全文获取类型
收费全文 | 899篇 |
免费 | 57篇 |
出版年
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 10篇 |
2016年 | 22篇 |
2015年 | 39篇 |
2014年 | 46篇 |
2013年 | 58篇 |
2012年 | 73篇 |
2011年 | 56篇 |
2010年 | 21篇 |
2009年 | 34篇 |
2008年 | 44篇 |
2007年 | 50篇 |
2006年 | 50篇 |
2005年 | 26篇 |
2004年 | 43篇 |
2003年 | 32篇 |
2002年 | 34篇 |
2001年 | 18篇 |
2000年 | 24篇 |
1999年 | 17篇 |
1998年 | 14篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1969年 | 7篇 |
1968年 | 5篇 |
1967年 | 4篇 |
排序方式: 共有956条查询结果,搜索用时 31 毫秒
71.
Meister J Weber D Martino V Sterner O Anke T 《Zeitschrift für Naturforschung. C, Journal of biosciences》2007,62(1-2):11-15
The medicinal plant Eupatorium arnottianum can be found in the Northeast and center of Argentina and the South of Bolivia. From plant material collected in Argentina an endophytic Phomopsis was isolated. The fungus was identified by microscopic features and analysis of its ITS sequence. Cultures yielded, besides mellein and nectriapyrone, a novel depsidone derivative for which we propose the name phomopsidone (1). The structure of 1 was determined from its spectroscopic data. 相似文献
72.
Eloise Mastrangelo Patrice Vachette Federica Cossu Francesca Malvezzi Martino Bolognesi Mario Milani 《Biophysical journal》2015,108(3):714-723
Smac-DIABLO in its mature form (20.8 kDa) binds to baculoviral IAP repeat (BIR) domains of inhibitor of apoptosis proteins (IAPs) releasing their inhibitory effects on caspases, thus promoting cell death. Despite its apparent molecular mass (∼100 kDa), Smac-DIABLO was held to be a dimer in solution, simultaneously targeting two distinct BIR domains. We report an extensive biophysical characterization of the protein alone and in complex with the X-linked IAP (XIAP)-BIR2-BIR3 domains. Our data show that Smac-DIABLO adopts a tetrameric assembly in solution and that the tetramer is able to bind two BIR2-BIR3 pairs of domains. Our small-angle x-ray scattering-based tetrameric model of Smac-DIABLO/BIR2-BIR3 highlights some conformational freedom of the complex that may be related to optimization of IAPs binding. 相似文献
73.
74.
Ambruosi B Uranio MF Sardanelli AM Pocar P Martino NA Paternoster MS Amati F Dell'Aquila ME 《PloS one》2011,6(11):e27452
Phthalates are ubiquitous environmental contaminants because of their use in plastics and other common consumer products. Di-(2-ethylhexyl) phthalate (DEHP) is the most abundant phthalate and it impairs fertility by acting as an endocrine disruptor. The aim of the present study was to analyze the effects of in vitro acute exposure to DEHP on oocyte maturation, energy and oxidative status in the horse, a large animal model. Cumulus cell (CC) apoptosis and oxidative status were also investigated. Cumulus-oocyte complexes from the ovaries of slaughtered mares were cultured in vitro in presence of 0.12, 12 and 1200 μM DEHP. After in vitro maturation (IVM), CCs were removed and evaluated for apoptosis (cytological assessment and TUNEL) and intracellular reactive oxygen species (ROS) levels. Oocytes were evaluated for nuclear chromatin configuration. Matured (Metaphase II stage; MII) oocytes were further evaluated for cytoplasmic energy and oxidative parameters. DEHP significantly inhibited oocyte maturation when added at low doses (0.12 μM; P<0.05). This effect was related to increased CC apoptosis (P<0.001) and reduced ROS levels (P<0.0001). At higher doses (12 and 1200 μM), DEHP induced apoptosis (P<0.0001) and ROS increase (P<0.0001) in CCs without affecting oocyte maturation. In DEHP-exposed MII oocytes, mitochondrial distribution patterns, apparent energy status (MitoTracker fluorescence intensity), intracellular ROS localization and levels, mt/ROS colocalization and total SOD activity did not vary, whereas increased ATP content (P<0.05), possibly of glycolytic origin, was found. Co-treatment with N-Acetyl-Cysteine reversed apoptosis and efficiently scavenged excessive ROS in DEHP-treated CCs without enhancing oocyte maturation. In conclusion, acute in vitro exposure to DEHP inhibits equine oocyte maturation without altering ooplasmic energy and oxidative stress parameters in matured oocytes which retain the potential to be fertilized and develop into embryos even though further studies are necessary to confirm this possibility. 相似文献
75.
