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   6624篇
  免费   552篇
  国内免费   1300篇
安全科学   553篇
废物处理   135篇
环保管理   720篇
综合类   3298篇
基础理论   2297篇
污染及防治   575篇
评价与监测   291篇
社会与环境   364篇
灾害及防治   243篇
  2024年   40篇
  2023年   119篇
  2022年   206篇
  2021年   227篇
  2020年   293篇
  2019年   176篇
  2018年   270篇
  2017年   298篇
  2016年   372篇
  2015年   208篇
  2014年   166篇
  2013年   196篇
  2012年   500篇
  2011年   469篇
  2010年   288篇
  2009年   234篇
  2008年   208篇
  2007年   237篇
  2006年   232篇
  2005年   726篇
  2004年   1080篇
  2003年   879篇
  2002年   163篇
  2001年   124篇
  2000年   92篇
  1999年   116篇
  1998年   63篇
  1997年   137篇
  1996年   48篇
  1995年   39篇
  1994年   39篇
  1993年   74篇
  1992年   64篇
  1991年   51篇
  1990年   6篇
  1989年   17篇
  1986年   3篇
  1985年   1篇
  1984年   2篇
  1983年   2篇
  1982年   8篇
  1980年   1篇
  1974年   1篇
  1916年   1篇
排序方式: 共有8476条查询结果,搜索用时 15 毫秒
161.
稠油污水生化性处理技术研究   总被引:1,自引:0,他引:1  
为了探讨稠油污水能否使用生物法处理,以生活污水和农药厂生化池原菌种经过诱导驯化,分别培养了可以在稠油污水中生长的好氧菌种革兰氏阴性菌G-1和厌氧菌种革兰氏阴性菌G-2.以G-2和G-1对稠油污水进行顺序处理,可使其BOD5/CODCr达到0.26;采用SBR法对新疆稠油污水放大处理试验的结果:COD降至150 mg/L以下,各项指标达到GB8978-1998二级排放标准.  相似文献   
162.
采用化学法自动控制处理含铬和含镍电镀废水,选择合适的化学药剂和pH、ORP控制参数,连续式处理电镀废水.运行结果表明:该工艺简单、处理效果良好、运行稳定、可操作性好、运行成本适中、能很好的适应水质的波动,处理后的水质完全符合排放标准.  相似文献   
163.
采用生态系统健康理论分析开发区生态环境问题具有较强的理论意义和现实意义。着重构建了开发区生态系统健康评价的指标体系和模糊评价模型,提出评价标准。并对苏州高新区生态系统健康进行评价。进而指出制约因子并提出相应的诊断方案,为其优化生态系统结构和完善系统功能提供科学依据。  相似文献   
164.
Public Perception of Flood Hazard in the Niger Delta,Nigeria   总被引:3,自引:0,他引:3  
Summary Our study had the aim of understanding how floodplain dwellers regard the risk of flooding. About 500 questionnaires were administered to landowners in the selected settlements in the study area using systematic random sampling. The results of analysis show, among other things, that the population regards most important the causes of floods as heavy, prolonged rainfall and river overflow. Nevertheless, they have little knowledge of the frequency of severe floods, and flood alleviation schemes. Most flood victims do not get compensation or relief during flood disaster, and the reason why they remain in the study area is influenced by their occupations, especially fishing, subsistence agriculture, and the presence of crude oil in the region which has attracted many migrants who cannot afford the high cost of accommodation and are therefore forced to live in vulnerable areas of the floodplain. Finally, the study concludes that flood control in the region needs the cooperation of government, community efforts and an enlightenment programmes through environmental education and mass media.  相似文献   
165.
Sagoff [Journal of Agricultural and Environmental Ethics 18 (2005), 215–236] argues, against growing empirical evidence, that major environmental impacts of non-native species are unproven. However, many such impacts, including extinctions of both island and continental species, have both been demonstrated and judged by the public to be harmful. Although more public attention has been focused on non-native animals than non-native plants, the latter more often cause ecosystem-wide impacts. Increased regulation of introduction of non-native species is, therefore, warranted, and, contra Sagoff’s assertions, invasion biologists have recently developed methods that greatly aid prediction of which introduced species will harm the environment and thus enable more efficient regulation. The fact that introduced species may increase local biodiversity in certain instances has not been shown to result in desired changes in ecosystem function. In other locales, they decrease biodiversity, as they do globally.  相似文献   
166.
A study of a watershed planning process in the Cache River Watershed in southern Illinois revealed that class divisions, based on property ownership, underlay key conflicts over land use and decision-making relevant to resource use. A class analysis of the region indicates that the planning process served to endorse and solidify the locally-dominant theory that landownership confers the right to govern. This obscured the class differences between large full-time farmers and small-holders whose livelihood depends on non-farm labor. These two groups generally opposed one another regarding wetland drainage. Their common identity as “property owner” consolidated the power wielded locally by large farmers. It also provided an instrument – the planning document – for state and federal government agencies to enhance their power and to bring resources to the region. The planning process simultaneously ameliorated conflicts between government agencies and the large farmers, while enhancing the agencies’ capacity to reclaim wetlands. In this contradictory manner, the plan promoted the environmental aims of many small-holders, and simultaneously disempowered them as actors in the region’s political economy. An erratum to this article is available at .  相似文献   
167.
168.
Summary The balance of evidence suggests a perceptible human influence on global ecosystems. Human activities are affecting the global ecosystem, some directly and some indirectly. If researchers could clarify the extent to which specific human activities affect global ecosystems, they would be in a much better position to suggest strategies for mitigating against the worst disturbances. Sophisticated statistical analysis can help in interpreting the influence of specific human activities on global ecosystems more carefully. This study aims at identifying significant or influential human activities (i.e. factors) on CO2 emissions using statistical analyses. The study was conducted for two cases: (i) developed countries and (ii) developing countries. In developed countries, this study identified three influential human activities for CO2 emissions: (i) combustion of fossil fuels, (ii) population pressure on natural and terrestrial ecosystems, and (iii) land use change. In developing countries, the significant human activities causing an upsurge of CO2 emissions are: (i) combustion of fossil fuels, (ii) terrestrial ecosystem strength and (iii) land use change. Among these factors, combustion of fossil fuels is the most influential human activity for CO2 emissions both in developed and developing countries. Regression analysis based on the factor scores indicated that combustion of fossil fuels has significant positive influence on CO2 emissions in both developed and developing countries. Terrestrial ecosystem strength has a significant negative influence on CO2 emissions. Land use change and CO2 emissions are positively related, although regression analysis showed that the influence of land use change on CO2 emissions was still insignificant. It is anticipated, from the findings of this study, that CO2 emissions can be reduced by reducing fossil-fuel consumption and switching to alternative energy sources, preserving exiting forests, planting trees on abandoned and degraded forest lands, or by planting trees by social/agroforestry on agricultural lands.  相似文献   
169.
Ethological farm programs as they exist in Switzerland are compared with environmental farm programs in respect of demand and supply. Because animal welfare is not a public good but rather a relation that causes psychological externalities, the demand for animal welfare has a different standing in economic theory than the demand for a clean environment. The supply of animal welfare by farmers, however, largely follows the patterns known from the delivery of environmental goods. Farm size, age and education, and also family size and capital intensity are influencing variables. The paper concludes that the design of ethological farm programs should be based on broad public discussions as described by deliberation theorists rather than willingness-to-pay studies.  相似文献   
170.
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