全文获取类型
收费全文 | 30633篇 |
免费 | 277篇 |
国内免费 | 298篇 |
专业分类
安全科学 | 847篇 |
废物处理 | 1263篇 |
环保管理 | 3933篇 |
综合类 | 5368篇 |
基础理论 | 7775篇 |
环境理论 | 11篇 |
污染及防治 | 8196篇 |
评价与监测 | 2093篇 |
社会与环境 | 1519篇 |
灾害及防治 | 203篇 |
出版年
2022年 | 244篇 |
2021年 | 254篇 |
2020年 | 172篇 |
2019年 | 247篇 |
2018年 | 448篇 |
2017年 | 442篇 |
2016年 | 682篇 |
2015年 | 535篇 |
2014年 | 853篇 |
2013年 | 2447篇 |
2012年 | 997篇 |
2011年 | 1303篇 |
2010年 | 1010篇 |
2009年 | 1153篇 |
2008年 | 1318篇 |
2007年 | 1375篇 |
2006年 | 1209篇 |
2005年 | 1057篇 |
2004年 | 1017篇 |
2003年 | 1005篇 |
2002年 | 973篇 |
2001年 | 1232篇 |
2000年 | 861篇 |
1999年 | 518篇 |
1998年 | 361篇 |
1997年 | 366篇 |
1996年 | 410篇 |
1995年 | 429篇 |
1994年 | 421篇 |
1993年 | 338篇 |
1992年 | 347篇 |
1991年 | 337篇 |
1990年 | 359篇 |
1989年 | 318篇 |
1988年 | 316篇 |
1987年 | 256篇 |
1986年 | 263篇 |
1985年 | 261篇 |
1984年 | 273篇 |
1983年 | 268篇 |
1982年 | 278篇 |
1981年 | 277篇 |
1980年 | 215篇 |
1979年 | 245篇 |
1978年 | 190篇 |
1977年 | 175篇 |
1976年 | 165篇 |
1975年 | 165篇 |
1973年 | 164篇 |
1972年 | 176篇 |
排序方式: 共有10000条查询结果,搜索用时 546 毫秒
111.
An introduction to critical loads 总被引:1,自引:0,他引:1
Bull KR 《Environmental pollution (Barking, Essex : 1987)》1992,77(2-3):173-176
The critical loads approach to emission controls of gaseous pollutants is a concept with a short but eventful history. Despite difficulties with definitions and agreed values, its acceptance within the UN-ECE Convention on Long Range Transboundary Air Pollution has provided the impetus for developing methods to put critical loads to a practical use-the revision of the UNECE emission protocols for sulphur and nitrogen. Methodologies first focus upon quantifying a pollutant threshold at which harmful effects occur on particular sensitive receptors (usually biological species). This threshold is known as the critical load for deposited pollutants, and as the critical level for gaseous pollutants acting on receptors. To calculate a critical load, biological effects are usually 'translated' to critical chemical values, e.g. harmful effects on fish 'translate' to alkalinity or aluminium concentrations in water; thus, critical load calculations may be based upon the chemistry of a system. Such calculations may be performed using simple, steady-state models, whilst the use of more complex, dynamic models provides an insight into the past and future trends. Maps of critical loads can be drawn using calculated values, and maps of pollutant deposition data will then show geographical areas where critical loads are exceeded. Spatial emission-deposition models can identify sources contributing to areas of excess loads and quantify necessary emission reductions. Optimization procedures applied to such models can derive abatement strategies related to economic costs and critical load effects. The critical load calculations may also be used to underpin the setting of target loads; these are pollutant loads, determined by political agreement, which take account of social, economic and political considerations. 相似文献
112.
This paper documents the rapid expansion and changes in food aid flows to Sub-Saharan Africa up to mid-1985. Trends for Sub-Saharan Africa as a whole and for the more seriously affected countries are examined, as are the comparative experiences of food aid of individual countries in the region. Table 11 lists the Sub-Saharan African countries and indicates the most seriously affected food-short countries, as defined by the WFP/FAO task force. It should be borne in mind that some practical problems exist in compiling data on food aid. These include lack of availability of reliable data, especially of most recent data; lack of common terminology and definitions; and different accounting systems. These data problems are sometimes a source of confusion. However, the basic facts are clear: food aid gradually emerged during the early 1980s as a resource too often of considerable significance to many countries of Sub-Saharan Africa. These trends were only accelerated with the crisis of 1984-1985. These facts provide a point of reference for further analysis of the sources of the crisis, its actual dimensions and consequences. 相似文献
113.
Horry Rosemary Booth Colin A. Mahamadu Abdul–Majeed Manu Patrick Georgakis Panos 《Environment, Development and Sustainability》2022,24(9):10585-10615
Environment, Development and Sustainability - Realisation of the sustainable development goals (SDGs) will provide improvements to people's lives and longevity of the planet. The architectural,... 相似文献
114.
Andharia Jigar K. Haldar Sanjay Samaddar Shilpa Maiti Subarna 《Environment, Development and Sustainability》2022,24(9):11449-11469
Environment, Development and Sustainability - Drying of fish at the Sagar Island (21.7269° N, 88.1096° E) is generally carried out in open sun on the seashore on plastic sheets or mat of... 相似文献
115.
Rate-temperature responses in scyphozoan medusae and polyps 总被引:1,自引:0,他引:1
The effects of temperature on oxygen consumption and spontaneous rhythmic activity have been investigated in various stages of the life histories of 3 species of jellyfish from the Chesapeake Bay, USA. All 3 species clearly show the ability to acclimate positively to temperature change. Thermal sensitivity of metabolism in the winter medusa Cyanea capillata fulva is fairly low at temperature intervals which are experienced in nature. Polyps of the two summer medusae, Chrysaora quinquecirrha and Aurelia aurita, show reduced metabolic sensitivity at temperatures normally accompanying high developmental activity and the onset of strobilation. 相似文献
116.
117.
118.
119.
120.