全文获取类型
收费全文 | 1180篇 |
免费 | 95篇 |
国内免费 | 234篇 |
专业分类
安全科学 | 266篇 |
废物处理 | 4篇 |
环保管理 | 99篇 |
综合类 | 532篇 |
基础理论 | 313篇 |
环境理论 | 1篇 |
污染及防治 | 69篇 |
评价与监测 | 40篇 |
社会与环境 | 136篇 |
灾害及防治 | 49篇 |
出版年
2024年 | 7篇 |
2023年 | 22篇 |
2022年 | 45篇 |
2021年 | 62篇 |
2020年 | 52篇 |
2019年 | 46篇 |
2018年 | 47篇 |
2017年 | 52篇 |
2016年 | 56篇 |
2015年 | 65篇 |
2014年 | 61篇 |
2013年 | 131篇 |
2012年 | 71篇 |
2011年 | 87篇 |
2010年 | 72篇 |
2009年 | 55篇 |
2008年 | 54篇 |
2007年 | 72篇 |
2006年 | 67篇 |
2005年 | 54篇 |
2004年 | 42篇 |
2003年 | 41篇 |
2002年 | 36篇 |
2001年 | 39篇 |
2000年 | 25篇 |
1999年 | 29篇 |
1998年 | 32篇 |
1997年 | 15篇 |
1996年 | 5篇 |
1995年 | 18篇 |
1994年 | 18篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1509条查询结果,搜索用时 15 毫秒
141.
Is Current Consumption Excessive? A General Framework and Some Indications for the United States 总被引:3,自引:0,他引:3
Abstract: Many prior studies have explored the implications of human population growth and environmentally problematic technologies for biodiversity loss and other forms of environmental degradation. Relatively few, however, have examined the impacts of the level and composition of consumption. We offer a framework that shows how the level and composition of a society's total consumption relate to the uses of various forms of capital and to the sustainability of natural resources and human well-being. We relate the framework to two main approaches—top–down macro studies and bottom–up computer models—for measuring whether overall consumption in the United States satisfies a sustainability requirement. Existing top–down studies have shortcomings that bias their results toward optimism, and current computer simulation models, although strong on revealing biophysical outcomes, are limited in their ability to evaluate impacts on human well-being. Although some ambiguities arise in determining whether overall consumption in the United States is excessive, our conclusions regarding the composition of U.S. consumption are unambiguous. Distorted consumption patterns and associated production methods lead to excessively rapid natural resource depletion; greater conservation would yield gains to current and future generations that more than compensate for the sacrifices involved. Public policies that deal with the composition problem not only would help conserve natural resources and improve current welfare but also would reduce the costs of meeting the goal of sustainability. 相似文献
142.
Abstract: Conservation biologists and others hypothesize that humankind's "ecological footprint" is affected not only by the sheer intensity of human activity but also by its spatial arrangement. We used a multivariate statistical model and state-level data to evaluate correlations between species imperilment and the level and spatial distribution of human settlement and infrastructure development in the United States. The level of human activity—measured by the number of people and households, incidence of roads, and intensity of nighttime lights—was significantly correlated with the ecological imperilment of species. Our regression models consistently showed that a 1% increase in the level of human activity across the United States was associated with about a 0.25% increase in the proportion of plant and animal species considered at risk of extinction by The Nature Conservancy. The distribution of human activity did not affect species imperilment. Our results point to rising levels of human activity—and not some particular (e.g., sprawling) distribution of human activity—as the most relevant anthropogenic factor explaining biodiversity loss in the United States. 相似文献
143.
Thomas Eisner Jeffrey Conner James E. Carrel John P. McCormick Amy J. Slagle Carl Gans James C. O'Reilly 《Chemoecology》1990,1(2):57-62
Summary Frogs(Rana pipiens) fed on blister beetles (Meloidae) or cantharidin, retain cantharidin systemically. After cessation of feeding, they void the compound relatively quickly. Systemic cantharidin does not protect frogs against ectoparasitic feeding by leeches(Hirudo medicinalis) or predation by snakes(Nerodia sipedon). As suggested by our data, and from reports in the early literature, ingestion of cantharidin-containing frogs can pose a health threat to humans.Paper no. 95 of the seriesDefense Mechanisms of Arthropods; no. 94 is LaMunyon & Eisner, Psyche (in press) 相似文献
144.
城市人居环境评价体系的研究及应用 总被引:25,自引:0,他引:25
在国内外人居环境理论研究及实践的基础上,提出了由系统层、子系统层和指标层构成的城市人居环境评价指标体系,其中系统层由社会经济环境、自然生态环境、公共设施建设、环境资源保护和环境管理能力五部分组成,子系统层由16个指标组成,指标层由43个具体指标组成。利用统计分析法(Delphi)确定各指标的权值。同时,针对本指标体系结构提出了单项评价和综合评价相结合的评价模式,并设置了城市人居环境质量指数和系统协调度两个综合性指标来全面评价城市人居环境质量。通过对重庆市渝北城区的综合评价,评价结果较客观地反映了该城区的实际。 相似文献
145.
上消化道出血的常见诱因分析及护理对策 总被引:2,自引:0,他引:2
本文对上消化道出血的常见诱因进行了分析,并对临床护理方法进行了实践探讨,以求对上消化道出血的护理工作提供参考. 相似文献
146.
147.
Owing to its unique nutritional and immunological characteristics, human milk is the most important food source for infants. Breast milk can, however, also be a pathway of maternal excretion of toxic elements. Selected toxic elements (As, Pb, Mn,a Hg and Cd) were determined in human breast milk and blood samples obtained from 120 subjects related to an integrated steel plant environment located in central India. Samples of breast milk and blood from subjects living outside the steel plant environment were also analyzed for comparative study. Higher levels of these toxic elements were found in blood samples as compared to breast milk samples. Plant workers showed the higher presence of these metals in their breast milk and blood samples compared to the residents of the area and the subjects living outside the industrial environment, respectively. Mn, Pb and Hg have shown a higher tendency to associate with blood and breast milk than As and Cd. The order of occurrence of these metals in blood and milk samples thus found is Mn > Pb > Hg > As > Cd. 相似文献
148.
松胞素B对人血淋巴细胞和CHL细胞微核率的影响 总被引:2,自引:0,他引:2
研究了不同浓度的松胞素B对人血淋巴细胞和中国仓鼠肺成纤维细胞(CHL)分裂吉周期和微核率的影响。结果表明,松胞素B浓度增高过高能引起细胞微核率增高。在本研究中,对CHL细胞微核率试验以3μg/mL松胞素B较适合;而对人血淋巴细胞微核试验,松胞素B浓度以2-4μg/mL为宜,松胞表B浓度过高会提高微核背景值,降低试验的灵敏度和精确性。 相似文献
149.
导游人力资源的现状分析与对策 总被引:6,自引:0,他引:6
邹伏霞 《湖南环境生物职业技术学院学报》2004,10(4):352-355
随着导游职业的社会化,导游数量急剧上升,但导游质量却是年年下降,本文就目前我国导游人力资源的学历、等级等现状为主,分析其现状和所存在的问题,并提出相应的对策与建议。 相似文献
150.
人地协同论:可持续发展模型构建的基础 总被引:6,自引:0,他引:6
人地协同论是在陆地系统科学、非线性系统理论基础上建立起来的关于可持续发展的一个数理模型,它以社会与自然的交互作用、交界面性质及其演化规律为研究对象。本文根据系统生态学理论,提出了关于可持续生存的数学定义。 相似文献