全文获取类型
收费全文 | 7283篇 |
免费 | 549篇 |
国内免费 | 2898篇 |
专业分类
安全科学 | 141篇 |
废物处理 | 264篇 |
环保管理 | 917篇 |
综合类 | 5022篇 |
基础理论 | 2647篇 |
环境理论 | 2篇 |
污染及防治 | 812篇 |
评价与监测 | 558篇 |
社会与环境 | 260篇 |
灾害及防治 | 107篇 |
出版年
2024年 | 28篇 |
2023年 | 106篇 |
2022年 | 168篇 |
2021年 | 154篇 |
2020年 | 127篇 |
2019年 | 130篇 |
2018年 | 145篇 |
2017年 | 157篇 |
2016年 | 148篇 |
2015年 | 202篇 |
2014年 | 251篇 |
2013年 | 638篇 |
2012年 | 400篇 |
2011年 | 293篇 |
2010年 | 271篇 |
2009年 | 273篇 |
2008年 | 278篇 |
2007年 | 442篇 |
2006年 | 454篇 |
2005年 | 332篇 |
2004年 | 254篇 |
2003年 | 301篇 |
2002年 | 333篇 |
2001年 | 351篇 |
2000年 | 464篇 |
1999年 | 539篇 |
1998年 | 425篇 |
1997年 | 417篇 |
1996年 | 507篇 |
1995年 | 414篇 |
1994年 | 362篇 |
1993年 | 258篇 |
1992年 | 183篇 |
1991年 | 214篇 |
1990年 | 135篇 |
1989年 | 97篇 |
1988年 | 66篇 |
1987年 | 69篇 |
1986年 | 34篇 |
1985年 | 37篇 |
1984年 | 74篇 |
1983年 | 53篇 |
1982年 | 27篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 27篇 |
1975年 | 33篇 |
1974年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 47 毫秒
981.
Leaves of the oak, Quercus cerris, and thalli of the epiphytic lichen, Parmelia caperata, from the Travale-Radicondoli geothermal area (central Italy) were analyzed for their trace elements (As, B, Cd, Cu, Fe, Hg, Mn, Pb, Zn). the results showed that concentrations of arsenic and boron in leaf and lichen samples were higher than in remote areas. the mean concentrations of many trace elements were higher in lichens than in oak leaves, suggesting that these organisms can be used in similar biomonitoring studies. the levels of boron and manganese were higher in tree leaves, so that for these two elements, the higher plant foliage could constitute a better biomonitor than lichens. the correlations found between the concentrations of cadmium and manganese in leaves and lichens suggests foliar leaching and washing of the elements down the tree trunk, where lichens may intercept them. 相似文献
982.
Sesbania rostrata in pure and amended Pb/Zn tailings. About 90% of seeds of S. rostrata germinated in pure Pb/Zn tailings, which contained high concentrations of Pb, Zn, Cu, and Cd. Although seedling growth suffered
from the adverse environment of Pb/Zn tailings, they became established on tailings stands, in the greenhouse, as well as
on the actual tailings dam, and completed their life cycle in 4 months. Dry matter production and nitrogen accumulation was
3200 kg/ha and 69.4 kg/ha, respectively in the actual tailings dam. Applying inorganic fertilizer to Pb/Zn tailings led to
no obvious improvement in growth and nodulation of S. rostrata, while tailings amended by river sediment or domestic refuse rich in organic matter improved the growth and nodulation of
the species. Azorhizobium caulinodans survived and formed N-fixing stem and root nodules in S. rostrata grown in pure Pb/Zn tailings with a nodule biomass exceeding 300 mg fresh matter per plant. 相似文献
983.
The distribution of Cd, Cu, Fe, Hg, Mn, Ni, Pb, and Zn concentration in five algae species (Enteromorpha intestinalis, Enteromorpha linza, Ulva lactuca, Corallina mediterranea, Pterocladia capillacea) collected from three areas having different types of metal contamination along Alexandria coastal waters (Egypt) were determined by Atomic Absorption Spectrometry. The recovery study was carried out using a Certified Reference Material TORT-2. The obtained heavy metal contents indicate that different species demonstrate various degree of metal accumulation. Enteromorpha intestinalis (green algae) recorded the highest levels of Fe and Mn while Corallina mediterranea (Calcareous red algae) recorded the highest concentration of Pb, Ni, and Cd in the three areas under study. According to the present study, filamentous algae (Enteromorpha intestinalis) showed the ability to concentrate greater amount of trace elements than the foliaceous ones (Enteromorpha linza). In each area, mercury concentration has nearly the same value for all species under study. 相似文献
984.
以由地洛试剂为氧化剂,用分光光度法测定染料废水中对氨基酚的含量,进行了波长,贝特洛试剂用量及显色时间等分析条件的选择。精密度和准确度实验结果表明,该准确,快速,可用于染料废水中对氨基酚的测定。 相似文献
985.
