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951.
Michael A. Chernousov Kelly Baylor Richard C. Stahl Mark M. Stecker Lynn Y. Sakai Sui Lee-Arteaga Francesco Ramirez David J. Carey 《Matrix biology》2010,29(5):357-368
The extracellular matrix of peripheral nerve is formed from a diverse set of macromolecules, including glycoproteins, collagens and proteoglycans. Recent studies using knockout animal models have demonstrated that individual components of the extracellular matrix play a vital role in peripheral nerve development and regeneration. In this study we identified fibrillin-1 and fibrillin-2, large modular structural glycoproteins, as components of the extracellular matrix of peripheral nerve. Previously it was found that fibrillin-2 null mice display joint contractures, suggesting a possible defect of the peripheral nervous system in these animals. Close examination of the peripheral nerves of fibrillin-2 deficient animals described here revealed some structural abnormalities in the perineurium, while general structure of the nerve and molecular composition of nerve extracellular matrix remained unchanged. We also found that in spite of the obvious motor function impairment, fibrillin-2 null mice failed to display changes of nerve conduction properties or nerve regeneration capacity. Based on the data obtained we can conclude that peripheral neuropathy should be excluded as the cause of the impairment of locomotory function and joint contractures observed in fibrillin-2 deficient animals. 相似文献
952.
Transcriptional activation of jun and actin genes by estrogen during mitogenic stimulation of rat uterine cells. 总被引:4,自引:0,他引:4
953.
Francesco Nonnis Marzano Fabio Fiori Guogang Jia Mariachiara Chiantore 《Polar Biology》2000,23(11):753-758
The paucity of investigations on the presence of artificial radionuclides and their bioaccumulation in Antarctic fauna is
due to the erroneous belief that this area is pristine. We report evidence that significant levels of the artificial radionuclides
Sr-90, Cs-137, Am-241 and plutonium isotopes can be found in sponges, bivalves, krill and demersal fish fauna of Terra Nova
Bay (Ross Sea), sometimes with a seasonal pattern. Increasing concentrations of Cs-137 were detected in the bivalve Adamussium colbecki (Antarctic scallop) during austral summer months, as a result of major trophic activity and changes in metabolic rates. Bioconcentration
factors for artificial radionuclides in different Antarctic species are presented and discussed in relation to their different
trophic strategies. Unexpectedly high radiocesium bioconcentration factors determined in bivalves suggested the particular
role played by filter feeding in bioaccumulation, particularly in summer when radionuclide bioavailability is enhanced. The
feeding preference of the trematomiid fish Trematomus bernacchii for the scallop A. colbecki is confirmed, not only by fish gut content analyses, but also through radiometric results. Transuranics bioaccumulation by
sensitive species allowed some interesting comparisons on the different plutonium contamination of the southern hemisphere
with respect to the northern one.
Accepted: 25 April 2000 相似文献
954.
Palumbo E Favier CF Deghorain M Cocconcelli PS Grangette C Mercenier A Vaughan EE Hols P 《FEMS microbiology letters》2004,239(1):131-138
A stable mutant of Lactobacillus plantarum deficient in alanine racemase (Alr) was constructed by two successive homologous recombination steps. When the mutant was supplemented with D-alanine, growth and viability were unaffected. Surprisingly, deprivation of d-alanine during exponential growth did not result in a rapid and extensive lysis as observed in Alr-deficient strains of Escherichia coli or Bacillus subtilis. Rather, the starved mutant cells underwent a growth arrest and were gradually affected in viability with a decrease in colony forming units over 99% in less than 24 h. Additionally, fluorescent techniques demonstrated a loss of cell envelope integrity in the starved cells. Prolonged d-alanine starvation resulted in cells with an aberrant morphology. Scanning and transmission electron microscopy analyses revealed an increase in cell length, deficiencies in septum formation, thinning of the cell envelope and perforation of the cell wall in the septum region. We discuss the involvement of peptidoglycan hydrolases in these phenotypic defects in the context of the crucial role played by D-alanine in peptidoglycan biosynthesis and teichoic acids substitution. 相似文献
955.
A crucial event in DNA replication is the polymerase switch from the synthesis of a short RNA/DNA primer by DNA polymerase alpha/primase to the pro?cessive elongation by DNA polymerase delta. In order to shed light on the role of replication factor C (RF-C) in this process, the effects of RF-C on DNA polymerase alpha were investigated. We show that RF-C stalls DNA polymerase alpha after synthesis of approximately 30 nucleotides, while not inhibiting the polymerase activity per se. This suggested that RF-C and the length of the primer may be two important factors contributing to the polymerase switch. Furthermore the DNA binding properties of RF-C were tested. Band shift experiments indicated that RF-C has a preference for 5' recessed ends and double-stranded DNA over 3' ends. Finally PCNA can be loaded onto a DNA template carrying a RNA primer, suggesting that a DNA moiety is not necessarily required for the loading of the clamp. Thus we propose a model where RF-C, upon binding to the RNA/DNA primer, influences primer synthesis and sets the conditions for a polymerase switch after recruiting PCNA to DNA. 相似文献
956.
