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981.
Bramanti V Bronzi D Tomassoni D Costa A Raciti G Avitabile M Amenta F Avola R 《Neurochemical research》2008,33(12):2593-2600
In this research we aimed to investigate the interactions between growth factors (GFs) and dexamethasone (DEX) on cytoskeletal
proteins GFAP and vimentin (VIM) expression under different experimental conditions. Condition I: 24 h pretreatment with bFGF,
subsequent 72 h switching in serum-free medium (SFM) and final addition of GFs, alone or by two in the last 24 h, after a
prolonged (60 h) DEX treatment. Condition II: 36 h pretreatment with DEX (with bFGF in the last 24 h), followed by SFM for
60 h and final addition for 24 h with growth factors alone or two of them togheter. Western blot analysis data showed a marked
GFAP expression in cultures submitted to Condition I comparing results to untreated or treated controls. VIM expression was
instead significantly reduced after GFs addition in the last 24 h of 60 h DEX treatment, respect to control DEX-pretreated
ones. Referring data to untreated controls, VIM expression was significantly enhanced after GFs addition. GFAP showed also
a significant increase in astrocytes submitted to Condition II, respect to untreated or treated control cultures. VIM expression
was up and down regulated under Condition II. Collectively, our findings evidence an interactive dialogue between GFs and
DEX in astroglial cultures, co-pretreated with DEX and bFGF, regulating cytoskeletal network under stressfull conditions.
Special issue article in honor of Dr. Anna Maria Giuffrida-Stella. 相似文献
982.
Modelling metapopulations with stochastic membrane systems 总被引:2,自引:0,他引:2
Metapopulations, or multi-patch systems, are models describing the interactions and the behavior of populations living in fragmented habitats. Dispersal, persistence and extinction are some of the characteristics of interest in ecological studies of metapopulations. In this paper, we propose a novel method to analyze metapopulations, which is based on a discrete and stochastic modelling framework in the area of Membrane Computing. New structural features of membrane systems, necessary to appropriately describe a multi-patch system, are introduced, such as the reduction of the maximal parallel consumption of objects, the spatial arrangement of membranes and the stochastic creation of objects. The role of the additional features, their meaning for a metapopulation model and the emergence of relevant behaviors are then investigated by means of stochastic simulations. Conclusive remarks and ideas for future research are finally presented. 相似文献
983.
Kobbe D Blanck S Demand K Focke M Puchta H 《The Plant journal : for cell and molecular biology》2008,55(3):397-405
RecQ helicases play an important role in the maintenance of genomic stability in pro- and eukaryotes. This is highlighted by the human genetic diseases Werner, Bloom's and Rothmund–Thomson syndrome, caused by respective mutations in three of the five human RECQ genes. The highest numbers of RECQ homologous genes are found in plants, e.g. seven in Arabidopsis thaliana . However, only limited information is available on the functions of plant RecQ helicases, and no biochemical characterization has been performed. Here, we demonstrate that AtRECQ2 is a (d)NTP-dependent 3'→5' DNA helicase. We further characterized its basal properties and its action on various partial DNA duplexes. Importantly, we demonstrate that AtRECQ2 is able to disrupt recombinogenic structures: by disrupting various D-loop structures, AtRECQ2 may prevent non-productive recombination events on the one hand, and may channel repair processes into non-recombinogenic pathways on the other hand, thus facilitating genomic stability. We show that a synthetic partially mobile Holliday junction is processed towards splayed-arm products, possibly indicating a branch migration function for AtRECQ2. The biochemical properties defined in this work support the hypothesis that AtRECQ2 might be functionally orthologous to the helicase part of the human RecQ homologue HsWRN. 相似文献
984.
