2007年 | 665篇 |
2006年 | 627篇 |
2005年 | 504篇 |
2004年 | 488篇 |
2003年 | 499篇 |
2002年 | 434篇 |
2001年 | 543篇 |
2000年 | 424篇 |
1999年 | 243篇 |
1998年 | 199篇 |
1997年 | 192篇 |
1996年 | 208篇 |
1995年 | 216篇 |
1994年 | 208篇 |
1993年 | 205篇 |
1992年 | 215篇 |
1991年 | 203篇 |
1990年 | 204篇 |
1989年 | 175篇 |
1988年 | 152篇 |
1987年 | 132篇 |
1986年 | 157篇 |
1985年 | 158篇 |
1984年 | 160篇 |
1983年 | 162篇 |
1982年 | 156篇 |
1981年 | 162篇 |
1980年 | 151篇 |
1979年 | 145篇 |
1978年 | 108篇 |
1977年 | 121篇 |
1974年 | 109篇 |
1973年 | 91篇 |
1972年 | 107篇 |
1971年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Electrocution on overhead power structures negatively affects avian populations in diverse ecosystems worldwide, contributes to the endangerment of raptor populations in Europe and Africa, and is a major driver of legal action against electric utilities in North America. We investigated factors associated with avian electrocutions so poles that are likely to electrocute a bird can be identified and retrofitted prior to causing avian mortality. We used historical data from southern California to identify patterns of avian electrocution by voltage, month, and year to identify species most often killed by electrocution in our study area and to develop a predictive model that compared poles where an avian electrocution was known to have occurred (electrocution poles) with poles where no known electrocution occurred (comparison poles). We chose variables that could be quantified by personnel with little training in ornithology or electric systems. Electrocutions were more common at distribution voltages (≤33 kV) and during breeding seasons and were more commonly reported after a retrofitting program began. Red‐tailed Hawks (Buteo jamaicensis) (n = 265) and American Crows (Corvus brachyrhynchos) (n = 258) were the most commonly electrocuted species. In the predictive model, 4 of 14 candidate variables were required to distinguish electrocution poles from comparison poles: number of jumpers (short wires connecting energized equipment), number of primary conductors, presence of grounding, and presence of unforested unpaved areas as the dominant nearby land cover. When tested against a sample of poles not used to build the model, our model distributed poles relatively normally across electrocution‐risk values and identified the average risk as higher for electrocution poles relative to comparison poles. Our model can be used to reduce avian electrocutions through proactive identification and targeting of high‐risk poles for retrofitting. Modelo Predictivo del Riesgo de Electrocución de Aves en Líneas Eléctricas Elevadas 相似文献
112.
113.
KEN LONGENECKER YVONNE L. CHAN ROBERT J. TOONEN DAVID B. CARLON TERRY L. HUNT ALAN M. FRIEDLANDER EDWARD E. DEMARTINI 《Conservation biology》2014,28(5):1322-1330
Reef‐fish management and conservation is hindered by a lack of information on fish populations prior to large‐scale contemporary human impacts. As a result, relatively pristine sites are often used as conservation baselines for populations near sites affected by humans. This space‐for‐time approach can only be validated by sampling assemblages through time. We used archaeological remains to evaluate whether the remote, uninhabited Northwestern Hawaiian Islands (NWHI) might provide a reasonable proxy for a lightly exploited baseline in the Main Hawaiian Islands (MHI). We used molecular and morphological techniques to describe the taxonomic and size composition of the scarine parrotfish catches present in 2 archaeological assemblages from the MHI, compared metrics of these catches with modern estimates of reproductive parameters to evaluate whether catches represented by the archaeological material were consistent with sustainable fishing, and evaluated overlap between size structures represented by the archaeological material and modern survey data from the MHI and the NWHI to assess whether a space‐for‐time substitution is reasonable. The parrotfish catches represented by archaeological remains were consistent with sustainable fishing because they were dominated by large, mature individuals whose average size remained stable from prehistoric (AD approximately 1400–1700) through historic (AD 1700–1960) periods. The ancient catches were unlike populations in the MHI today. Overlap between the size structure of ancient MHI catches and modern survey data from the NWHI or the MHI was an order of magnitude greater for the NWHI comparison, a result that supports the validity of using the NWHI parrotfish data as a proxy for the MHI before accelerated, heavy human impacts in modern times. Evidencia Arqueológica de la Validez de Poblaciones de Peces en Arrecifes Sin Explotar como Objetivos de Apoderamiento para Poblaciones Actuales 相似文献
114.
