全文获取类型
收费全文 | 422篇 |
免费 | 51篇 |
国内免费 | 62篇 |
专业分类
安全科学 | 40篇 |
环保管理 | 127篇 |
综合类 | 174篇 |
基础理论 | 74篇 |
污染及防治 | 27篇 |
评价与监测 | 10篇 |
社会与环境 | 44篇 |
灾害及防治 | 39篇 |
出版年
2024年 | 2篇 |
2023年 | 12篇 |
2022年 | 20篇 |
2021年 | 15篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 12篇 |
2017年 | 26篇 |
2016年 | 21篇 |
2015年 | 28篇 |
2014年 | 23篇 |
2013年 | 35篇 |
2012年 | 33篇 |
2011年 | 25篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 17篇 |
2007年 | 37篇 |
2006年 | 16篇 |
2005年 | 10篇 |
2004年 | 13篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有535条查询结果,搜索用时 671 毫秒
351.
William Y B. Chang 《Journal of the American Water Resources Association》1997,33(3):605-614
ABSTRACT: Proxy climate data for the last 500 years collected from the archives of counties in the Yangtze River Delta, China, were analyzed to identify the occurrence of extreme climate events, the pattern of such occurrences and their relationships to El Nino-Southern Oscillation (ENSO). This study identified the cycle periods of 3.5, 5.5 and 8.6 years for floods and 18.5 years for droughts in the Yangtze River Delta during the last 500 year period and noted 16 regional (delta wide) extreme events during this period. All regional (delta wide) extreme climate events during the last 500 years (since 1500 A.D.) occurred either during or immediately after ENSO (5–6 year) activities. Hydrological impacts of extreme climate events, such as major floods and droughts, on human systems have long been among the foremost concerns of the Pacific Rim countries. Management of systems increasingly dominated by humans, such as Asian delta regions, should, therefore, include consideration of major climate variability, ENSO events and the extent of climate changes, as well as consideration of the trends associated with human growth and institutional changes. 相似文献
352.
Public values toward forests have changed since the late 1980s, from a commodity-oriented perspective toward a more inclusive
(commodity and non-commodity) orientation. This study examines the influence of four indicators of population diversity (age,
ethnic background, place of residence, and gender) on amenity values of forests, environmental attitudes, and forest value—attitude
correspondence. Four values of public and private forests were assessed, wood production (utilitarian value), clean air (a
life support value), scenic beauty (an aesthetic value), and heritage (a spiritual value). Environmental attitudes were measured
using a modified version of the New Environmental Paradigm scale. Five hundred and forty-eight randomly selected residents
of households in 13 states of the Southern United States participated in a telephone interview. Age and ethnic background
were found to moderate the value—attitude relationship, with the strength of the association being dependent upon the type
of forest (i.e., public or private) and the forest value (i.e., utilitarian, life support, spiritual, and aesthetic). Females,
younger persons (less than 43 years old), and whites reported lower utilitarian values of forests than their respective counterparts.
Results are interpreted within the context of an emerging post-material society, in which a biocentric orientation to forests
and the natural environment may be favored more by a younger (versus older) generation and increasingly racially diverse U.S.
population. Implications for managing forests using a multiple-values (versus multiple-uses) approach are discussed. 相似文献
353.
354.
Blood collected from 62 fetuses aged 20–38 weeks of gestation was studied. The values of ten lipid parameters were determined: cholesterol (TC), triglycerides (TGs), apolipoprotein Al (apo A1), apolipoprotein B (apo B), apolipoprotein E (apo E), total apolipoprotein CIII (apo CIII), apolipoprotein CIII present in particles containing apo B (apo CIII LpB) or not (apo CIII Lp non-B), lipoparticles A1 (LpA1), and lipoprotein a (Lp(a)). The results show that, except for apo E, all the studied parameters were present in lower concentrations than in adults and newborns, and that Lp(a) is not detectable at that stage in life. 相似文献
355.
用平衡实验及动力学实验研究了我国南方4种红壤的表面质子化及铝的溶解与质子缓冲之间的关系.结果表明,由于游离氧化铁的含量、活性及对铝溶解反应位的掩盖程度等与质子化密切相关因素的不同影响,4种红壤的总H+消耗量和铝溶解量不同,宁海红壤和嵊县红壤的质子化程度及H+的总消耗量大于永春红壤和屯溪红壤;屯溪红壤铝的溶解量最大,宁海红壤铝的溶解量最小.尽管屯溪红壤铝的溶解量最大,但H+的总消耗量却最小.当红壤中氧化铁含量较高时,铝的溶解在H+消耗中只起次要作用,质子化过程是H+消耗的主要途径. 相似文献
356.
