全文获取类型
收费全文 | 879篇 |
免费 | 47篇 |
国内免费 | 230篇 |
专业分类
安全科学 | 63篇 |
废物处理 | 12篇 |
环保管理 | 173篇 |
综合类 | 353篇 |
基础理论 | 319篇 |
环境理论 | 3篇 |
污染及防治 | 90篇 |
评价与监测 | 45篇 |
社会与环境 | 79篇 |
灾害及防治 | 19篇 |
出版年
2024年 | 8篇 |
2023年 | 17篇 |
2022年 | 20篇 |
2021年 | 35篇 |
2020年 | 24篇 |
2019年 | 30篇 |
2018年 | 42篇 |
2017年 | 38篇 |
2016年 | 54篇 |
2015年 | 34篇 |
2014年 | 39篇 |
2013年 | 82篇 |
2012年 | 55篇 |
2011年 | 78篇 |
2010年 | 37篇 |
2009年 | 68篇 |
2008年 | 41篇 |
2007年 | 73篇 |
2006年 | 65篇 |
2005年 | 39篇 |
2004年 | 28篇 |
2003年 | 37篇 |
2002年 | 31篇 |
2001年 | 20篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 2篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1156条查询结果,搜索用时 15 毫秒
961.
962.
963.
微塑料是一种新型污染物,可以在环境中长期存在并造成生态风险.目前,微塑料污染已成为全球性的重大环境问题.借助新的技术途径,提高微塑料识别的简便性和可靠性,并系统分析各类环境介质中微塑料的污染特征,明确微塑料的环境效应,对科学准确评价微塑料污染的环境风险具有重要意义.机器学习技术通过学习和解析大量数据建立结果评估或预测模型,目前已广泛应用于微塑料领域的相关研究.机器学习的应用可以提高视觉和光谱识别微塑料的自动化程度和识别效率,为微塑料污染溯源提供方法支撑并有助于揭示微塑料的复杂环境效应机制.通过综述机器学习技术在微塑料识别与环境风险评估中的应用研究进展,概括了机器学习在上述方向的应用特点和局限性,为机器学习在相关方向的发展和应用提出建议与展望. 相似文献
964.
周立军 《中国安全科学学报》2010,20(12)
为有效解决跨区域灭火应急救援工作中统一指挥难、行动协调难、资源调配难和协同效应难等问题,基于网络在跨区域管理工作中的重要性以及协同原理理论,提出跨区域灭火应急救援协作网络的概念,并分析跨区域灭火应急救援协作网络在跨区域灭火应急救援工作中的功能与作用,最后提出了跨区域灭火应急救援协作网络的结构框架及运行机制。结果表明:协作网络与跨区域灭火应急救援工作相结合具有重要意义,今后的工作重点应是研究构建跨区域灭火应急救援协作网络的影响因素、可行性、实用性以及相关配套设施和宏观运行环境等。 相似文献
965.
966.
JunJie Wu David Zilberman Bruce A. Babcock 《Journal of Environmental Economics and Management》2001,41(3):333
Resource purchasing funds have become a major tool for environmental protection and resource conservation. These funds use various strategies to target resources for conservation, the choice of which may lead to striking differences in environmental performance. This paper develops an analytical framework to analyze the impact of alternative targeting strategies on different interest groups, including consumers, producers, labor, and environmentalists. We show that ignoring the output price effect of purchasing funds reduces environmental gain and in some cases may make a purchasing fund counterproductive, and we argue that the optimal design of targeting criteria must consider the price feedback effect. 相似文献
967.
Magas OK Gunter JT Regens JL 《Environmental science and pollution research international》2007,14(1):19-23
Background, Aim and Scope
A series of severe air pollution episodes in Europe and North America prior to 1960 have focused scientific and regulatory
attention on the adverse effects of air pollution on human health. As a consequence of significant reductions in ambient air
pollution levels in the intervening years, scientists and public health officials have become more concerned with the potential
health effects of exposure to routine concentrations of air pollution. Several recent time series studies conducted world-wide
have found relatively low levels of air pollutants that are below national standards were associated with adverse effects
on mortality and morbidity.
This study examined the effects of ambient air pollution indicators on the daily rate of pediatric hospital admissions for
asthma in the Oklahoma City Metropolitan area from 2001-2003.
Results:
Negative binomial regression analysis revealed significant relationships between the total number of hospitalizations per
day and the one-hour maximum NO2 level, the proportion of susceptible children < 5 years old, and the ratio of temperature
to humidity.
