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81.
Rodolfo A. Golluscio Amy T. Austin Guillermo C. García Martínez Marina Gonzalez-Polo Osvaldo E. Sala Robert B. Jackson 《Ecosystems》2009,12(4):686-697
We explored the net effects of grazing on soil C and N pools in a Patagonian shrub–grass steppe (temperate South America).
Net effects result from the combination of direct impacts of grazing on biogeochemical characteristics of microsites with
indirect effects on relative cover of vegetated and unvegetated microsites. Within five independent areas, we sampled surface
soils in sites subjected to three grazing intensities: (1) ungrazed sites inside grazing exclosures, (2) moderately grazed
sites adjacent to them, and (3) intensely grazed sites within the same paddock. Grazing significantly reduced soil C and N
pools, although this pattern was clearest in intensely grazed sites. This net effect was due to the combination of a direct
reduction of soil N content in bare soil patches, and indirect effects mediated by the increase of the cover of bare soil
microsites, with lower C and N content than either grass or shrub microsites. This increase in bare soil cover was accompanied
by a reduction in cover of preferred grass species and standing dead material. Finally, stable isotope signatures varied significantly
among grazed and ungrazed sites, with δ15N and δ13C significantly depleted in intensely grazed sites, suggesting reduced mineralization with increased grazing intensity. In
the Patagonian steppe, grazing appears to exert a negative effect on soil C and N cycles; sound management practices must
incorporate the importance of species shifts within life form, and the critical role of standing dead material in maintaining
soil C and N stocks and biogeochemical processes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Author Contributions RAG designed study, performed research, analyzed data, wrote the paper; ATA designed study, wrote the paper; CGGM designed
study, performed research, analyzed data; MGP performed research; OES designed study; RBJ designed study, contributed new
methods. 相似文献
82.
Srilakshmi M Sharma Dongseok Choi Stephen R Planck Christina A Harrington Carrie R Austin Jinnell A Lewis Tessa N Diebel Tammy M Martin Justine R Smith James T Rosenbaum 《Arthritis research & therapy》2009,11(6):R168-9
Introduction
Axial spondyloarthropathy (SpA) is a group of inflammatory diseases, with ankylosing spondylitis as the prototype. SpA affects the axial skeleton, entheses, joints and, at times, the eyes. This study tested the hypothesis that SpA is characterized by a distinct pattern of gene expression in peripheral blood of affected individuals compared with healthy controls. 相似文献83.
Maren de Vries Adil S. Mohamed Rachel A. Prescott Ana M. Valero-Jimenez Ludovic Desvignes Rebecca OConnor Claire Steppan Joseph C. Devlin Ellie Ivanova Alberto Herrera Austin Schinlever Paige Loose Kelly Ruggles Sergei B. Koralov Annaliesa S. Anderson Joseph Binder Meike Dittmann 《Journal of virology》2021,95(10)
84.
Andreas Lackner Robert Sehlke Marius Garmhausen Giuliano Giuseppe Stirparo Michelle Huth Fabian TitzTeixeira Petra van der Lelij Julia Ramesmayer Henry F Thomas Meryem Ralser Laura Santini Elena Galimberti Mihail Sarov A Francis Stewart Austin Smith Andreas Beyer Martin Leeb 《The EMBO journal》2021,40(8)
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An insulator element 3′ to the CFTR gene binds CTCF and reveals an active chromatin hub in primary cells 下载免费PDF全文
Neil P. Blackledge Christopher J. Ott Austin E. Gillen Ann Harris 《Nucleic acids research》2009,37(4):1086-1094
Regulation of expression of the CFTR gene is poorly understood. Elements within the basal promoter of the gene do not fully explain CFTR expression patterns, suggesting that cis-regulatory elements are located elsewhere, either within the locus or in adjacent chromatin. We previously mapped DNase I hypersensitive sites (DHS) in 400 kb spanning the CFTR locus including a cluster of sites close to the 3′-end of the gene. Here we focus on a DHS at +6.8 kb from the CFTR translation end-point to evaluate its potential role in regulating expression of the gene. This DHS, which encompasses a consensus CTCF-binding site, was evident in primary human epididymis cells that express abundant CFTR mRNA. We show by DNase I footprinting and electophoretic mobility shift assays that the cis-regulatory element within this DHS binds CTCF in vitro. We further demonstrate that the element functions as an enhancer blocker in a well-established in vivo assay, and by using chromatin immunoprecipitation that it recruits CTCF in vivo. Moreover, we reveal that in primary epididymis cells, the +6.8 kb DHS interacts closely with the CFTR promoter, suggesting that the CFTR locus exists in a looped conformation, characteristic of an active chromatin hub. 相似文献
87.
