全文获取类型
收费全文 | 423篇 |
免费 | 14篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 25篇 |
废物处理 | 2篇 |
环保管理 | 86篇 |
综合类 | 63篇 |
基础理论 | 219篇 |
污染及防治 | 1篇 |
评价与监测 | 4篇 |
社会与环境 | 31篇 |
灾害及防治 | 9篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 15篇 |
2016年 | 18篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 14篇 |
2012年 | 21篇 |
2011年 | 21篇 |
2010年 | 15篇 |
2009年 | 27篇 |
2008年 | 34篇 |
2007年 | 38篇 |
2006年 | 30篇 |
2005年 | 27篇 |
2004年 | 30篇 |
2003年 | 12篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 16篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有440条查询结果,搜索用时 15 毫秒
311.
Martin?PlathEmail author Jakob?Parzefall Kay?E.?K?rner Ingo?Schlupp 《Behavioral ecology and sociobiology》2004,55(6):596-601
In many species, females prefer large males as mating partners. Male size can easily be determined visually. We examined how such mate choice evolves when individuals are deprived of sensory information previously used to determine male quality. Using a cave-dwelling population of Atlantic mollies, Poecilia mexicana, as a model, we asked whether the female mating preference for large male body size still occurs in this cave fish, or whether it is lacking due to the absence of visual communication in the cave environment. In simultaneous choice tests we compared the time females spent with a large or a small male. In the river-dwelling and cave-dwelling fish, as well as the population originating from the cave entrance, we found a significant preference for large males in light. Hence, the ancestral mating preference of surface-dwelling mollies has been maintained during the evolution of the cave form. However, only the cave population exhibited a mating preference in darkness. Determination of male body size appears to have been taken over by a non-visual sensory system, probably the lateral line.Communicated by K. Lindström 相似文献
312.
Public Preferences for Compensatory Mitigation of Salt Marsh Losses: a Contingent Choice of Alternatives 总被引:1,自引:0,他引:1
Abstract: Human activities continue to eliminate or degrade wetlands that provide rich habitat for many species. Compensatory mitigation, including creation of new wetlands, restoration of previously degraded wetlands, or preservation of existing wetlands, is one policy option that seeks to maintain no net loss of wetland habitat. Public support of wetland mitigation is essential because the public incurs the cost for many mitigation projects in the form of higher taxes. Therefore, public preferences should be considered when decisions are made about wetland mitigation options. We used a contingent-choice survey in Rhode Island to identify factors affecting public support for different types of compensatory wetland mitigation. Results were based on 640 survey responses. The amount of wetland lost during the original development project had no significant effect on the preferred mitigation alternative. Preferences for preservation, restoration, and no-action alternatives varied according to respondents' gender, education, and income. Certain general considerations applied, however, regardless of mitigation type. Respondents were willing to incur increases in taxes and fees for most mitigation projects. The larger the mitigation project and the lower the cost, the more likely it was to gain public support. The presence of endangered species contributed to public support, but less significantly than public access. Public access can be critical to public support, particularly if the size of the wetland is small or the cost is high. If the cost of providing public access, such as a boardwalk or viewing tower, is relatively small, the gain in public support for mitigation expenditures may well allow a substantial expansion of the area involved in mitigation projects and thus a greater increase in the amount of habitat conservation. 相似文献
313.
Craig A. Walling Nick J. Royle Neil B. Metcalfe Jan Lindström 《Behavioral ecology and sociobiology》2007,61(7):1007-1014
It is well documented that poor early nutrition can have profound negative effects on adult life-history traits. However,
it has also been demonstrated that organisms can undergo compensatory resource allocation strategies (such as an accelerated
growth rate) if food availability improves, so as to mitigate the effects of the poor early conditions. Previous research
has indicated that elevated growth rates can incur costs in the longer term, such as an increased rate of senescence and shorter
lifespan. We tested whether a phase of compensatory growth after a period of reduced food availability earlier in life affected
the sexual attractiveness of adult male green swordtails Xiphophorus helleri, a species in which it has previously been documented that females prefer larger-bodied and longer-tailed males. The experiment
compared the attractiveness of size-matched brothers that had experienced contrasting growth trajectories as juveniles; the
experiments were initially conducted in the middle of a male’s sexually reproductive life and were then repeated towards the
very end of life. At both ages, males that had undergone compensatory growth were equally as attractive as their brothers
that had grown normally. These results suggest that the growth compensation benefits males through an increase in their attractiveness
over that which they would have had if they had remained on their original growth trajectory. The lack of change in relative
attractiveness with age indicates that the compensation does not cause greater deterioration in secondary sexual characters
at older ages than in continuously well-fed males. 相似文献
314.