Patrizia Morena Baldini Paolo De Vito Daniela Vismara Claudia Bagni Francesca Zalfa Marilena Minieri Paolo Di Nardo 《Cellular physiology and biochemistry》2005,15(1-4):77-88
AIMS: The present study was performed to evaluate Atrial Natriuretic Peptide (ANP) effects on intracellular pH, phospholipase D and ROS production and the possible relationship among them in HepG2 cells. Cancer extracellular microenvironment is more acidic than normal tissues and the activation of NHE-1, the only system able to regulate pHi homeostasis in this condition, can represent an important event in cell proliferation and malignant transformation. METHODS: The ANP effects on pHi were evaluated by fluorescence spectrometry. The effects on p38 MAPK and ROS production were evaluated by immunoblots and analysis of DCF-DA fluorescence, respectively. RT-PCR analysis and Western blotting were used to determine the ANP effect on mRNA NHE-1 expression and protein levels. PLD-catalyzed conversion of phosphatidylcholine to phosphatydilethanol (PetOH), in the presence of ethanol, was monitored by thin layer chromatography. RESULTS: A significant pHi decrease was observed in ANP-treated HepG2 cells and this effect was paralleled by the enhancement of PLD activity and ROS production. The ANP effect on pHi was coupled to an increased p38 MAPK phosphorylation and a down-regulation of mRNA NHE-1 expression and protein levels. Moreover, the relationship between PLD and ROS production was demonstrated by calphostin-c, a potent inhibitor of PLD. At the same time, all assessed ANP-effects were mediated by NPR-C receptors. CONCLUSION: Our results indicate that ANP recruits a signal pathway associated with p38 MAPK, NHE-1 and PLD responsible for ROS production, suggesting a possible role for ANP as novel modulator of ROS generation in HepG2 cells. 相似文献
985.
Leaf phyllotaxis: Does it really affect light capture? 总被引:1,自引:0,他引:1
The intriguing mathematical properties of leaf phyllotaxis still attract scientific attention after centuries of research.
Phyllotaxis, and in particular the divergence angle between successive leaves, have been frequently interpreted in terms of
maximization of light capture, although certain model simulations of light capture by vertical shoots revealed minor effects
of phyllotaxis in comparison with the effect of other morphological features of the plant. However, these simulations assumed
a number of simplifications, did not take into account diffuse light, and were not based on real plants with their natural
range of morphological variation. This study was aimed at filling these gaps by examining the influence on light harvesting
of shoot architecture and divergence angle in four species with spiral phyllotaxis (Quercus ilex, Arbutus unedo, Heteromeles arbutifolia and Daphne gnidium) with a realistic 3-D model (Y-plant). A wide range of divergence angles (from 100° to 154°) was observed within each species,
with 144° being the most frequent one. These different divergence angles rendered very different vertical projections of the
shoot due to contrasting patterns of leaf overlap as seen from above, but they rendered indistinguishable light interception
efficiencies (Ea). Setting the leaves with an opposite-decussate phyllotaxis led, however, to a 40–50% decrease of Ea. The
interplay of internode length, leaf size and shape, and leaf elevation angle led to significant species differences in Ea.
Thus, only particular phyllotaxis (e.g., decussate) might be functionally inefficient under certain combinations of the various
morphological variables that influence light capture of a shoot.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
986.
Giampietro Viola Laura Facciolo Daniela Vedaldi Silvia Disarò Giuseppe Basso Francesco Dall'Acqua 《Photochemical & photobiological sciences》2004,3(3):237-239
Treatment of cells with UVA radiation in combination with linear psoralens induces a cell-cycle block and subsequent apoptosis, whereas angular derivatives produce apoptosis without affecting the cellular cycle. 相似文献
987.
Improved Production of Heterologous Proteins by a Glucose Repression-Defective Mutant of Kluyveromyces lactis 总被引:1,自引:0,他引:1 下载免费PDF全文
Claudia Donnini Francesca Farina Barbara Neglia Maria Concetta Compagno Daniela Uccelletti Paola Goffrini Claudio Palleschi 《Applied microbiology》2004,70(5):2632-2638
The secreted production of heterologous proteins in Kluyveromyces lactis was studied. A glucoamylase (GAA) from the yeast Arxula adeninivorans was used as a reporter protein for the study of the secretion efficiencies of several wild-type and mutant strains of K. lactis. The expression of the reporter protein was placed under the control of the strong promoter of the glyceraldehyde-3-phosphate dehydrogenase of Saccharomyces cerevisiae. Among the laboratory strains tested, strain JA6 was the best producer of GAA. Since this strain is known to be highly sensitive to glucose repression and since this is an undesired trait for biomass-oriented applications, we examined heterologous protein production by using glucose repression-defective mutants isolated from this strain. One of them, a mutant carrying a dgr151-1 mutation, showed a significantly improved capability of producing heterologous proteins such as GAA, human serum albumin, and human interleukin-1β compared to the parent strain. dgr151-1 is an allele of RAG5, the gene encoding the only hexokinase present in K. lactis (a homologue of S. cerevisiae HXK2). The mutation in this strain was mapped to nucleotide position +527, resulting in a change from glycine to aspartic acid within the highly conserved kinase domain. Cells carrying the dgr151-1 allele also showed a reduction in N- and O-glycosylation. Therefore, the dgr151 strain may be a promising host for the production of heterologous proteins, especially when the hyperglycosylation of recombinant proteins must be avoided. 相似文献
988.
