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   115篇
  免费   3篇
  国内免费   2篇
  2022年   4篇
  2021年   3篇
  2020年   4篇
  2019年   6篇
  2018年   4篇
  2017年   3篇
  2016年   1篇
  2015年   2篇
  2014年   4篇
  2013年   23篇
  2012年   5篇
  2011年   5篇
  2010年   3篇
  2009年   4篇
  2008年   4篇
  2007年   3篇
  2006年   2篇
  2005年   4篇
  2004年   1篇
  2003年   6篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1999年   3篇
  1998年   3篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1985年   3篇
  1981年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1972年   2篇
排序方式: 共有120条查询结果,搜索用时 15 毫秒
61.
Wetland conservation in the Indo-tropics can benefit from the protection of the charismatic Fishing Cat. India, supporting ∼ 40% of its known range, is a stronghold for the species. Here, using multiple information sources we outline a framework to safeguard fishing cats in India. Specifically, we a) estimated district-level Conservation priority scores (using presence records, and habitat suitability and habitat connectivity) to identify ecologically important habitats, b) estimated state-level Conservation likelihood scores assessing the success potential of any conservation intervention, c) collated district-level Conservation initiative information identifying ongoing efforts for species and/or habitat conservation. We consecutively assessed the spatial congruence between (a), (b) and (c) to delineate species’ conservation areas and corresponding action goals (blueprint). Using information on habitat suitability, we also delineated survey landscapes. Although Fishing Cat records were found in 12 Indian states, only a small proportion of the state area was identified harbouring optimal habitat for the species. Three broad habitat clusters - Terai arc, Eastern coast, and Brahmaputra floodplains - were identified, with overall high habitat connectivity. Most districts ranking high in Conservation priority scored low in Conservation likelihood. Districts with Fishing Cat presence (n = 60) were delineated into four tiers of action landscapes and the majority of districts classified as survey landscapes (n = 156) were found in the Terai arc. We use our results to recommend and discuss conservation actions for districts identified in our blueprint. Flagship species conservation approach has substantial potential to enrich wetland conservation, for which our blueprint can act as a baseline.  相似文献   
62.
Individual discrimination provides animals the opportunity to adjust their exposure and behavior when interacting with other animals, both conspecifics and heterospecifics. Meadow voles, Microtus pennsylvanicus, were exposed to scents of house cats, Felis catus. Our first experiment tested whether meadow voles could discriminate between caudal, interdigital, and facial scents produced by a cat with a habituation–dishabituation paradigm. Upon exposure to the familiar scent and a novel one, meadow voles did not investigate either scent more than the other. Our second experiment tested whether meadow voles discriminate between the facial scents of different cats. When exposed to a familiar scent of one cat and the unfamiliar scent of another cat, the meadow voles did discriminate and investigated the unfamiliar scent more than the familiar scent. The results suggest that meadow voles will discriminate between cats using any scent that the cat may inadvertently leave within the environment, thereby reducing the vole's risk of predation by that individual.  相似文献   
63.
64.
Rabbits killing birds: modelling the hyperpredation process   总被引:7,自引:1,他引:6  
1.  Introduced rabbits are known to have catastrophic effects on oceanic islands, either by direct destruction of the vegetative cover, or by the resulting disturbance of indigenous vertebrates.
2.  Another dramatic effect, less well known, but potentially of major importance, is the hyperpredation process. This process, related to apparent competition, predicts that an introduced prey species, well adapted to high predation pressure, could induce the extinction of an indigenous prey, through the sudden increased population size of an introduced predator. In many island ecosystems, the simultaneous presence of introduced feral cats and rabbits is thus potentially a further threat for small vertebrates endemic of these islands.
3.  Through a mathematical model, we tested this hypothesis, using a tri-trophic system comprising an indigenous prey (birds), an introduced prey (rabbits) and an introduced predator (cats), and we demonstrated the theoretical existence of the hyperpredation process.
4.  In addition, the numerical analysis of the model allowed a quantification of this process. It shows that the conditions required for an indigenous species to cope with the hyperpredation process imply very high intrinsic growth rates and/or carrying capacity, as well as behavioural anti-predator response to the introduced predator. Since these conditions are unlikely to be met, this process is a further potential threat to most indigenous vertebrate prey.
5.  Finally, our model shows that, although it can be induced by both types of adaptation together or alone, behavioural adaptations alone are more powerful in generating the hyperpredation process, than are life history traits adaptations.  相似文献   
65.
Zhou J  Shi XM  Peng QS  Hua GP  Hua TM 《动物学研究》2011,32(5):533-539
对人类和动物的心理学研究证实,老年个体的视觉对比敏感度相对青年个体显著下降。为揭示其可能的神经机制,采用在体细胞外单细胞记录技术研究青、老年猫(Felis catus)初级视皮层(primary visual cortex,V1)细胞对不同视觉刺激对比度的调谐反应。结果显示,老年猫V1细胞对视觉刺激反应的平均对比敏感度比青年猫显著下降,这与灵长类报道的研究结果相一致,表明衰老影响视皮层细胞对视觉刺激反应的对比敏感度是灵长类和非灵长类哺乳动物中普遍存在的现象,并可能是介导老年性视觉对比敏感度下降的神经基础。另外,与青年猫相比,老年猫初级视皮层细胞对视觉刺激的反应性显著增强,信噪比下降,感受野显著增大,表明衰老导致的初级视皮层细胞对视觉刺激反应的对比敏感度下降伴随着皮层内抑制性作用减弱。  相似文献   
66.