Susanna Andersson 《Chemoecology》2003,13(1):1-11
Summary. For butterflies to be efficient foragers, they need to
be able to recognize rewarding flowers. Flower signals such as colours
and scents assist this recognition process. For plant species to attract
and keep butterflies as pollinators, species-specific floral signals are
crucial. The aim of this study is to investigate foraging responses to
floral scents in three temperate butterfly species, Inachis io L.
(Nymphalidae), Aglais urticae L. (Nymphalidae), and
Gonepteryx rhamni L. (Pieridae), in behavioural choice
bioassays. The butterflies were allowed to choose bet-ween flower models
varying in scent and colour (mauve or green). Flowers or vegetative
parts from the plants Centaurea scabiosa L. (Asteraceae),
Cirsium arvense (L.) (Asteraceae), Knautia arvensis (L.)
(Dipsacaceae), Buddleja davidii Franchet (Loganicaeae), Origanum vulgareL. (Lamiaceae), Achillea millefolium L. (Asteraceae), and
Philadelphus coronarius L. (Hydrangiaceae) were used as scent
sources. All visits to the models — those that included probing and
those that did not — were counted, as was the duration of these
behaviours. Both flower-naive and flower-experienced (conditioned to
sugar-water rewards, the colour mauve, and specific floral scents)
butterflies were tested for their preference for floral versus
vegetative scents, and to floral scent versus colour. The butterflies
were also tested for their ability to switch floral scent preferences in
response to rewards. Flower-naive butterflies demonstrated a preference
for the floral scent of the butterfly-favourable plants C.
arvense and K. arvensis over the floral scent of the non-favourable
plants Achillea millefolium (Asteraceae), and Philadelphus
coronarius cv. (Hydrangiaceae). Most of the butterflies that were
conditioned to floral scents of either C. arvense, K. arvensis,
or B. davidii readily switched theirfloral scent preferences to
the one most recently associated with reward, thus demonstrating that
floral scent constancy is a result from learning. These findings suggest
that these butterflies use floral scent as an important cue signal to
initially identify and subsequently recognize and distinguish among
rewarding plants.
Received 2 September 2001; accepted 9 September 2002. 相似文献
315.
Michelle A. Shackleton Michael D. Jennions John Hunt 《Behavioral ecology and sociobiology》2005,58(1):1-8
Females are generally assumed to prefer larger, more dominant males. However, a growing number of studies that control for male-male competition have shown no correlation between dominance and attractiveness. Aggressive males can interfere with female mate preference either by physically coercing females into mating or by driving submissive males away and restricting mate choice. The most common method of assessing female mate choice is by using simultaneous two-choice tests. These control for male-male interactions, but usually interfere with physical and chemical cues involved in mate selection or alter male behaviour. They are therefore unsuitable for many study species, especially insects. Another method is the no-choice test that measures a females latency to mating when placed with a single male as an indication of male attractiveness. No-choice tests control for male-male aggression while allowing full contact between pairs (they allow actual mating to be directly observed rather than to occur based on a correlated behaviour). So far, however, no study has confirmed that males that entice females to mate sooner actually enjoy increased longer-term mating success. As such, the accuracy of no-choice tests as a method of examining mate choice remains untested. Here, we used no-choice tests on the black field cricket, Teleogryllus commodus, to show that (1) females did not prefer males that won fights (dominant males), and (2) latency to mating predicts actual mating success. We have clearly demonstrated the usefulness of no-choice tests and, considering the advantages of this method, they should be more often considered for a wider variety of taxa.Communicated by D. Gwynne 相似文献
316.
