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631.
论述土肥基础与持续发展农业的基本内涵和特征;从历史的经验教训、片面发展经济的现实、地力监测的情况等方面,论证了土肥基础对持续发展农业的重要性;分析了广东省土肥基础的现状,提出了一系列加强土肥基础的对策:建立健全有关法规、有计划地扩大耕地面积、加强地力建设、改造中低产田和保护耕地环境等. 相似文献
632.
Enhancement of Farmland Biodiversity within Set-Aside Land 总被引:7,自引:0,他引:7
Abstract: The efficacy of agricultural set-aside policies for protecting farmland biodiversity is widely debated. Based on a meta-analysis of 127 published studies, we found that land withdrawn from conventional production unequivocally enhances biodiversity in North America and Europe. The number of species of birds, insects, spiders, and plants is 1–1.5 standard deviation units higher on set-aside land, and population densities increase by 0.5–1 standard deviation units. Set-aside land may be especially beneficial for desirable taxa because North American bird species that have exhibited population declines react most positively to set-aside agricultural land. Larger and older plots protect more species and higher densities, and set-aside land is more effective in countries with less-intensive agricultural practices and higher fractions of land removed from production. Although policies specifically designed to protect biodiversity might work even better, current incentives clearly improve the standing of plants and animals in farmland. 相似文献
633.
刘红梅 《湖南环境生物职业技术学院学报》2007,13(4):42-44
提升农业职业教育水平和提高农业职业院校办学效益,要本着收益原则与承受能力原则相结合、公平原则与效率原则相结合、确实原则与透明度原则相结合.在对农业高等职业教育成本补偿的现状进行了较为充分的分析研究后,建议通过合理确定学费补偿标准、增加国家财政负担份额、利用贷款制、发展教育储蓄、实行订单式培养、积极拓展经费来源等途径来完善农业高等职业教育成本补偿. 相似文献
634.
El Gamri T 《Environmental monitoring and assessment》2004,99(1-3):57-73
Sudan is the largest country in Africa with an area of about 2.5 million km2; the country hosts a population of about 31 million people. About two-thirds of the country area is located within arid and
semi-arid regions. Recently, especially during the last half of the previous century, these regions were subject to various
forms of land degradation. This paper discusses the general prospects and constraints of desert agriculture. It also presents
a detailed case study of West Omdurman, which is located in a semi-desert climatic zone. The ambitious plans to utilise the
area for agricultural production were initiated because of the relatively fertile soil, availability of water and the proximity
of the area to marketing and export centres. The paper discusses the different land use systems experienced in the area, reasons
for failure are identified and possible remedies discussed. In addition, constraints facing the proposed West Omdurman Canal
Project are also discussed. Finally, the paper reviews the major research findings of Rawakeeb Dryland Research Center with
regard to promoting agricultural productivity. 相似文献
635.
Mario Gellrich Priska Baur Niklaus E. Zimmermann 《Environmental Modeling and Assessment》2007,12(4):269-278
In many European mountain regions, natural forest regrowth on abandoned agricultural land and the related consequences for
the environment are issues of increasing concern. We developed a spatial statistical model based on multiple geophysical and
socio-economic variables to investigate the pattern of natural forest regrowth in the Swiss mountain area between the 1980s
and 1990s. Results show that forest regrowth occurred primarily in areas with low temperature sum, intermediate steepness
and soil stoniness as well as close to forest edges and relatively close to roads. Model results suggest that regions with
weak labor markets are favored in terms of land abandonment and forest regrowth. We could not find an effect of population
change on land abandonment and forest regrowth. Therefore, we conclude that decision makers should consider non-linearities
in the pattern of forest regrowth and the fact that labor markets have an effect on land abandonment and forest regrowth when
designing measures to prevent agricultural land abandonment and natural forest regrowth in the Swiss mountains. 相似文献
636.
基塘系统:研究回顾与展望 总被引:2,自引:0,他引:2
基塘系统是一种具有独特创造性的低洼土地利用方式和生态循环农业模式,在中国小农经济时期发挥了重要作用。20世纪50年代以来基塘系统逐渐受到学界重视,并曾引起国内外的广泛关注。当前系统梳理和总结基塘系统研究进展,对我国相关重要农业文化遗产的保护与现代高效生态农业发展具有重要支撑意义。论文基于基塘系统主要公开文献,从基塘系统的概念内涵、起源演变、结构功能、推广应用、动态保护等方面介绍国内外研究进展。资料分析显示:相对太湖流域基塘系统,针对珠江三角洲基塘系统的研究更为丰富;有关太湖流域桑基鱼塘起源的论证还存在分歧;基塘系统的经济功能衰退,其生态服务功能和遗产文化价值研究急需加强;传统基塘农业保护与创新发展还需加强技术、管理、政策等方面研究的支持。未来值得重视的研究方向有:1)加强对基塘系统生态服务功能研究,更全面客观地评估基塘系统的综合效益;2)基于农业文化遗产视角,开展基塘系统的动态保护与适应性管理研究;3)多学科深入研究基塘系统的作用机理,更好地总结与比较太湖流域与珠江三角洲基塘系统结构功能的异同;4)深入论证基塘系统的起源与演变过程,明确它在中国和全球农业史中的重要地位。 相似文献
637.
