全文获取类型
收费全文 | 19850篇 |
免费 | 261篇 |
国内免费 | 178篇 |
专业分类
安全科学 | 674篇 |
废物处理 | 766篇 |
环保管理 | 3004篇 |
综合类 | 2978篇 |
基础理论 | 5330篇 |
环境理论 | 7篇 |
污染及防治 | 5117篇 |
评价与监测 | 1276篇 |
社会与环境 | 995篇 |
灾害及防治 | 142篇 |
出版年
2022年 | 145篇 |
2021年 | 168篇 |
2020年 | 147篇 |
2019年 | 207篇 |
2018年 | 301篇 |
2017年 | 325篇 |
2016年 | 472篇 |
2015年 | 341篇 |
2014年 | 472篇 |
2013年 | 1576篇 |
2012年 | 599篇 |
2011年 | 833篇 |
2010年 | 698篇 |
2009年 | 702篇 |
2008年 | 869篇 |
2007年 | 881篇 |
2006年 | 835篇 |
2005年 | 664篇 |
2004年 | 717篇 |
2003年 | 644篇 |
2002年 | 597篇 |
2001年 | 788篇 |
2000年 | 533篇 |
1999年 | 337篇 |
1998年 | 280篇 |
1997年 | 277篇 |
1996年 | 276篇 |
1995年 | 294篇 |
1994年 | 320篇 |
1993年 | 265篇 |
1992年 | 281篇 |
1991年 | 251篇 |
1990年 | 279篇 |
1989年 | 261篇 |
1988年 | 211篇 |
1987年 | 187篇 |
1986年 | 174篇 |
1985年 | 189篇 |
1984年 | 208篇 |
1983年 | 202篇 |
1982年 | 201篇 |
1981年 | 207篇 |
1980年 | 155篇 |
1979年 | 166篇 |
1978年 | 143篇 |
1977年 | 121篇 |
1975年 | 123篇 |
1974年 | 118篇 |
1973年 | 112篇 |
1972年 | 137篇 |
排序方式: 共有10000条查询结果,搜索用时 943 毫秒
611.
CSIRO Sustainable Ecosystems is constructing a spatially explicit modelling system capable of exploring alternative land and water policy alternatives against plausible price, cost, and climate scenarios for the next 20 years. INSIGHT will be used to identify the likely impacts of land and water policy options on regional economies and structural adjustment. Flowcharts have been constructed for most of the major crop and pasture and associated economic models for commodities produced in the Lachlan River Catchment of New South Wales. This enabled the most important components and interrelationships within these models to be readily identified. The next step has been to construct models at the regional scale that contain the essential elements of the more-detailed point models. The paper describes the progress to date in describing these models, and how they have been integrated into a coordinated agricultural crop production evaluation system. 相似文献
612.
A. P. Altshuller S. L. Kopczynski D. Wilson W. Lonneman F. D. Sutterfield 《Journal of the Air & Waste Management Association (1995)》2013,63(10):791-794
Effects associated with photochemical air pollution were measured during irradiation of n-butane-nitrogen oxide or n-butane-ethane-nitrogen oxide mixtures, with small amounts of propylene or toluene added. The effects measured including nitrogen dioxide and oxidant dosages, yields of formaldehyde and peroxy-acetyl nitrate, and eye irritation response. The results obtained clearly show that beneficial effects result from selective changes in hydrocarbon composition as well as from reduction of total hydrocarbon concenfration. Exclusion of olefins and alkylbenzenes was highly effective in reducing oxidant dosage, formaldehyde and peroxyacetyl nitrate concentrations, and eye irritation response. The only penalty was a modest increase in nitrogen dioxide dosage. A large reduction in nitrogen oxide concentration reduced nitrogen dioxide dosage and eye irritation response, but with the penalty of a large increase in oxidant dosage. The desirability of preferentially reducing olefins and alkylbenzenes rather than paraffinic hydrocarbons, acetylene, and benzene is strongly supported by this study. Research and development efforts should be directed toward preferential hydrocarbon control by mechanical or catalytic control 相似文献
613.
F. Pacifico S.P. Harrison C.D. Jones S. Sitch 《Atmospheric environment (Oxford, England : 1994)》2009,43(39):6121-6135
Biogenic volatile organic compounds (BVOCs) play an important role in atmospheric chemistry and the carbon cycle. Isoprene is quantitatively the most important of the non-methane BVOCs (NMBVOCs), with an annual emission of about 400–600 TgC; about 90% of this is emitted by terrestrial plants. Incorporating a mechanistic treatment of isoprene emissions within land-surface schemes has recently become a focus for the modelling community, the aim being to quantify the potential magnitude of associated climate feedbacks. However, these efforts are hampered by major uncertainties about why plants emit isoprene and the relative importance of different environmental controls on isoprene emission. The availability and reliability of observations of isoprene fluxes from different types of vegetation is limited, and this also imposes constraints on model development. Nevertheless, progress is being made towards the development of mechanistic models of isoprene emission which, in conjunction with atmospheric chemistry models, will ultimately allow improved quantification of the feedbacks between the terrestrial biosphere and climate under past and future climate states. 相似文献
614.
615.
