首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1997篇
  免费   16篇
  国内免费   12篇
安全科学   54篇
废物处理   89篇
环保管理   207篇
综合类   176篇
基础理论   391篇
环境理论   3篇
污染及防治   739篇
评价与监测   212篇
社会与环境   148篇
灾害及防治   6篇
  2023年   23篇
  2022年   57篇
  2021年   65篇
  2020年   28篇
  2019年   29篇
  2018年   49篇
  2017年   59篇
  2016年   106篇
  2015年   66篇
  2014年   114篇
  2013年   184篇
  2012年   134篇
  2011年   162篇
  2010年   88篇
  2009年   89篇
  2008年   130篇
  2007年   117篇
  2006年   103篇
  2005年   67篇
  2004年   61篇
  2003年   53篇
  2002年   66篇
  2001年   32篇
  2000年   16篇
  1999年   13篇
  1998年   10篇
  1997年   9篇
  1996年   12篇
  1995年   13篇
  1994年   15篇
  1993年   8篇
  1992年   3篇
  1991年   6篇
  1990年   5篇
  1989年   2篇
  1986年   2篇
  1983年   4篇
  1982年   2篇
  1981年   2篇
  1979年   2篇
  1978年   1篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1973年   1篇
  1966年   2篇
  1965年   3篇
  1964年   1篇
  1958年   2篇
  1956年   1篇
排序方式: 共有2025条查询结果,搜索用时 9 毫秒
31.
32.
In general, tourism plays a significant role in the economy of archipelagos and islands. The Autonomous Region of the Azores has a great potential for tourism, offering multiple attractions, both natural and cultural, creating a big challenge for a sustainable tourism policy since little attention has been paid to the archipelagos and their special needs. This work aims to understand the profile and type of ecotourist that visits the Azores. This knowledge is of great importance for a better management and development of nature-based tourism, and products tailored to the needs and expectations of visitors. The data were collected by means of exit surveys conducted at the Airport of São Miguel Island, the larger and most populated island of the archipelago, during the high tourist season—July–September 2009. The analysis of the visitor’s profile and preferences is crucial to draw adequate strategies of management for tourism, while it helps to adequate the offer to the demand. Results showed that 41.1 % of the tourists claimed to be attracted to the islands due to their “natural values” (e.g., landscape, biodiversity, and geodiversity). The most practiced activities were whale-watching (32.4 %) and mountaineering/hiking (31.6 %), followed by diving (7 %) and other sports (5.1 %). The tourists’ profile points to a mainstream, soft, and incidental type of ecotourist. This information helps to develop and support a strategic planning and management, both at local and regional levels, for sustainable tourism policies.  相似文献   
33.
34.
Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions.  相似文献   
35.
Local rural and indigenous communities have assumed increasing responsibility for conservation within and between areas buffering the impacts of agricultural or resource‐extraction zones and protected areas. Empowering local communities as central partners in conservation and climate‐change mitigation has allowed many people to gain access to land and citizenship rights but has provided limited improvements in access to social services and economic opportunities even as expectation about their role as environmental stewards grows. These expectations, however, are inconsistent with reality. We conducted multiple field studies in Brazil since the mid‐1980s to illustrate the discrepancies between conservation programs and local conditions and expectations. We suggest that public policies and conservation programs should not delegate responsibility for managing protected areas to local and indigenous communities without considering local needs and expectations and locals’ attitudes toward conservation. In other words, behavior that maintains or improves the environment should not be treated as traditional based on the expectations of outsiders. Framing local populations as traditional environmentalists creates contradictions and frustrations for local populations and for conservation professionals and policy makers.  相似文献   
36.
A newly analytical method based on QuEChERS extraction followed by gas chromatography with mass spectrometry (GC-MS) analysis was developed and validated for the quantification of 18 PCBs in wild (from Matosinhos Beach, Portugal) and cultivated (from Ria de Arousa, Spain) mussel samples, pooled by sex. Wild animals showed higher PCB levels than cultivated mussels, with males from both origins, presenting an upper contamination profile comparing with females. This fact seems to be correlated with few biometric parameters, but other interdependencies, not addressed herein, such as distinct lipid contents between sexes, as a consequence of the gametogenic stage, may also explain this data. Overall, data reiterate the importance of investigating the presence of PCBs in marine biological samples, which can act both as bioindicators of environmental contamination, either as food quality controls for human health.  相似文献   
37.
Environmental Science and Pollution Research - Due to human activities, there is an increasing presence of agrochemicals residues in water bodies, which could be attributed to an increased use of...  相似文献   
38.
Environmental Science and Pollution Research - The total cultivated area in Brazil reached to 62 million ha in 2018, with the predominance of genetically modified soybean and corn (36 and 17...  相似文献   
39.
Environmental Science and Pollution Research - This study assessed the effect of rinsing and boiling on total content of As (tAs) and of its inorganic and organic forms in different types of rice...  相似文献   
40.
Environmental Science and Pollution Research - Mg-Fe layered double hydroxide intercalated with chloride (Mg-Fe-Cl LDH) was synthetized, characterized, and evaluated as adsorbent to remove nitrate...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号