首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   377篇
  免费   7篇
  国内免费   4篇
安全科学   13篇
废物处理   12篇
环保管理   116篇
综合类   41篇
基础理论   115篇
环境理论   1篇
污染及防治   50篇
评价与监测   21篇
社会与环境   12篇
灾害及防治   7篇
  2022年   6篇
  2021年   7篇
  2020年   4篇
  2019年   4篇
  2018年   5篇
  2017年   10篇
  2016年   6篇
  2015年   7篇
  2014年   6篇
  2013年   25篇
  2012年   13篇
  2011年   16篇
  2010年   17篇
  2009年   20篇
  2008年   18篇
  2007年   15篇
  2006年   18篇
  2005年   16篇
  2004年   13篇
  2003年   8篇
  2002年   11篇
  2001年   10篇
  2000年   6篇
  1999年   9篇
  1998年   11篇
  1997年   5篇
  1996年   8篇
  1995年   7篇
  1994年   5篇
  1993年   5篇
  1992年   7篇
  1991年   5篇
  1990年   4篇
  1989年   3篇
  1987年   4篇
  1986年   3篇
  1985年   2篇
  1984年   4篇
  1983年   5篇
  1982年   6篇
  1981年   5篇
  1980年   9篇
  1979年   2篇
  1978年   3篇
  1976年   2篇
  1975年   1篇
  1974年   3篇
  1973年   3篇
  1972年   3篇
  1954年   2篇
排序方式: 共有388条查询结果,搜索用时 31 毫秒
1.
Environmental Science and Pollution Research - There is mixed evidence surrounding the relationship between tobacco use and COVID-19 infection/progression. The current study investigates beliefs...  相似文献   
2.
ABSTRACT: The use of nonparametric tests for monotonic trend has flourished in recent years to support routine water quality data analyses. The validity of an assumption of independent, identically distributed error terms is an important concern in selecting the appropriate nonparametric test, as is the presence of missing values. Decision rules are needed for choosing between alternative tests and for deciding whether and how to pre-process data before trend testing. Several data pre-processing procedures in conjunction with the Mann-Kendall tau and the Seasonal Kendall test (with and without serial correlation correction) are evaluated using synthetic time series with generated serial correlation and missing data. A composite test (pre-testing for serial correlation followed by one of two trend tests) is evaluated and was found to perform satisfactorily.  相似文献   
3.
4.
To comply with EU recycling targets for packaging waste, the UK relies on an industry run and market based eco-tax levied by reprocessors on obligated businesses. After examining the details of this approach, the use of Packaging Waste Recovery Notes is assessed in terms of its allocative impact and the contribution made to eco-efficiency. The evidence indicates the UK system has minimized the cost of delivering current EU targets, but has not been able to deliver allocative efficiency or to demonstrate dynamic improvements in resource use. Its effectiveness in meeting impending higher targets remains open to question.  相似文献   
5.
Progress in the greening of UK local government has been hampered by uncertainty about the relationship between resource use and environmental protection. Ecological modernizationmay offer the most appropriateparadigm to reconcile economic, social and environmentalinterpretationsof sustainability. The transition from corporate to strategic environmental management currently being attempted by some 'green' authorities can be construed as an attempt to promote ecological modernization in the form of institutional learning. Fife Council in Scotland provides an interesting case study. Progress with corporate environmental management has become bound up with a radical devolution of decision making. Efforts to link the authority's Sustainable Development Policy to a Local Agenda 21 programme have been initiated with the piloting of sustainability indicators.  相似文献   
6.
Estimates of animal methane emissions   总被引:2,自引:0,他引:2  
The enteric methane emissions into the atmospheric annually from domestic animals total about 77 Tg. Another 10 to 14 Tg are likely released from animal manure disposal systems. About 95% of global animal enteric methane is from ruminants, a consequence of their large populations, body size and appetites combined with the extensive degree of anaerobic microbial fermentation occurring in their gut. Accurate methane estimates are particularly sensitive to cattle and buffalo census numbers and estimated diet consumption. Since consumption is largely unknown and must be predicted, accuracy is limited often by the information required, i.e., distribution of animals by class, weight and productivity. Fraction of the diet lost as enteric methane mostly falls into the range of 5.5–6.5% of gross energy intake for the world's cattle, sheep and goats. Manure methane emissions are heavily influenced by fraction of disposal by anaerobic lagoon. Non-ruminants, i.e., swine, become major contributors to these emissions.  相似文献   
7.
Seventeen Longhurst Hardy Plankton Recorder profiles were taken over a diel cycle in January 1990 to study the feeding of four major copepods over the South Georgia shelf. Ontogenetic changes in vertical migration were followed and feeding cycles determined by gut fluorometry for Calanoides acutus Stage CV, Calanus sinillimus CV and CVI, C. propinquus CV and Rhincalanus gigas CV and CVI. In common with a neighbouring oceanic site visited two weeks later and reported elsewhere, all four species had a diel cycle of feeding and migration. The vertical distributions of C. simillimus (all stages), R. gigas (nauplii) and Euphausia frigida (postlarvae) were similar at both sites, the night being spent within the chlorophyll maximum at 15 to 30 m. However, the biomass dominants, C. acutus and R. gigas, dwelt below the chlorophyll maximum, about 30 m deeper than their oceanic counterparts. Unlike the oceanic site, feeding at the shelf site was not restricted to darkness, but increased 6 to 10 h before nightfall and finished at dawn; the intervening period coincided with sinking and digestion. Daylight feeding may have been induced by the shorter night, lower light levels or greater food requirements at the shelf site, despite planktonic predators being over three times more abundant. Daily ration estimates for R. gigas at both sites were only 2% body carbon per day. These low values contrast with its smaller competirors, whose rations were in the range 5.6 to 27%.  相似文献   
8.
Resting metabolic rate was measured in demersal stages of the teleostNotothenia neglecta Nybelin from the South Orkney Islands, Antarctica, from 1985 to 1987. The relationship between and body mass (Mb) conformed to the general relationship , wherea is a proportionality constant andb is the scaling exponent. (mg O2 h–1) was found to scale toMb (0.82±0.011) in the summer (November to April, 1.6 to 1 850 g,n=56) and toMb (0.76±0.013) in the winter (May to October, 0.9 to 1 850 g,n=57) (values ofb are means ± SD). Although the scaling exponents were significantly different (P<0.01), was similar in the juvenile stages of summer- and winter-caught fish matched for body mass. The effects of activity on oxygen consumption was studied using a Brett respirometer. Adult stages had a factorial aerobic scope for activity of 5.7, which is similar to that reported for demersal fish from temperate latitudes. The effects of temperature on resting metabolism was investigated in fish with similar sedentary lifestyles from the North Sea (Agonus cataphractus andMyoxocephalus scorpius) and the Indo-West Pacific (Paracirrhites forsteri, P. arcatus, Neocirrhites armatus andExallias brevis). Extrapolated values of for the tropical species approached zero at 5 to 10°C. For a standard 50 g fish, for the tropical species at 25°C was in the range 3.4 to 4.4 mg O2 h–1, compared with 1.3 mg O2 h–1 forNotothenia neglecta at its acclimation temperature. Thus, the maximum metabolic rate of sedentary tropical species at 24°C is likely to be 2 to 4 times higher than inN. neglecta at 0°C. This suggests that the energy available for sustained activity is significantly lower in cold- than in warm-water fish.  相似文献   
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号