Brenda M. Alexander Priyanka Singh Kathy J. Austin Rebecca R. Cockrum Kristi M. Cammack Bret W. Hess Gary E. Moss Peter W. Nathanielsz Stephen P. Ford 《Animal reproduction science》2009,116(1-2):58-64
Sexual differentiation of the brain occurs between d 30 and 70 in the fetal lamb. The objective of this experiment was to determine if maternal fatness affects fetal steroid production and expression of their receptors which may ultimately alter endocrine systems postnatally. Fetuses were collected from ewes fed at either 100% (Control; n = 5) or 150% (Fat; n = 6) of NRC recommendations from 60 d prior to breeding until collection at 75 d of gestation. Hypothalamic and amygdala neural tissues were collected from twin male/female fetuses. Serum concentrations of testosterone were greater (P < 0.001) in male fetuses compared to female fetuses. Further, male fetuses from Fat ewes had greater (P < 0.05) serum concentrations of testosterone than male fetuses from Control ewes, but differences in testicular steroidogenic enzyme mRNA were not detected (P = 0.18). Quantity of hypothalamic mRNA for estrogen receptor (ER) β tended (P = 0.1) to be influenced by a sex by treatment interaction. Messenger RNA for ER-β was greater in female fetuses than male fetuses from Control ewes (P = 0.05). Although amount of ER-β mRNA did not differ among male fetuses (P = 0.7), amounts tended to be less (P = 0.07) in female fetuses from Fat ewes compared to those from Control ewes, and did not differ (P ≥ 0.8) from male fetuses. Hypothalamic ER-α mRNA tended (P = 0.1) to be less in fetuses from Fat ewes compared to Control fetuses but was not influenced (P = 0.3) by fetal sex or their interaction. Amount of mRNA for hypothalamic progesterone receptor tended (P = 0.06) to be greater in male fetuses than female fetuses and tended to be less (P = 0.06) in fetuses from Fat ewes than in Control fetuses, but did not differ by any sex by treatment interaction (P = 0.6). Hypothalamic RNA for the androgen receptor did not differ by sex, dam nutritional treatment, or the interaction. Likewise, amygdala RNA for the estrogen or androgen receptor did not differ (P ≥ 0.3) by sex, treatment, or their interaction. Dam fatness appears to decrease the expression of progesterone receptor, ER-α, and decrease amount of ER-β in the female fetuses while increasing circulating concentrations of testosterone in male fetuses. Altered expression of hypothalamic receptor genes by the uterine environment may affect adult responses to stress, sexual behavior and/or the pattern of gonadotropin release in response to gonadal steroids. 相似文献
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Mark Stanback Austin Mercandante Wesley Anderson Howell Burke Rebecca Jameson 《Journal of avian biology》2009,40(6):650-652
Nest boxes provide sheltered nesting sites for both passerines and paper wasps. Although neither wasps nor birds appear to evict the other once one is fully established, it is unclear which is the dominant competitor at the onset of the breeding season. Using wire mesh, we excluded birds but not golden paper wasps Polistesfuscatus from alternating boxes along a transect through edge habitat in North Carolina from 2006 – 2008. If wasps dominate Carolina chickadees Poecile carolinensis and eastern bluebirds Sialia sialis during the early spring (all have similar nest initiation dates), we would expect wasps to settle in both box types at equal frequencies. However, if birds dominate wasps, we would expect wasp nests to be concentrated in “bird‐proof” boxes. We found wasps in bird‐proof boxes significantly more often than in bird‐accessible boxes, indicating that secondary‐cavity nesting birds are able to exclude wasps from available nest sites. Additionally, we found that during the period of nest initiation, birds usurp wasps more often than vice versa. 相似文献
90.