全文获取类型
收费全文 | 4096篇 |
免费 | 394篇 |
国内免费 | 275篇 |
专业分类
安全科学 | 330篇 |
废物处理 | 86篇 |
环保管理 | 1055篇 |
综合类 | 1254篇 |
基础理论 | 1269篇 |
环境理论 | 22篇 |
污染及防治 | 151篇 |
评价与监测 | 68篇 |
社会与环境 | 476篇 |
灾害及防治 | 54篇 |
出版年
2024年 | 7篇 |
2023年 | 102篇 |
2022年 | 103篇 |
2021年 | 132篇 |
2020年 | 171篇 |
2019年 | 158篇 |
2018年 | 159篇 |
2017年 | 231篇 |
2016年 | 246篇 |
2015年 | 222篇 |
2014年 | 181篇 |
2013年 | 374篇 |
2012年 | 249篇 |
2011年 | 332篇 |
2010年 | 271篇 |
2009年 | 236篇 |
2008年 | 192篇 |
2007年 | 237篇 |
2006年 | 174篇 |
2005年 | 142篇 |
2004年 | 122篇 |
2003年 | 83篇 |
2002年 | 70篇 |
2001年 | 85篇 |
2000年 | 72篇 |
1999年 | 59篇 |
1998年 | 39篇 |
1997年 | 35篇 |
1996年 | 36篇 |
1995年 | 28篇 |
1994年 | 33篇 |
1993年 | 25篇 |
1992年 | 19篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1971年 | 5篇 |
排序方式: 共有4765条查询结果,搜索用时 15 毫秒
71.
简要介绍了中国的能源供求现状,指出中国能源的两大特征:①煤炭消费为主;②人均消费低、能源利用率低。笔者强调,中国能源对外依存增大,已成为能源输入国;提出逐步调整以煤为主的能源结构,实现能源替代,构建优质化、多元化的能源结构的策略;着重从5个方面进行调整———重点解决石油供不应求的能源结构性矛盾、加强煤炭资源的清洁和优质开发利用、发展以利用洁净煤技术为基础的电力工业、提高核电的比例、加强新能源和可再生能源的开发利用,确保我国能源的安全稳定供应和可持续发展。 相似文献
72.
The concept of substituting bio‐diesel produced from plantations on eroded soils for conventional diesel fuel has gained wide‐spread attention in India. In recent months, the Indian central Government as well as some state governments have expressed their support for bringing marginal lands, which cannot be used for food production, under cultivation for this purpose. Jatropha curcas is a well established plant in India. It produces oil‐rich seeds, is known to thrive on eroded lands, and to require only limited amounts of water, nutrients and capital inputs. This plant offers the option both to cultivate wastelands and to produce vegetable oil suitable for conversion to bio‐diesel. More versatile than hydrogen and new propulsion systems such as fuel cell technology, bio‐diesel can be used in today's vehicle fleets worldwide and may also offer a viable path to sustainable transportation, i.e., lower greenhouse gas emissions and enhanced mobility, even in remote areas. Mitigation of global warming and the creation of new regional employment opportunities can be important cornerstones of any forward looking transportation system for emerging economies. 相似文献
73.
Dalia Streimikiene 《Natural resources forum》2005,29(4):322-333
This article summarizes some of the results from the application of the indicators for sustainable energy development (ISED) tool for analyzing Lithuania's energy sector, in terms of trends, setting energy policy goals and monitoring progress towards these goals. This experience illustrates the potential applicability of the ISED methodology for energy policy development in economies in transition, using Lithuania as an example. The article presents a summary of the results achieved and conclusions arrived at from the analysis of six priority areas in the context of the research project coordinated by the International Atomic Energy Agency, and provides recommendations for the development of sustainable energy policy using the ISED approach. 相似文献
74.
Life cycle energy impacts of automotive liftgate inner 总被引:1,自引:0,他引:1
This paper compares the life cycle energy use of a cast-aluminum, rear liftgate inner and a conventional, stamped steel liftgate inner used in a minivan. Using the best available aggregate life cycle inventory data and a simple spreadsheet-level analysis, energy comparisons were made at both the single-vehicle and vehicle-fleet levels. Since the product manufacture and use are distributed over long periods of time that, in a fleet, are not simple linear combinations of single product life cycles. Thus, it is all the products in use over a period of time, rather than a single product, that are more appropriate for the life cycle analysis. Using a set of consistent data, analyses also examine sensitivity to the level of analysis and the assumptions to determine the most favorable materials with respect to life cycle energy benefits.As expected, life cycle energy impacts of aluminum are lower than steel at a single-vehicle level – energy savings are determined to be 1.8 GJ/vehicle. Most energy savings occur at the vehicle operation phase due to improved fuel economy from lightweighting. The energy benefits are realized only very close to the average vehicle life of 14 years. With the incremental growth of the vehicle fleet, it takes longer – about 21 years – for aluminum to achieve life cycle equivalence with steel. The number of years aluminum needs to achieve equivalence with steel was found to be quite sensitive to aluminum manufacturing energy and fuel economy. As the steel industry races to compete with other materials for automotive lightweighting, a systems approach, instead of part-to-part comparison, is more appropriate in the determination of viability of aluminum substitution from an energy perspective. 相似文献
75.
