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101.
Capsule Kleptoparasitic activities of older chicks from earlier nests did not contribute to late reproductive declines. Aims To determine whether intraspecific interactions, such as kleptoparasitism and aggression, were experienced more frequently by birds breeding late in the season as a result of exposure to breeders at a more advanced stage. If so, to investigate whether this was the cause of the observed seasonal decline in reproductive parameters observed at Bird Island, where nesting density is high and interactions are more probable. Methods Plots were fenced within the colony, exploiting natural variability in distribution of early and peak breeders to create two treatments: plots with only late-laying terns and those with a mixture of early-, peak- and late-layers. Hatching success, productivity and the growth and survival of chicks were measured for all late-laying pairs. Intraspecific interactions, adult attendance and provisioning of chicks were recorded during 9600 minutes of nest observations made within two periods: a few days after hatching and one week later. Results The frequency of intraspecific interactions was maintained by the kleptoparasitic activities of older chicks within the mixed-laying-date treatment and was significantly lower in plots containing only late breeders with chicks of similar ages (mean 11.0 days). The overall rate was rarely greater than two interactions per nest per hour and there was no corresponding reduction in the growth or survival of chicks from late nests or any change in the provisioning activities of late-breeding adults. Conclusion Increased frequency of intraspecific interactions experienced by late breeders in the presence of early-breeding conspecifics resulted from the kleptoparasitic activities of older chicks but was not sufficient to contribute to the observed seasonal reproductive decline at this dense breeding colony. 相似文献
102.
Karl L. Evans David I. Leech Humphrey Q.P. Crick Jeremy J.D. Greenwood Kevin J. Gaston 《Bird Study》2013,60(1):75-85
Capsule Daylength, rather than latitude, was found to be an important determinant of variation in clutch size. Aims To describe the nature of spatial and temporal variation in clutch size, and explore the ecological correlates of these patterns. Methods We tested the prediction that seasonal declines in clutch size will be greater at higher latitudes. The environmental variables focused on were the influence of daylength, plant productivity, seasonality (i.e. Ashmole's hypothesis) and physiological mechanisms that relate clutch size to ambient temperature. We used data from 1980 to 2003 on spatial variation in clutch size across Britain for single‐brooded species, in which clutch size can be taken as a measure of annual reproductive investment. We included all seven species, from five families, with sufficient data in the British Trust for Ornithology's Nest Record Scheme. Results There are strong seasonal declines in clutch size but little evidence for latitudinal gradients in clutch size or in latitudinal gradients in the rate of seasonal clutch size decline. Of the environmental variables investigated, daylength had the most marked effect on clutch size; this was positive in diurnal species and negative in the one nocturnal species. Conclusions Although this study was confined to a relatively small latitudinal range of 8°, we found marked latitudinal gradients in a number of factors thought to drive spatial patterns in clutch size. Moreover, such variation is of sufficient magnitude to generate spatial patterns in other ecological variables in Britain. There is thus no simple explanation for the lack of a latitudinal gradient in clutch size. The results concerning daylength indicate that the time available for foraging is an important determinant of variation in clutch size. 相似文献
103.
Laura L. Yates Carsten Schnatwinkel Lee Hazelwood Lauren Chessum Anju Paudyal Helen Hilton M. Rosario Romero Jonathan Wilde Debora Bogani Jeremy Sanderson Caroline Formstone Jennifer N. Murdoch Lee A. Niswander Andy Greenfield Charlotte H. Dean 《Developmental biology》2013,373(2):267-280
During lung development, proper epithelial cell arrangements are critical for the formation of an arborized network of tubes. Each tube requires a lumen, the diameter of which must be tightly regulated to enable optimal lung function. Lung branching and lumen morphogenesis require close epithelial cell–cell contacts that are maintained as a result of adherens junctions, tight junctions and by intact apical–basal (A/B) polarity. However, the molecular mechanisms that maintain epithelial cohesion and lumen diameter in the mammalian lung are unknown. Here we show that Scribble, a protein implicated in planar cell polarity (PCP) signalling, is necessary for normal lung morphogenesis. Lungs of the Scrib mouse mutant Circletail (Crc) are abnormally shaped with fewer airways, and these airways often lack a visible, ‘open’ lumen. Mechanistically we show that Scrib genetically interacts with the core PCP gene Vangl2 in the developing lung and that the distribution of PCP pathway proteins and Rho mediated cytoskeletal modification is perturbed in ScribCrc/Crc lungs. However A/B polarity, which is disrupted in Drosophila Scrib mutants, is largely unaffected. Notably, we find that Scrib mediates functions not attributed to other PCP proteins in the lung. Specifically, Scrib localises to both adherens and tight junctions of lung epithelia and knockdown of Scrib in lung explants and organotypic cultures leads to reduced cohesion of lung epithelial cells. Live imaging of Scrib knockdown lungs shows that Scrib does not affect bud bifurcation, as previously shown for the PCP protein Celsr1, but is required to maintain epithelial cohesion. To understand the mechanism leading to reduced cell–cell association, we show that Scrib associates with β-catenin in embryonic lung and the sub-cellular distribution of adherens and tight junction proteins is perturbed in mutant lung epithelia. Our data reveal that Scrib is required for normal lung epithelial organisation and lumen morphogenesis by maintaining cell–cell contacts. Thus we reveal novel and important roles for Scrib in lung development operating via the PCP pathway, and in regulating junctional complexes and cell cohesion. 相似文献
104.