Mapping the organization of axis of motion selective features in human area MT using high-field fMRI
Zimmermann J Goebel R De Martino F van de Moortele PF Feinberg D Adriany G Chaimow D Shmuel A Uğurbil K Yacoub E 《PloS one》2011,6(12):e28716
Functional magnetic resonance imaging (fMRI) at high magnetic fields has made it possible to investigate the columnar organization of the human brain in vivo with high degrees of accuracy and sensitivity. Until now, these results have been limited to the organization principles of early visual cortex (V1). While the middle temporal area (MT) has been the first identified extra-striate visual area shown to exhibit a columnar organization in monkeys, evidence of MT's columnar response properties and topographic layout in humans has remained elusive. Research using various approaches suggests similar response properties as in monkeys but failed to provide direct evidence for direction or axis of motion selectivity in human area MT. By combining state of the art pulse sequence design, high spatial resolution in all three dimensions (0.8 mm isotropic), optimized coil design, ultrahigh field magnets (7 Tesla) and novel high resolution cortical grid sampling analysis tools, we provide the first direct evidence for large-scale axis of motion selective feature organization in human area MT closely matching predictions from topographic columnar-level simulations. 相似文献
76.
Marinaro C Butti E Bergamaschi A Papale A Furlan R Comi G Martino G Muzio L 《PloS one》2011,6(4):e19419
Radial Glia (RG) cells constitute the major population of neural progenitors of the mouse developing brain. These cells are located in the ventricular zone (VZ) of the cerebral cortex and during neurogenesis they support the generation of cortical neurons. Later on, during brain maturation, RG cells give raise to glial cells and supply the adult mouse brain of Neural Stem Cells (NSC). Here we used a novel transgenic mouse line expressing the CreER(T2) under the control of AspM promoter to monitor the progeny of an early cohort of RG cells during neurogenesis and in the post natal brain. Long term fate mapping experiments demonstrated that AspM-expressing RG cells are multi-potent, as they can generate neurons, astrocytes and oligodendrocytes of the adult mouse brain. Furthermore, AspM descendants give also rise to proliferating progenitors in germinal niches of both developing and post natal brains. In the latter--i.e. the Sub Ventricular Zone--AspM descendants acquired several feature of neural stem cells, including the capability to generate neurospheres in vitro. We also performed the selective killing of these early progenitors by using a Nestin-GFP(flox)-TK allele. The forebrain specific loss of early AspM expressing cells caused the elimination of most of the proliferating cells of brain, a severe derangement of the ventricular zone architecture, and the impairment of the cortical lamination. We further demonstrated that AspM is expressed by proliferating cells of the adult mouse SVZ that can generate neuroblasts fated to become olfactory bulb neurons. 相似文献
77.
78.
Milani M Pesce A Nardini M Ouellet H Ouellet Y Dewilde S Bocedi A Ascenzi P Guertin M Moens L Friedman JM Wittenberg JB Bolognesi M 《Journal of inorganic biochemistry》2005,99(1):97-109
Truncated hemoglobins (trHbs) are low-molecular-weight oxygen-binding heme-proteins distributed in eubacteria, cyanobacteria, unicellular eukaryotes, and in higher plants, constituting a distinct group within the hemoglobin (Hb) superfamily. TrHbs display amino acid sequences 20-40 residues shorter than classical (non)vertebrate Hbs and myoglobins, to which they are scarcely related by sequence similarity. The trHb tertiary structure is based on a 2-on-2 alpha-helical sandwich, which represents a striking editing of the highly conserved 3-on-3 alpha-helical globin fold, achieved through deletion/truncation of alpha-helices and specific residue substitutions. Despite their 'minimal' polypeptide chain span, trHbs display an inner tunnel/cavity system held to support ligand diffusion to/from the heme distal pocket, accumulation of heme ligands within the protein matrix, and/or multiligand reactions. Moreover, trHbs bind and effectively stabilize the heme and recognize diatomic ligands (i.e., O2, CO, NO, and cyanide), albeit with varying thermodynamic and kinetic parameters. Here, structural bases for heme binding and diatomic ligand recognition by trHbs are reviewed. 相似文献
79.
80.
Martino P 《Reviews in clinical and experimental hematology》2005,9(2):1 p preceding E1