全文获取类型
收费全文 | 32374篇 |
免费 | 2403篇 |
国内免费 | 6481篇 |
专业分类
安全科学 | 4622篇 |
废物处理 | 820篇 |
环保管理 | 4766篇 |
综合类 | 18668篇 |
基础理论 | 3537篇 |
环境理论 | 18篇 |
污染及防治 | 3226篇 |
评价与监测 | 1647篇 |
社会与环境 | 2271篇 |
灾害及防治 | 1683篇 |
出版年
2024年 | 127篇 |
2023年 | 587篇 |
2022年 | 931篇 |
2021年 | 1153篇 |
2020年 | 1172篇 |
2019年 | 938篇 |
2018年 | 863篇 |
2017年 | 1200篇 |
2016年 | 1442篇 |
2015年 | 1409篇 |
2014年 | 1506篇 |
2013年 | 1969篇 |
2012年 | 2289篇 |
2011年 | 2455篇 |
2010年 | 1797篇 |
2009年 | 1866篇 |
2008年 | 1452篇 |
2007年 | 2240篇 |
2006年 | 2219篇 |
2005年 | 1874篇 |
2004年 | 1580篇 |
2003年 | 1613篇 |
2002年 | 1369篇 |
2001年 | 1146篇 |
2000年 | 1031篇 |
1999年 | 999篇 |
1998年 | 739篇 |
1997年 | 604篇 |
1996年 | 462篇 |
1995年 | 435篇 |
1994年 | 389篇 |
1993年 | 336篇 |
1992年 | 250篇 |
1991年 | 191篇 |
1990年 | 123篇 |
1989年 | 70篇 |
1988年 | 75篇 |
1987年 | 44篇 |
1986年 | 31篇 |
1985年 | 36篇 |
1984年 | 30篇 |
1983年 | 35篇 |
1982年 | 23篇 |
1981年 | 22篇 |
1980年 | 21篇 |
1979年 | 25篇 |
1978年 | 11篇 |
1977年 | 16篇 |
1973年 | 17篇 |
1971年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The main purpose of this study is to assess economic vulnerability of small island development regions as part of their sustainability constraints. By combining economic and environmental time series data, we assessed a composite index of economic vulnerability which is constructed from three exogenous variables, namely economic exposure, economic remoteness, and economic impact of environmental and natural disasters. We used the Amami Islands, Kagoshima Prefecture, Japan as the case studies for this paper.The results indicated that using a gross island products based valuation index, Kikaijima is the most vulnerable island in the Amami Islands with a composite economic vulnerability index (CEVI) value of 0.678, while by using a per capita based index, Okinoerabujima is considered the most vulnerable island with a CEVI value of 0.680. From the results we also revealed that smaller islands have relative higher vulnerability than the bigger one, which also confirms some previous country-level vulnerability studies.However, it is matter of fact that some islands that have relatively high vulnerability also have good economic performance as shown by their per capita income. In this regard, it can be argued that the success of these small islands could have been achieved in spite of and not because of their inherent vulnerability conditions as an indicator of sustainability constraint. Regarding these findings, we also examined a comparison between vulnerability results and the preliminary concept of an island's resilience in order to capture another perspective on sustainability assessment in a small island region. 相似文献
42.
Zhang Jing Feng Zhiming Yang Yanzhao 《中国人口.资源与环境(英文版)》2006,4(2):33-40
The article puts forward the process and means of regional water and land balance research, and then from two scenarios which are the balances under natural regulation and human intervention, calculated and analysed the balance between water and land on Ningxia Plain. For the balance under natural regulation named farmland water balance, using farmland water resource balance equation, the research estimated the monthly farmland" water balance of 8 major crops for all of the 12 counties on Ningxia Plain in the period of 1960-2001; for the balance under human intervention, the research estimated land-use water balance equation of the counties in 2000, and calculated the balance between land use and water resources including irrigating water of all the 12 counties on Ningxia Plain. Results showed that ①precipitation can not meet the water demand of the crops for growth and development on Ningxia Plain, and water shortage is the primary character of farmland water balance under natural regulation. ②the diversity of water and land balance of different counties is distinctly influenced by the crop structure, water quantity for irrigation and irrigation level. ③Irrigation water could meet the crop water demand on Ningxia Plain in 2000, but there was not much space to expand irrigating cultivated land. 相似文献
43.