Georgia Mavrommati Kostas Bithas Mark E. Borsuk Richard B. Howarth 《Conservation biology》2016,30(6):1173-1181
In the Anthropocene, coupled human and natural systems dominate and only a few natural systems remain relatively unaffected by human influence. On the one hand, conservation criteria based on areas of minimal human impact are not relevant to much of the biosphere. On the other hand, conservation criteria based on economic factors are problematic with respect to their ability to arrive at operational indicators of well‐being that can be applied in practice over multiple generations. Coupled human and natural systems are subject to economic development which, under current management structures, tends to affect natural systems and cross planetary boundaries. Hence, designing and applying conservation criteria applicable in real‐world systems where human and natural systems need to interact and sustainably coexist is essential. By recognizing the criticality of satisfying basic needs as well as the great uncertainty over the needs and preferences of future generations, we sought to incorporate conservation criteria based on minimal human impact into economic evaluation. These criteria require the conservation of environmental conditions such that the opportunity for intergenerational welfare optimization is maintained. Toward this end, we propose the integration of ecological–biological thresholds into decision making and use as an example the planetary‐boundaries approach. Both conservation scientists and economists must be involved in defining operational ecological–biological thresholds that can be incorporated into economic thinking and reflect the objectives of conservation, sustainability, and intergenerational welfare optimization. 相似文献
115.
116.
117.
Stephen T. Deyrup Laura E. Eckman Eleanor E. Lucadamo Patrick H. McCarthy Jacqueline C. Knapp Scott R. Smedley 《Chemoecology》2014,24(4):145-157
Delphastus catalinae (Horn) is a predatory ladybird beetle (Coccinellidae) commonly used as a biocontrol agent against greenhouse infestation by whiteflies. It belongs to the basal subfamily Microweisinae, a group for which chemical defenses have not been previously investigated. The larval and pupal stages of D. catalinae possess minute secretory hairs that produce droplets containing compounds of both isoprenoid and polyketide origin. Bioassays with the predatory ant Crematogaster lineolata showed both the larval and pupal secretions to be deterrent. Moreover, isolated secretion components, from both classes of compounds, displayed antipredator activity against the ant. Experiments with D. catalinae larvae fed isotopically labeled glucose showed 13C-incorporation into both categories of compounds within the pupal secretion, demonstrating that these antipredator compounds, which differ from the typical nitrogenous defensive molecules of coccinellids, are biosynthesized endogenously. This suggests that the wide use of alkaloids by more derived coccinellids may have arisen after their divergence from the more basal Microweisinae. 相似文献
118.