Kerry J. Schimenti Sky K. Feuer Laurie B. Griffin Nancy R. Graham Claire A. Bovet Suzanne Hartford Janice Pendola Carl Lessard John C. Schimenti Jeremy O. Ward 《Genetics》2013,194(2):447-457
Mammalian male fertility relies on complex inter- and intracellular signaling during spermatogenesis. Here we describe three alleles of the widely expressed A-kinase anchoring protein 9 (Akap9) gene, all of which cause gametogenic failure and infertility in the absence of marked somatic phenotypes. Akap9 disruption does not affect spindle nucleation or progression of prophase I of meiosis but does inhibit maturation of Sertoli cells, which continue to express the immaturity markers anti-Mullerian hormone and thyroid hormone receptor alpha in adults and fail to express the maturation marker p27Kip1. Furthermore, gap and tight junctions essential for blood–testis barrier (BTB) organization are disrupted. Connexin43 (Cx43) and zona occludens-1 are improperly localized in Akap9 mutant testes, and Cx43 fails to compartmentalize germ cells near the BTB. These results identify and support a novel reproductive tissue-specific role for Akap9 in the coordinated regulation of Sertoli cells in the testis. 相似文献
105.
Jeremy L. Yap Huabo Wang Angela Hu Jay Chauhan Kwan-Young Jung Robert B. Gharavi Edward V. Prochownik Steven Fletcher 《Bioorganic & medicinal chemistry letters》2013,23(1):370-374
A structure–activity relationship (SAR) study of the c-Myc (Myc) inhibitor 10074-G5 (N-([1,1′-biphenyl]-2-yl)-7-nitrobenzo[c][1,2,5]oxadiazol-4-amine, 1) – which targets a hydrophobic domain of the Myc oncoprotein that is flanked by arginine residues – was executed in order to determine its pharmacophore. Whilst the 7-nitrobenzofurazan was found to be critical for inhibitory activity, the ortho-biphenyl could be replaced with a para-carboxyphenyl group to furnish the new inhibitor JY-3-094 (3q). Around five times as potent as the lead with an IC50 of 33 μM for disruption of the Myc–Max heterodimer, JY-3-094 demonstrated excellent selectivity over Max–Max homodimers, with no apparent effect at 100 μM. Importantly, the carboxylic acid of JY-3-094 improves the physicochemical properties of the lead compound, which will facilitate the incorporation of additional hydrophobicity that might enhance Myc inhibitory activity further still. 相似文献
106.
Markus Geisen Chantal Billard Alexandra Broerse Lluisa Cros Ian Probert Jeremy Young 《欧洲藻类学杂志》2013,48(4):531-550
New holococcolith-heterococcolith life-cycle associations are documented based on observations of combination coccospheres. Daktylethra pirus is shown to be a life-cycle phase of Syracosphaera pulchra and Syracolithus quadriperforatus a life-cycle phase of Calcidiscus leptoporus. In addition, new observations from cultures confirm the life-cycle associations of Crystallolithus braarudii with Coccolithus pelagicus and of Zygosphaera hellenica with Coronosphaera mediterranea. In all four cases previous work has shown that the heterococcolithophorid species is associated with another holococcolithophorid. Two other examples of a heterococcolithophorid being associated with two holococcolithophorids have previously been identified, so this seems to be a common phenomenon. The six examples are reviewed to determine whether a single underlying mechanism is likely to be responsible for all cases. It is concluded that there is no single mechanism but rather that the six examples fall into three categories: (a) in two cases the holococcolith types are probably simply ecophenotypic morphotypes; (b) in two other cases the holococcolith types are discrete and are paralleled by morphometric differences in the heterococcolith types; (c) in the final two cases the holococcolith types are discrete but are not paralleled by any obvious morphological variation in the heterococcolith morphology. We infer that cryptic speciation may be widespread in heterococcolithophorid phases and that study of holococcolithophorid phases can provide key data to elucidate this phenomenon. 相似文献
107.
