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961.
Sequential shrinkage and swelling underlie P2X7-stimulated lymphocyte phosphatidylserine exposure and death 总被引:1,自引:0,他引:1
Taylor SR Gonzalez-Begne M Dewhurst S Chimini G Higgins CF Melvin JE Elliott JI 《Journal of immunology (Baltimore, Md. : 1950)》2008,180(1):300-308
Patterns of change in cell volume and plasma membrane phospholipid distribution during cell death are regarded as diagnostic means of distinguishing apoptosis from necrosis, the former being associated with cell shrinkage and early phosphatidylserine (PS) exposure, whereas necrosis is associated with cell swelling and consequent lysis. We demonstrate that cell volume regulation during lymphocyte death stimulated via the purinergic receptor P2X7 is distinct from both. Within seconds of stimulation, murine lymphocytes undergo rapid shrinkage concomitant with, but also required for, PS exposure. However, within 2 min shrinkage is reversed and swelling ensues ending in cell rupture. P2X7-induced shrinkage and PS translocation depend upon K+ efflux via KCa3.1, but use a pathway of Cl- efflux distinct from that previously implicated in apoptosis. Thus, P2X7 stimulation activates a novel pathway of cell death that does not conform to those conventionally associated with apoptosis and necrosis. The mixed apoptotic/necrotic phenotype of P2X7-stimulated cells is consistent with a potential role for this death pathway in lupus disease. 相似文献
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In this paper we demonstrate a UV-B-mediated link between host plants, herbivores and their parasitoids, using a model system
consisting of a host plant Brassica oleracea, a herbivore Plutella xylostella and its parasitoid Cotesia plutellae. Ultraviolet-B radiation (UV-B) is a potent elicitor of a variety of changes in the chemistry, morphology and physiology
of plants and animals. Recent studies have demonstrated that common signals, such as jasmonic acid (JA), play important roles
in the mechanisms by which plants respond to UV-B and to damage by herbivores. Plant responses elicited by UV-B radiation
can affect the choices of ovipositing female insects and the fitness of their offspring. This leads to the prediction that,
in plants, the changes induced as a consequence of UV damage will be similar to those elicited in response to insect damage,
including knock-on effects upon the next trophic level, predators. In our trials female P. xylostella oviposited preferentially on host plants grown in depleted UV-B conditions, while their larvae preferred to feed on tissues
from UV-depleted regimes over those from UV-supplemented ones. Larval feeding patterns on UV-supplemented tissues met the
predictions of models which propose that induced defences in plants should disperse herbivory; feeding scars were significantly
smaller and more numerous – though not significantly so – than those on host plant leaves grown in UV-depleted conditions.
Most importantly, female parasitoids also showed a clear pattern of preference when given the choice between host plants and
attendant larvae from the different UV regimes; however, in the case of the female parasitoids, the choice was in favour of
potential hosts foraging on UV-supplemented tissues. This study demonstrates the potential for UV-B to elicit a variety of
interactions between trophic levels, most likely mediated through effects upon host plant chemistry. 相似文献
968.
CENH3 morphogenesis reveals dynamic centromere associations during synaptonemal complex formation and the progression through male meiosis in hexaploid wheat 下载免费PDF全文
Adél Sepsi James D. Higgins John S. Heslop‐Harrison Trude Schwarzacher 《The Plant journal : for cell and molecular biology》2017,89(2):235-249
During meiosis, centromeres in some species undergo a series of associations, but the processes and progression to homologous pairing is still a matter of debate. Here, we aimed to correlate meiotic centromere dynamics and early telomere behaviour to the progression of synaptonemal complex (SC) construction in hexaploid wheat (2n = 42) by triple immunolabelling of CENH3 protein marking functional centromeres, and SC proteins ASY1 (unpaired lateral elements) and ZYP1 (central elements in synapsed chromosomes). We show that single or multiple centromere associations formed in meiotic interphase undergo a progressive polarization (clustering) at the nuclear periphery in early leptotene, leading to formation of the telomere bouquet. Critically, immunolabelling shows the dynamics of these presynaptic centromere associations and a structural reorganization of the centromeric chromatin coinciding with key events of synapsis initiation from the subtelomeric regions. As short stretches of subtelomeric synapsis emerged at early zygotene, centromere clusters lost their strong polarization, gradually resolving as individual centromeres indicated by more than 21 CENH3 foci associated with unpaired lateral elements. Only following this centromere depolarization were homologous chromosome arms connected, as observed by the alignment and fusion of interstitial ZYP1 loci elongating at zygotene so synapsis at centromeres is a continuation of the interstitial synapsis. Our results thus reveal that centromere associations are a component of the timing and progression of chromosome synapsis, and the gradual release of the individual centromeres from the clusters correlates with the elongation of interstitial synapsis between the corresponding homologues. 相似文献
969.
Multiple sequence alignment with the Clustal series of programs 总被引:2,自引:0,他引:2
Chenna R Sugawara H Koike T Lopez R Gibson TJ Higgins DG Thompson JD 《Nucleic acids research》2003,31(13):3497-3500
The Clustal series of programs are widely used in molecular biology for the multiple alignment of both nucleic acid and protein sequences and for preparing phylogenetic trees. The popularity of the programs depends on a number of factors, including not only the accuracy of the results, but also the robustness, portability and user-friendliness of the programs. New features include NEXUS and FASTA format output, printing range numbers and faster tree calculation. Although, Clustal was originally developed to run on a local computer, numerous Web servers have been set up, notably at the EBI (European Bioinformatics Institute) (http://www.ebi.ac.uk/clustalw/). 相似文献
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Kim HG Kishikawa S Higgins AW Seong IS Donovan DJ Shen Y Lally E Weiss LA Najm J Kutsche K Descartes M Holt L Braddock S Troxell R Kaplan L Volkmar F Klin A Tsatsanis K Harris DJ Noens I Pauls DL Daly MJ MacDonald ME Morton CC Quade BJ Gusella JF 《American journal of human genetics》2008,82(1):199-207
Autism is a neurodevelopmental disorder of complex etiology in which genetic factors play a major role. We have implicated the neurexin 1 (NRXN1) gene in two independent subjects who display an autism spectrum disorder (ASD) in association with a balanced chromosomal abnormality involving 2p16.3. In the first, with karyotype 46,XX,ins(16;2)(q22.1;p16.1p16.3)pat, NRXN1 is directly disrupted within intron 5. Importantly, the father possesses the same chromosomal abnormality in the absence of ASD, indicating that the interruption of α-NRXN1 is not fully penetrant and must interact with other factors to produce ASD. The breakpoint in the second subject, with 46,XY,t(1;2)(q31.3;p16.3)dn, occurs ~750 kb 5′ to NRXN1 within a 2.6 Mb genomic segment that harbors no currently annotated genes. A scan of the NRXN1 coding sequence in a cohort of ASD subjects, relative to non-ASD controls, revealed that amino acid alterations in neurexin 1 are not present at high frequency in ASD. However, a number of rare sequence variants in the coding region, including two missense changes in conserved residues of the α-neurexin 1 leader sequence and of an epidermal growth factor (EGF)-like domain, respectively, suggest that even subtle changes in NRXN1 might contribute to susceptibility to ASD. 相似文献