Discussion:
This study of the total number of children aged ≤ 14 years old experiencing hospitalizations on a daily basis in the Oklahoma
City area from 2001-2003 underscores factors other than ambient air pollution, especially when concentrations are low, affect
hospitalizations for pediatric asthma. For example, information related to indoor air quality, health care, family history,
and exposure to environmental tobacco smoke and other irritants are not obtainable. Yet, those factors are risk drivers for
asthma. Similarly, health privacy requirements prevented obtaining data on physiological factors specific to each child such
as differentials in airways functional capacity or other impairments influenced asthma exacerbation. This makes calculating
relative risk inappropriate.
Conclusions:
Although ambient air pollution concentrations and meteorological conditions influence pediatric asthma hospitalizations, they
are not the major predictors in the Oklahoma City metropolitan area. This is consistent with other research that finds limited
effects associated with low levels for concentrations of the criteria pollutants. 相似文献
968.
Su Mei Liu Xiao Na Li Jing Zhang Hao Wei Jing Ling Ren Gui Ling Zhang 《Water, Air, & Soil Pollution: Focus》2007,7(6):625-643
Three cruises were carried out in Jiaozhou Bay (JZB) in the neap tide in October 2002 (fall) and in both neap and spring tides
in May 2003 (spring) to understand the relative importance of external nutrient inputs versus physical transport and internal
biogeochemical processes. Nutrients (, , , , silicic acid, total dissolved nitrogen (TDN) and phosphorus (TDP), dissolved organic nitrogen (DON) and phosphorus (DOP))
were measured. The concentrations of nutrients were higher in the northern part than in the southern part. High concentrations
of and DON in JZB demonstrated the anthropogenic input. Ambient nutrient ratios indicated that the potential limiting nutrients
for phytoplankton growth were silicon, and then phosphorus. Nutrients showed an obvious tidal effect with low values at flood
tide and high values at ebb tide. Nutrient elements were transported into JZB in the north and output in the south (i.e.,
into the Yellow Sea), which varied with season, tidal cycle and investigation sites. Water exchange between JZB and the Yellow
Sea exports , and DON out of JZB, while it inputs , silicic acid and DOP into JZB. Nutrient budgets demonstrate that riverine input and wastewater discharge are major sources
of nutrients, while residual flow is of minor importance in JZB ecosystem. JZB is a sink for the nutrient elements we studied
except for DON. Stoichiometric calculations demonstrate that JZB is a net autotrophic system. 相似文献
969.
以17β雌二醇为标准参考物质,对基于受体作用理论的环境激素分析方法实验条件进行了重构和优化,建立了环境类雌激素分析方法。结果表明:用营养缺陷型培养基30℃恒温振荡66 h培养时间进行重组基因酵母的复苏与增殖,20℃~35℃水浴样品与酵母混合液培养3~6 h暴露,优先选用机溶剂处理法释放β-半乳糖苷酶,35℃恒温水浴进行酶活测试反应,采用反应终止后2.5 h 420 nm波长进行分析测试,同时实际样品的分析,加测不少于一个的稀释水样效应值,可使方法更加科学高效、准确度高,应用于各类实际样品分析。 相似文献
970.
AINHOA MAGRACH WILLIAM F. LAURANCE ASIER R. LARRINAGA LUIS SANTAMARIA 《Conservation biology》2014,28(5):1342-1348
Forest fragmentation dramatically alters species persistence and distribution and affects many ecological interactions among species. Recent studies suggest that mutualisms, such as pollination and seed dispersal, are more sensitive to the negative effects of forest fragmentation than antagonisms, such as predation or herbivory. We applied meta‐analytical techniques to evaluate this hypothesis and quantified the relative contributions of different components of the fragmentation process (decreases in fragment size, edge effects, increased isolation, and habitat degradation) to the overall effect. The effects of fragmentation on mutualisms were primarily driven by habitat degradation, edge effects, and fragment isolation, and, as predicted, they were consistently more negative on mutualisms than on antagonisms. For the most studied interaction type, seed dispersal, only certain components of fragmentation had significant (edge effects) or marginally significant (fragment size) effects. Seed size modulated the effect of fragmentation: species with large seeds showed stronger negative impacts of fragmentation via reduced dispersal rates. Our results reveal that different components of the habitat fragmentation process have varying impacts on key mutualisms. We also conclude that antagonistic interactions have been understudied in fragmented landscapes, most of the research has concentrated on particular types of mutualistic interactions such as seed dispersal, and that available studies of interspecific interactions have a strong geographical bias (arising mostly from studies carried out in Brazil, Chile, and the United States). Meta‐Análisis de los Efectos de la Fragmentación del Bosque sobre las Interacciones Interespecíficas 相似文献