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961.
Aitor Payros Josep Tosquella Gilen Bernaola Jaume Dinars-Turell Xabier Orue-Etxebarria Victoriano Pujalte 《Palaeogeography, Palaeoclimatology, Palaeoecology》2009,280(3-4):313-332
The Early/Middle Eocene (Ypresian/Lutetian) transition is represented by a hiatus in many North European sections, including those in which the classic stratotypes were originally defined. However, the Global Stratotype Section and Point of the Lutetian Stage, which is still pending definition, should be placed at a globally correlatable event included within that unrepresented interval. The Pyrenean Eocene outcrops display sedimentary successions that offer the rare opportunity to analyse the Ypresian/Lutetian boundary interval in almost continuous sections and in very different settings. Seven reference stratigraphic sections were selected on the basis of their quality and correlated by means of biomagnetostratigraphic data. This correlation framework casts light on the sequence of chronostratigraphic events that characterize the Ypresian/Lutetian boundary interval, which may prove useful in defining the main correlation criterion of the base of the Lutetian.All of the Pyrenean sections show a similar sedimentary evolution, despite being up to 350 km apart from each other, containing deposits of different origins (intrabasinal carbonate sediments, siliciclastic sediments sourced from the Iberian plate, and terrigenous sediments sourced from the uplifting Pyrenees) and despite having been accumulated in different sedimentary environments (from continental to deep marine) and in different geodynamic settings (piggy-back basin, foreland basin and cratonic margin). This common evolution can be readily interpreted in terms of a sea-level driven depositional sequence whose lowstand and transgressive systems tracts are included within the Ypresian/Lutetian boundary interval. The Pyrenean Ypresian/Lutetian depositional sequence can reasonably be correlated with depositional sequences from classic North European areas, shedding light on the palaeoenvironmental history which in those areas has not been recorded. Furthermore, these depositional sequences may possibly correlate with others from the Antarctic Ocean and from New Jersey, as well as with oceanic temperature variations, suggesting that they might be the result of climatically-driven glacioeustatic sea-level changes. Should this hypothesis prove correct, it would confirm previous suggestions that the onset of Antarctic glaciations needs to be backshifted to the late Ypresian at least. 相似文献
962.
Joseph M. Craine rew J. Elmore Marcos P. M. Aidar Mercedes Bustamante Todd E. Dawson Erik A. Hobbie Ansgar Kahmen Michelle C. Mack Kendra K. McLauchlan ers Michelsen Gabriela B. Nardoto Linda H. Pardo Josep Peñuelas Peter B. Reich Edward A. G. Schuur William D. Stock Pamela H. Templer Ross A. Virginia Jeffrey M. Welker Ian J. Wright 《The New phytologist》2009,183(4):980-992
Ratios of nitrogen (N) isotopes in leaves could elucidate underlying patterns of N cycling across ecological gradients. To better understand global-scale patterns of N cycling, we compiled data on foliar N isotope ratios (δ15 N), foliar N concentrations, mycorrhizal type and climate for over 11 000 plants worldwide. Arbuscular mycorrhizal, ectomycorrhizal, and ericoid mycorrhizal plants were depleted in foliar δ15 N by 2‰, 3.2‰, 5.9‰, respectively, relative to nonmycorrhizal plants. Foliar δ15 N increased with decreasing mean annual precipitation and with increasing mean annual temperature (MAT) across sites with MAT ≥ −0.5°C, but was invariant with MAT across sites with MAT < −0.5°C. In independent landscape-level to regional-level studies, foliar δ15 N increased with increasing N availability; at the global scale, foliar δ15 N increased with increasing foliar N concentrations and decreasing foliar phosphorus (P) concentrations. Together, these results suggest that warm, dry ecosystems have the highest N availability, while plants with high N concentrations, on average, occupy sites with higher N availability than plants with low N concentrations. Global-scale comparisons of other components of the N cycle are still required for better mechanistic understanding of the determinants of variation in foliar δ15 N and ultimately global patterns in N cycling. 相似文献
963.
