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   1836篇
  免费   232篇
  国内免费   46篇
安全科学   34篇
废物处理   16篇
环保管理   456篇
综合类   321篇
基础理论   1050篇
环境理论   3篇
污染及防治   56篇
评价与监测   42篇
社会与环境   131篇
灾害及防治   5篇
  2023年   65篇
  2022年   55篇
  2021年   78篇
  2020年   78篇
  2019年   74篇
  2018年   72篇
  2017年   82篇
  2016年   88篇
  2015年   100篇
  2014年   89篇
  2013年   121篇
  2012年   74篇
  2011年   98篇
  2010年   116篇
  2009年   113篇
  2008年   105篇
  2007年   122篇
  2006年   82篇
  2005年   74篇
  2004年   68篇
  2003年   26篇
  2002年   30篇
  2001年   41篇
  2000年   32篇
  1999年   20篇
  1998年   21篇
  1997年   18篇
  1996年   20篇
  1995年   18篇
  1994年   16篇
  1993年   18篇
  1992年   11篇
  1991年   8篇
  1990年   5篇
  1989年   4篇
  1988年   4篇
  1987年   10篇
  1986年   4篇
  1985年   4篇
  1984年   3篇
  1983年   7篇
  1982年   7篇
  1981年   8篇
  1980年   7篇
  1979年   4篇
  1978年   4篇
  1973年   1篇
  1972年   1篇
  1971年   4篇
  1968年   1篇
排序方式: 共有2114条查询结果,搜索用时 218 毫秒
281.
生物多样性保护依赖于健全的国际立法和国家立法。中国已颁布一系列有关生物多样性保护的法律和条例。这些法规的实施,使生物多样性保护工作取得重大进展,但还存在许多不足和空白。本文概述了中国在生物多样性保护方面的立法现状,在此基础上,针对存在问题,并根据《生物多样性公约》要求,从生态系统、物种和遗传多样性保护3个层次上阐明需要完善和加强法规建设的若干方面和需求。  相似文献   
282.
当前,任何地区的生物多样性都是自然和社会因素长期综合作用所造成。生物多样性最丰富的地区不一定全部由顶极植被所覆盖,而常常是一些包括所有演替类型的地方。本文通过讨论自然环境的变化和人类生产活动对不同区域景观的影响,探讨有关生物多样性的保护问题。  相似文献   
283.
本文针对目前环境保护的热点之一——全球和地区性生物多样性保护,对其中的一个基础理论问题,即区域生物多样性评价标准进行了探索;从理论上对制定这一标准的必要性、可行性、生物多样性的基本内涵、区域生物多样性中心标准的意义及标准制定的原则和依据进行了阐述,并在此基础上提出了我国区域生物多样性中心标准的基本框架。  相似文献   
284.
Damage to Cauliflower Coral by Monofilament Fishing Lines in Hawaii   总被引:1,自引:0,他引:1  
Abstract:  Many fishing methods and gear types used in coral reefs cause physical damage to the reef substratum. Only recently have monofilament fishing lines been recognized as a cause of coral damage and death. We assessed the extent of damage caused by monofilament fishing lines to the cauliflower coral (  Pocillopora meandrina ) colonies in fished and adjacent unfished zones at seven sites in the main Hawaiian islands. We examined coral colonies for the presence or absence of fishing line and for the degree of damage (dead, no live coral surface; damaged, some dead coral surface; or intact, no dead coral surface) in nine 25-m2 grids. The mean proportion of colonies entangled with fishing lines in fished zones ranged from 0.18 to 0.44. The mean proportion of dead or damaged colonies was higher in fished than adjacent unfished zones, and there was a positive linear relationship between the proportion of colonies entangled with fishing lines and the proportion of dead or damaged colonies. These results indicate that monofilament fishing lines have a negative impact on the health and survival of P. meandrina colonies. Because tourism and related recreational fishing activities are expanding rapidly in many tropical states and nations, we recommend that the degrading effects of fishing lines on corals be considered in the design and management of tourism development.  相似文献   
285.
286.
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   
287.