A Method for Constructing a Social Vulnerability Index: An Application to Hurricane Storm Surges in a Developed Country 总被引:11,自引:1,他引:11
Lisa Rygel David O’sullivan Brent Yarnal 《Mitigation and Adaptation Strategies for Global Change》2006,11(3):741-764
An important goal of vulnerability assessment is to create an index of overall vulnerability from a suite of indicators. Constructing
a vulnerability index raises several problems in the aggregation of these indicators, including the decision of assigning
weights to them. The purpose of this paper is to demonstrate a method of aggregating vulnerability indicators that results
in a composite index of vulnerability, but that avoids the problems associated with assigning weights. The investigators apply
a technique based on Pareto ranking to a complex, developed socioeconomic landscape exposed to storm surges associated with
hurricanes. Indicators of social vulnerability to this hazard are developed and a principal components analysis is performed
on proxies for these indicators. Overall social vulnerability is calculated by applying Pareto ranking to these principal
components. The paper concludes that it is possible to construct an effective index of vulnerability without weighting the
individual vulnerability indicators. 相似文献
357.
358.
Cost-effective hotspot identification is an important issue in hazardous waste site characterization and evaluation. Composite sampling techniques are known to be cost effective when the cost of measurement is substantially higher than the cost of sampling. Although compositing incurs no loss of information on the means, information on individual sample values is lost due to compositing. In particular, if the interest is in identifying the largest individual sample value, the composite sampling techniques are not able to do so. Under certain assumptions, it may be possible to satisfactorily predict individual sample values using the composite sample data, but it is not generally possible to identify the largest individual sample value. In this paper, we propose two methods of identifying the largest individual sample value with some additional measurement effort. Both methods are modifications of the simple sweep-out method proposed earlier. Since analytical results do not seem to be feasible, performance of the proposed methods is assessed via simulation. The simulation results show that both the proposed methods, namely the locally sequential sweep-out and the globally sequential sweep-out, are better than the simple sweep-out method.Prepared with partial support from the Statistical Analysis and Computing Branch, Environmental Statistics and Information Division, Office of Policy, Planning, and Evaluation, United States Environmental Protection Agency, Washington, DC under a Cooperative Agreement Number CR-821531. The contents have not been subjected to Agency review and therefore do not necessarily reflect the views of the Agency and no official endorsement should be inferred. 相似文献
359.
为了从价值观和调节焦点的双重视角给煤矿企业新生代员工的安全管理提供科学依据,在文献研究和问卷调查的基础上,对 244 个有效样本进行分析,揭示煤矿企业新生代员工工作价值观的具体内容,结合动机理论和调节焦点理论,构建煤矿企业新生代员工工作价值观、调节焦点和安全绩效的结构方程模型。研究结果表明:煤矿企业新生代员工的工作价值观包含发展导向、自我导向、关系认同、独立自主、利益导向和创造导向6个因子结构;煤矿企业新生代员工的工作价值观、调节焦点和安全绩效两两之间均显著相关;煤矿企业新生代员工的工作价值观不仅可以直接预测安全绩效,还可以通过调节焦点的中介作用间接影响煤矿员工的安全绩效。 相似文献
360.
200 years of sustainability in forestry: Lessons from history 总被引:4,自引:0,他引:4
K. Freerk Wiersum 《Environmental management》1995,19(3):321-329
Since the end of the 1980s the concept of sustainable development has gained general acceptance, but much uncertainty still
exists on how to operationalize this concept. In forestry the concept of sustainability has been an accepted principle since
the 18th century. The experiences with its application in forestry may contribute towards obtaining a better insight into
the implications and operational significance of the concept of sustainability. This article describes the history of sustainability
in forestry, including the various social values on which its interpretation has been based. The original principle of sustained
yield has gradually been broadened to a more inclusive principle of sustainable forest management. The dynamics in social
valuation of forest resources resulted in various attempts at practical operationalization of the principle. Notwithstanding
200 years of efforts to operationalize the concept of sustainability, its exact application in forestry remains troublesome.
Three lessons are drawn: (1) the need to recognize the different nature of ecological limits and social dynamics, (2) the
role of dynamic social values with respect to forest resources, and (3) the significance of operational experiences in trying
to attain sustainability within a concrete context. 相似文献