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   3205篇
  免费   7篇
  国内免费   45篇
安全科学   65篇
废物处理   174篇
环保管理   321篇
综合类   425篇
基础理论   1151篇
污染及防治   689篇
评价与监测   224篇
社会与环境   203篇
灾害及防治   5篇
  2023年   14篇
  2022年   53篇
  2021年   35篇
  2020年   7篇
  2019年   16篇
  2018年   124篇
  2017年   145篇
  2016年   204篇
  2015年   58篇
  2014年   24篇
  2013年   44篇
  2012年   442篇
  2011年   232篇
  2010年   46篇
  2009年   49篇
  2008年   59篇
  2007年   69篇
  2006年   72篇
  2005年   398篇
  2004年   537篇
  2003年   406篇
  2002年   47篇
  2001年   39篇
  2000年   19篇
  1999年   32篇
  1998年   7篇
  1997年   10篇
  1996年   6篇
  1995年   11篇
  1994年   5篇
  1993年   2篇
  1992年   4篇
  1991年   7篇
  1990年   4篇
  1989年   4篇
  1985年   3篇
  1981年   2篇
  1977年   1篇
  1975年   3篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1971年   2篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
  1961年   1篇
  1959年   1篇
  1957年   1篇
排序方式: 共有3257条查询结果,搜索用时 15 毫秒
11.
Overestimates of black carbon in soils and sediments   总被引:2,自引:0,他引:2  
Several recent reports suggest that black carbon (BC), which broadly encompasses charcoal, soot, and other forms of pyrogenic carbon, may constitute a significant proportion of the refractory carbon in soil and sedimentary organic matter. BC is a sink for biospheric and atmospheric carbon dioxide, and is intimately tied to the biogeochemical cycling of both carbon and oxygen through its role in organic matter cycling. Additionally, BC may represent a large fraction of the missing carbon sink in global carbon accounting. Here, we demonstrate that documented measurements of BC may be the result of methodological artifacts, which inadvertently overestimate the amount of BC. We found that a widely used thermal oxidative method can create a residue that falls under the operational definition of BC in samples that are relatively BC-free. Moreover, during this procedure, labile organic matter constituents are condensed into pyrogenic carbon, implying that the labile components are present in lesser quantities. These methodological deficiencies are promoting overestimates in the amount of refractory carbon in soil and sedimentary organic matter and may endorse inaccuracies in the rates of carbon fluxes, the mean residence times of terrestrial carbon, and organic matter burial rates in oceanic environments.  相似文献   
12.
The invertebrate neuromodulator octopamine is known to be involved in bees' associative learning, enhancing the responsiveness of a bee to a conditioned stimulus. In this study, we tested the effect of octopamine on the choice behavior of free-flying bumblebees using a two-phase experiment in an array of artificial flowers. During the first phase of the experiment, the bee was allowed to collect octopamine-laden sugar water from two types of equally rewarding flowers (yellow versus blue). In the second phase, one type of flower was set to be unrewarding. The behavior of the bee (proportion of visits to the unrewarding flowers) over the two phases was fitted to a sigmoid regression model. Our results show that octopamine had no significant effect on the bees' equilibrium choice or on the overall rate of the behavioral change in response to the change in reward. Rather, octopamine significantly affected the time interval between the change in reward status and the initiation of behavioral change in the bee.  相似文献   
13.
The first part of this paper discusses the links between hazard, risk and vulnerability (HRV) analysis and the development of mitigative strategies. The second part discusses the need to include public participation when completing an HRV analysis. Two current HRV models are used to illustrate the general failure of HRV analysis to include public participation. The third part of this paper provides a brief overview of the Hazard, Impact, Risk and Vulnerability (HIRV) model and its use of public participation. The paper concludes by offering a synopsis of a case study in the town and regional area surrounding Barriere, British Columbia, Canada. This case study demonstrates a positive outcome when public participation is incorporated into an HIRV analysis.  相似文献   
14.
