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91.
The present work proposes new boundaries for the current submediterranean territories of the Iberian Peninsula, defining them
at the smallest scale attempted to date. The boundaries proposed are not sharp divisions but somewhat ‘gradual’, reflecting
the transitional nature of the territories they encompass. Climate change predictions were used to estimate how the distribution
of these submediterranean regions might change in the near future. The maps constructed are based on the distribution of marcescent
Quercus species—trees that characterise the submediterranean plant landscape where they form the main forest communities. To determine
their climatic range, the distribution of different types of Iberian oak forest was represented in ‘climate diagrams’ (ordination
diagrams derived from principal components analysis), both in terms of individual species and groups of species based on leaf
ecophysiological type, i.e. marcescent (Submediterranean), sclerophyllous (Mediterranean), semideciduous (Mediterranean) and
deciduous (Eurosiberian). The climate range of each type of forest was determined, and the means of representative climate
variables are analysed by one way ANOVA. The variables differentiating the forest groups were also examined by discriminant
analysis. The range of the climate variables found to be associated with the majority of marcescent forests was used to determine
the distribution of territories throughout the Peninsula with the same conditions (i.e. whether marcescent forests were present
or not), thus providing a map of the Iberian submediterranean territories. Predictions of climate change were used to investigate
possible climate-induced modifications in the boundaries of these territories in the near future. The patterns obtained show
dramatic reductions in the extension of the Iberian submediterranean environment. Submediterranean conditions will probably
disappear from the areas where they currently reign, and it seems unlikely that any new, large submediterranean areas will
form by displacement towards higher altitudes. The outlook for the unique submediterranean vegetation of the Iberian Peninsula
is gloomy.
相似文献
Helios Sainz-OlleroEmail: |
92.
Beatrice Carlsson Elin Kindberg Javier Buesa Gustaf E. Rydell Marta Fos Lidón Rebeca Montava Reem Abu Mallouh Ammi Grahn Jesús Rodríguez-Díaz Juan Bellido Alberto Arnedo G?ran Larson Lennart Svensson 《PloS one》2009,4(5)
In November 2004, 116 individuals in an elderly nursing home in El Grao de Castellón, Spain were symptomatically infected with genogroup II.4 (GII.4) norovirus. The global attack rate was 54.2%. Genotyping of 34 symptomatic individuals regarding the FUT2 gene revealed that one patient was, surprisingly, a non-secretor, hence indicating secretor-independent infection. Lewis genotyping revealed that Lewis-positive and negative individuals were susceptible to symptomatic norovirus infection indicating that Lewis status did not predict susceptibility. Saliva based ELISA assays were used to determine binding of the outbreak virus to saliva samples. Saliva from a secretor-negative individual bound the authentic outbreak GII.4 Valencia/2004/Es virus, but did not in contrast to secretor-positive saliva bind VLP of other strains including the GII.4 Dijon strain. Amino acid comparison of antigenic A and B sites located on the external loops of the P2 domain revealed distinct differences between the Valencia/2004/Es and Dijon strains. All three aa in each antigenic site as well as 10/11 recently identified evolutionary hot spots, were unique in the Valencia/2004/Es strain compared to the Dijon strain. To the best of our knowledge, this is the first example of symptomatic GII.4 norovirus infection of a Lea+b− individual homozygous for the G428A nonsense mutation in FUT2. Taken together, our study provides new insights into the host genetic susceptibility to norovirus infections and evolution of the globally dominating GII.4 viruses. 相似文献
93.
García-Escarp M Martinez-Muñoz V Barquinero J Sales-Pardo I Domingo JC Marin P Petriz J 《Cell and tissue research》2005,319(3):405-412
The lack of specific markers for stem cells makes the physical identification of this compartment difficult. Hematopoietic stem cells differ in their repopulating and self-renewal potential. Our study shows that multiple classes of human hematopoietic CD34+ greatly differ in telomere length. Flow-cytometry-based fluorescent in situ hybridization and confocal microscopy of CD34+ cells has revealed remarkable telomere length heterogeneity, with a hybridization pattern consistent with different classes of human hematopoietic progenitor cells. These results also point to the existence of a significant clonal heterogeneity among primitive hematopoietic cells and provide the first evidence of a rare fraction of CD34+ cells with large telomeres in humans. Marta García-Escarp and Vanessa Martinez-Muñoz contributed equally to this work.This work was supported by a grant to J.P. from the Spanish Ministry of Science and Technology (SAF2002-02618) and by a grant to V.M.-M. from DakoCytomation. 相似文献
94.
