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81.
GIRARD VINCENT 《Palaeontology》2012,55(3):653-659
Abstract: Two extraordinarily well‐preserved testate amoebae are described from Late Albian age amber from south‐western France. The specimens are attributed to a new family, the Hemiarcherellidae fam. nov., and are described as Hemiarcherella christellae gen. et sp. nov. The amoebae described herein originate from highly fossiliferous amber pieces. Based on syninclusions, Hemiarcherella christellae was a soil‐dwelling organism, probably an active bacterivore. This taxon represents the third species of testate amoebae described from mid‐Cretaceous French amber. Analysis of this fossil amoeba fauna illustrates the uniqueness of mid‐Cretaceous French amber deposits. Indeed, most amoebae found in amber have been assigned to modern species, corroborating the hypothesis of morphological stasis in different microbial lineages. However, the well‐preserved amoebae fauna found in French amber can be distinguished clearly from modern species and help us to better understand the fossil record of these organisms. 相似文献
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Does competition with wind‐pollinated species alter Echium plantagineum's attractiveness to a common pollinator Bombus terrestris?
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FLORIANE FLACHER AMANDINE HANSART ERIC MOTARD ABDOU MOUTALAB FOFANA OCEANE VINCENT BENOIT GESLIN ISABELLE DAJOZ XAVIER RAYNAUD 《Ecological Entomology》2017,42(5):617-628
1. In insect‐pollinated plants, pollinator attraction is influenced by flowers (e.g. number, size) and their associated rewards (e.g. pollen, nectar). These traits can depend on plant interactions. Indeed, below‐ground competition between plants can lead to a decrease in flower or reward production in insect‐pollinated species. 2. Wind‐pollinated plants, in particular, which are almost never studied in plant–pollinator networks, can alter insect‐pollinated plants' attractiveness through competition for nutrients. The response of pollinators to such changes has never been investigated. 3. A pot experiment was carried out in which an insect‐pollinated species, Echium plantagineum, was grown in binary mixture with three wind‐pollinated species selected to exert a panel of competitive interactions. Below‐ground competition was controlled using dividers limiting interspecific root competition. Floral traits of E. plantagineum (i.e. flower production, floral display size, flower size and nectar production) were measured. For each species mixture, the visits (i.e. first visit, number of visits, 10‐min sequences) of Bombus terrestris individuals released in a flight cage containing two pots were followed, one with and one without below‐ground competition. 4. Below‐ground competition significantly affected nectar's sucrose concentration but did not influence flower and nectar production. Likewise, pollinator visits were not influenced by below‐ground competition. Competitor identity significantly influenced flower and reward production of E. plantagineum, with a decrease in the presence of the most competitive wind‐pollinated species. A tendency for faster flower visitation events was also detected in the presence of the least competitive competitor. This study raises new questions regarding the influence of wind‐pollinated plants on plant–pollinator interactions. 相似文献
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P. LESZEK D. VINCENT FIONA M. GETLIFFE F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1992,108(1):55-81
VINCENT, P. L. D. & GETLIFFE, F. M., 1992. Elucidative studies on the generic concept of Senecio (Asteraceae) . This paper presents the results of studies of the generic concept of Senecio sensu stricto. The sample of taxa studied consisted of 93 Natal senecios (including seven varieties and two forms), five Cape heterochromous senecios and nine non-southern African senecios, including the type of the genus, S. vulgaris L. Also included in the study were six species from taxonomically closely related genera in the tribe Senecioneae and one Senecio of uncertain taxonomic position. The phenotype of these taxa was investigated with respect to a large number (122) of morphological and micromorphological characters. Six characters were selected as being taxonomically important with respect to elucidating the generic concept of Senecio sensu stricto. The generic concept of Senecio has been provisionally re-circumscribed and the generic status of each of the senecios and non-senecios studied has been tested according to this concept of Senecio sensu stricto sensu Vincent. In the light of this concept of Senecio , the following species are recommended for exclusion from Senecio sensu stricto sensu Vincent: S. cissampelinus, S. transvaalensis, S. syringifolius and S. hockii. The following species are considered to be peripheral to Senecio sensu stricto sensu Vincent: S. tanacetopsis, S. seminiveus, S. medley-woodii, S. tamoides, S. helminthioides, S. barbertonicus, S. brevilorus, S. viminalis, S. radicans and S.fulgens. Before any taxonomic changes are made to the current composition of Senecio , the concept of Senecio sensu stricto sensu Vincent, is being tested on a worldwide sample of the genus. 相似文献
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VINCENT ROUSSET LAETITIA PLAISANCE CHRISTER ERSÉUS MARK E. SIDDALL GREG W. ROUSE 《Biological journal of the Linnean Society. Linnean Society of London》2008,95(3):447-464
Clitellata (earthworms, leeches, and allies) is a clade of segmented annelid worms that comprise more than 5000 species found worldwide in many aquatic and terrestrial habitats. According to current views, the first clitellates were either aquatic (marine or freshwater) or terrestrial. To address this question further, we assessed the phylogenetic relationships among clitellates using parsimony, maximum likelihood and Bayesian analyses of 175 annelid 18S ribosomal DNA sequences. We then defined two ecological characters (Habitat and Aquatic‐environment preferences) and mapped those characters on the trees from the three analyses, using parsimony character‐state reconstruction (i.e. Fitch optimization). We accommodated phylogenetic uncertainty in the character mapping by reconstructing character evolution on all the trees resulting from parsimony and maximum likelihood bootstrap analyses and, in the Bayesian inference, on the trees sampled using the Markov chain Monte Carlo algorithm. Our analyses revealed that an ‘aquatic’ ancestral state for clitellates is a robust result. By using alterations of coding characters and constrained analyses, we also demonstrated that the hypothesis for a terrestrial origin of clitellates is not supported. Our analyses also suggest that the most recent ancestor of clitellates originated from a freshwater environment. However, we stress the importance of adding sequences of some rare marine taxa to more rigorously assess the freshwater origin of Clitellata. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 447–464. 相似文献
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