Gilad Yaakov Alba Duch María García-Rubio Josep Clotet Javier Jimenez Andrés Aguilera Francesc Posas 《Molecular biology of the cell》2009,20(15):3572-3582
Control of cell cycle progression by stress-activated protein kinases (SAPKs) is essential for cell adaptation to extracellular stimuli. Exposure of yeast to osmostress activates the Hog1 SAPK, which modulates cell cycle progression at G1 and G2 by the phosphorylation of elements of the cell cycle machinery, such as Sic1 and Hsl1, and by down-regulation of G1 and G2 cyclins. Here, we show that upon stress, Hog1 also modulates S phase progression. The control of S phase is independent of the S phase DNA damage checkpoint and of the previously characterized Hog1 cell cycle targets Sic1 and Hsl1. Hog1 uses at least two distinct mechanisms in its control over S phase progression. At early S phase, the SAPK prevents firing of replication origins by delaying the accumulation of the S phase cyclins Clb5 and Clb6. In addition, Hog1 prevents S phase progression when activated later in S phase or cells containing a genetic bypass for cyclin-dependent kinase activity. Hog1 interacts with components of the replication complex and delays phosphorylation of the Dpb2 subunit of the DNA polymerase. The two mechanisms of Hog1 action lead to delayed firing of origins and prolonged replication, respectively. The Hog1-dependent delay of replication could be important to allow Hog1 to induce gene expression before replication. 相似文献
964.
Meritxell Pérez-González Josep María Torres-Rodríguez Antoni Martínez-Roig Sonia Segura Gemma Griera Laura Triviño Marta Pasarín 《Revista iberoamericana de micología》2009,26(4):228-232
ObjectiveTo evaluate the prevalence of tinea capitis, tinea pedis, and tinea unguium in children from several schools of Barcelona city.MethodsDuring the period of 2003–2004, a prospective cross-sectional study was carried out in 1,305 children (9% immigrant population) between the ages 3 and 15 in 17 schools in Barcelona. A systematic examination of the feet, (including nails and scalp), was performed to identify lesions compatible with tinea. Cultures of scalp and feet samples were done and analysis of environmental samples was performed for dermatophyte isolation.ResultsDermatophytes were isolated in 2.9% of the samples with a prevalence of 2.5% in feet, 0.23% in scalp, and 0.15% in nails of the feet. The predominant etiologic agents in feet were Trichophyton mentagrophytes in 45.7% of the cases and Trichophyton rubrum in 31.4%. In the nails, T. rubrum and Trichophyton tonsurans were isolated, while T. mentagrophytes (2 cases) and Trichophyton violaceum (1 case) were identified in scalp samples. Forty-five per cent of dermatophytes were isolated from healthy feet, the majority of cases in children 13–15 years old (p<0.05). Microsporum gypseum was the only agent identified in the environmental samples, and was also found in one of the cases of tinea pedis.ConclusionThe results of this study demonstrate a low prevalence of tinea capitis and tinea unguium in school children of Barcelona. On the contrary, high prevalence of dermatophytes in feet was found. It highlights the high prevalence of healthy carriers of dermatophytes in feet. 相似文献
965.
Josep Garre-Olmo Margarita Flaqué Jordi Gich Teresa Osuna Pulido Josefina Turbau Natalia Vallmajo Marta Vi?as Secundí López-Pousa Registry of Dementia of Girona Study Group 《BMC neurology》2009,9(1):5
Background
Traditional epidemiological studies do not allow elucidating the reality of referral and diagnosis patterns of dementia in routine clinical practice within a defined territory. This information is useful and necessary in order to plan and allocate healthcare resources. This paper presents the results from a dementia case registry based on epidemiological surveillance fundamentals. 相似文献966.
Removal of introns during pre-mRNA splicing is a critical processin gene expression, and understanding its control at both single-geneand genomic levels is one of the great challenges in Biology.Splicing takes place in a dynamic, large ribonucleoprotein complexknown as the spliceosome. Combining Genetics and Biochemistry,Saccharomyces cerevisiae provides insights into its mechanisms,including its regulation by RNA–protein interactions.Recent genome-wide analyses indicate that regulated splicingis broad and biologically relevant even in organisms with arelatively simple intronic structure, such as yeast. Furthermore,the possibility of coordination in splicing regulation at genomiclevel is becoming clear in this model organism. This shouldprovide a valuable system to approach the complex problem ofthe role of regulated splicing in genomic expression. 相似文献
967.