Environmental, genetic, and social factors associated with captive maintenance of small felids (Felis spp.) were systematically examined at eight different zoos to determine which of these factors most closely correlated with successful reproduction. Almost half of all the pairings examined failed to produce offspring. However, at least some representatives of the 20 species examined successfully reproduced, suggesting that failure to breed could not be solely attributed to species specific requirements. Multiple regression techniques revealed an association between number of litters produced and number of medical treatments, latitude range of wild counterparts, group size (all negatively correlated), and a positive correlation with husbandry style. These findings have direct relevance to how small cats are managed in captivity. Specifically, when small felids are maintained in groups larger than a pair (1.1), they are not likely to reproduce. Furthermore, a husbandry style in which keepers spent considerable time talking to, and interacting with, the cats under their care was more likely to result in offspring than one in which these interactions did not occur. These and other results generated suggestions for management techniques necessary to assure the continued survival of small cats in captivity.  相似文献   
67.
Six adult Leopardus tigrinus (oncilla) were studied to characterize stages of the seminiferous epithelium cycle and its relative frequency and duration, as well as morphometric parameters of the testes. Testicular fragments were obtained (incisional biopsy), embedded (glycol methacrylate), and histologic sections examined with light microscopy. The cycle of the seminiferous epithelium was categorized into eight stages (based on the tubular morphology method). The duration of one seminiferous epithelium cycle was 9.19 d, and approximately 41.37 d were required for development of sperm from spermatogonia. On average, diameter of the seminiferous tubules was 228.29 μm, epithelium height was 78.86 μm, and there were 16.99 m of testicular tubules per gram of testis. Body weight averaged 2.589 kg, of which 0.06 and 0.04% were attributed to the testis and seminiferous tubules, respectively. In conclusion, there were eight distinct stages in the seminiferous epithelium, the length of the seminiferous epithelium cycle was close to that in domestic cats and cougars, and testicular and somatic indexes were similar to those of other carnivores of similar size.  相似文献   
68.
Fourteen strains of Gram-negative, anaerobic, fluoroquinolone-resistant, non-sporulating rods were isolated from various infections in cats and dogs, as well as from wounds in humans after cat- or dog-bites. These strains were characterized by sequencing of the 16S-23S rDNA internal transcribed spacer (ITS) regions, 16S rDNA, DNA-DNA hybridization, phylogenetic analysis, and phenotypic tests. The results indicate that the novel strains belong to a distinct species, closely related to Fusobacterium nucleatum. The species Fusobacterium canifelinum sp. nov. is proposed, with strain ATCC BAA 689T as the type strain.  相似文献   
69.
Peng QS  Zhou J  Shi XM  Hua GP  Hua TM 《动物学研究》2011,32(3):337-342
以前的电生理研究结果显示, 老年哺乳动物视皮层细胞的自发反应及对视觉刺激的诱发反应比青年动物的显著增加, 而对光栅刺激的方位和运动方向选择性却显著下降。然而, 这种视皮层细胞功能的老年性改变是否因青、老年猫细胞对不同麻醉水平的敏感性差异引起尚不清楚。为探讨该问题, 以常用的麻醉药——乌拉坦(Urethane)为实验对象, 通过改变其麻醉剂量分别记录青、老年猫初级视皮层细胞对不同方位和运动方向光栅刺激的调谐反应。研究结果显示, 在基础麻醉量的基础上, 累积增加 50 mg 和 100 mg 乌拉坦对青、老年猫视皮层细胞的自发反应和诱发反应以及对光栅刺激方位和运动方向的选择性不产生显著影响, 累积增加 150 mg 乌拉坦会导致青、老年猫视皮层细胞对视觉刺激的反应性下降, 但下降的幅度相似。以上研究结果表明, 不同剂量的乌拉坦对青、老年动物视皮层细胞的反应性具有相似的影响。  相似文献   
70.
Unmethylated CpG-ODN are known to enhance Th1-type immune response. However, optimal sequences of CpG-ODN for activating Th1-type immune cells vary among species. It is necessary to identify the effective CpG-ODN sequences in each species. In the present study, in order to identify the sequences of CpG-ODN that produce fIFN-γ in cats, 14 kinds of ODN were synthesized and examined regarding their ability to induce fIFN-γ in feline PBMC and splenocytes. It was shown that some CpG-ODN significantly induced fIFN-γ production in splenocytes, but not in PBMC. We found that three kinds of CpG-ODN (no. 2, 5'-ggTGCATCGATGCAGggggG-3'; no. 5, 5'-ggTGCGTCGACGCAGggggG-3'; no. 10, 5'-ggTGCTACGTAGCAGggggG-3') specifically and significantly induced fIFN-γ production in feline splenocytes. The reverse sequences, GpC-ODN, do not cause significant fIFN-γ production. The fIFN-γ production inductivity of a mixture of CpG-ODN nos. 2, 5 and 10 was higher than those of individual CpG-ODN. When the CpG-ODN mixture was encapsulated in an MCL and administrated to cats, the number of fIFN-γ(+) cells in PBMC significantly increased. CpG-ODN nos. 2, 5 and 10 should be useful to elicit a Th1-type immune response as a vaccine adjuvant in cats.  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