全文获取类型
收费全文 | 19129篇 |
免费 | 364篇 |
国内免费 | 3542篇 |
专业分类
安全科学 | 734篇 |
废物处理 | 1383篇 |
环保管理 | 2046篇 |
综合类 | 5987篇 |
基础理论 | 4654篇 |
环境理论 | 2篇 |
污染及防治 | 5270篇 |
评价与监测 | 1357篇 |
社会与环境 | 1206篇 |
灾害及防治 | 396篇 |
出版年
2024年 | 5篇 |
2023年 | 151篇 |
2022年 | 480篇 |
2021年 | 388篇 |
2020年 | 282篇 |
2019年 | 263篇 |
2018年 | 1777篇 |
2017年 | 1762篇 |
2016年 | 1553篇 |
2015年 | 667篇 |
2014年 | 814篇 |
2013年 | 1049篇 |
2012年 | 1339篇 |
2011年 | 2194篇 |
2010年 | 1355篇 |
2009年 | 1244篇 |
2008年 | 1601篇 |
2007年 | 1789篇 |
2006年 | 496篇 |
2005年 | 384篇 |
2004年 | 318篇 |
2003年 | 413篇 |
2002年 | 401篇 |
2001年 | 266篇 |
2000年 | 270篇 |
1999年 | 246篇 |
1998年 | 257篇 |
1997年 | 242篇 |
1996年 | 222篇 |
1995年 | 173篇 |
1994年 | 118篇 |
1993年 | 122篇 |
1992年 | 104篇 |
1991年 | 79篇 |
1990年 | 54篇 |
1989年 | 26篇 |
1988年 | 27篇 |
1987年 | 10篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 22篇 |
1983年 | 16篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
21.
通过滇池鲤鱼与松花坝水库和国内外同类鲤鱼的元素含量对比,确认滇池鲤鱼受工业污水的危害影响主要是As、Se。鱼体As、Se含量目前已经超过正常值,Ni、Cr、Cu、Fe、Pb比正常值偏低,其它元素属正常值范围。为了避免过多的元素富集,建议滇池鲤鱼以半年到一年为生长捕捞期为宜。 相似文献
22.
The alpine musk deer (Moschus chrysogaster) is a key species of some terrestrial ecosystems, it has an important economic and conservative significance as a kind of medical animal in China. Due to the interaction between natural forces and human disturbance, the habitats of alpine musk deer are fragmented and isolated in different mountains and the populations are confronted with many problems of survival. In this paper, we discuss the impact of habitat fragmentation and isolation on alpine musk deer populations based on the investigation on the population densities and sizes and environmental factors in different reserves, as well as on the analysis of its ecological adaptability. We found that the alpine musk deer has strong ecological adaptability; the population development of alpine musk deer may benefit from the reduction of the forest area and even from the fragmentation and isolation of the habitat to a certain extent. However, deforestion should not be encouraged only for the alpine musk deer population, but should also be based on the overall consideration of biodiversity conservation. 相似文献
23.
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
24.
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
25.
Environmental factors have long been shown to influence species distributions, with range limits often resulting from environmental
stressors exceeding organism tolerances. However, these abiotic factors may differentially affect species with multiple life-history
stages. Between September 2004 and January 2006, the roles of temperature and nutrient availability in explaining the southern
distributions of two understory kelps, Pterygophora californica and Eisenia arborea (Phaeophyceae, Laminariales), were investigated along the coast of California, USA and the Baja California Peninsula, Mexico,
by limiting either: (a) tissue nitrogen uptake and storage by adult sporophytes during periods of elevated temperature, and/or
(b) production of embryonic sporophytes by microscopic gametophytes. Results suggest that while adult sporophytes of both
species are tolerant of high temperatures and low nutrients, reproduction by their microscopic stages is not. Specifically,
while E. arborea produced embryonic sporophytes at both 12 and 18°C, temperatures commonly observed throughout the southern portion of its
range, P. californica produced sporophytes at 12 but not at 18°C. As a result, it appears that the southern distribution of P. californica, which ends in northern Baja California, Mexico, may be limited by temperature acting on its microscopic stages. In contrast,
the ability of E. arborea’s microscopic and adult stages to tolerate elevated temperatures allows it to persist in the warmer southern waters of Baja
California, as well as to the north along the California coast where both species co-occur. 相似文献
26.