The variable C-terminus of cysteine string proteins modulates exocytosis and protein-protein interactions 总被引:2,自引:0,他引:2
Cysteine string proteins (Csps) are vesicle proteins involved in neurotransmission and hormone exocytosis. They are composed of distinct domains: a variable N-terminus, a J-domain followed by a linker region, a cysteine-rich string, and a C-terminus which diverges among isoforms. Their precise function and interactions are not fully understood. Using insulin exocytosis as a model, we show that the linker region and the C-terminus, but not the variable N-terminus, regulate overall secretion. Moreover, endogenous Csp1 binds in a calcium-dependent manner to monomeric VAMP2, and this interaction requires the C-terminus of Csp. The interaction is isoform specific as recombinant Csp1 binds VAMP1 and VAMP7, but not VAMP3. Cross-linking in permeabilized clonal beta-cells revealed homodimerization of Csp which is stimulated by Ca(2+) and again modulated by the variant C-terminus. Our data suggest that both interactions of Csp occur during exocytosis and may explain the effect of the variant C-terminus of this chaperon protein on peptide hormone secretion. 相似文献
957.
Mandili G Khadjavi A Gallo V Minero VG Bessone L Carta F Giribaldi G Turrini F 《The FEBS journal》2012,279(12):2182-2191
Doxorubicin is commonly considered to exert its anti-tumor activity by triggering apoptosis of cancer cells through DNA damage. Recent reports have shown that Doxorubicin elicits a marked heat shock response, and that either inhibition or silencing of heat shock proteins enhance the Doxorubicin apoptotic effect in neuroblastoma cells. In order to investigate whether Doxorubicin may also act through protein modification, we performed a proteomic analysis of ubiquitinated proteins. Here we show that nanomolar Doxorubicin treatment of neuroblastoma cells caused: (a) dose-dependent over-ubiquitination of a specific set of proteins in the absence of measurable inhibition of proteasome, (b) protein ubiquination patterns similar to those with Bortezomib, a proteasome inhibitor, (c) depletion and loss of activity of ubiquitinated enzymes such as lactate dehydrogenase and α-enolase, and (d) a decrease in HSP27 solubility, probably a consequence of its binding to denatured proteins. These data strongly reinforce the hypothesis that Doxorubicin may also exert its effect by damaging proteins. 相似文献
958.
Palmirotta R De Marchis ML Ludovici G Leone B Savonarola A Ialongo C Spila A De Angelis F Ferroni P Della-Morte D Guadagni F 《The International journal of biological markers》2012,27(2):e90-e98
Multicenter studies and biobanking projects require blood transportation from the participating center to a central collection or diagnostic laboratory. The impact of time delays between venous blood collection and peripheral blood mononuclear cells (PBMC) isolation prior to RNA extraction may affect the quality and quantity of isolated nucleic acids for genomic applications. Thus, standard operating procedure (SOP) optimization for the treatment of biological samples before RNA extraction is crucial in a biological repository. In order to define SOPs for whole blood preservation prior to RNA extraction, we sought to determine whether different blood storage times (0, 3, 6, 10, 24, and 30 hours) prior to PBMCs isolation and storage at -80°C, could affect the quality and quantity of extracted RNA. After spectrophotometric quantification, the quality and integrity of RNA were assessed by agarose gel electrophoresis, RNA integrity number and real time-PCR (RT-PCR).?Across the different time points we did not observe significant differences within the first 24 hours of blood storage at room temperature, while a significant loss in RNA yield and integrity was detected between 24 and 30 hours. We conclude that time delays before PBMCs isolation prior to RNA extraction may have a significant impact on downstream molecular biological applications. 相似文献
959.
Tight control of mRNA expression is required for cell differentiation; imbalanced regulation may lead to developmental disorders and cancer. The activity of the translational machinery (including ribosomes and translation factors) regulates the rate (slow or fast) of translation of encoded proteins, and the quality of these proteins highly depends on which mRNAs are available for translation. Specific RNA-binding and ribosomal proteins seem to play a key role in controlling gene expression to determine the differentiation fate of the cell. This demonstrates the important role of RNA-binding proteins, specific ribosome-binding proteins and microRNAs as key molecules in controlling the specific proteins required for the differentiation or dedifferentiation of cells. This delicate balance between specific proteins (in terms of quality and availability) and post-translational modifications occurring in the cytoplasm is crucial for cell differentiation, dedifferentiation and oncogenic potential. In this review, we report how defects in the regulation of mRNA translation can be dependent on specific proteins and can induce an imbalance between differentiation and dedifferentiation in cell fate determination. 相似文献
960.
From the aerial parts of Artemisia alba of Calabrian origin, five oxygenated nerolidol derivatives were isolated, two of them bearing hydroperoxyl groups. Structures were elucidated by spectral data and chemical reactions. Acetylation of the major hydroperoxyl constituent afforded a tris-nor aldehydic derivative as a result of loss of acetone from an unstable intermediate perester. An internally consistent set of 13C NMR assignments for the natural products and some derivatives is presented. 相似文献