Silva J Silva JM Barradas M García JM Domínguez G García V Peña C Gallego I Espinosa R Serrano M Bonilla F 《Mutation research》2006,594(1-2):78-85
Frequent chromosome 3 losses have been described in several tumors types, which strongly suggest the presence of one or several tumor suppressor genes. Recently, a novel candidate tumor suppressor gene termed Ris-1 (for Ras-induced senescence 1) has been identified at chromosomal position 3p21.3. Ris-1 has been proposed to participate in anti-tumor responses that resemble cellular senescence and that are elicited by oncogenes such as Ras. To analyze the role of Ris-1 as a putative tumor suppressor gene in human breast cancer, we have performed a real-time quantitative analysis of its mRNA expression in 60 patients. Moreover, we carried out a first approach to evaluate the most common inactivation mechanism that can affect expression levels of tumor suppressor genes (mutation, promoter hypermethylation and allelic losses). Furthermore, a correlation study between expression as well as inactivating mechanisms of Ris-1 and several clinico-pathological parameters of the tumors was designed, with the objective of appraising the prognostic value of Ris-1 status. Decreased expression of Ris-1 was observed in 23% of the cases and overexpressed Ris-1 was detected in 15% of the primary breast tumors. Our data showed high frequency of LOH (30%) at one of the markers used. Nevertheless, a polymorphism related with the expression levels was described. Statistically significant correlations were found between decreased Ris-1 expression and negative progesterone receptors, as well as between overexpressing Ris-1 tumors and high histological grade. Despite all these data, we conclude that the suggested role of Ris-1 as tumor suppressor gene is not evident, at least in breast cancer. Future and larger series studies in different tumor types are necessary to clarify Ris-1 function in human cancer. 相似文献
95.
96.
Yésica García‐Ramos Marta Paradís‐Bas Judit Tulla‐Puche Fernando Albericio 《Journal of peptide science》2010,16(12):675-678
CM resin is a totally PEG‐based resin, made exclusively from primary ether bonds and therefore highly chemically stable. Compared to other PEG resins, it exhibits good loading and is user friendly because of its free‐flowing form upon drying. It shows improved performance over PS resins for the preparation of hydrophobic, highly structured poly‐Arg peptides. In combination with ψPros, it allows the synthesis of small proteins such as the chemokine RANTES. Like other PEG‐based resins, CM resin swells well in biocompatible solvents such as water, thereby allowing on‐bead screening. Furthermore, the high loading of this resin permits the use of a tiny quarter of a bead as a microreactor for HPLC and MALDI‐TOF analysis, thus further extending its applications in the field of combinatorial chemistry. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
97.
Towards a biogeographic regionalization of the European biota 总被引:1,自引:0,他引:1
Aim To determine if it is possible to generate analytically derived regionalizations for multiple groups of European plants and animals and to explore potential influences on the regions for each taxonomic group. Location Europe. Methods We subjected range maps of trees, butterflies, reptiles, amphibians, birds and mammals to k‐means clustering followed by v‐fold cross‐validation to determine the pattern and number of regions (clusters). We then used the mean range sizes of species in each group as a correlate of the number of regions obtained for each taxon, and climate and species richness gradients as correlates of the spatial arrangement of the group‐specific regions. We also included the pattern of tree clusters as a predictor of animal clusters in order to test the ‘habitat templet’ concept as an explanation of animal distribution patterns. Results Spatially coherent clusters were found for all groups. The number of regions ranged from three to eight and was strongly associated with the mean range sizes of the species in each taxon. The cluster patterns of all groups were associated with various combinations of climate, underlying species richness gradients and, in the case of animals, the arrangement of tree clusters, although the rankings of the correlates differed among groups. In four of five groups the tree pattern was the strongest single predictor of the animal cluster patterns. Main conclusions Despite a long history of human disturbance and habitat modification, the European biota retains a discernable biogeographic structure. The primary driver appears to be aspects of climate related to water–energy balance, which also influence richness gradients. For many animals, the underlying habitat structure, as measured by tree distributions, appears to have a strong influence on their biogeographic structure, highlighting the need to preserve natural forest formations if we want to preserve the historical signal found in geographic distributions. 相似文献
98.
Emma Barahona Ana Navazo Fátima Yousef‐Coronado Daniel Aguirre de Cárcer Francisco Martínez‐Granero Manuel Espinosa‐Urgel Marta Martín Rafael Rivilla 《Environmental microbiology》2010,12(12):3185-3195
Motility is a key trait for rhizosphere colonization by Pseudomonas fluorescens. Mutants with reduced motility are poor competitors, and hypermotile, more competitive phenotypic variants are selected in the rhizosphere. Flagellar motility is a feature associated to planktonic, free‐living single cells, and although it is necessary for the initial steps of biofilm formation, bacteria in biofilm lack flagella. To test the correlation between biofilm formation and rhizosphere colonization, we have used P. fluorescens F113 hypermotile derivatives and mutants affected in regulatory genes which in other bacteria modulate biofilm development, namely gacS (G), sadB (S) and wspR (W). Mutants affected in these three genes and a hypermotile variant (V35) isolated from the rhizosphere were impaired in biofilm formation on abiotic surfaces, but colonized the alfalfa root apex as efficiently as the wild‐type strain, indicating that biofilm formation on abiotic surfaces and rhizosphere colonization follow different regulatory pathways in P. fluorescens. Furthermore, a triple mutant gacSsadBwspR (GSW) and V35 were more competitive than the wild‐type strain for root‐tip colonization, suggesting that motility is more relevant in this environment than the ability to form biofilms on abiotic surfaces. Microscopy showed the same root colonization pattern for P. fluorescens F113 and all the derivatives: extensive microcolonies, apparently held to the rhizoplane by a mucigel that seems to be plant produced. Therefore, the ability to form biofilms on abiotic surfaces does not necessarily correlates with efficient rhizosphere colonization or competitive colonization. 相似文献
99.