International trade in exotic pets is an important and increasing driver of biodiversity loss and often compromises the standards required for good animal welfare. We systematically reviewed the scientific and gray literature and used the United Nations Environment Programme ‐ World Conservation Monitoring Centre (UNEP‐WCMC) Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) trade database to establish temporal and geographical trade patterns of live exotic birds, mammals, and reptiles and to describe trends in research, taxonomic representation, and level of threat and legal protection of species traded. Birds were the most species‐rich and abundant class reported in trade; reptiles were second most abundant but unusually the most studied in this context; and mammals were least abundant in trade. Mammalian and reptilian species traded as pets were more likely to be threatened than expected by random. There have been a substantial number of Appendix I listed captive‐bred mammals and birds and wild‐caught birds and reptiles reported in trade to CITES. We identified the Middle East's emerging role as a driver of demand for exotic pets of all taxa alongside the well‐established and increasing role of South America and Southeast Asia in the market. Europe, North America, and the Middle East featured most heavily in trade reports to CITES, whereas trade involving South America and Southeast Asia were given most emphasis in the literature. For effective monitoring of and appropriate response to the international exotic pet trade, it is imperative that the reliability and detail of CITES trade reports improve and that scientific research be directed toward those taxa and locations that are most vulnerable. El Mercado Global de Mascotas Exóticas 2006‐2012 相似文献
119.
JONATHAN M. JESCHKE SVEN BACHER TIM M. BLACKBURN JAIMIE T. A. DICK FRANZ ESSL THOMAS EVANS MIRIJAM GAERTNER PHILIP E. HULME INGOLF KÜHN AGATA MRUGAŁA JAN PERGL PETR PYŠEK WOLFGANG RABITSCH ANTHONY RICCIARDI DAVID M. RICHARDSON AGNIESZKA SENDEK MONTSERRAT VILÀ MARTEN WINTER SABRINA KUMSCHICK 《Conservation biology》2014,28(5):1188-1194
Non‐native species cause changes in the ecosystems to which they are introduced. These changes, or some of them, are usually termed impacts; they can be manifold and potentially damaging to ecosystems and biodiversity. However, the impacts of most non‐native species are poorly understood, and a synthesis of available information is being hindered because authors often do not clearly define impact. We argue that explicitly defining the impact of non‐native species will promote progress toward a better understanding of the implications of changes to biodiversity and ecosystems caused by non‐native species; help disentangle which aspects of scientific debates about non‐native species are due to disparate definitions and which represent true scientific discord; and improve communication between scientists from different research disciplines and between scientists, managers, and policy makers. For these reasons and based on examples from the literature, we devised seven key questions that fall into 4 categories: directionality, classification and measurement, ecological or socio‐economic changes, and scale. These questions should help in formulating clear and practical definitions of impact to suit specific scientific, stakeholder, or legislative contexts. Definiendo el Impacto de las Especies No‐Nativas 相似文献
120.
BEN C. SCHEELE DAVID A. HUNTER LAURA F. GROGAN LEE BERGER JON E. KOLBY MICHAEL S. MCFADDEN GERRY MARANTELLI LEE F. SKERRATT DON A. DRISCOLL 《Conservation biology》2014,28(5):1195-1205
Wildlife diseases pose an increasing threat to biodiversity and are a major management challenge. A striking example of this threat is the emergence of chytridiomycosis. Despite diagnosis of chytridiomycosis as an important driver of global amphibian declines 15 years ago, researchers have yet to devise effective large‐scale management responses other than biosecurity measures to mitigate disease spread and the establishment of disease‐free captive assurance colonies prior to or during disease outbreaks. We examined the development of management actions that can be implemented after an epidemic in surviving populations. We developed a conceptual framework with clear interventions to guide experimental management and applied research so that further extinctions of amphibian species threatened by chytridiomycosis might be prevented. Within our framework, there are 2 management approaches: reducing Batrachochytrium dendrobatidis (the fungus that causes chytridiomycosis) in the environment or on amphibians and increasing the capacity of populations to persist despite increased mortality from disease. The latter approach emphasizes that mitigation does not necessarily need to focus on reducing disease‐associated mortality. We propose promising management actions that can be implemented and tested based on current knowledge and that include habitat manipulation, antifungal treatments, animal translocation, bioaugmentation, head starting, and selection for resistance. Case studies where these strategies are being implemented will demonstrate their potential to save critically endangered species. Intervenciones para Reducir el Riesgo de Extinción en Anfibios Amenazados por la Quitridiomicosis 相似文献