Methodological Basis of Ecological Safety Standards for the Technogenic Impact of Mineral Resource Exploitation 总被引:1,自引:0,他引:1
A new methodological approach to the development of biological and technological safety standards for the impact of underground mining on the natural biota is proposed. 相似文献
44.
Whereas past research has treated co-management of common pool resources as if villagers and project implementing authorities
were the only relevant actors, numerous external factors beyond the control of these two partners create barriers to successful
co-management. This paper draws on discussions with Forest Department officials to examine the influence of these forces on
the outcomes of Joint Forest Management (JFM) in Tamil Nadu, India. An empirical inquiry into the operational aspects of JFM
indicates the important roles of political parties, powerful people, and other state institutions and functionaries as well
as the flow of foreign funding. Further, the strong demand by local people for socio-economic development interventions as
opposed to improvement of degraded forests belittles the role of the Forest Department relative to other departments. Numerous
other conditioning factors and relationships are explored. The authors call for reforms in public governance to allow better
participation of all the actors involved for this participatory management approach to succeed and sustain. 相似文献
45.
N. O. Kin 《Russian Journal of Ecology》2008,39(4):254-260
Heavy metal accumulation by plant communities has been studied in different zones of impact of gas field development. The contents of heavy metals in different blocks of plant communities has proved to depend not only on the location of phytocenosis but also on its species composition. Communities dominated by species of the family Poaceae contain smaller amounts of heavy metals than those dominated by species of the family Asteraceae, especially of the genus Artemisia. The order of precedence in the accumulation of heavy metals in different blocks of plant communities has been revealed. 相似文献
46.
Although stewardship has been widely defined and used in environmental management and planning, there is a dearth of studies
that describe how the lay public perceives this concept. A national sample of residents in 14 states who live near DOE nuclear
facilities were interviewed to delineate public understanding and awareness of the stewardship program of the U.S. Department
of Energy (DOE). This study discusses the findings of the survey and discusses how institutional trust influences public participation
and resident’s choices of potential stewards. Almost 40% of the respondents could not define stewardship; those who did, believed
that ‘responsibility,’ ‘management,’ and ‘accountability’ are key elements of stewardship. In addition, about a third of the
respondents identified Federal groups and the DOE as potential stewards.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue 相似文献
47.
48.
现行财税体制下我国耕地资源数量变化的实证研究 总被引:1,自引:0,他引:1
耕地资源数量变化受到人口、经济等诸多因素的影响,而财税体制是影响耕地资源数量变化的更深屡次原因。通过数量关系的初步观察和作用机理分析说明我国现行财税体制对耕地资源数量变化存在正反两方面作用,总体来看,对耕地资源保护不利。计量结果进一步证实了我国现行财税体制对耕地资源数量变化存在显著影响。揭示了其影响的方向和大小。根据研究结果,文章有针对性地提出了增加地方财政预算收入,合理分配土地出让金比例和科学使用土地出让金等相关政策建议。 相似文献
49.
50.
根据环境意识结构.设计了旅游管理部门环境意识调查问卷。其主要的指标体系包括:旅游环境知识水平、旅游环境态度、旅游环境评价和旅游环境行为四个方面。对指标体系各部分之间以及每一指标部分的每一题目之间的相对重要性进行权重的确定.而且对各部分的每道题目的各个选项予以赋分。基于权重和赋分.结合调查问卷的实际情况,设计了指标体系各部分评价模型和环境意识总体评价模型。以此来计算草原旅游发展中旅游管理部门环境意识水平的综合得分。经过分析得知,旅游管理部门环境意识模式是“环境知识制约型”模式。 相似文献