An interdisciplinary review of current and future approaches to improving human–predator relations
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)
S. Pooley M. Barua W. Beinart A. Dickman G. Holmes J. Lorimer A.J. Loveridge D.W. Macdonald G. Marvin S. Redpath C. Sillero‐Zubiri A. Zimmermann E.J. Milner‐Gulland 《Conservation biology》2017,31(3):513-523
In a world of shrinking habitats and increasing competition for natural resources, potentially dangerous predators bring the challenges of coexisting with wildlife sharply into focus. Through interdisciplinary collaboration among authors trained in the humanities, social sciences, and natural sciences, we reviewed current approaches to mitigating adverse human–predator encounters and devised a vision for future approaches to understanding and mitigating such encounters. Limitations to current approaches to mitigation include too much focus on negative impacts; oversimplified equating of levels of damage with levels of conflict; and unsuccessful technical fixes resulting from failure to engage locals, address hidden costs, or understand cultural (nonscientific) explanations of the causality of attacks. An emerging interdisciplinary literature suggests that to better frame and successfully mitigate negative human–predator relations conservation professionals need to consider dispensing with conflict as the dominant framework for thinking about human–predator encounters; work out what conflicts are really about (they may be human–human conflicts); unravel the historical contexts of particular conflicts; and explore different cultural ways of thinking about animals. The idea of cosmopolitan natures may help conservation professionals think more clearly about human–predator relations in both local and global context. These new perspectives for future research practice include a recommendation for focused interdisciplinary research and the use of new approaches, including human‐animal geography, multispecies ethnography, and approaches from the environmental humanities notably environmental history. Managers should think carefully about how they engage with local cultural beliefs about wildlife, work with all parties to agree on what constitutes good evidence, develop processes and methods to mitigate conflicts, and decide how to monitor and evaluate these. Demand for immediate solutions that benefit both conservation and development favors dispute resolution and technical fixes, which obscures important underlying drivers of conflicts. If these drivers are not considered, well‐intentioned efforts focused on human–wildlife conflicts will fail. 相似文献
76.
Effects of productivity on biodiversity in forest ecosystems across the United States and China
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)
In the global campaign against biodiversity loss in forest ecosystems, land managers need to know the status of forest biodiversity, but practical guidelines for conserving biodiversity in forest management are lacking. A major obstacle is the incomplete understanding of the relationship between site primary productivity and plant diversity, due to insufficient ecosystem‐wide data, especially for taxonomically and structurally diverse forest ecosystems. We investigated the effects of site productivity (the site's inherent capacity to grow timber) on tree species richness across 19 types of forest ecosystems in North America and China through 3 ground‐sourced forest inventory data sets (U.S. Forest Inventory and Analysis, Cooperative Alaska Forest Inventory, and Chinese Forest Management Planning Inventory). All forest types conformed to a consistent and highly significant (P < 0.001) hump‐shaped unimodal relationship, of which the generalized coefficients of determination averaged 20.5% over all the forest types. That is, tree species richness first increased as productivity increased at a progressively slower rate, and, after reaching a maximum, richness started to decline. Our consistent findings suggest that forests of high productivity would sustain few species because they consist mostly of flat homogeneous areas lacking an environmental gradient along which a diversity of species with different habitats can coexist. The consistency of the productivity–biodiversity relationship among the 3 data sets we examined makes it possible to quantify the expected tree species richness that a forest stand is capable of sustaining, and a comparison between the actual species richness and the sustainable values can be useful in prioritizing conservation efforts. 相似文献
77.
We designed 3 image‐based field guides to tropical forest plant species in Ghana, Grenada, and Cameroon and tested them with 1095 local residents and 20 botanists in the United Kingdom. We compared users’ identification accuracy with different image formats, including drawings, specimen photos, living plant photos, and paintings. We compared users’ accuracy with the guides to their accuracy with only their prior knowledge of the flora. We asked respondents to score each format for usability, beauty, and how much they would pay for it. Prior knowledge of plant names was generally low (<22%). With a few exceptions, identification accuracy did not differ significantly among image formats. In Cameroon, users identifying sterile Cola species achieved 46–56% accuracy across formats; identification was most accurate with living plant photos. Botanists in the United Kingdom accurately identified 82–93% of the same Cameroonian species; identification was most accurate with specimens. In Grenada, users accurately identified 74–82% of plants; drawings yielded significantly less accurate identifications than paintings and photos of living plants. In Ghana, users accurately identified 85% of plants. Digital color photos of living plants ranked high for beauty, usability, and what users would pay. Black and white drawings ranked low. Our results show the potential and limitations of the use of field guides and nonspecialists to identify plants, for example, in conservation applications. We recommend authors of plant field guides use the cheapest or easiest illustration format because image type had limited bearing on accuracy; match the type of illustration to the most likely use of the guide for slight improvements in accuracy; avoid black and white formats unless the audience is experienced at interpreting illustrations or keeping costs low is imperative; discourage false‐positive identifications, which were common; and encourage users to ask an expert or use a herbarium for groups that are difficult to identify. Pruebas Empíricas de Guías de Campo de Plantas Hawthorne, Cable & Marshall 相似文献
78.
