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61.
Catherine E. Hart Gabriela S. Blanco Michael S. Coyne Carlos Delgado-Trejo Brendan J. Godley T. Todd Jones Antonio Resendiz Jeffrey A. Seminoff Matthew J. Witt Wallace J. Nichols 《PloS one》2015,10(2)
To further describe movement patterns and distribution of East Pacific green turtles (Chelonia mydas agassizii) and to determine threat levels for this species within the Eastern Pacific. In order to do this we combined published data from existing flipper tagging and early satellite tracking studies with data from an additional 12 satellite tracked green turtles (1996-2006). Three of these were tracked from their foraging grounds in the Gulf of California along the east coast of the Baja California peninsula to their breeding grounds in Michoacán (1337-2928 km). In addition, three post-nesting females were satellite tracked from Colola beach, Michoacán to their foraging grounds in southern Mexico and Central America (941.3-3020 km). A further six turtles were tracked in the Gulf of California within their foraging grounds giving insights into the scale of ranging behaviour. Turtles undertaking long-distance migrations showed a tendency to follow the coastline. Turtles tracked within foraging grounds showed that foraging individuals typically ranged up to 691.6 km (maximum) from release site location. Additionally, we carried out threat analysis (using the cumulative global human impact in the Eastern Pacific) clustering pre-existing satellite tracking studies from Galapagos, Costa Rica, and data obtained from this study; this indicated that turtles foraging and nesting in Central American waters are subject to the highest anthropogenic impact. Considering that turtles from all three rookeries were found to migrate towards Central America, it is highly important to implement conservation plans in Central American coastal areas to ensure the survival of the remaining green turtles in the Eastern Pacific. Finally, by combining satellite tracking data from this and previous studies, and data of tag returns we created the best available distributional patterns for this particular sea turtle species, which emphasized that conservation measures in key areas may have positive consequences on a regional scale. 相似文献
62.
63.
Shaiany Sabrina Lopes Gomes Cleber Witt Saldanha Camila Siqueira Neves Marizia Trevizani Nádia Rezende Barbosa Raposo Marcela Morato Notini Marcelo de Oliveira Santos José Marcello Salabert Campos Wagner Campos Otoni Lyderson Facio Viccini 《Plant Cell, Tissue and Organ Culture》2014,118(1):45-56
Pfaffia glomerata (Spreng.) Pedersen, known worldwide as Brazilian ginseng, has an important commercial value due to its pharmaceutical properties. In addition to the newly described karyological traits and the first estimation of DNA content, this study reports a protocol for the successful induction of tetraploidy. Natural diploid individuals (2n = 34) showed a symmetric karyotype, centromeric DAPI+ bands, one chromosome pair with a CMA+ band and 45S rDNA site and another with one 5S rDNA site. To induce chromosome duplication, small nodal buds were cultured in semi-solid MS-based medium with 2.22 μM BA, 2.69 μM NAA, and colchicine or oryzalin at 10, 15, 20, 25, and 30 μM for 1 or 2 weeks before being transferred to MS basal medium. The results showed that colchicine induced tetraploid plants, mainly after 1 week of exposure, whereas oryzalin treatment induced only mixoploid plants. The tetraploid plants exhibited twice the chromosome number and DNA content and twice the number of chromosome markers observed for the diploids. Chromosome duplication reduced the dry mass of the stems and roots of the polyploid plants compared to the diploids, and the stomatal density was also reduced on the abaxial and adaxial leaf surfaces of the polyploids. Additionally, the production of β-ecdysone was 50 % higher in the tetraploids than in the diploids. Thus, chromosome doubling showed that is possible to increase the content of β-ecdysone, highlighting the considerable potential of this technique to produce new cultivars with high commercial value. 相似文献
64.