Pheromones may convey information about mate quality and social status. In the field cricket Gryllus integer, females mount the males for copulation, such that males cannot coerce females to mate. We examined whether virgin G. integer females preferred the scent of potentially dominant males to that of subordinate males. First, we collected pheromones by confining males on filter paper. Next, we offered filter paper from each of two size-matched males and control paper to females that had never been exposed to males, and measured the time spent by the female on each kind of paper. Finally, dominance status of the males in each size-matched pair was determined by pitting the two males against one another in agonistic contests. When offered filter paper from subsequently dominant versus subsequently subordinate males, females spent more time on the paper from the dominant male than the subordinate male, and much less time on control paper. Thus, pheromones may inform female G. integer about a male's potential to achieve dominant social status. Male pheromones were also associated with the female's tendency to mount a male. In contrast to cockroaches, where females prefer the scent of subordinate males (presumably to avoid risk of injury), female crickets prefer the scent of potentially dominant males and are more likely than males to wound their mating partners. 相似文献
317.
论现阶段我国城市化的道路选择及政策取向 总被引:3,自引:0,他引:3
顾裕文 《湖南环境生物职业技术学院学报》2004,10(1):46-49
通过我国城市化现状的分析,结合我国具体国情,具体提出相当一段时期内我国城市化道路的选择:大、中、小不同城市协调发展、整体推进;东、中、西不同经济发展地带区别对待,体现层次.同时,还要求相应的政策、制度、法规等及时跟上,加快城市化步伐. 相似文献
318.
旅游时空模式与目的地的选择 总被引:8,自引:1,他引:7
旅游时空因素和旅游目的地的选择具有微妙而复杂的关系。本文把旅游资源市场、旅游目的地以及旅游活动和旅游行为动态地纳入旅游时空模式之中进行分析,探讨了施游时空因素与目的地选择之间的关系,并从大、中、小3个尺度分析了目标市场的旅游时空行为。 相似文献
319.
Mark Sagoff 《Environmental management》1996,20(6):897-911
This paper describes two frameworks—utilitarian and Kantian—society uses to make decisions concerning environmental management and, in particular, species protection. The utilitarian framework emphasizes the consequences of choices for prior preferences. A perfectly competitive market, on this model, correctly values environmental resources. The Kantian approach identifies rules appropriate to recognized situations given the identity of the decision maker. It relies on democratic political processes and institutions to provide the means by which citizens determine the identity of their community—its moral character and aspirations—and match appropriate rules to recognized situations. This paper argues that markets do not fail in any general way in measuring the economic value of plants and animals. Market prices, in general, correctly represent the marginal or exchange value of species. If society legislates against extinction, this must be understood as an exercise in Kantian decision making in view of the moral value of species, not as an attempt to correct a market failure or to promote social welfare or utility. 相似文献
320.
科学评价生物多样性价值可为生物多样性和生态系统经济学(the Economics of Ecosystems and Biodiversity,TEEB)支持下的生物资源管理提供有效的技术方法和政策依据,对受威胁物种的保护尤为重要.从TEEB的理念和研究目标出发,以我国特有保护植物——翅果油树(Elaeagnus mollis)为例,采用选择试验法定量评估受访者对受威胁物种保护和开发的偏好以及支付意愿;针对种植面积、产品开发、树苗品种、保护投入和农户收益这5项物种属性,在多模型比较的基础上最终选择随机参数模型(RPL)和潜在分层模型(LCM)进行价值评估.结果表明:基于RPL模型得出受访者的偏好选择具有异质性,正选择偏好的属性变量按重要性表现为“保护增加投入” > “高低端产品同时开发” > “农户收益” > “树苗品种” > “种植面积”,其中对“保护增加投入”的支付意愿〔331.0元/(户·a)〕最高,其次为“高低端产品同时开发”〔242.71元/(户·a)〕;对“保护不投入”为负选择偏好,且支付意愿〔-154.71元/(户·a)〕最低.基于LCM模型可将受访者分为保护偏好型和发展偏好型2个潜在类别,前者所占样本比例远高于后者,他们更愿意在物种保护方面支付较多的费用,而后者更愿意在产品开发上支付较多的费用.补偿剩余分析得到,翅果油树保护和开发的最大价值为285.62元/(户·a).研究显示,选择试验法在受威胁物种保护及价值评估中具有良好的适用性,评估结果可为物种保护政策的制定提供科学依据. 相似文献