Giovanni Bernardo Simone D’Alessandro 《Journal of Environmental Planning and Management》2019,62(3):399-423
This article investigates the potential impact of sustainable energy action plans (SEAPs) on local development through a two-step methodology involving participatory planning and quantitative analysis. The first phase relies on a participatory system mapping (PSM) approach and generates a causal structure at the basis of the urban model. In the second phase, we transform the qualitative map into a system dynamic model which evaluates the effect of the SEAP on social, economic and environmental indicators. This methodology was applied to the case of Cascina Municipality (Italy). Through scenario analysis, we show that some indirect feedback can harm the achievement of the 20% emission reduction target. This process allows the local authority and stakeholders to evaluate the impact of emission reduction policies on CO2 emissions and local development, thereby generating collective learning on the systemic implications of the plan. We show that this method can enhance the ambition of emission mitigation efforts by small towns. 相似文献
79.
Athanasios A. Rentizelas Athanasios I. Tolis Ilias P. Tatsiopoulos 《Waste management (New York, N.Y.)》2014,34(1):36-48
Municipal Solid Waste (MSW) disposal has been a controversial issue in many countries over the past years, due to disagreement among the various stakeholders on the waste management policies and technologies to be adopted. One of the ways of treating/disposing MSW is energy recovery, as waste is considered to contain a considerable amount of bio-waste and therefore can lead to renewable energy production. The overall efficiency can be very high in the cases of co-generation or tri-generation. In this paper a model is presented, aiming to support decision makers in issues relating to Municipal Solid Waste energy recovery. The idea of using more fuel sources, including MSW and agricultural residue biomass that may exist in a rural area, is explored. The model aims at optimizing the system specifications, such as the capacity of the base-load Waste-to-Energy facility, the capacity of the peak-load biomass boiler and the location of the facility. Furthermore, it defines the quantity of each potential fuel source that should be used annually, in order to maximize the financial yield of the investment. The results of an energy tri-generation case study application at a rural area of Greece, using mixed MSW and biomass, indicate positive financial yield of investment. In addition, a sensitivity analysis is performed on the effect of the most important parameters of the model on the optimum solution, pinpointing the parameters of interest rate, investment cost and heating oil price, as those requiring the attention of the decision makers. Finally, the sensitivity analysis is enhanced by a stochastic analysis to determine the effect of the volatility of parameters on the robustness of the model and the solution obtained. 相似文献
80.
NÁRGILA G. MOURA ALEXANDER C. LEES ALEXANDRE ALEIXO JOS BARLOW SIDNEI M. DANTAS JOICE FERREIRA MARIA DE FÁTIMA C. LIMA TOBY A. GARDNER 《Conservation biology》2014,28(5):1271-1281
Local, regional, and global extinctions caused by habitat loss, degradation, and fragmentation have been widely reported for the tropics. The patterns and drivers of this loss of species are now increasingly well known in Amazonia, but there remains a significant gap in understanding of long‐term trends in species persistence and extinction in anthropogenic landscapes. Such a historical perspective is critical for understanding the status and trends of extant biodiversity as well as for identifying priorities to halt further losses. Using extensive historical data sets of specimen records and results of contemporary surveys, we searched for evidence of local extinctions of a terra firma rainforest avifauna over 200 years in a 2500 km2 eastern Amazonian region around the Brazilian city of Belém. This region has the longest history of ornithological fieldwork in the entire Amazon basin and lies in the highly threatened Belém Centre of Endemism. We also compared our historically inferred extinction events with extensive data on species occurrences in a sample of catchments in a nearby municipality (Paragominas) that encompass a gradient of past forest loss. We found evidence for the possible extinction of 47 species (14% of the regional species pool) that were unreported from 1980 to 2013 (80% last recorded between 1900 and 1980). Seventeen species appear on the International Union for Conservation of Nature Red List, and many of these are large‐bodied. The species lost from the region immediately around Belém are similar to those which are currently restricted to well‐forested catchments in Paragominas. Although we anticipate the future rediscovery or recolonization of some species inferred to be extinct by our calculations, we also expect that there are likely to be additional local extinctions, not reported here, given the ongoing loss and degradation of remaining areas of native vegetation across eastern Amazonia. Doscientos Años de Extinciones Locales de Aves en la Amazonia Oriental 相似文献