Amino terminus of the interleukin-8 receptor is a major determinant of receptor subtype specificity. 总被引:9,自引:0,他引:9
G J LaRosa K M Thomas M E Kaufmann R Mark M White L Taylor G Gray D Witt J Navarro 《The Journal of biological chemistry》1992,267(35):25402-25406
Interleukin-8 (IL-8) is a key mediator in the migration of neutrophils from the circulation to the site of inflammation in the tissue. IL-8 is secreted by many cell types in response to proinflammatory stimuli such as interleukin 1, tumor necrosis factor, and lipopolysaccharide and is a potent chemoattractant and activator of neutrophils. Neutrophil activating peptide-2 (NAP-2) and melanoma growth-stimulatory activity (MGSA/GRO) are structurally and functionally related to IL-8 and, like IL-8, bind to specific G protein-coupled receptors on neutrophils. In the present study two closely related cloned IL-8 receptor subtypes are characterized by expression of the cDNA clones in monkey kidney cells (COS-7) or chinese hamster ovary cells and analysis of their ligand binding profiles. Both receptor subtypes bind 125I-labeled IL-8 with similar high affinity, however, the F3R receptor binds IL-8 exclusively, while the 4Ab receptor binds both IL-8 and MGSA/GRO with high affinity and NAP-2 with lesser affinity. Furthermore, we demonstrate with the use of intersubtype chimeric receptors that the specificity of ligand binding to both IL-8 receptor subtypes is dictated by the heterogeneous NH2-terminal domain. The F3R receptor is representative of a restricted IL-8 receptor subtype, and 4Ab represents a nonrestricted receptor subtype. It is proposed that these subtypes be named IL-8 receptors alpha and beta, respectively. 相似文献
65.
66.
Stephan Zindel Vera Ehret Marina Ehret Madeleine Hentschel Samantha Witt Andreas Kr?mer David Fiebig Norbert Jüttner Sabrina Fr?ls Felicitas Pfeifer Hans-Lothar Fuchsbauer 《PloS one》2016,11(2)
Streptomyces mobaraensis DSM 40847 secretes transglutaminase that cross-links proteins via γ-glutamyl-ε-lysine isopeptide bonds. Characterized substrates are inhibitory proteins acting against various serine, cysteine and metalloproteases. In the present study, the bacterial secretome was examined to uncover additional transglutaminase substrates. Fractional ethanol precipitation of the exported proteins at various times of culture growth, electrophoresis of the precipitated proteins, and sequencing of a 39 kDa protein by mass spectrometry revealed the novel beta-lactamase Sml-1. As indicated by biotinylated probes, Sml-1, produced in E. coli, exhibits glutamine and lysine residues accessible for transglutaminase. The chromogenic cephalosporin analogue, nitrocefin, was hydrolyzed by Sml-1 with low velocity. The obtained Km and kcat values of the recombinant enzyme were 94.3±1.8 μM and 0.39±0.03 s-1, respectively. Penicillin G and ampicillin proved to be weak inhibitors of nitrocefin hydrolysis (Ki of 0.1 mM and 0.18 mM). Negligible influence of metals on β-lactamase activity ruled out that Sml-1 is a Zn2+-dependent class B beta-lactamase. Rather, sequence motifs such as SITK, YSN, and HDG forming the active core in a hypothetical structure may be typical for class C beta-lactamases. Based on the results, we assume that the novel transglutaminase substrate ensures undisturbed growth of aerial hyphae in Streptomyces mobaraensis by trapping and inactivating hostile beta-lactam antibiotics. 相似文献
67.
Further characterization of the binding of human recombinant interleukin 2 to heparin and identification of putative binding sites 总被引:1,自引:1,他引:1
We have previously provided compelling evidence that human recombinant
interleukin 2 (IL-2) binds to the sulfated polysaccharides heparin, highly
sulfated heparan sulfate and fucoidan. Here we show that IL-2 binding is
dependent on heparin chain length, but with fragments as small as 15-mers
retaining binding activity. The addition of exogenous heparin has no effect
on the in vitro biological activity of IL-2. In addition soluble IL-2
receptor alpha and beta polypeptides do not compete with heparin for the
binding of IL-2. IL-2 bound by heparin is still recognized by two IL-2
specific monoclonal antibodies, 3H9 and H2- 8, whose epitopes lie in the
amino terminal region. Murine IL-2 unlike its human counterpart fails to
bind to heparin. Human IL-2 analogs with single amino acid substitutions at
positions Lys43, Thr51, and Gln126 analogs no longer bind to heparin. By
contrast the Arg38Ala analog retains heparin full heparin binding activity.