Jeremy I. Martin 《The International Journal of Life Cycle Assessment》2013,18(7):1279-1279
108.
Fibrosis is a major clinical problem associated with as many as 45% of all natural deaths in developed nations.It can affect all organs and accumulating evidence indicates that fibrogenesis is not merely a bystander product of injury, but is a central pathological problem directly contributing to loss of organ function. In the majority of clinical cases, fibrogenesis is strongly associated with the recruitment of leukocytes, even in the absence of infection. Although chronic infections are a significant cause of fibrogenesis, in most cases fibrotic disease occurs in the context of sterile injury, such as microvascular disease, toxic epithelial injury or diabetes mellitus. Fibrogenesis is a direct consequence of the activation of extensive, and previously poorly appreciated, populations of mesenchymal cells in our organs which are either wrapped around capillaries and known as ‘pericytes’, or embedded in interstitial spaces between cell structures and known as resident ‘fibroblasts’. Recent fate-mapping and complementary studies in several organs indicate that these cells are the precursors of the scar-forming myofibroblasts that appear in our organs in response to injury. Here we will review the literature supporting a central role for these cells in fibrogenesis, and highlight some of the critical cell to cell interactions that are necessary for the initiation and continuation of the fibrogenic process. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease. 相似文献
109.
Noah M Ivers Jacqueline Young Jill J Francis Jan Barnsley Baiju R Shah Ross E Upshur Jeremy M Grimshaw Merrick Zwarenstein 《Implementation science : IS》2013,8(1):142
Background
Audit and feedback to physicians is a commonly used quality improvement strategy, but its optimal design is unknown. This trial tested the effects of a theory-informed worksheet to facilitate goal setting and action planning, appended to feedback reports on chronic disease management, compared to feedback reports provided without these worksheets.Methods
A two-arm pragmatic cluster randomized trial was conducted, with allocation at the level of primary care clinics. Participants were family physicians who contributed data from their electronic medical records. The ‘usual feedback’ arm received feedback every six months for two years regarding the proportion of their patients meeting quality targets for diabetes and/or ischemic heart disease. The intervention arm received these same reports plus a worksheet designed to facilitate goal setting and action plan development in response to the feedback reports. Blood pressure (BP) and low-density lipoprotein cholesterol (LDL) values were compared after two years as the primary outcomes. Process outcomes measured the proportion of guideline-recommended actions (e.g., testing and prescribing) conducted within the appropriate timeframe. Intention-to-treat analysis was performed.Results
Outcomes were similar across groups at baseline. Final analysis included 20 physicians from seven clinics and 1,832 patients in the intervention arm (15% loss to follow up) and 29 physicians from seven clinics and 2,223 patients in the usual feedback arm (10% loss to follow up). Ten of 20 physicians completed the worksheet at least once during the study. Mean BP was 128/72 in the feedback plus worksheet arm and 128/73 in the feedback alone arm, while LDL was 2.1 and 2.0, respectively. Thus, no significant differences were observed across groups in the primary outcomes, but mean haemoglobin A1c was lower in the feedback plus worksheet arm (7.2% versus 7.4%, p<0.001). Improvements in both arms were noted over time for one-half of the process outcomes.Discussion
Appending a theory-informed goal setting and action planning worksheet to an externally produced audit and feedback intervention did not lead to improvements in patient outcomes. The results may be explained in part by passive dissemination of the worksheet leading to inadequate engagement with the intervention.Trial registration
ClinicalTrials.gov NCT00996645110.
Randa?Attieh Marie-Pierre?GagnonEmail author Carole?A?Estabrooks France?Légaré Mathieu?Ouimet Geneviève?Roch El?Kebir?Ghandour Jeremy?Grimshaw 《Implementation science : IS》2013,8(1):138