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   389篇
  免费   6篇
  国内免费   10篇
安全科学   25篇
废物处理   4篇
环保管理   86篇
综合类   94篇
基础理论   123篇
环境理论   1篇
污染及防治   18篇
评价与监测   22篇
社会与环境   15篇
灾害及防治   17篇
  2023年   1篇
  2022年   5篇
  2021年   2篇
  2020年   2篇
  2019年   10篇
  2018年   4篇
  2017年   9篇
  2016年   9篇
  2015年   7篇
  2014年   8篇
  2013年   42篇
  2012年   14篇
  2011年   29篇
  2010年   16篇
  2009年   22篇
  2008年   26篇
  2007年   20篇
  2006年   22篇
  2005年   18篇
  2004年   13篇
  2003年   19篇
  2002年   11篇
  2001年   12篇
  2000年   13篇
  1999年   16篇
  1998年   8篇
  1997年   5篇
  1996年   7篇
  1995年   5篇
  1994年   5篇
  1993年   8篇
  1992年   4篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1985年   2篇
  1984年   3篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1978年   1篇
排序方式: 共有405条查询结果,搜索用时 15 毫秒
381.
In a field experiment on the island of Helgoland (southeast North Sea), we investigated whether migration strategy or competition between the sexes cause the differential timing of spring migration of male and female northern wheatears (Oenanthe oenanthe) (males migrating earlier). The study included two subspecies, heading towards Greenland/Iceland and Scandinavia, respectively, and is based on colour-ringing and remote weighing of individuals. Despite food offered ad libitum, most Scandinavian birds left the island on the day of arrival or stayed only 1–3 days, whereas more than half of Greenlandic/Icelandic birds stayed for up to 12 days and refuelled rapidly. In the latter subspecies, males showed a positive correlation of departure fuel load and fuel deposition rate, resembling time-minimizers in optimal migration theory. In contrast, females departed irrespective of fuel deposition rate, with an approximately constant level of fuel stores. This level was lower than in males, but sufficient to enable by-passing of stopover sites en route, allowing us to regard females as time-minimizers also. Since females are not able to reach Greenland without additional refuelling elsewhere and males appeared to have a larger potential for by-passing stopover sites, time-selection seems to be more pronounced in males and may be the reason for earlier migration of males. Intraspecific aggressive interactions between colour-ringed birds were predominantly won by the initiator, by males and by larger birds, whereas fuel load and subspecies did not affect the outcome. Although compared to females, males were more often dominant at the feeding stations or held territories, refuelling patterns could not be explained by dominance. Subordinate or non-territorial birds did not refuel at a lower rate or depart with lower fuel loads than dominant or territorial birds. In non-territorial birds, the restricted access to feeding stations was made up with larger doses of food taken per visit, leading to the same energy intake as that of dominant and territorial birds. Therefore, competition during stopover could be eliminated as the reason for differential timing of migration of male and female wheatears, but this result may be species-specific.Communicated by W. Wiltschko  相似文献   
382.
In most mammals, larger adult body size correlates with lower fundamental frequency and more closely spaced formants in vocalizations relative to juveniles. In alarm whistles of two free-living rodents, the speckled ground squirrel Spermophilus suslicus and yellow ground squirrel S. fulvus, these cues to body size were absent despite prominent differences in body weight and skull and larynx sizes between juveniles and adults. No significant correlations were found between the individual maximum fundamental frequency and body weight, both within age classes and for pooled samples of all animals within species. Furthermore, the mean alarm whistle maximum fundamental frequencies did not differ significantly between age classes (juvenile versus adult) in the speckled squirrel and were even significantly lower in juvenile yellow squirrels. We discuss the hypothesis that the obfuscation of vocal differences between juvenile and adult squirrels may represent a special adaptation of pup vocal behaviour—a form of “vocal mimicry,” resulting in imitation of adult vocal pattern to avoid infanticide and age-dependent predation risk.  相似文献   
383.
中国区域环境影响评价的发展   总被引:10,自引:0,他引:10  
王云 《上海环境科学》2000,19(12):550-552
我国区域环境影响评价的发展,根据其理论方法研究和环境评价管理的进程,可分为提出、探索和开展3个阶段,并具有理论方法研究和环境评价管理建设密切配合,着重于规划控制技术和顺应发展中国家经济发展对环境管理的需要等发展特点。  相似文献   
384.
人员可靠性与系统安全   总被引:3,自引:3,他引:3  
论述了人员可靠性对系统安全的影响,分析了它的特点和应采用的研究方法,介绍了笔者近年来在核电站人员可靠性基础研究方面的情况,并对研究的发展趋势进行了展望。  相似文献   
385.
Two field studies examined the role of attitudes, subjective norms, perceived control, anticipated emotions, past behaviour and desire in the prediction of pro-environmental behavioural intention. The model of goal-directed behaviour (MGB) was applied to predict intentions to use public transportation instead of the private car for going to work (Study 1, N=180), and to recycle household waste (Study 2, N=154). Multiple regression and structural equation modeling were used to test the hypotheses in studies 1 and 2, respectively. As expected, results of the two studies indicate that negative anticipated emotions and past behaviour are significant predictors of desire to engage in pro-environmental action. Desire, in turn, positively predicts pro-environmental behavioural intentions. A direct link between past behaviour and intentions was also detected. Implications of the results for the promotion of pro-environmental behaviour are discussed.  相似文献   
386.