These experimental findings together with molecular modeling studies
suggest two putative heparin binding sites on human IL-2, one involving
four basic residues, Lys48, Lys49, Lys54, and His55, and the other being a
discontinuous site comprising Lys43, Lys64, Arg81, and Arg83. Neither of
these two clusters is completely conserved in murine IL-2. Overall our data
suggest that the binding of human IL-2 to heparin and heparan sulfate does
not interfere with IL-2/IL-2 receptor interactions. Therefore, binding to
glycosaminoglycan may be a mechanism for retaining the cytokine in an
active form close to its site of secretion in the tissue, thus favoring a
paracrine role for IL-2.
相似文献
68.
Immunocytochemistry was used to describe the distribution of serotonin-like immunoreactive (5HT-IR) neurons and neuronal processes
in the central nervous system (CNS), the synganglion, of two ixodid tick species; the winter tick, Dermacentor albipictus and the lone star tick, Amblyomma americanum. 5HT-IR neurons were identified in the synganglion of both tick species. D. albipictus had a significantly higher number of 5HT-IR neurons than A. americanum. The labeling pattern and number of 5HT-IR neurons were significantly different between sexes in D. albipictus, but were not significantly different between sexes in A. americanum. 5HT-IR neurons that were located in the cortex of the synganglion projected processes into the neuropils, invading neuromeres
in the supraesophageal ganglion including the protocerebrum, postero-dorsal, antero-dorsal and cheliceral neuromeres. In the
subesophageal ganglion, dense 5HT-IR neuronal processes were found in the olfactory lobes, pedal, and opisthosomal neuromeres.
Double-labeling with neurobiotin backfilled from the first leg damaged at the Haller’s organ revealed serotoninergic neuronal
processes surrounding the glomeruli in the olfactory lobes. The high number of the 5HT-IR neurons and the extensive neuronal
processes present in various regions of the synganglion suggest that serotonin plays a significant role in tick physiology.
This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or
a recommendation by the USDA for its use.
The U.S. Government’s right to retain a non-exclusive, royalty free license in and to any copyright is acknowledged. 相似文献
69.
T cell development occurs in the thymus throughout life. Recent experimental findings show that the seeding of the thymus by multi-potent stem cells from the bone marrow is periodic rather than continuous, as previously assumed. However it is well known that the output rate of cells from the thymus is relatively constant. A quantitative model is used to verify the current hypotheses regarding T cell development in the steady state mouse thymus. The results show that the thymus could be at a periodic steady state with out-of-phase thymocyte populations. Experiments to examine possible periodic fluctuations in the thymus are proposed and methods for further analysis are outlined. 相似文献
70.
Hennig H Fleischmann R Fredebohm A Hagmayer Y Nagler J Witt A Theis FJ Geisel T 《PloS one》2011,6(10):e26457
Although human musical performances represent one of the most valuable achievements of mankind, the best musicians perform imperfectly. Musical rhythms are not entirely accurate and thus inevitably deviate from the ideal beat pattern. Nevertheless, computer generated perfect beat patterns are frequently devalued by listeners due to a perceived lack of human touch. Professional audio editing software therefore offers a humanizing feature which artificially generates rhythmic fluctuations. However, the built-in humanizing units are essentially random number generators producing only simple uncorrelated fluctuations. Here, for the first time, we establish long-range fluctuations as an inevitable natural companion of both simple and complex human rhythmic performances. Moreover, we demonstrate that listeners strongly prefer long-range correlated fluctuations in musical rhythms. Thus, the favorable fluctuation type for humanizing interbeat intervals coincides with the one generically inherent in human musical performances. 相似文献