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971.
Karen Goossens Ann Van Soom Mario Van Poucke Leen Vandaele Jo Vandesompele Alex Van Zeveren Luc J Peelman 《BMC developmental biology》2007,7(1):64
Background
Normal preimplantation embryo development encompasses a series of events including first cleavage division, activation of the embryonic genome, compaction and blastocyst formation. 相似文献972.
Edgcomb VP Molyneaux SJ Böer S Wirsen CO Saito M Atkins MS Lloyd K Teske A 《Extremophiles : life under extreme conditions》2007,11(2):329-342
Growth and survival of hyperthermophilic archaea in their extreme hydrothermal vent and subsurface environments are controlled
by chemical and physical key parameters. This study examined the effects of elevated sulfide concentrations, temperature,
and acidic pH on growth and survival of two hydrothermal vent archaea (Pyrococcus strain GB-D and Thermococcus fumicolans) under high temperature and pressure regimes. These two strains are members of the Thermococcales, a family of hyperthermophilic,
heterotrophic, sulfur-reducing archaea that occur in high densities at vent sites. As actively growing cells, these two strains
tolerated regimes of pH, pressure, and temperature that were in most cases not tolerated under severe substrate limitation.
A moderate pH of 5.5–7 extends their survival and growth range over a wider range of sulfide concentrations, temperature and
pressure, relative to lower pH conditions. T. fumicolans and Pyrococcus strain GB-D grew under very high pressures that exceeded in-situ pressures typical of hydrothermal vent depths, and included
deep subsurface pressures. However, under the same conditions, but in the absence of carbon substrates and electron acceptors,
survival was generally lower, and decreased rapidly when low pH stress was combined with high pressure and high temperature.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
973.
p53 functions to prevent malignant progression, in part by inhibiting proliferation or inducing the death of potential tumour cells. One of the most important regulators of p53 is MDM2, a RING domain E3 ligase that ubiquitinates p53, leading to both proteasomal degradation and relocation of p53 from the nucleus to the cytoplasm. Previous studies have suggested that although polyubiquitination is required for degradation, monoubiquitination of p53 is sufficient for nuclear export. Using a p53-ubiquitin fusion protein we show that ubiquitination contributes to two steps before export: exposure of a carboxy-terminal nuclear export sequence (NES), and dissociation of MDM2. Monoubiquitination can directly promote further modifications of p53 with ubiquitin-like proteins and MDM2 promotes the interaction of the SUMO E3 ligase PIASy with p53, enhancing both sumoylation and nuclear export. Our results suggest that modifications such as sumoylation can regulate the strength of the p53-MDM2 interaction and participate in driving the export of p53. 相似文献
974.
Vikhanskaya F Toh WH Dulloo I Wu Q Boominathan L Ng HH Vousden KH Sabapathy K 《Nature cell biology》2007,9(6):698-705
975.
976.
977.
During cytokinesis, constriction of a cortical contractile ring generates a furrow that partitions one cell into two. The contractile ring contains three filament systems: actin, bipolar myosin II filaments, and septins, GTP-binding hetero-oligomers that polymerize to form a membrane-associated lattice. The contractile ring also contains a potential filament crosslinker, Anillin, that binds all three filament types. Here, we show that the contractile ring possesses an intrinsic symmetry-breaking mechanism that promotes asymmetric furrowing. Asymmetric ingression requires Anillin and the septins, which promote the coalescence of components on one side of the contractile ring, but is insensitive to a 10-fold reduction in myosin II levels. When asymmetry is disrupted, cytokinesis becomes sensitive to partial inhibition of contractility. Thus, asymmetric furrow ingression, a prevalent but previously unexplored feature of cell division in metazoans, is generated by the action of two conserved furrow components and serves a mechanical function that makes cytokinesis robust. 相似文献
978.
Andrew G. Stephen Siddhartha A.K. Datta Karen M. Worthy Lakshman Bindu Matthew J. Fivash Kevin B. Turner Daniele Fabris Alan Rein Robert J. Fisher 《Journal of biomolecular techniques》2007,18(4):259-266
The interaction of the HIV Gag polyprotein with nucleic acid is a critical step in the assembly of viral particles. The Gag polyprotein is composed of the matrix (MA), capsid (CA), and nucleocapsid (NC) domains. The NC domain is required for nucleic acid interactions, and the CA domain is required for Gag-Gag interactions. Previously, we have investigated the binding of the NC protein to d(TG)(n) oligonucleotides using surface plasmon resonance (SPR) spectroscopy. We found a single NC protein is able to bind to more than one immobilized oligonucleotide, provided that the oligonucleotides are close enough together. As NC is believed to be the nucleic acid binding domain of Gag, we might expect Gag to show the same complex behavior. We wished to analyze the stoichiometry of Gag binding to oligonucleotides without this complication due to tertiary complex formation. We have therefore analyzed Gag binding to extremely low oligonucleotide density on SPR chips. Such low densities of oligonucleotides are difficult to accurately quantitate. We have determined by Fourier transform ion cyclotron (FTICR) mass spectrometry that four molecules of NC bind to d(TG)(10) (a 20-base oligonucleotide). We developed a method of calibrating low-density surfaces using NC calibration injections. Knowing the maximal response and the stoichiometry of binding, we can precisely determine the amount of oligonucleotide immobilized at these very-low-density surfaces (<1 Response Unit). Using this approach, we have measured the binding of Gag to d(TG)(10). Gag binds to a 20-mer with a stoichiometry of greater than 4. This suggests that once Gag is bound to the immobilized oligonucleotide, additional Gag molecules can bind to this complex. 相似文献
979.
980.