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71.
Anna Lynn Suer David W. Phillips 《Journal of experimental marine biology and ecology》1983,67(3):243-259
Larvae of Urechis caupo Fisher & MacGinitie, reared in the laboratory, were exposed to potential settlement stimuli, including natural sediment from adult burrows, and “scent” obtained from the skin of adult animals. Competent larvae settled rapidly and specifically in response to adult burrow sediment when compared with their responses to other natural and abiotic sediments. Larvae also responded specifically to chemical “scent” from adult animals when the “scent” of another echiuran worm, Listriolobus pelodes Fisher served as a control. Larval responses to chemical “scent” were as great as their responses to natural burrow sediment. Hence, it is likely that larvae settle gregariously in nature in response to “scent” on sediment grains of adult burrows. The chemical “scent” had a molecular weight between ≈3500 and 14000 daltons, as determined by dialysis. It quickly lost its effectiveness in promoting settlement after it was heated to 80 °C, but was relatively stable at ambient ocean temperatures, retaining its effectiveness for several days. It was soluble in sea water. However, larvae did not respond to the chemical “scent”, unless it was adsorbed onto a surface. Purely tactile stimuli, such as the shape, texture, and size-distribution of particles, were not important settlement cues during these experiments. 相似文献
72.
Milton Maciel Jr. Fábia da Silva Pereira Cruz Marli Tenório Cordeiro Márcia Archer da Motta Klécia Marília Soares de Melo Cassemiro Rita de Cássia Carvalho Maia Regina Célia Bressan Queiroz de Figueiredo Ricardo Galler Marcos da Silva Freire Joseph Thomas August Ernesto T. A. Marques Rafael Dhalia 《PLoS neglected tropical diseases》2015,9(4)
Attenuated yellow fever (YF) virus 17D/17DD vaccines are the only available protection from YF infection, which remains a significant source of morbidity and mortality in the tropical areas of the world. The attenuated YF virus vaccine, which is used worldwide, generates both long-lasting neutralizing antibodies and strong T-cell responses. However, on rare occasions, this vaccine has toxic side effects that can be fatal. This study presents the design of two non-viral DNA-based antigen formulations and the characterization of their expression and immunological properties. The two antigen formulations consist of DNA encoding the full-length envelope protein (p/YFE) or the full-length envelope protein fused to the lysosomal-associated membrane protein signal, LAMP-1 (pL/YFE), aimed at diverting antigen processing/presentation through the major histocompatibility complex II precursor compartments. The immune responses triggered by these formulations were evaluated in H2b and H2d backgrounds, corresponding to the C57Bl/6 and BALB/c mice strains, respectively. Both DNA constructs were able to induce very strong T-cell responses of similar magnitude against almost all epitopes that are also generated by the YF 17DD vaccine. The pL/YFE formulation performed best overall. In addition to the T-cell response, it was also able to stimulate high titers of anti-YF neutralizing antibodies comparable to the levels elicited by the 17DD vaccine. More importantly, the pL/YFE vaccine conferred 100% protection against the YF virus in intracerebrally challenged mice. These results indicate that pL/YFE DNA is an excellent vaccine candidate and should be considered for further developmental studies. 相似文献
73.
Elsa Leitão Ana Catarina Costa Claudia Brito Lionel Costa Rita Pombinho 《Cell cycle (Georgetown, Tex.)》2014,13(6):928-940
Listeria monocytogenes (Lm) is a human intracellular pathogen widely used to uncover the mechanisms evolved by pathogens to establish infection. However, its capacity to perturb the host cell cycle was never reported. We show that Lm infection affects the host cell cycle progression, increasing its overall duration but allowing consecutive rounds of division. A complete Lm infectious cycle induces a S-phase delay accompanied by a slower rate of DNA synthesis and increased levels of host DNA strand breaks. Additionally, DNA damage/replication checkpoint responses are triggered in an Lm dose-dependent manner through the phosphorylation of DNA-PK, H2A.X, and CDC25A and independently from ATM/ATR. While host DNA damage induced exogenously favors Lm dissemination, the override of checkpoint pathways limits infection. We propose that host DNA replication disturbed by Lm infection culminates in DNA strand breaks, triggering DNA damage/replication responses, and ensuring a cell cycle delay that favors Lm propagation. 相似文献
74.
