全文获取类型
收费全文 | 2054篇 |
免费 | 183篇 |
国内免费 | 2篇 |
出版年
2023年 | 14篇 |
2022年 | 29篇 |
2021年 | 59篇 |
2020年 | 25篇 |
2019年 | 30篇 |
2018年 | 47篇 |
2017年 | 33篇 |
2016年 | 73篇 |
2015年 | 109篇 |
2014年 | 100篇 |
2013年 | 128篇 |
2012年 | 182篇 |
2011年 | 168篇 |
2010年 | 115篇 |
2009年 | 85篇 |
2008年 | 126篇 |
2007年 | 131篇 |
2006年 | 135篇 |
2005年 | 99篇 |
2004年 | 100篇 |
2003年 | 86篇 |
2002年 | 81篇 |
2001年 | 26篇 |
2000年 | 22篇 |
1999年 | 24篇 |
1998年 | 21篇 |
1997年 | 7篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 15篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 11篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1967年 | 3篇 |
1966年 | 2篇 |
排序方式: 共有2239条查询结果,搜索用时 15 毫秒
151.
152.
Lorin A Lins L Stroobant V Brasseur R Charloteaux B 《Biochemical and biophysical research communications》2007,355(3):649-653
In this study, we determined the minimal N-terminal fusion peptide of the gp30 of the bovine leukemia virus on the basis of the tilted peptide theory. We first used molecular modelling to predict that the gp30 minimal fusion peptide corresponds to the 15 first residues. Liposome lipid-mixing and leakage assays confirmed that the 15-residue long peptide induces fusion in vitro and that it is the shortest peptide inducing optimal fusion since longer peptides destabilize liposomes to the same extent but not shorter ones. The 15-residue long peptide can thus be considered as the minimal fusion peptide. The effect of mutations reported in the literature was also investigated. Interestingly, mutations related to glycoproteins unable to induce syncytia in cell-cell fusion assays correspond to peptides predicted as non-tilted. The relationship between obliquity and fusogenicity was also confirmed in vitro for one tilted and one non-tilted mutant peptide. 相似文献
153.
Viana R Towler MC Pan DA Carling D Viollet B Hardie DG Sanz P 《The Journal of biological chemistry》2007,282(22):16117-16125
Mammalian AMP-activated protein kinase is a serine/threonine protein kinase that acts as a sensor of cellular energy status. AMP-activated protein kinase is a heterotrimer of three different subunits, i.e. alpha, beta, and gamma, with alpha being the catalytic subunit and beta and gamma having regulatory roles. Although several studies have defined different domains in alpha and beta involved in the interaction with the other subunits of the complex, little is known about the regions of the gamma subunits involved in these interactions. To study this, we have made sequential deletions from the N termini of the gamma subunit isoforms and studied the interactions with alpha and beta subunits, both by two-hybrid analysis and by co-immunoprecipitation. Our results suggest that a conserved region of 20-25 amino acids in gamma1, gamma2, and gamma3, immediately N-terminal to the Bateman domains, is required for the formation of a functional, active alphabetagamma complex. This region is required for the interaction with the beta subunits. The interaction between the alpha and gamma subunits does not require this region and occurs instead within the Bateman domains of the gamma subunit, although the alpha-gamma interaction does appear to stabilize the beta-gamma interaction. In addition, sequential deletions from the C termini of the gamma subunits indicate that deletion of any of the CBS (cystathionine beta-synthase) motifs prevents the formation of a functional complex with the alpha and beta subunits. 相似文献
154.
