全文获取类型
收费全文 | 89705篇 |
免费 | 1224篇 |
国内免费 | 1090篇 |
专业分类
安全科学 | 3715篇 |
废物处理 | 3257篇 |
环保管理 | 13764篇 |
综合类 | 21238篇 |
基础理论 | 26080篇 |
环境理论 | 73篇 |
污染及防治 | 14260篇 |
评价与监测 | 5419篇 |
社会与环境 | 3712篇 |
灾害及防治 | 501篇 |
出版年
2022年 | 813篇 |
2021年 | 803篇 |
2020年 | 648篇 |
2019年 | 873篇 |
2018年 | 1118篇 |
2017年 | 1162篇 |
2016年 | 2170篇 |
2015年 | 1840篇 |
2014年 | 2592篇 |
2013年 | 9261篇 |
2012年 | 2107篇 |
2011年 | 2319篇 |
2010年 | 3243篇 |
2009年 | 3388篇 |
2008年 | 1893篇 |
2007年 | 1755篇 |
2006年 | 2188篇 |
2005年 | 2218篇 |
2004年 | 2524篇 |
2003年 | 2354篇 |
2002年 | 1912篇 |
2001年 | 2210篇 |
2000年 | 1938篇 |
1999年 | 1496篇 |
1998年 | 1368篇 |
1997年 | 1354篇 |
1996年 | 1475篇 |
1995年 | 1571篇 |
1994年 | 1477篇 |
1993年 | 1319篇 |
1992年 | 1301篇 |
1991年 | 1287篇 |
1990年 | 1233篇 |
1989年 | 1191篇 |
1988年 | 1040篇 |
1987年 | 975篇 |
1986年 | 988篇 |
1985年 | 1057篇 |
1984年 | 1157篇 |
1983年 | 1164篇 |
1982年 | 1172篇 |
1981年 | 1094篇 |
1980年 | 943篇 |
1979年 | 920篇 |
1978年 | 823篇 |
1977年 | 718篇 |
1976年 | 640篇 |
1974年 | 607篇 |
1973年 | 630篇 |
1972年 | 629篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
461.
Resource estimates alone will not give advance warning of encroaching production difficulties. An analysis of the general stages in the evolution of petroleum production and discovery and of industry statistics provides an estimate of when the stage characterised by increasing production in the market economy countries outside the United States and Canada will end. The analysis indicates that the year of maximum production will be in the 1990s. Economic growth aggravates the difficulties accompanying the production decline by advancing the date of peak production and by increasing the adjustments that must be made as oil production declines. Des prévisions de ressources à elles seules ne constituent pas des signes précurseurs de difficultés croissantes de production. Une analyse des étapes générales marquant l'evolution de la découverte et de la production du pétrole ainsi que des statistiques industrielles nous permet de prévoir l'époque à laquelle prendra fin la phase de production accrue dans les pays à économie de marché en dehors des Etats-Unis et du Canada. Cette analyse révèle que l'année de production maximale se situera dans les années 90. La croissance économique accentue les difficultés qui accompagnent le déclin de la production de pétrole en avancant la date à laquelle cell-ci atteindra son plafond et en augmentant le nombre d'ajustements qui s'avèrent nécessaires au fur et à mesure qu'elle baisse. Las evaluaciones de recursos no dan por si solas un aviso anticipado de las dificultades de producción. Un análisis de las etapas principales en la evolución del descubrimiento y producción de petróleo y de las estadísticas industriales provee un estimado de cuando va a terminar la etapa caracterizada por un crecimiento de producción en los paises de economias de mercado otros que Estados Unidos y Canada. El análisis indica que el año de producción máxima se hallará en la década del 90. El crecimiento económico agrava las dificultades debidas a la declinación de la producción al adelantar la fecha de máxima producción (pico) y al aumentar los ajustes que deven hacerse cuando la producción de petróleos disminuye. 相似文献
462.