Insular ecosystems have been subjected to severe hardship during the last millennia. Large numbers of insular bird species
have undergone local disappearances and full extinctions, and a high number of insular birds are currently categorised as
endangered species. In most of these cases, extinction—or endangerment—is in direct relation to the arrival of ‘aboriginal’
and/or imperialist waves of human settlement. Insular bird extinction events have been documented to have occurred at times
corresponding to aboriginal settlement at many archipelagos and isolated islands, such as the Hawaiian Islands, New Zealand,
the West Indies or the tropical Pacific Islands. However, no bird extinctions could be attributed to the first settlers of
the Canary Islands—until now. The first accelerator mass spectrometer radiocarbon (14C) dating of collagen from a bone of the Dune Shearwater Puffinus holeae (3395 ± 30 year BP), an extinct bird from the Canary Islands, indicates a late Holocene extinction event. This relatively
recent date, together with some features of this bird (large body size, breeding areas situated at very accessible places)
and the absence of its bones from the entire archaeological record suggests that the extinction occurred close to the time
that the first human settlement occurred on the islands. 相似文献
968.
Federica Amici Filippo Aureli Josep Call 《American journal of physical anthropology》2010,143(2):188-197
Differences in cognitive skills across taxa, and between monkeys and apes in particular, have been explained by different hypotheses, although these often are not supported by systematic interspecific comparisons. Here, we directly compared the cognitive performance of the four great apes and three monkey species (spider monkeys, capuchin monkeys, and long‐tailed macaques), differing in their phylogenetic‐relatedness and socioecology. We tested subjects on their ability to remember object locations (memory task), track object displacements (transposition task), and obtain out‐of‐reach rewards (support task). Our results showed no support for an overall clear‐cut distinction in cognitive skills between monkeys and apes as species performance varied substantially across tasks. Although we found differences in performance at tracking object displacements between monkeys and apes, interspecific differences in the other two tasks were better explained in terms of differential socioecology, especially differential levels of fission–fusion dynamics. A cluster analysis using mean scores of each condition of the three tasks for each species suggested that the only dichotomy might be between members of the genus Pan and the rest of the tested species. These findings evidence the importance of using multiple tasks across multiple species in a comparative perspective to test different explanations for the enhancement of specific cognitive skills. Am J Phys Anthropol 143:188–197, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
969.
Carlo Polidori Pablo Mendiola Josep D. Asís José Tormos Jesús Selfa 《Journal of Ethology》2010,28(2):353-361
Studies which quantitatively analyse how aculeate parasitoids exploit their window of opportunity to find and attack a host
are scarce, despite the recognized importance of parasitic pressure as a driving force that promotes aggregate nesting in
their hosts. We have studied the activity and behaviour of the velvet ant Nemka viduata, an ectoparasitoid of immature stages of the digger wasp Stizus continuus. Due to the resource exploited by the parasitoid (mature larvae and prepupae), and in general agreement with basic optimal
foraging theory, we expected a major activity at late stages of the host seasonal provisioning period, an independence from
the host daily provisioning patterns and a spatial positive association with host nest density. In accordance with these predictions,
during the season, the parasitoid resulted was more active at the end of the host provisioning period, and across the day,
it showed an inverse quadratic pattern of activity, in contrast to the positive one shown by the host. Thus, at both temporal
scales, N. viduata activity was highly asynchronous with that of the host. At a spatial scale, however, the activity of the velvet ants was
correlated with host nest density, although there is weak evidence suggesting that areas of high host density suffered from
a higher rate of parasitism. Multivariate analyses confirmed a number of relevant factors associated with velvet ants’ activity,
including nest density (positive), air temperature and the hour of the day (both negative). In addition, the activity of both
male S. continuus and male N. viduata entered in the models in association with female parasitoid’s activity, probably because of their mating strategy. 相似文献
970.