Anna Corcione Elisa Ferretti Maria Bertolotto Franco Fais Lizzia Raffaghello Andrea Gregorio Claudya Tenca Luciano Ottonello Claudio Gambini Glaucia Furtado Sergio Lira Vito Pistoia 《PloS one》2009,4(12)
Background
Fractalkine/CX3CL1, a surface chemokine, binds to CX3CR1 expressed by different lymphocyte subsets. Since CX3CL1 has been detected in the germinal centres of secondary lymphoid tissue, in this study we have investigated CX3CR1 expression and function in human naïve, germinal centre and memory B cells isolated from tonsil or peripheral blood.Methodology/Principal Findings
We demonstrate unambiguously that highly purified human B cells from tonsil and peripheral blood expressed CX3CR1 at mRNA and protein levels as assessed by quantitative PCR, flow cytometry and competition binding assays. In particular, naïve, germinal centre and memory B cells expressed CX3CR1 but only germinal centre B cells were attracted by soluble CX3CL1 in a transwell assay. CX3CL1 signalling in germinal centre B cells involved PI3K, Erk1/2, p38, and Src phosphorylation, as assessed by Western blot experiments. CX3CR1+ germinal centre B cells were devoid of centroblasts and enriched for centrocytes that migrated to soluble CX3CL1. ELISA assay showed that soluble CX3CL1 was secreted constitutively by follicular dendritic cells and T follicular helper cells, two cell populations homing in the germinal centre light zone as centrocytes. At variance with that observed in humans, soluble CX3CL1 did not attract spleen B cells from wild type mice. OVA immunized CX3CR1−/− or CX3CL1−/− mice showed significantly decreased specific IgG production compared to wild type mice.Conclusion/Significance
We propose a model whereby human follicular dendritic cells and T follicular helper cells release in the light zone of germinal centre soluble CX3CL1 that attracts centrocytes. The functional implications of these results warrant further investigation. 相似文献75.
PIAS proteins as repressors of Oct4 function 总被引:1,自引:0,他引:1
Tolkunova E Malashicheva A Parfenov VN Sustmann C Grosschedl R Tomilin A 《Journal of molecular biology》2007,374(5):1200-1212
76.
Eugenia Negredo Anna Bonjoch Moisés Gómez-Mateu Carla Estany Jordi Puig Nuria Perez-Alvarez Joaquin Rosales Silvana di Gregorio Luis del Rio Guadalupe Gómez Bonaventura Clotet 《PloS one》2012,7(10)
Background
Algorithms for bone mineral density (BMD) management in HIV-infected patients are lacking. Our objective was to assess how often a dual-energy x-ray absorptiometry (DXA) scan should be performed by assessing time of progression to osteopenia/osteoporosis.Methods
All DXA scans performed between 2000 and 2009 from HIV-infected patients with at least two DXA were included. Time to an event (osteopenia and osteoporosis) was assessed using the Kaplan–Meier method. Strata (tertiles) were defined using baseline minimum T scores. Differences between strata in time to an event were compared with the log-rank test.Results
Of 391 patients (1,639 DXAs), 49.6% had osteopenia and 21.7% osteoporosis at their first DXA scan. Of the 112 (28.6%) with normal BMD, 35.7% progressed to osteopenia; median progression time was 6.7 years. These patients were stratified: “low-risk" (baseline minimum T score >−0.2 SD), “middle-risk" (between −0.2 and −0.6 SD), and “high-risk" (from −0.6 to −1 SD); median progression time to osteopenia was 8.7, >7.2, and 1.7 years, respectively (p<0.0001). Of patients with osteopenia, 23.7% progressed to osteoporosis; median progression time was >8.5 years. Progression time was >8.2 years in “low-risk" tertile (T score between −1.1 and −1.6 SD), >8.5 years in “middle-risk" (between −1.6 and −2), and 3.2 years in “high-risk" (from −2 to −2.4) (p<0.0001).Conclusions
Our results may help to define the BMD testing interval. The lowest T score tertiles would suggest recommending a subsequent DXA in 1–2 years; in the highest tertiles, ≥6 years. Early intervention in patients with bone demineralization could reduce fracture–related morbidity/mortality. 相似文献77.