越南的养虾业正处在对生产体系的基础改造,使其转变成一个重要产业的过程中.该地区其他国家的经验,特别是高投入生产体系占主导地位的泰国的经验表明,现在正是通过干预使养虾业改道进入在生态、社会和经济上更可持续的道路.在泰国,实施强化的体系和复杂的产业组织的多年经验并没有获得可持续的解决办法.这里所面临的任务是使社会重新赢得控制并沿着更有效和良性发展的道路改变改革的发展方向.我们的分析结果表明,这两个国家的现行方法不可能使养虾业可持续的发展,需要对整个对虾的生产、喂养、加工、供销及管理的方式进行全面改革.  相似文献   
15.
The integrity of social insect colonies is maintained by members recognising and responding to the chemical cues present on the cuticle of any intruder. Nevertheless, myrmecophiles use chemical mimicry to gain access to these nests, and their mimetic signals may be acquired through biosynthesis or through contact with the hosts or their nest material. The cuticular hydrocarbon profile of the myrmecophilous salticid spider Cosmophasis bitaeniata closely resembles that of its host ant Oecophylla smaragdina. Here, we show that the chemical resemblance of the spider does not arise through physical contact with the adult ants, but instead the spider acquires the cuticular hydrocarbons by eating the ant larvae. More significantly, we show that the variation in the cuticular hydrocarbon profiles of the spider depends upon the colony of origin of the ant larvae prey, rather than the parentage of the spider.  相似文献   
16.
Foraging desert ants, Cataglyphis fortis, encounter different sequences of visual landmarks while navigating by path integration. This paper explores the question whether the storage of landmark information depends on the context in which the landmarks are learned during an ant's foraging journey. Two experimental set-ups were designed in which the ants experienced an artificial landmark panorama that was placed either around the nest entrance (nest marks) or along the vector route leading straight towards the feeder (route marks). The two training paradigms resulted in pronounced differences in the storage characteristics of the acquired landmark information: memory traces of nest marks were much more robust against extinction and/or suppression than those of route marks. In functional terms, this result is in accord with the observation that desert ants encounter new route marks during every foraging run but always pass the same landmarks when approaching the nest entrance.  相似文献   
17.
Population differences in anti-predator behaviour have been demonstrated in several species, although less is known about the genetic basis of these traits. To determine the extent of genetic differences in boldness (defined as exploration of a novel object) and shoaling within and between zebrafish (Danio rerio) populations, and to examine the genetic basis of shoaling behaviour in general, we carried out a study that involved laboratory-raised fish derived from four wild-caught populations. Controlling for differences in rearing environment, significant inter-population differences were found in boldness but not shoaling. A larger shoaling experiment was also performed using one of the populations as the basis of a North Carolina type II breeding design (174 fish in total) to estimate heritability of shoaling tendency. A narrow-sense heritability estimate of 0.40 was obtained, with no apparent dominance effects.  相似文献   
18.
19.
This paper examines how legal standards of liability may apply to geologic carbon storage. The liability regime governing geologic carbon storage will shape the technology's cost-effectiveness and overall attractiveness. We classify potential sources of liability into operational, in situ, and climate liability. As a first step, we explore in situ liability in the United States. After summarizing legal standards of liability including negligence, breach of implied warranty, strict liability, and product liability, we discuss how liability may be addressed at the level of the federal government, state government, industry, and the firm. Finally, we address the implications of judicial treatment of liability for carbon storage, including the apportionment of liability and the adequacy of current regulations.  相似文献   
20.
Community mitigation of hazard impact requires hazard knowledge and preparedness on the part of the members of diverse and complex communities. Longitudinal research in the tropical cyclone prone north of Australia has gathered extensive datasets on community awareness, preparedness and knowledge, in order to contribute to education campaigns and mitigation strategies. Data have been used to identify issues of vulnerability to cyclones and capacity to deal with the hazard. This has been developed as a community vulnerability and capacity model that may be applied to diverse communities in order to assess levels of capability to mitigate and deal with the cyclone hazard. The model is presented here in a simplified form as its development is evolving and ongoing.  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