Management of common-pool natural resources is commonly implemented under institutional models promoting devolved decision-making, such as co-management and community-based management. Although participation of local people is critical to the success of devolved commons management, few studies have empirically investigated how individuals’ participation is related to socioeconomic factors that operate at multiple scales. Here, we evaluated how individual- and community-scale factors were related to levels of individual participation in management of community-based marine protected areas in Indonesia. In addressing this aim, we drew on multiple bodies of literature on human behaviour from economics and social science, including the social-ecological systems framework from the literature on common-pool resources, the theory of planned behaviour from social psychology, and public goods games from behavioural economics. We found three key factors related to level of participation of local people: subjective norms, structural elements of social capital, and nested institutions. There was also suggestive evidence that participation was related to people’s cooperative behavioural disposition, which we elicited using a public goods game. These results point to the importance of considering socioeconomic factors that operate at multiple scales when examining individual behaviour. Further, our study highlights the need to consider multiscale mechanisms other than those designed to appeal to self-interested concerns, such as regulations and material incentives, which are typically employed in devolved commons management to encourage participation. Increased understanding of the factors related to participation could facilitate better targeting of investments aimed at encouraging cooperative management.  相似文献   
387.
This paper describes an individual-based model, MORPH, that has been designed to predict the effect of environmental change on foraging animal populations. The key assumptions of MORPH are that individuals within populations behave in order to maximise their perceived fitness, but that perceived fitness may not always be positively related to the actual chances of survival and reproduction. MORPH has been parameterised for coastal birds on several European sites and predicted the effect of environmental change, caused by factors such as habitat loss, disturbance from humans and sea-level rise, on the survival and body condition of these species. However, MORPH contains a basic framework to describe animal physiology and foraging behaviour, and the distribution and abundance of the resources required by these animals. Therefore, MORPH is not restricted to coastal birds, and is potentially applicable to a wider range of systems. To be applied to a forager system, MORPH requires parameters describing (i) the distribution of the food supply and how food quality and abundance changes through time; (ii) the rate at which foragers consume food given the abundance of food and competitors; (iii) the amount of food the forager must consume each day to survive; (iv) the distribution and seasonal changes in other factors which influence the foraging behaviour and survival of foragers. The purpose of this paper is to (i) describe MORPH, (ii) give examples of its application, (iii) describe the types of systems to which MORPH can be applied, and (iv) publish its source code and a user guide.  相似文献   
388.
Recently, China, Japan, and the Republic of Korea (Korea) are conducting a government-commissioned feasibility study on the Free Trade Agreement among the three countries (CJKFTA) to form a regional free trade zone in East Asia. Considering that freer trade can cause unexpected impact on domestic environment, there is a need to evaluate the environmental impact of such a trade policy. This move should be made to help negotiators understand and pay more attention to environmental issues during CJKFTA negotiations, and to help lobby with the government to carry out appropriate policy instruments for adaptation or mitigation. Following the Chain Reaction Assessment Method that integrates and links the elements of trade, production, and environment, the present research aims to quantitatively assess CJKFTA’s possible impact on China’s environment. This is done by estimating the variations of China’s major conventional pollutants and greenhouse gases (GHGs) emission in two policy scenarios to represent CJKFTA’s scale and composition effects on China’s environment. Estimating the variations is based on a static Computable General Equilibrium model, working with Global Trade Analysis Project (GTAP) 7 database and China’s energy-environment statistics. Based on these assessments, CJKFTA is predicted to lead to notable environmental impact, including increased emissions of agricultural total nitrogen, agricultural total phosphorus, chemical oxygen demand, and GHGs. On the other hand, decreased emissions of industrial SO2 and dust are also expected to happen. Suitable policies need to be made to combat negative effects and amplify positive ones, while aiming at a more sustainable regional freer trade system.  相似文献   
389.
Different types of predators often elicit different antipredator responses in a common type of prey. Alternatively, some prey species may adopt a general response, which provides limited protection from many different types of predator. The Trinidadian guppy, Poecilia reticulata, is faced with a wide range of different predators throughout its range and is known to display varying levels of antipredator behavior depending on the predator assemblage. Pike cichlids, Crenicichla frenata, are regarded as the primary aquatic guppy predator in streams in the northern mountain range in Trinidad. As such, they are seen to be responsible for many of the differences in morphology, life history traits, and behavior between guppy populations from areas with few predators and those from areas with many pike cichlids. In this study we investigated how guppies responded when faced with different predator species using three common aquatic predators. We exposed shoals of ten guppies to one out of four treatments: no predator (control), pike cichlid, acara cichlid (Aequidens pulcher), and wolf fish (Hoplias malabaricus); and we made behavioral observations on both focal individuals and the shoal as a whole. Guppies showed significantly greater levels of predator inspection and shoaling behavior, foraged less, spent more time in the surface water, and stayed in significantly larger shoals when faced with pike cichlids than in other treatments. We discuss these results in the context of multiple predator effects.  相似文献   
390.
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