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   32篇
  免费   1篇
  2017年   1篇
  2013年   2篇
  2012年   3篇
  2011年   1篇
  2010年   3篇
  2009年   3篇
  2008年   4篇
  2007年   2篇
  2006年   4篇
  2001年   1篇
  1996年   1篇
  1995年   2篇
  1990年   2篇
  1989年   2篇
  1986年   1篇
  1984年   1篇
排序方式: 共有33条查询结果,搜索用时 647 毫秒
1.
ABSTRACT

This paper presents a framework effort to allow the experimentation of various devices in order to automatically record, detect and classify marine mammal vocalizations in the open sea. Some tools for the protection of Killer Whales and other cetaceans are founded in the analysis of their recorded vocalizations. With this framework we are able to test every part under controlled conditions before open sea experiments. Some of these devices have been designed to localize and track open sea populations in order to facilitate data collection for conservation management.

At this moment the framework consists of the basic necessary instruments and IT resources for continuously multichannel recording of vocalizations from four specimens of Killer Whale. The enormous raw data stream forces the implementation of a data reduction strategy. As a result, the present research is focused in the development of techniques for this purpose that will allow the automatic classification of events and obtain statistical data. Complementarily, our research goals are also focused on the design of prototypes for source localization using time tags of events on multiple channels for continuous real time logging of behaviour and position of specimens. This paper presents some preliminary results of automatically detected calls.  相似文献   
2.
3.
The mangrove rivulus Kryptolebias marmoratus a small cyprinodont fish native to tropical and subtropical waters from Florida to Brazil, is one of two known self-fertilizing, hermaphroditic vertebrates of which K. marmoratus displays androdioecy, a complex system of reproduction in which hermaphrodites and males are present. This study describes the behavioral repertoires observed during dyadic interactions in the laboratory. Kryptolebias marmoratus exhibited 23 distinctive acts or behaviors. Acts were divided into four categories: aggressive, submissive, neutral, and reproductive. Leading and following behaviors played important roles in the behavioral repertoires of these fish. In hermaphrodite-male dyads, males exclusively initiated the reproductive process and actively pursued hermaphrodites. When hermaphrodites were paired, there was no evidence that they behaved like other simultaneous hermaphrodites that alternate sexual roles (e.g. serranids). Hermaphrodites were extremely aggressive towards one another, and the aggressor established dominance rapidly. Male-male dyads were divided into two subdivisions based on the presence or absence of the caudal ocellus on one fish. A caudal ocellus on one male appeared to signal the possibility of a potential mating partner to males lacking it. Pairings of males without an ocellus were similar to hermaphrodite-hermaphrodite dyads in that both members of the pair were aggressive towards one another. These observations may be indicative of interactions taking place in natural communities or assemblages of fish in which both males and hermaphrodites occur and provide evidence on the role of dyadic interactions in the mixed-mating strategies [Current Zoology 56 (1): 6-17, 2010].  相似文献   
4.
This study describes the ultrastructure at 'the line of weakness' in the male puparium of Elenchus tenuicornis (Kirby) (Insecta: Strepsiptera). Superficially this line looked like an area of untanned cuticle but ultrastructurally it had an undifferentiated epicuticle, an untanned exocuticle and a loose textured endocuticle. It is speculated that the E. tenuicornis pharate adult male prior to emergence smears a chemical solution on the inner rim of the 'line of weakness' which dissolves the exo- and endocuticles. Following this, the slightest pressure exerted by the ptilinum of the male breaks open the cap of the puparium.  相似文献   
5.
6.
ABSTRACT