Tone River supplies most of the water requirements of the Tokyo Metropolitan Area (TMA). Lowering of Tone flow and yearly
fluctuation, however, is causing water shortage along TMA nowadays. This study investigated the future water availability
scenarios under climatic changes. A state-of-the-art approach to utilize the output of several GCM has been demonstrated to
investigate the future water availability scenarios for TMA from the Tone River. An integrated modeling approach for water
balance considering several hydrological risk indices was adopted to quantify the future changes in this case. It is observed
that the future summer precipitation along the Tone basin is going to be increased considerably, while an almost constant
or decreasing trend is observed for winter season. Natural flow availability for winter or spring seasons thus can be crucial
under future scenarios. After reservoir routing, the hydrological risk indices estimated, however, were not found to be changed
significantly due to the presence of a robust reservoir system at the upstream. 相似文献
27.
Ricardo Braun 《Environment, Development and Sustainability》2007,9(4):387-411
The implementation of sustainable development may seem a simple concept when written on paper. However to carry-out long term
actions put forward by the Agenda 21 (AG21) at the local level represents one of the main challenges as municipal governments
in general do not have the capacity to effectively implement the process.
Regional environmental assessment (REA) has shown to be effective in supporting decision-making not only to correct environmental
problems due to past unsustainable social-economic developments but also help local governments to implement sustainable actions.
However this requires long-term investments of AG21 plans and projects. The allocation of regular and consistent financial
resources is one of the main ingredients for the sustainable development process. But traditional plans and projects financed
by national and/or international funds may not be sustainable in the long-term because they become dependent on external funding.
Research demonstrate that innovative economic instruments such as ecotaxes represent a feasible alternative to sponsor local
sustainability because taxes are collected permanently by the government and could be invested in continuous actions. Ecotaxes
experiences have provided important reference to structure a municipal incentive model (MIM) to sponsor AG21’s environmental
plans and projects on a long-term (permanent) basis.
However sustainable development cannot be solely through economic investments. A comprehensive municipal environmental management
scheme (MEMS) has been established to support the incentive model. The scheme seeks not only to improve local institutional
framework but also incentive continuous participation of local stakeholders at all levels of society. Participatory events
and the provision of incentives (educational and financial) are key to motivate society to protect the environment and support
actively the sustainable development process as emphasised in the RIO-92 Conference. 相似文献
28.
长江中游平原湖区农业开发地域分工与农产品专业化生产研究 总被引:6,自引:1,他引:5
农业生产地域分工与农产品专业化生产是使农业从自然经济阶段向以市场为导向的商品农产品生产转变的一个标志。本文在分析该区农业布局现状及其存在问题的基础上,提出了农业总体布局的设想与不同类型地域农业开发的主攻方向与对策,并对市场经济体制下粮食、棉花、猪、禽、水产品等农产品生产基地的地域选择、建设规模与技术措施等进行了探讨。 相似文献
29.
Dynamics and Causation of Environmental Equity, Locally Unwanted Land Uses, and Neighborhood Changes
Feng Liu 《Environmental management》1997,21(5):643-656
/ Why are some environmental risks distributed disproportionately in the neighborhoods of the minorities and the poor? A hypothesis was proposed in a recent study that market dynamics contributed to the current environmental inequity. That is, locally unwanted land uses (LULUs) make the host communities home to more poor people and people of color. This hypothesis was allegedly supported by a Houston case study, whereby its author analyzed the postsiting changes of the socioeconomic characteristics of the neighborhoods surrounding solid waste facilities. I argue that such an analysis of postsiting changes alone is insufficient to test the causation hypothesis. Instead, I propose a conceptual framework for analysis of environmental equity dynamics and causation. I suggest that the presiting neighborhood dynamics and the characteristics of control neighborhoods be analyzed as the first test for the causation hypothesis. Furthermore, I present theories of neighborhood change and then examine alternative hypotheses that these theories offer for explaining neighborhood changes and for the roles of LULUs in neighborhood changes. These alternative hypotheses should be examined when analyzing the relationship between LULUs and neighborhood changes in a metropolitan area. Using this framework of analysis, I revisited the Houston case. First, I found no evidence that provided support for the hypothesis that the presence of LULUs made the neighborhoods home to more blacks and poor people, contrary to the conclusion made by the previous study. Second, I examined alternative hypotheses for explaining neighborhood changes-invasion-succession, other push forces, and neighborhood life-cycle; the former two might offer better explanation.KEY WORDS: Environmental equity and justice; Locally unwanted lane uses; Siting; Market dynamics; Invasion-succession; Neighborhood changes 相似文献
30.
Jiao Youzhou Xue Huizan He Chao Wang Zigang Ma Xiaoran Liu Xinxin Liu Liang Chang Chun Petracchini Francesco Li Panpan 《Environment, Development and Sustainability》2022,24(4):4709-4726
Environment, Development and Sustainability - Anaerobic digestion (AD) is an attractive straw resource treatment technology as it can improve the utilization efficiency of straw resource. Raw straw... 相似文献