全文获取类型
收费全文 | 83篇 |
免费 | 15篇 |
国内免费 | 11篇 |
出版年
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 10篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 4篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 7篇 |
2008年 | 3篇 |
2007年 | 8篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2002年 | 4篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 15 毫秒
11.
Transcriptome response of the foundation plant Spartina alterniflora to the Deepwater Horizon oil spill 下载免费PDF全文
12.
Morgan R. CrookJr. 《Human ecology: an interdisciplinary journal》2007,35(2):223-237
Evidence of a pile-dwelling community and seral environmental conditions during the late Mid-Holocene (ca 4,000–3,000 years
b.p.) is explored through archaeological data and paleoecological information from the Bilbo Site at the mouth of the Savannah
River along the Georgia coast, U.S.A. It is argued that pile dwellings were a central feature of the cultural adaptive system,
allowing settlements to be located in wetlands that provided optimal access to the evolving food resources of multiple, dynamic
environments. It also is suggested that the adaptive strategy included residential stability and a more complex organizational
structure than that exhibited by modern hunter-gatherers living in marginal environments.
An erratum to this article can be found at 相似文献
13.
14.
Summary The socially parasitic mode of founding new colonies by queens of the European amazon antPolyergus rufescens was analysed in the laboratory. Newly-mated females of this obligatory slave-maker were individually introduced into queenright and queenless artificially established colonies of bothFormica cunicularia (the slave present in the natal dulotic nest) andF. rufibarbis (another potentialServiformica host). Particular attention was devoted to the behavioural patterns displayed by these young queens during the usurpation phases. Our observations, supported also by video-taping, show that the slave-making female, before laying her eggs, must penetrate the host colony, kill the resident queen, become accepted by the adult workers and appropriate the host brood. The parasite was almost always adopted in the colonies ofF. cunicularia, whereas in the presence ofF. rufibarbis it was generally killed in a short time. The failure in the attempt of usurping the colonies ofF. rufibarbis is discussed in relation to the host specificity typical of this slave-maker. Finally, egg-laying byPolyergus successful usurpers, the subsequent eclosion of the brood, and its complete social integration in the newly-established mixed colonies were also recorded. 相似文献
15.
Energy dynamics within incipient colonies of the southern African mound dwelling harvester termite Trinervitermes trinervoides (Sj?stedt) (Termitidae: Nasutitermitinae) were investigated. Development of incipient colonies established from field collected
alates and changes in energy content of reproductives and brood were studied over a 25 week period in the laboratory. Colonies
were then transferred into the field to study the established of the first mound. An initial four-week egg-laying cycle started
within a week of pairing. Hatching occurred six weeks later. Two lines emerged from first instar undifferentiated larvae.
Small larvae moulted first into minor presoldiers and then minor soldiers. Large larvae developed into major workers. Foraging
began once second instar major workers had differentiated 20 weeks after colony foundation. First instar major workers did
not forage but there is evidence of pre-foraging utilisation of soil humus. The epigeous mound was produced after three years.
The energy available to maintain incipient termite colonies until the first workers start foraging is crucial to their survival.
The royal pair of T. trinervoides does not feed during the rearing of the first brood, the fate of which depends largely on the reproductives accumulated energy
reserves. The males and females expended 84.54 and 83.07% respectively of their total energy during this period. Once foraging
started, the energy content of the royal pair increased and a second egg-laying cycle began.
Received 25 July 2007; revised 19 March and 22 May 2008; accepted 4 September 2008. 相似文献
16.
Elizabeth E. Hieb Edem A. Eniang Lucy W. Keith-Diagne Ruth H. Carmichael 《The Journal of wildlife management》2021,85(4):674-685
Globally, increasing coastal development requires construction and maintenance of transportation infrastructure that affects terrestrial and aquatic ecosystems. Construction of bridges as part of transportation networks introduces a series of risks to aquatic species near construction zones. We reviewed relevant literature and obtained exemplary case studies to synthesize potential effects of bridge construction on the West Indian manatee (Trichechus manatus), a nearshore megafauna species vulnerable to human activities. Stages of bridge construction including dredging, pile driving, and installation and assembly of bridge components each involve potential direct and indirect effects on manatees. Direct effects such as vessel interactions, entanglement or ingestion, and entrainment may result in acute physical injury or mortality. Indirect effects from construction such as habitat obstruction or degradation and increased noise from construction activities can alter behavior and intraspecies communication and reduce access to essential resources. Some effects of construction may be immediately difficult to quantify, but cumulative effects through time can result in major habitat and species loss. To prevent large-scale negative effects of construction on manatees and other aquatic species, use and evaluation of mitigation strategies should be implemented pre-, during, and post-construction. As the global human population increasingly occupies coastal zones, effective planning of coastal development, including bridge and other in-water construction, will be essential to support conservation and recovery efforts for manatees and other species at risk in these areas. © 2021 The Wildlife Society. 相似文献
17.
Evidence of an evolutionary‐developmental trade‐off between drag avoidance and tolerance strategies in wave‐swept intertidal kelps (Laminariales,Phaeophyceae) 下载免费PDF全文
Kelps are a clade of morphologically diverse, ecologically important habitat‐forming species. Many kelps live in wave‐swept environments and are exposed to chronic flow‐induced stress. In order to grow and survive in these harsh environments, kelps can streamline (reducing drag coefficient) to avoid drag or to increase attachment and breakage force to tolerate it. We aimed to quantify the drag tolerance and streamlining strategies of kelps from wave‐swept intertidal habitats. We measured drag coefficient and tenacity of populations from eight kelp species over a wide range of sizes to determine whether kelps avoid dislodgement by reducing drag coefficient or by increasing tenacity as they grow, and whether these traits are traded off. We employed phylogenetic comparative methods to rule out potentially confounding effects of species' relatedness. There was a significant negative relationship between drag avoidance and tolerance strategies, even after incorporating phylogeny. Kelps that were more tenacious were less able to reduce drag, resulting in a continuum from “tolerators” to “streamliners,” with some species demonstrating intermediate, mixed strategies. Drag and tenacity were correlated with geometric properties (i.e., second moment of area) of the stipe in large kelps. Results presented in this study suggest that kelps are either strong or streamlined, but not both. This continuum is consistent with avoidance and tolerance trade‐offs that have been documented in many different biological systems and may have widespread implications for the evolution of large macroalgae, perhaps driving morphological diversity within this group. 相似文献
18.
19.
20.
Due to a continuing shift toward reducing/minimizing the use of chemicals in honey bee colonies, we explored the possibility
of using small cell foundation as a varroa control. Based on the number of anecdotal reports supporting small cell as an efficacious
varroa control tool, we hypothesized that bee colonies housed on combs constructed on small cell foundation would have lower
varroa populations and higher adult bee populations and more cm2 brood. To summarize our results, we found that the use of small cell foundation did not significantly affect cm2 total brood, total mites per colony, mites per brood cell, or mites per adult bee, but did affect adult bee population for
two sampling months. Varroa levels were similar in all colonies throughout the study. We found no evidence that small cell
foundation was beneficial with regard to varroa control under the tested conditions in Florida. 相似文献