Community gardens (CGs) in university settings are faced with challenges associated with a transient and inexperienced population of student gardeners, but they also have the potential to have a lasting impact on the food behaviours of many young people. This paper undertakes a systematic critical review of literature about University Community Gardens for Sustainability (UCGS) in order to suggest directions of future research in the emerging field research about CGs within and outside of universities. The literature shows that UCGS have similar benefits to those identified in urban CG literature; but with greater emphasis on both the educational and environmental sustainability benefits, suggesting an under-used potential of CGs in these areas. We argue that a better understanding of the particular challenges and benefits of UCGS could improve outcomes of CGs in all settings. Therefore we recommend that future should explore: (1) participant transience in CGs, thereby helping sustainability projects with large volunteer bases learn to cope with challenges this poses in order to maximise the garden’s impacts; (2) whether/how participating in CGs can contribute to changes in attitudes/behaviours with regards to sustainability and be used as a tool for Education for Sustainability in and outside of university settings and (3) failed cases of CGs to genuinely understand factors that contribute to success. By addressing these areas we can improve our understanding of how community gardening can contribute to our communities, universities and environment, and can begin to make these potential contributions a reality. 相似文献
638.
Joseph P. Herring Richard C. Schultz Thomas M. Isenhart 《Journal of the American Water Resources Association》2006,42(1):145-155
An observational study was conducted at the watershed scale using land cover (vegetation) data to assess the absence or presence of riparian buffers in three northeastern Missouri watersheds. Forests and grasslands lying within a 61 m (200 ft) parallel band directly adjacent to streams were considered “buffers” for improving or protecting water quality and were characterized according to their length, width, and vegetation type. Results indicated that riparian buffers were abundant throughout the watersheds but were typically narrow along first‐order and second‐order streams; in many cases they may not have been wide enough to provide adequate stream protection. At least 90 percent of all streams had buffer vegetation immediately adjacent to the streambanks, but as few as 31 percent of first‐order streams had buffers extending to 61 m from the stream on at least one side. On‐site evaluations are needed to determine the condition of these forests and grasslands and their ability to process nonpoint source pollutants. The results will be useful for providing natural resource managers with knowledge of current watershed conditions as well as in identifying specific locations for future conservation efforts within each watershed. 相似文献
639.
Zhang Yanqing 《中国减灾(英文版)》2003,(1)
Globalfreshwaterresourcesaregettingincreasinglyscarce ,enlargingtheareaofdrylandandmakingthesituationworse .Thus,theresearchanddevelopmentondrylandagro technologyiscatchingpeople’sincreasingattention .DrylandareasinChinaaremainlydis tributedinnorthern 1 6 provinces (municipalities ,autonomousregions) ,whosedrylandagri cultureplaysanimportantrolein 2 1stcenturyChina’sagriculture .Majorissuesfacedbydrylandagro techdevelopment Inearly 1 980s ,addressingtheseverescarcityofwaterinthenorthernCh… 相似文献
640.
Henk Verhoog Mirjam Matze Edith Lammerts van Bueren Ton Baars 《Journal of Agricultural and Environmental Ethics》2003,16(1):29-49
Producers, traders, and consumers oforganic food regularly use the concept of thenatural (naturalness) to characterize organicagriculture and or organic food, in contrast tothe unnaturalness of conventional agriculture.Critics sometimes argue that such use lacks anyrational (scientific) basis and only refers tosentiment. In our project, we made an attemptto clarify the content and the use of theconcepts of nature and naturalness in organicagriculture, to relate this conception todiscussions within bioethical literature, andto draw the implications for agriculturalpractice and policy.Qualitative interviews were executed with arange of people in the field of organicagriculture and with consumers of organicproducts, on the basis of a list of statementsabout the meaning of the concept of naturalnessformulated by the authors. Based on the resultsof the interviews, we distinguished 3 aspectsof the concept of naturalness: natural as theorganic (life processes), natural as theecological, and natural as referring to thecharacteristic nature of an entity. We relatedthese conceptual aspects to three mainapproaches within the field of organicagriculture: the no chemicals approach, theagro-ecological approach, and the integrityapproach. It became clear that these approachescan also be recognized in the change ofattitude of farmers as they convert fromconventional to organic agriculture, and in theattitudes of consumers of organic foodproducts.We conclude that the idea of ``naturalness' canbe used to characterize organic agriculture andto distinguish it from conventionalagriculture, but only if naturalness not onlyrefers to not using chemicals but also toecological principles and respect for theintegrity of life. Thus perceived, theprinciple of naturalness can also serve as aguide to future developments in the field oforganic agriculture. As part of the holocentricethics of organic farming the value ofnaturalness has three dimensions: a cognitiveone, an emotive one, and a normative one. 相似文献