全文获取类型
收费全文 | 89篇 |
免费 | 0篇 |
出版年
2020年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2015年 | 1篇 |
2013年 | 10篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有89条查询结果,搜索用时 46 毫秒
1.
Robert H.Cowie J. S. Jones 《Biological journal of the Linnean Society. Linnean Society of London》1998,65(3):233-255
In 1985 we resurveyed the sites on the Marlborough Downs in southern England at which Cain and Currey in 1960/61 sampled Cepaea snails and thence introduced the term 'area effects' to describe large areas of uniform morph frequency. Some sites no longer harboured Cepaea and at others the species composition had changed, with a general spread of Cepaea hortensis at the expense of Cepaea nemoralis. The majority, however, permitted comparison of morph frequencies between the two surveys. In C. nemoralis, we detected a significant overall decrease in the frequency of the brown morph and estimate selection as 5–9% per generation. There was no apparent change in frequencies of banded morphs. In C. hortensis we detected a significant overall increase in the frequency of unbanded shells (1–3% selection per generation) and an almost significant decrease in the frequency of fusions within the banded class. There was insufficient colour polymorphism in C. hortensis to allow analysis of colour morph frequencies. These changes—all in the direction of reduced absorption of solar energy—resemble others detected in both species at other localities in southern England. Possible explanations include large-scale climatic effects and changes in vegetation. 相似文献
2.
Kenneth C. Emberton 《Evolution; international journal of organic evolution》1995,49(3):469-475
In the southern Appalachian region of North America, the phylogenetically convergent shells of the polygyrid snails Triodopsinae Neohelix major (Binney) and Polygyrinae Mesodon normalis (Pilsbry) are even more convergent in size and shape in sympatry (7 sites) than in allopatry (23 and 10 sites). Environmental correlations account for 34% and 30% of size and shape variations in N. major (larger, taller, and more loosely coiled at northern, high-altitude, sheltered sites), but for only 14% and 9% in M. normalis (larger, flatter, and more loosely coiled at south-facing, exposed sites). The statistical significance of the sympatric convergence dropped out when these correlations were removed. This phenomenon helps account for the many cases in eastern North America of nearly identical land-snail shells in sympatry and questions the importance of competitive character displacement in the evolution of land-snail shell morphology. This apparently nonmimetic case of sympatric convergence provides an unusually precise and well-delimited, naturally replicated experiment in evolutionary morphology, which is analyzed for controlling factors in a follow-up paper. 相似文献
3.
Francesco Criscione 《Molluscan research.》2015,35(1):65-71
The new, monotypic camaenid genus Setocallosa is described for the new species S. pathutchingsae from Arnhem Land, Top End of the Northern Territory. This camaenid is characterized by a combination of distinct morphological features, such as a small, weakly elevated shell with widely open umbilicus and thick callus on the parietal wall, a wide epiphallic flagellum, elongated penis and short bursa copulatrix with subglobose end. The relationships of Setocallosa with the other camaenid genera in the area are investigated by means of mtDNA, but its phylogenetic position remains ambiguous. S. pathutchingsae occurs in sympatry with Arnhemtrachia ramingining, but based on morphology the two camaenids can be readily differentiated.http://zoobank.org/urn:lsid:zoobank.org:pub:1C50CF24-7FEE-446A-9724-A0A4E850B5AA 相似文献
4.
5.
6.
7.
贵州洞穴淡水、陆生贝类区系及新种记述 总被引:11,自引:1,他引:10
首次报道了贵州省安龙县、贵阳市、独山县、荔波县、安顺市、开阳县、息烽县、盘县、兴义市、大方县、普定县等39个洞穴内不同生境的淡水、陆生贝类,经鉴定得淡水、陆生螺类共计71种,分隶于15科,36属,其中淡水螺类3科4属5种;陆生螺类66种,12科32属;1新种,即荔波双边凹螺Chamalycaeus libonensis sp.nov.附有种类名录,栖息环境及地理分布,并对洞穴中的淡水、陆生贝类区系组成进行了讨论,对新种进行了详细的描述,与近似种进行了比较。 相似文献
8.
Six species of Gastrocopta have been identified from the Pilbara region, Western Australia, by means of comparative analyses of shell and mtDNA variation. Three of these species, Gastrocopta hedleyi, Gastrocopta larapinta and Gastrocopta servilis, have been recorded in the Pilbara for the first time. Gastrocopta sp. CW1 is probably new to science and might be endemic to the region. By contrast, Gastrocopta hedleyi, Gastrocopta larapinta and Gastrocopta mussoni are shown to be widespread. 相似文献
9.
D. W. Burton 《New Zealand journal of zoology.》2013,40(3):391-402
Abstract Pallial systems are described for 10 athoracophorid species: Athoracophorus bitentaculatus, Pseudaneitea dendyi, P. gigantea, P. papillata, P. pallida, P. aspera, P. schauinslandi, P. multistriata, and Palliopodex verrucosus from the New Zealand and sub antarctic area; and Triboniophorus graeffei from Australia. In the New Zealand and subantarctic species the kidney is invariably bilobed, the ureter is extensively folded and connected to the intestine by an elongate tubule running initially through the lung, and the pneumostome, anus, and excretory pores are widely sepamted. Triboniophorus graeffei has the pneumostome, anus, and excretory pore closely associated, a compact kidney, and a more simply folded ureter. The New Zealand and subantarctic representatives are considered to be more advanced. Reasons for the development of the features they display are discussed, as is the function and evolution of the entire pallial system. An account of the variation in the pallial complex of Athoracophorus bitentaculatus is included. 相似文献
10.
Evolutionary relationships of euthyneuran gastropods (Mollusca): a cladistic re-evaluation of morphological characters 总被引:6,自引:0,他引:6
Morphological characters of the Euthyneura available from the literature were re-evaluated in terms of terminology and primary homology. A total of 77 characters and 75 taxa were retained in a data matrix. Several assumptions on character weights and types were tested. In the cladistic analyses, it appeared that the data matrix was highly homoplastic, and only robust nodes (those which were little modified by variations in weight and coding of characters) were retained in a concensus tree. The evolutionary histories of all characters and monophylies of higher euthyneuran taxa were discussed. The following interrelationships of the taxa were obtained in a consensus tree: the clade Heterobranchia includes paraphyletic allogastropod taxa which emerge basally, and the clade Euthyneura. The latter includes the clade Pulmonata and at least 10 opisthobranch clades of unresolved relationship (Thecosomata, Gymnosomata, Acochlidioidea, Pyramidelloidea, Runcinoidea, Cephalaspidea, Sacoglossa, Umbraculoidea, Pleurobranchoidea, Nudibranchia). The Pulmonata include basommatophoran paraphyletic taxa and the clade Geophila (Onchidiidae, Soleolifera, Stylommatophora). The position of the Sacoglossa and the monophyly of the Notaspidea are also discussed. © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society , 2002, 135 , 403–470. 相似文献