Impaired carotenogenesis can affect organization and functionality of etioplast membranes 总被引:1,自引:0,他引:1
Isabella Moro Francesca Dalla Vecchia Nicoletta La Rocca Flavia Navari-Izzo Mike Frank Quartacci Daniela Di Baccio Wolfhart Rüdiger Nicoletta Rascio 《Physiologia plantarum》2004,122(1):123-132
The effects of impaired carotenogenesis on plastid membrane organization, functionality and stability were studied in etiolated barley plants grown at 20 and 30°C. The plants were treated with norflurazon or amitrole, two herbicides affecting phytoene desaturation and lycopene cyclization, respectively. At 20°C, the amitrole-treated etioplasts, which accumulated lycopene in their inner membranes, exhibited disorganized prolamellar bodies, containing a prevalent form of non-phototransformable protochlorophyllide (Pchlide). They also showed a certain difficulty in reducing the phototransformable pigment to chlorophyllide when exposed to light, and were unable to reform the active ternary complex [protochlorophyllide–oxidoreductase (POR)–Pchlide–NADPH] when placed back in darkness. No ultrastructural alterations were found in norflurazon-treated etioplasts, with carotenogenesis inhibited at the phytoene desaturation step. In these latter organelles, Pchlide, whose forms were comparable with those of the control etioplasts, was photoreduced quickly after illumination and the ternary complex was reformed during a subsequent dark period. Thus, the impaired carotenogenesis leading to the accumulation of lycopene showed greater interference with the etioplast membrane arrangement and functionality than did the earlier interruption of the biosynthetic pathway at the phytoene level. This might be due to the different interactions of the distinct carotenoid precursors with other membrane components. However, in etioplasts of norflurazon-treated plants, a rise in growth temperature caused a partial demolition of prolamellar bodies, showing a lowered thermostability of the carotenoid-deficient membranes. This latter effect strengthens the concept that a correct and complete carotenogenesis pathway, leading to the synthesis of polar carotenoids (i.e. xanthophylls), is required for the maintenance of stable plastid membranes. 相似文献
989.
Daniela M. Simeonovska-Nikolova 《Acta theriologica》2004,49(2):157-165
Vocal sounds of 15 individuals ofCrocidura leucodon (Hermann, 1780) emitted during agonistic and amicable interactions in male-male, female-female and male-female dyadic encounters,
and intraspecific cage groups, were studied. An analysis of spectral properties, along with an examination of context and
function, were performed. The sounds registered during agonistic interactions showed an increase, then a decrease in frequency,
often followed a complex undulating curve. The dominant frequency (DF) was 10.7±0.05 kHz, and duration (DU) was 104.2±4.4
ms. The calls emitted by shrews at investigation and grooming often ended with chirping notes (DF=4.8±0.2 kHz, DU=23.5±1.1
ms). While clustering and huddling up to the partner, the animals produced calls consisting of short notes with a very low
intensity (DF=1.0±0.07 kHz, DU=35.2±0.8 ms). Based on these finding, it can be assumed that threatening sounds, emitted in
agonistic encounters, allow shrews to avoid conflicts, while those, emitted when clustering and huddling up to the partner,
contribute to maintenance of group cohesiveness. The variability of frequency ranges and intensity of sounds probably reflects
the territorial and gregarious behaviour ofC. leucodon and adaptation to communication in variable acoustic environments. 相似文献
990.