78.
Behavioural responses in three ichneumonid pollen beetle parasitoids to volatiles emitted from different phenological stages of oilseed rape 总被引:6,自引:0,他引:6
Martin Jönsson Anna Lindkvist & Peter Anderson 《Entomologia Experimentalis et Applicata》2005,115(3):363-369
Pollen beetles (Meligethes spp.; Coleoptera: Nitiduliae) are a major pest of oilseed rape, Brassica napus L. (Brassicaceae) in northern Europe. Phradis interstitialis Thomson, P. morionellus Holmgr., and Tersilochus heterocerus Thomson (Hymenoptera: Ichneumonidae) are among the most frequent pollen beetle parasitoids. These three species differ in temporal occurrence, as well as in preferred host stage. The behavioural responses of female parasitoids to odours from oilseed rape at bud and flowering stage were evaluated in two‐choice experiments. The role of visual stimuli was examined by combining green and yellow colours with odour stimuli. All three species were attracted to odours from the bud stage of oilseed rape. Tersilochus heterocerus was attracted to odours of flowering rape, but the two Phradis species avoided the flower odours. However, when the odours of flowering rape were combined with yellow, and odours of the bud stage were combined with green, P. interstitialis was equally attracted to both stimuli, and T. heterocerus showed an increased preference for flower odours, while no effect of colours could be found in P. morionellus. The observed differences in responses between the parasitoids may reflect differences in their biology and may be involved in the niche segregation of these often coexisting species. The volatile blends released from the two phenological stages were identified and compared. Clearly, odours can be reliable cues for differentiating between oilseed rape in the bud and flowering stage. Of 20 identified compounds, 18 were released at a significantly higher rate from flowering plants. The terpenes sabinene, myrcene, limonene, and (E,E)‐α‐farnesene were the dominant volatiles in the bud and flower headspace. A group of aromatic compounds including benzaldehyde, methyl benzoate, and phenyl acetaldehyde were mainly released from flowering rape. 相似文献
79.
Incorporation of proteins in biomimetic giant unilamellar vesicles (GUVs) is one of the hallmarks towards cell models in which we strive to obtain a better mechanistic understanding of the manifold cellular processes. The reconstruction of transmembrane proteins, like receptors or channels, into GUVs is a special challenge. This procedure is essential to make these proteins accessible to further functional investigation. Here we describe a strategy combining two approaches: cell-free eukaryotic protein expression for protein integration and GUV formation to prepare biomimetic cell models. The cell-free protein expression system in this study is based on insect lysates, which provide endoplasmic reticulum derived vesicles named microsomes. It enables signal-induced translocation and posttranslational modification of de novo synthesized membrane proteins. Combining these microsomes with synthetic lipids within the electroswelling process allowed for the rapid generation of giant proteo-liposomes of up to 50 μm in diameter. We incorporated various fluorescent protein-labeled membrane proteins into GUVs (the prenylated membrane anchor CAAX, the heparin-binding epithelial growth factor like factor Hb-EGF, the endothelin receptor ETB, the chemokine receptor CXCR4) and thus presented insect microsomes as functional modules for proteo-GUV formation. Single-molecule fluorescence microscopy was applied to detect and further characterize the proteins in the GUV membrane. To extend the options in the tailoring cell models toolbox, we synthesized two different membrane proteins sequentially in the same microsome. Additionally, we introduced biotinylated lipids to specifically immobilize proteo-GUVs on streptavidin-coated surfaces. We envision this achievement as an important first step toward systematic protein studies on technical surfaces. 相似文献
80.
Tatiana P. da Silva Carmem B. W. Giacoia-Gripp Carolina A. Schmaltz Flavia M. Sant` Anna Valeria Rolla Mariza G. Morgado 《PloS one》2013,8(6)