Roles of glutamine in neurotransmission 总被引:1,自引:0,他引:1
Glutamine (Gln) is found abundantly in the central nervous system (CNS) where it participates in a variety of metabolic pathways. Its major role in the brain is that of a precursor of the neurotransmitter amino acids: the excitatory amino acids, glutamate (Glu) and aspartate (Asp), and the inhibitory amino acid, γ-amino butyric acid (GABA). The precursor-product relationship between Gln and Glu/GABA in the brain relates to the intercellular compartmentalization of the Gln/Glu(GABA) cycle (GGC). Gln is synthesized from Glu and ammonia in astrocytes, in a reaction catalyzed by Gln synthetase (GS), which, in the CNS, is almost exclusively located in astrocytes (Martinez-Hernandez et al., 1977). Newly synthesized Gln is transferred to neurons and hydrolyzed by phosphate-activated glutaminase (PAG) to give rise to Glu, a portion of which may be decarboxylated to GABA or transaminated to Asp. There is a rich body of evidence which indicates that a significant proportion of the Glu, Asp and GABA derived from Gln feed the synaptic, neurotransmitter pools of the amino acids. Depolarization-induced-, calcium- and PAG activity-dependent releases of Gln-derived Glu, GABA and Asp have been observed in CNS preparations in vitro and in the brain in situ. Immunocytochemical studies in brain slices have documented Gln transfer from astrocytes to neurons as well as the location of Gln-derived Glu, GABA and Asp in the synaptic terminals. Patch-clamp studies in brain slices and astrocyte/neuron co-cultures have provided functional evidence that uninterrupted Gln synthesis in astrocytes and its transport to neurons, as mediated by specific carriers, promotes glutamatergic and GABA-ergic transmission. Gln entry into the neuronal compartment is facilitated by its abundance in the extracellular spaces relative to other amino acids. Gln also appears to affect neurotransmission directly by interacting with the NMDA class of Glu receptors. Transmission may also be modulated by alterations in cell membrane polarity related to the electrogenic nature of Gln transport or to uncoupled ion conductances in the neuronal or glial cell membranes elicited by Gln transporters. In addition, Gln appears to modulate the synthesis of the gaseous messenger, nitric oxide (NO), by controlling the supply to the cells of its precursor, arginine. Disturbances of Gln metabolism and/or transport contribute to changes in Glu-ergic or GABA-ergic transmission associated with different pathological conditions of the brain, which are best recognized in epilepsy, hepatic encephalopathy and manganese encephalopathy. 相似文献
100.
Emilia Moreno-Ruiz Marta Galán-Díez Weidong Zhu Elena Fernández-Ruiz Christophe d'Enfert Scott G. Filler Pascale Cossart Esteban Veiga 《Cellular microbiology》2009,11(8):1179-1189
Candida albicans is a major cause of oropharyngeal, vulvovaginal and haematogenously disseminated candidiasis. Endocytosis of C. albicans hyphae by host cells is a prerequisite for tissue invasion. This internalization involves interactions between the fungal invasin Als3 and host E- or N-cadherin. Als3 shares some structural similarity with InlA, a major invasion protein of the bacterium Listeria monocytogenes . InlA mediates entry of L. monocytogenes into host cells through binding to E-cadherin. A role in internalization, for a non-classical stimulation of the clathrin-dependent endocytosis machinery, was recently highlighted. Based on the similarities between the C. albicans and L. monocytogenes invasion proteins, we studied the role of clathrin in the internalization of C. albicans . Using live-cell imaging and indirect immunofluorescence of epithelial cells infected with C. albicans , we observed that host E-cadherin, clathrin, dynamin and cortactin accumulated at sites of C. albicans internalization. Similarly, in endothelial cells, host N-cadherin, clathrin and cortactin accumulated at sites of fungal endocytosis. Furthermore, clathrin, dynamin or cortactin depletion strongly inhibited C. albicans internalization by epithelial cells. Finally, beads coated with Als3 were internalized in a clathrin-dependent manner. These data indicate that C. albicans , like L. monocytogenes, hijacks the clathrin-dependent endocytic machinery to invade host cells. 相似文献