The influence of cell mechanics, cell-cell interactions, and proliferation on epithelial packing 总被引:2,自引:0,他引:2
BACKGROUND: Epithelial junctional networks assume packing geometries characterized by different cell shapes, neighbor number distributions and areas. The development of specific packing geometries is tightly controlled; in the Drosophila wing epithelium, cells convert from an irregular to a hexagonal array shortly before hair formation. Packing geometry is determined by developmental mechanisms that likely control the biophysical properties of cells and their interactions. RESULTS: To understand how physical cellular properties and proliferation determine cell-packing geometries, we use a vertex model for the epithelial junctional network in which cell packing geometries correspond to stable and stationary network configurations. The model takes into account cell elasticity and junctional forces arising from cortical contractility and adhesion. By numerically simulating proliferation, we generate different network morphologies that depend on physical parameters. These networks differ in polygon class distribution, cell area variation, and the rate of T1 and T2 transitions during growth. Comparing theoretical results to observed cell morphologies reveals regions of parameter space where calculated network morphologies match observed ones. We independently estimate parameter values by quantifying network deformations caused by laser ablating individual cell boundaries. CONCLUSIONS: The vertex model accounts qualitatively and quantitatively for the observed packing geometry in the wing disc and its response to perturbation by laser ablation. Epithelial packing geometry is a consequence of both physical cellular properties and the disordering influence of proliferation. The occurrence of T2 transitions during network growth suggests that elimination of cells from the proliferating disc epithelium may be the result of junctional force balances. 相似文献
155.
Dutech C Enjalbert J Fournier E Delmotte F Barrès B Carlier J Tharreau D Giraud T 《Fungal genetics and biology : FG & B》2007,44(10):933-949
Although they represent powerful genetic markers in many fields of biology, microsatellites have been isolated in few fungal species. The aim of this study was to assess whether obtaining microsatellite markers with an acceptable level of polymorphism is generally harder from fungi than in other organisms. We therefore surveyed the number, nature and polymorphism level of published microsatellite markers in fungi from the literature and from our own data on seventeen fungal microsatellite-enriched libraries, and in five other phylogroups (angiosperms, insects, fishes, birds and mammals). Fungal microsatellites indeed appeared both harder to isolate and to exhibit lower polymorphism than in other organisms. This appeared to be due, at least in part, to genomic specificities, such as scarcity and shortness of fungal microsatellite loci. A correlation was observed between mean repeat number and mean allele number in the published fungal microsatellite loci. The cross-species transferability of fungal microsatellites also appeared lower than in other phylogroups. However, microsatellites have been useful in some fungal species. Thus, the considerable advantages of these markers make their development worthwhile, and this study provides some guidelines for their isolation. 相似文献
156.
Tarkowski M Vanoirbeek JA Vanhooren HM De Vooght V Mercier CM Ceuppens J Nemery B Hoet PH 《American journal of physiology. Lung cellular and molecular physiology》2007,292(1):L207-L214
The objective of the study was to characterize better the immunologic mechanisms underlying a previously developed animal model of chemical-induced asthma. BALB/c and severe combined immunodeficiency disease (SCID) mice received toluene diisocyanate (TDI) or vehicle on each ear on day 1 and/or day 7. On day 10, they were intranasally challenged with TDI or vehicle. Ventilatory function was monitored by whole body plethysmography for 40 min after challenge. Reactivity to methacholine was measured 23 h later: enhanced pause and actual resistance measurements. Pulmonary inflammation was assessed 1, 6, and 24 h after challenge by bronchoalveolar lavage (BAL). Tumor necrosis factor-alpha and macrophage inflammatory protein (MIP)-2 levels were measured in BAL. Immunological parameters included total IgE, IgG1, and IgG2a in serum, lymphocyte populations in auricular and cervical lymph nodes, and IL-4 and IFN-gamma levels in supernatants of lymph node cells, cultured with or without concanavalin A. Ventilatory changes suggestive of airway obstruction and increased methacholine reactivity were observed in all TDI-sensitized and TDI intranasally instilled mice, except in SCID mice. A neutrophil influx, accompanied by an increase in MIP-2 levels, was found in BAL of all responding groups 6 and 24 h after intranasal challenge. In BALB/c mice an increased level of CD19+ B cells was found in the auricular lymph nodes. IL-4 and IFN-gamma levels were increased in supernatants of concanavalin A-stimulated auricular lymph node cells from BALB/c mice completely treated with TDI. These results indicate that our model is dependent on the presence of lymphocytes, but it is not characterized by a preferential stimulation of Th1 or Th2 lymphocytes. 相似文献
157.
158.
159.
160.