We introduce an inexpensive electronic technique for monitoring the temporal aspects of any captive animal's acoustic signals. The electronic apparatus, attached to a data acquisition unit and personal computer, compares microphone output to a pre-set level and stores calling/non-calling data to disk. Total time calling and temporal signaling patterns of up to 256 individuals can be monitored for indefinite lengths of time. Sampling rate is adjustable, with a maximum rate of 6 samples/microphone/second. The capabilities of the system are illustrated with the field cricket Gryllus integer. Temporal aspects of acoustic signaling are discussed in terms of monitoring time scale and recognition of individual variation, energetics research, and hypothesis testing of the costs and benefits associated with mating success and predation.  相似文献   
7.
There is a negative relationship between trunk segment number and latitude among geophilomorph centipedes in general. A similar relationship is known to exist within the most intensively‐studied geophilomorph species, Strigamia maritima, and also within several other species from this group. Previously, it was considered that this relationship did not involve body length; instead, individuals of S. maritima with more segments were considered to be more finely subdivided (not longer) than those with fewer segments. This incorrect interpretation arose from the difficulty of reliably separating post‐embryonic stages and thus of making a simple and direct comparison. In the present study, we build on recent work that facilitates such comparisons; and we show conclusively that individuals with more segments are longer. Our finding means that it is now possible to connect the work on S. maritima in particular, and on geophilomorph centipedes in general, with the debate about Bergmann's ‘rule’: the proposal that body size increases with increasing latitude. There is a clear ‘converse‐Bergmann’ pattern, as has been found in several other taxa. We propose an adaptive hypothesis that may explain why geophilomorphs show this pattern. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.  相似文献   
8.
We developed and characterized primers for 11 variable microsatellite loci present in the genome of the flax rust, Melampsora lini. The microsatellite loci were identified by sequencing clones from a library of EcoRI DNA fragments enriched for four simple sequence repeat motifs (AAG, AAT, TC and TG). All 11 primer pairs successfully amplified DNA fragments from a sample of 102 M. lini isolates (98 isolated from Linum marginale and four from Linum usitatissimum), revealing a total of 32 alleles. Allelic diversity at the 11 loci ranged from 0.030 to 0.449.  相似文献   
9.
Abstract: Global climate warming is expected to cause systematic shifts in the distribution of species and consequently increase extinction risk. Conservation managers must be able to detect, measure and accurately predict range shifts in order to mitigate impacts on biodiversity. However, important responses to climate change may go unnoticed or be dismissed if we fail to collect sufficient baseline data and apply the most sensitive analytical tests. Here we use randomizations of a contemporary data set on rainforest birds of north‐eastern Australia to quantify the sensitivity of three measures for assessing range shifts along altitudinal gradients. We find that smaller range shifts are detectable by analysing change in the mean altitude of presence records rather than upper or lower range boundaries. For a moderate survey effort of 96 surveys, measurements of change in the mean altitude of 34 species have the capacity to provide strong inference for a mean altitudinal range shift as small as 40 m across the species assemblage. We also show that range shifts measured at range boundaries can be potentially misleading when differences in sampling effort between contemporary and historical data sets are not taken into account.  相似文献   
10.
Body size is often associated with a dietary divergence within taxonomically related groups so that large animals are often folivorous, while smaller species shift progressively towards omnivory or carnivory. This trend may be influenced by allometric constrains which result in relatively high energetic requirements, but low gut capacities in small animals, compared to their large counterparts. The common brushtail possum (Trichosurus vulpecula, Phalangeridae) has six subspecies ranging widely in weight (1–4 kg). They are not strictly folivorous, but supplement their diet with more nutritious, non‐foliar foods. We predicted that T. vulpecula subspecies diverged in diet in association with body size, with smaller subspecies consuming higher proportions of non‐foliar foods. We assessed this with a review and a meta‐analysis of previous Australian studies. We also investigated the previously unquantified diet of T. v. hypoleucus at three sites in the northern jarrah forest of Western Australia. Results from the meta‐analysis and the review supported our prediction. However, the large variability in the data highlighted their limitations and those of the techniques commonly used to quantify the diet of T. vulpecula. Nonetheless, small subspecies of T. vulpecula appear to consume higher proportions of non‐foliar foods. These results should encourage further research into the body size/diet relationship within T. vulpecula and other possum species. Results from the dietary study of T. v. hypoleucus emphasized their omnivorous diet, which was dominated by foliage and flowers and smaller proportions of invertebrates, seeds and fruits. The common brushtail possum is seldom an exclusive arboreal folivore, but rather ranges from folivory to omnivory.  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