986.
J. C. Day 《Journal of the American Water Resources Association》1972,8(6):1120-1136
Neither Canada nor the United States attach much importance to the International Joint Commission (IJC) judging by the size of staffs and annual budgets. The Commission has been restricted to a relatively minor number of functions in the Great Lakes-St. Lawrence. It has investigated: the degree and causes of water and air quality deterioration; the effects of hydroelectric and navigation projects on water levels; the impacts of water-level fluctuations; and the feasibility of a deep waterway from the St. Lawrence to the Hudson River. Projects approved by the Commission have produced less than might be expected through no fault of the Commission. The Great Lakes Fishery Commission has promoted little international management. Budgetary limitations restrict its lamprey control program; institutional limitations restrict its ability to deal effectively with fishery problems. Commission responsibilities are limited to coordination and advisory functions. Since Canada and the United States have not chosen to refer most aspects of river basin management to international bodies, an institutional void exists in the Great Lakes Basin to consider these questions on a continuous basis. There is a need for expanded international cooperation. 相似文献
987.
Ä.P. Lino Grima Susan Horton Shashi Kant 《Environment, Development and Sustainability》2003,5(3-4):297-314
Can development occur without running down natural resources in an unsustainable way? The concept of natural capital offers a way for those with divergent views (ecologists and economists for example) to discuss this difficult question. Four aspects are examined in detail. First, the role of institutions in facilitating sustainable development is discussed, with examples from forestry. Then examples from (eco)tourism illustrate the potential – and limits – of applicability of the concept. Measurement issues for natural capital are then considered in detail. Finally, the concept is applied to agricultural strategy in fragile lands, where the tradeoff between the environment and development is likely to be most severe. Some implications for future research and policy are developed. 相似文献
988.
Jeffrey Barber 《Environment, Development and Sustainability》2003,5(1-2):63-93
At the World Summit on Sustainable Development (WSSD), world leaders agreed that eliminating unsustainable production and consumption is one of the three overriding objectives of sustainable development. Achieving that objective should have been a major priority for the WSSD Plan of Implementation. Increases in consumption and production over the past decade were largely responsible for the worsening environmental and social trends. Unfortunately, the negotiators of the Plan paid insufficient attention to the lessons from 10 years of discussions about the concepts, the available policies and tools and their effectiveness, the impacts of those policies on developing countries, and the political commitment of countries in an era of globalization. Despite a promising proposal for a new ten-year work programme aimed at bridging the gap implementing the Agenda 21 commitments from Rio, Summit negotiators produced barely more than a muted echo of recommendations from the past which have yet to be taken seriously enough by the world's leaders in a comprehensive intergovernmental strategy. In the ten-year review of progress to achieve sustainable production and consumption (SPAC), governments quickly skipped past the critical work of examining why things are getting worse, avoiding the task of identifying the obstacles (which in some cases were themselves) and in turn avoiding the commitment to time-bound measurable targets. If nothing else, the WSSD demonstrated that a global strategy to achieve SPAC will come not from a UN consensus of world leaders but from a strategic alliance of responsible governments, civil society and others with a vision beyond the next election cycle. 相似文献
989.
New institutional economists have argued that there are many categories of institutions, including market and non-market institutions, which may prove economically efficient, specifically for public goods and common pool goods. The Government of India introduced a non-market community-based institution, known as Joint Forest Management (JFM), for forest management and protection in 1990. JFM is a sharing mechanism for forest planning and management based on sharing of rights and duties, control and decision-making authority over forestlands, between forest departments and local user groups. By 2001, 42 000 Village Forest Committees established under JFM were managing over 11.5 million ha forestland. These institutions have proved very useful, and have contributed to forest management as well as four aspects of sustainable human development (SHD) – ecological output, income generation, village infrastructure development, and community empowerment. In the long-term, community-based institutions will prove to be a foundation of SHD and participatory democracy. 相似文献
990.
The distribution of three important dissolved forms of nitrogen, viz. nitrate, nitrite and urea in the surface and bottom water samples collected from 27 selected hydrographic profiles, in the Arabian Sea, along the west coast of India is described. Of the three forms, nitrate concentrations were the highest and comparatively higher concentrations were observed in the bottom water. Decomposition of organic matter resulting in the release of the thermodynamically stable nitrogen species, i.e. nitrate, may be the major factor resulting in higher nitrate concentrations at these depths, where the water is also characterized by low values of dissolved oxygen and temperature. The significant positive correlation between A.O.U. and nitrate of the bottom water samples emphasizes the role of oxidative decomposition of organic matter which plays an active role in reducing the oxygen concentrations below the theoretical values since at this depth ( ≈200 m) the net production is taken to be zero. This is also evidenced by the negative correlation of nitrate with dissolved oxygen and temperature, for the bottom samples. 相似文献