Results of a recent intercomparison on the determination of trace elements in simulated air filter samples are reported. A large scatter of results is obtained for some elements and systematic differences between laboratories are observed. The performance of different methods, in particular neutron activation analysis and atomic absorption spectrophotometry, used by the various laboratories is discussed (air filter analysis; intercomparison; trace elements; control charts). 相似文献
463.
Marine Biology - The combined effects of temperature and salinity on the rate of oxygen consuption by the estuarine crab Panopeus herbstii Milne-Edwards (Crustacea: Decapoda: Xanthidae) were... 相似文献
464.
465.
466.
467.
This article examines the role of economic development agencies in strengthening the environmental performance of industry within rapidly industrialising East Asian economies. Three case-study examples are considered, namely, the role of the Industrial Development Board in reducing industrial pollution in Taiwan, pollution control in the palm oil industry in Malaysia, and the role of the Economic Development Board in influencing environmental performance of industry in Singapore. The concept of embedded autonomy is developed to consider the ways in which agencies of economic development can work with firms and industries while simultaneously remaining autonomous from these firms with respect to setting and enforcing performance standards. The three cases suggest that a form of policy integration that more directly integrates economic and environmental goals within agencies of economic development may be feasible, but only where there exists a strong autonomous government bureaucracy and where there is strong societal commitment to improving the environmental performance of industry. 相似文献
468.
There is a growing recognition that knowledge of indigenous communities, based on accumulated observations and experience over time, is significant for sustainable environmental management in collaboration with modern scientific knowledge. A number of innovative policy initiatives are currently being implemented in New Zealand to enable indigenous Maori tribes and sub-tribes to rehabilitate and manage their local fisheries in accordance with customary values and practices. These policies are an important milestone from an historical perspective as they are meant to recognise and empower the role of Maori as Treaty partners. The fisheries management regime in New Zealand now provides for Maori representation at the local level within a co-management framework that enables local Maori communities to exercise their customary rights. These institutional arrangements have been crafted to facilitate Maori input, based on customary values and practices, to complement modern Western management practices for sustainable harvesting of marine resources. Nevertheless, the degree to which these initiatives constitute an adequate response to Maori Treaty aspirations is debatable. A major constraint in this respect is that the government is compelled to recognise the needs of other, economically and politically more dominant, non-Maori user-groups in allocating and managing access to fishery resources and the marine environment. 相似文献
469.
In the UK for the period 1994-99, a broad range of environmental projects were given financial support through the European Agriculture Guidance and Guarantee Fund under the Objective 1 and Objective 5b programmes. This paper is concerned with the ex-post evaluation of these projects set within a Sustainable Development framework. The aim was to identify project types or characteristics that offered the greatest return on investment. A classification of six broad project types was adopted. The evaluation revealed that there were significant differences between individual projects with respect to the type and scale, and temporal and social distribution of the benefits they delivered. In particular, as well as delivering environmental and economic benefits, many projects made a significant contribution to the development of human and social capital. The paper concludes that it is possible to improve the basis for future project selection in order to maximise the returns on environmental investments in the context of sustainable development. 相似文献
470.
Gunavant M. Oza 《The Environmentalist》2003,23(2):189-192
Much of the forest wealth on the plains and in the hilly areas of India has been foolishly destroyed, and the rich heritage of wildlife has been slaughtered mostly for only temporary gain. The wanton axing of the larger indigenous trees and the uprooting of other floristic elements in the hills and on the lower slopes of the mountains, gradually impoverishes them, and may be followed by erosion that ultimately leaves the slopes barren. These alarming threats to the chir (Pinus roxburghii) and fir (Abies pindrow) forests of Kashmir will have disastrous consequences. Once densely-forested, the mountain slopes in Kashmir have become largely naked through too-heavy tapping and cutting of the trees; with concomitant landslides, frequent floods, and loss of fertile topsoil. Unfortunately, the people living in the areas of the chir and fir trees, do not play a proper part in their protection, and the last two decades have witnessed, year by year, the rapid march of urbanization and manifold destructive activities which have taken a heavy toll on these precious species. Urgent conservation measures are essential to preserve these endangered trees in Kashmir. 相似文献