Most of the mitigation measures against natural hazards can not be perfectly allocated via the common market mechanism, given their principle character of being a public good. Thus, different instruments need to be applied to retrieve their values. Economic valuation tools are one alternative to estimate preferences of individuals towards these goods. These methods are often difficult to operationalise and are not a feasible task for every single project. An alternative is offered by direct preference representation through involving affected interest groups actively in decisions. A critical question is whether the decision on protection measures can be left to public participation or should remain in the experts’ decision responsibility. It can be observed that the latter mode shows inefficiencies. In this paper, it is argued that participation could be one way to bring about the desired goal of increasing efficiency. The present work offers a discussion of the relevant political economic concepts in order to introduce the idea that participation can increase efficiency through achieving the Pareto criterion claimed in the realm of constitutional economics. Furthermore it will be shown that decision aiding tools, namely multi-criteria analysis, can integrate participation into actual decision making processes in a structured way. 相似文献
616.
R.D. Fleming J.R. Allsup T.R. French D.E. Eccleston 《Journal of the Air & Waste Management Association (1995)》2013,63(6):451-458
Air pollutants in exhaust gas produced from LP-gas (propane) were studied using both laboratory engines and vehicles. The objective of the study was both to evaluate propane as a low-pollution fuel and to provide information on adjustment of engine parameters for advantageous use of propane as a low-pollution fuel. Variables in the study were air-fuel ratio (A/F), ignition timing schedule, and ambient temperature. Data comparable to that for propane relating A/F and ambient temperature to emissions are shown for natural gas and for gasoline. 相似文献
617.
Igor Linkov Matthew D. Wood Renae Ditmer Anthony Cox Robert Ross 《The Environmentalist》2013,33(3):335-340
Individuals make decisions every day in group contexts which vary in size, structure, and purpose. The US Department of Defense (DoD) is a large organization composed of many groups, and like many organizations, it has a vested interest in improving the performance of its affiliated groups, especially as it concerns risk-informed decision-making. This article discusses current foibles and considerations for decision-making in DoD groups as identified through a workshop with experts in risk-informed decision-making, cognitive science, and military operations. Experts noted that terms associated with risk-informed decision-making were often misconstrued, that formal decision-making frameworks are underutilized, and that many considerations should be taken into account when attempting to improve decision-making performance. 相似文献
618.
JOSEPH D. WHITE KEVIN J. GUTZWILLER WYLIE C. BARROW LORI JOHNSON‐RANDALL LISA ZYGO PAMELA SWINT 《Conservation biology》2011,25(3):536-546
Abstract: Avian conservation efforts must account for changes in vegetation composition and structure associated with climate change. We modeled vegetation change and the probability of occurrence of birds to project changes in winter bird distributions associated with climate change and fire management in the northern Chihuahuan Desert (southwestern U.S.A.). We simulated vegetation change in a process‐based model (Landscape and Fire Simulator) in which anticipated climate change was associated with doubling of current atmospheric carbon dioxide over the next 50 years. We estimated the relative probability of bird occurrence on the basis of statistical models derived from field observations of birds and data on vegetation type, topography, and roads. We selected 3 focal species, Scaled Quail (Callipepla squamata), Loggerhead Shrike (Lanius ludovicianus), and Rock Wren (Salpinctes obsoletus), that had a range of probabilities of occurrence for our study area. Our simulations projected increases in relative probability of bird occurrence in shrubland and decreases in grassland and Yucca spp. and ocotillo (Fouquieria splendens) vegetation. Generally, the relative probability of occurrence of all 3 species was highest in shrubland because leaf‐area index values were lower in shrubland. This high probability of occurrence likely is related to the species’ use of open vegetation for foraging. Fire suppression had little effect on projected vegetation composition because as climate changed there was less fuel and burned area. Our results show that if future water limits on plant type are considered, models that incorporate spatial data may suggest how and where different species of birds may respond to vegetation changes. 相似文献
619.
Roser Rotchs-Ribalta Sara Ruas Karzan D. Ahmed Michael Gormally James Moran Jane Stout Blnaid White Daire
hUallachin 《Ambio》2021,50(2):346
Concerns over the loss of biodiversity and ecosystem services in farmland have prompted the development of agri-environment policy measures aimed at reducing farming pressure and maintaining semi-natural habitats in farmed landscapes. However, further knowledge is needed to guarantee successful agri-environment measures implementation. The current study assessed the quantity and the quality of semi-natural habitats in farms across a gradient of farming intensities in two contrasting regions in Ireland. Policy protection seemed fundamental for semi-natural habitats preservation. Habitats not protected by agricultural policy relied on extensive farming and are in danger of disappearing if they are intensified or abandoned. Due to the lack of policy incentives for habitat quality, no correlations were found between farming intensity and share of semi-natural habitats with habitat quality. Therefore, extensive farming and retention of habitats alone may not reverse the decline of farmland quality and biodiverisity and, thus, measures incentivising the environmental quality may be more successful.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01344-6) contains supplementary material, which is available to authorized users. 相似文献
620.
Sundar Sajimol Chokkalingam Lakshumanan Roy Priyadarsi D. Usha Tune 《Environmental science and pollution research international》2021,28(15):18495-18500
Environmental Science and Pollution Research - Increasing urbanization and anthropogenic activities of the last couple of decades have left significant amounts of plastic debris in both coastal and... 相似文献