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81.
CAROLIN A. REBERNIG GERALD M. SCHNEEWEISS KATHARINA E. BARDY PETER SCHÖNSWETTER JOSE L. VILLASEÑOR RENATE OBERMAYER TOD F. STUESSY HANNA WEISS‐SCHNEEWEISS 《Molecular ecology》2010,19(16):3421-3443
Pleistocene climatic fluctuations had major impacts on desert biota in southwestern North America. During cooler and wetter periods, drought‐adapted species were isolated into refugia, in contrast to expansion of their ranges during the massive aridification in the Holocene. Here, we use Melampodium leucanthum (Asteraceae), a species of the North American desert and semi‐desert regions, to investigate the impact of major aridification in southwestern North America on phylogeography and evolution in a widespread and abundant drought‐adapted plant species. The evidence for three separate Pleistocene refugia at different time levels suggests that this species responded to the Quaternary climatic oscillations in a cyclic manner. In the Holocene, once differentiated lineages came into secondary contact and intermixed, but these range expansions did not follow the eastwardly progressing aridification, but instead occurred independently out of separate Pleistocene refugia. As found in other desert biota, the Continental Divide has acted as a major migration barrier for M. leucanthum since the Pleistocene. Despite being geographically restricted to the eastern part of the species’ distribution, autotetraploids in M. leucanthum originated multiple times and do not form a genetically cohesive group. 相似文献
82.
Tetraploid Rangpur lime rootstock increases drought tolerance via enhanced constitutive root abscisic acid production 总被引:1,自引:0,他引:1
JOSE M. COLMENERO‐FLORES DOMINGO J. IGLESIAS JOSE A. PINA LUIS NAVARRO MANUEL TALON PATRICK OLLITRAULT RAPHAËL MORILLON 《Plant, cell & environment》2013,36(4):856-868
Whole‐genome duplication, or polyploidy, is common in many plant species and often leads to better adaptation to adverse environmental condition. However, little is known about the physiological and molecular determinants underlying adaptation. We examined the drought tolerance in diploid (2x) and autotetraploid (4x) clones of Rangpur lime (Citrus limonia) rootstocks grafted with 2x Valencia Delta sweet orange (Citrus sinensis) scions, named V/2xRL and V/4xRL, respectively. Physiological experiments to study root–shoot communication associated with gene expression studies in roots and leaves were performed. V/4xRL was much more tolerant to water deficit than V/2xRL. Gene expression analysis in leaves and roots showed that more genes related to the response to water stress were differentially expressed in V/2xRL than in V/4xRL. Prior to the stress, when comparing V/4xRL to V/2xRL, V/4xRL leaves had lower stomatal conductance and greater abscisic acid (ABA) content. In roots, ABA content was higher in V/4xRL and was associated to a greater expression of drought responsive genes, including CsNCED1, a pivotal regulatory gene of ABA biosynthesis. We conclude that tetraploidy modifies the expression of genes in Rangpur lime citrus roots to regulate long‐distance ABA signalling and adaptation to stress. 相似文献
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The distribution and abundance of gymnosome gastropods in theArgentine Sea and BrazilMalvinas Confluence during 19781979and 1988 were studied. The collections analyzed included 768quantitative samples obtained between 48°W and the coast,and from 35°S to 55°S. Two species were found. Spongiobranchaeaaustralis was the most frequent and abundant (up to 730 per1000 m3); its presence in the area was associated with the coreof the Malvinas Current. Clione antarctica was less abundant(maximum abundance: 230 per 1000 m3) and was also associatedwith the Malvinas Current. The geographic ranges of both speciesin the area are wider than previously described. Since the rangeof S. australis in the area extends far from the range of itsprey Clio, it is not clear whether S. australis can feed onthe thecosomatous pteropod Limacina (and not only on Clio, asdescribed in the bibliography) or it starves in that area. Duringthe 19781979 annual cycle, the abundance of both speciesfollowed neither the abundance patterns of their prey nor ofthe total zooplankton, and differed from each other. The residencetime of swarms of both gymnosomes were shorter than one month.As a general pattern, the aggregates are rapidly transportednorthward by the Malvinas Current and also penetrate the outershelf water, but they remain there only during a short periodand cannot preclude the final expatriation. So, the abundanceof gymnosomes in the area depends on passive migration morethan intrinsic population factors. (Received 9 July 1997; accepted 15 December 1997) 相似文献
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KATARZYNA MARCYSIAK MAGORZATA MAZUR ANGEL ROMO JOSE M. MONTSERRAT YAKOV DIDUKH KRYSTYNA BORATYSKA ANNA JASISKA PIOTR KOSISKI ADAM BORATYSKI 《Botanical journal of the Linnean Society. Linnean Society of London》2007,155(4):483-495
Juniperus excelsa and J. thurifera are considered to originate from the same ancestor. As a result of occurring in geographically isolated refuges – J. excelsa in SE Europe and SW Asia and J. thurifera in SW Europe and NW Africa – their divergence could have taken place at the end of the Tertiary, with the climate cooling. Juniperus foetidissima occurs in SE Europe and SW Asia in territories shared with J. excelsa and is similar to and sometimes misidentified with it. The occurrence of the latter two species over the same area suggests they should be more similar to each other than to the geographically distant J. thurifera . Four populations of J. excelsa ssp. excelsa , four of J. thurifera and two of Juniperus foetidissima were examined on the basis of features of 10 cones and 10 shoots of 18–36 specimens each. Results of discrimination analysis, Mahalanobis distances and cluster analysis showed great similarity to J. excelsa and J. thurifera , while J. foetidissima was more distant. The results support the hypothesis of a common ancestor of J. excelsa and J. thurifera , but suggest another origin of J. foetidissima . © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 483–495. 相似文献
90.
GARCIA EDITH H.; PENA-VALDIVIA CECILIA B.; ROGELIO AGUIRRE J. R.; MURUAGA JOSE S. M. 《Annals of botany》1997,79(2):207-213
Through the process of domestication, bean varieties have beenselected from their wild ancestors for various anthropocentrically-importantcharacteristics. In order to compare some agronomic and morphologicaltraits of a wild population and a modern variety (cv. Bayo Mecentral),the following variables were evaluated: growth habit; numberof nodes on the main stem; number of branches and pods per plant;flower and pod colours; stem length; days to initiation of flowering;days to physiological maturity and duration of flowering. Variationin each trait was recorded, particularly in the wild population.The growth habits of the wild population were very diverse andthere were positive and significant correlations between 13pairs of variables, including the number of nodes on the mainstem, pods per plant, days to flowering and duration of flowering,whereas domesticated beans gave only a few significant correlations.The analysis of principal components indicated that the linearcombination of agronomic and morphological variables, involvingthe first three principal components, accounted for 70% of thetotal variability of the data, and the populations were clearlyseparated as two biological entities by the first principalcomponent. This study confirms that the process of domesticationhas acted to reduce variation in a range of characters. Growth; growth habit; Phaseolus vulgaris ; domestication 相似文献