ABSTRACT

This article, through the use of political ecology perspectives on coercive conservation, aims to explain how in two separate Colombian Natural Parks and buffer zones, environmental policies designed to (re)take control of the frontier, have produced a similar territorial differentiation in the contention of illicit activities. Los Farallones in the Colombian Pacific and La Macarena/Puerto Rico in the Ariari region have experienced different stages of the armed conflict and are at the center of this analysis. I argue that in the contexts of both conflict escalation (1998–2007) and conflict de-escalation (2008–2016), the State in its attempt to control the frontier has not only had military intervention in areas of conservation but has also reinforced environmental programs that attack illegal mining and coca, producing both a territorially differentiated containment of illicit activities and an uneven progression of the illicit frontier.  相似文献   
288.
Abstract:  Marine protected areas, and other fishery management systems that impart partial or total protection from fishing, are increasingly advocated as an essential management tool to ensure the sustainable use of marine resources. Beneficial effects for fish species are well documented for tropical and reef systems, but the effects of marine protected areas remain largely untested in temperate waters. We compared trends in sport-fishing catches of nine fish species in an area influenced by a large (500-km2) towed-fishing-gear restriction zone and in adjacent areas under conventional fishery management controls. Over the period 1973–2002 the mean reported weight of above-average-sized (trophy) fish of species with early age at maturity and limited home range was greatest within the area influenced by the fishing-gear restriction zone. The reported weight of trophy fish of species that mature early also declined less and more slowly over time within the area influenced by the fishing-gear restriction zone. Importantly, the mean reported weight of trophy fish of species that mature late and those that undertake extensive spatial movements declined at the same rate in all areas. Hence these species are likely to require protected areas >500 km2 for effective protection. Our results also indicated that fish species with a localized distribution or high site fidelity may require additional protection from sport fishing to prevent declines in the number or size of fish within the local population.  相似文献   
289.
Abstract:  Ecologists and economists both use models to help develop strategies for biodiversity management. The practical use of disciplinary models, however, can be limited because ecological models tend not to address the socioeconomic dimension of biodiversity management, whereas economic models tend to neglect the ecological dimension. Given these shortcomings of disciplinary models, there is a necessity to combine ecological and economic knowledge into ecological-economic models. It is insufficient if scientists work separately in their own disciplines and combine their knowledge only when it comes to formulating management recommendations. Such an approach does not capture feedback loops between the ecological and the socioeconomic systems. Furthermore, each discipline poses the management problem in its own way and comes up with its own most appropriate solution. These disciplinary solutions, however, are likely to be so different that a combined solution considering aspects of both disciplines cannot be found. Preconditions for a successful model-based integration of ecology and economics include (1) an in-depth knowledge of the two disciplines, (2) the adequate identification and framing of the problem to be investigated, and (3) a common understanding between economists and ecologists of modeling and scale. To further advance ecological-economic modeling the development of common benchmarks, quality controls, and refereeing standards for ecological-economic models is desirable.  相似文献   
290.
Abstract:  Fire management is increasingly focusing on introducing heterogeneity in burning patterns under the assumption that "pyrodiversity begets biodiversity." This concept has been formalized as patch mosaic burning (PMB), in which fire is manipulated to create a mosaic of patches representative of a range of fire histories to generate heterogeneity across space and time. Although PMB is an intuitively appealing concept, it has received little critical analysis. Thus we examined ecosystems where PMB has received the most attention and has been the most extensively implemented: tropical and subtropical savannas of Australia and Africa. We identified serious shortcomings of PMB: the ecological significance of different burning patterns remains unknown and details of desired fire mosaics remain unspecified. This has led to fire-management plans based on pyrodiversity rhetoric that lacks substance in terms of operational guidelines and capacity for meaningful evaluation. We also suggest that not all fire patterns are ecologically meaningful: this seems particularly true for the highly fire-prone savannas of Australia and South Africa. We argue that biodiversity-needs-pyrodiversity advocacy needs to be replaced with a more critical consideration of the levels of pyrodiversity needed for biodiversity and greater attention to operational guidelines for its implementation.  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