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821.
Julia Jungnickel Kristina Haase Jens Konitzer Marco Timmer Claudia Grothe 《Developmental neurobiology》2006,66(9):940-948
Basic fibroblast growth factor (FGF‐2) is expressed in the peripheral nervous system and is up‐regulated after nerve lesion. It has been demonstrated that administration of FGF‐2 protects neurons from injury‐induced cell death and promotes axonal regrowth. Using transgenic mice over‐expressing FGF‐2 (TgFGF‐2), we addressed the importance of endogenously generated FGF‐2 on sensory neuron loss and sciatic nerve regeneration. After sciatic nerve transection, wild‐type and transgenic mice showed the same degree of cell death in L5 spinal ganglia. Also, the number of chromatolytic, eccentric, and pyknotic sensory neurons was not changed under elevated levels of FGF‐2. Morphometric evaluation of intact nerves from TgFGF‐2 mice revealed no difference in number and size of myelinated fibers compared to wild‐type mice. One week after crush injury, the number of regenerated axons was doubled and the myelin thickness was significantly smaller in transgenic mice. After 2 and 4 weeks, morphometric analysis and functional tests revealed no differences in recovery of sensory and motor nerve fibers. To study the role of FGF‐2 over‐expression on Schwann cell proliferation during the early regeneration process, we used BrdU‐labeling to mark dividing cells. In transgenic mice, the number of proliferating cells was significantly increased distal to the crush site compared to wild‐types. We propose that endogenously synthesized FGF‐2 influences early peripheral nerve regeneration by regulating Schwann cell proliferation, axonal regrowth, and remyelination. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 相似文献
822.
Spatiotemporal expression of connexin 39 and -43 during myoblast differentiation in cultured cells and in the mouse embryo 总被引:1,自引:0,他引:1
Connexin39 (Cx39) and connexin43 (Cx43) are known to be expressed during development of skeletal muscles. Here we have compared the expression pattern of both connexins during differentiation of established C(2)C(12) mouse myoblasts and in the mouse embryo. Cx43 is highly abundant in undifferentiated myoblasts, but no Cx39 protein was detected in these cells. Upon differentiation into myotubes, Cx39 expression increased. The consecutive expression of these connexins was also observed in the mouse embryo. Cx39 and Cx43 were found in different plaques in accordance with the notion that Cx43 is exclusively expressed in myoblasts and Cx39 in myotubes. Thus, differentiating C(2)C(12) cells in culture can serve to study the involvement of gap junctions in myogenesis, since expression of corresponding Cx39 and Cx43 proteins appears to be very similar as in the mouse embryo. 相似文献
823.
Connexin39 (Cx39) and connexin43 (Cx43) are known to be expressed during development of skeletal muscles. Here we have compared the expression pattern of both connexins during differentiation of established C2C12 mouse myoblasts and in the mouse embryo. Cx43 is highly abundant in undifferentiated myoblasts, but no Cx39 protein was detected in these cells. Upon differentiation into myotubes, Cx39 expression increased. The consecutive expression of these connexins was also observed in the mouse embryo. Cx39 and Cx43 were found in different plaques in accordance with the notion that Cx43 is exclusively expressed in myoblasts and Cx39 in myotubes. Thus, differentiating C2C12 cells in culture can serve to study the involvement of gap junctions in myogenesis, since expression of corresponding Cx39 and Cx43 proteins appears to be very similar as in the mouse embryo. 相似文献
824.
825.
Effect of ice melting on bacterial carbon fluxes channelled by viruses and protists in the Arctic Ocean 总被引:1,自引:0,他引:1
Julia A. Boras M. Montserrat Sala Jesus M. Arrieta Elisabet L. Sà Jorge Felipe Susana Agustí Carlos M. Duarte Dolors Vaqué 《Polar Biology》2010,33(12):1695-1707
During the last few years, extensive sea ice melting in the Arctic due to climate change has been detected, which could potentially
modify the organic carbon fluxes in these waters. In this study, the effect of sea ice melting on bacterial carbon channelling
by phages and protists has been evaluated in the northern Greenland Sea and Arctic Ocean. Grazing on bacteria by protists
was evaluated using the FLB disappearance method. Lysis of bacteria due to viral infections was measured using the virus reduction
approach. Losses of bacterial production caused by protists (PMMBP) dominated losses caused by viruses (VMMBP) throughout the study. Lysogenic viral production was detected in 7 out of 21 measurements and constituted from 33.9 to 100.0%
of the total viral production. Significantly higher PMMBP and lower VMMBP were detected in waters affected by ice melting compared with unaffected waters. Consequently, significantly more bacterial
carbon was channelled to the higher trophic levels in affected waters (13.05 ± 5.98 μgC l−1 day−1) than in unaffected waters (8.91 ± 8.33 μgC l−1 day−1). Viruses channelled 2.63 ± 2.45 μgC l−1 day−1 in affected waters and 4.27 ± 5.54 μgC l−1 day−1 in unaffected waters. We conclude that sea ice melting in the Arctic could modify the carbon flow through the microbial food
web. This process may be especially important in the case of massive sea ice melting due to climate change. 相似文献
826.
An experiment to quantify intra- and interobserver error in anatomical measurements found that interobserver measurements
can vary by over 14% of mean specimen length; disparity in measurement increases logarithmically with the number of contributors;
instructions did not reduce variation or measurement disparity; scale of the specimen influenced the precision of measurement
(relative error increasing with specimen size); different methods of taking a measurement yielded different results, although
they did not differ in terms of precision, and topographical complexity of the elements being considered may potentially influence
error (error increasing with complexity). These results highlight concerns about introduction of noise and potential bias
that should be taken into account when compiling composite datasets and meta-analyses. 相似文献
827.
Yao‐Bin Liu Yogendra Kharode Peter V.N. Bodine Paul J. Yaworsky John A. Robinson Julia Billiard 《Journal of cellular biochemistry》2010,109(4):794-800
The bioactive phospholipid, lysophosphatidic acid (LPA), acting through at least five distinct receptors LPA1–LPA5, plays important roles in numerous biological processes. Here we report that LPA induces osteoblastic differentiation of human mesenchymal stem cells hMSC‐TERT. We find that hMSC‐TERT mostly express two LPA receptors, LPA1 and LPA4, and undergo osteoblastic differentiation in serum‐containing medium. Inhibition of LPA1 with Ki16425 completely abrogates osteogenesis, indicating that this process is mediated by LPA in the serum through activation of LPA1. In contrast to LPA1, down‐regulation of LPA4 expression with shRNA significantly increases osteogenesis, suggesting that this receptor normally exerts negative effects on differentiation. Mechanistically, we find that in hMSC‐TERT, LPA induces a rise in both cAMP and Ca2+. The rise in Ca2+ is completely abolished by Ki16425, whereas LPA‐mediated cAMP increase is not sensitive to Ki16425. To test if LPA signaling pathways controlling osteogenesis in vitro translate into animal physiology, we evaluated the bones of LPA4‐deficient mice. Consistent with the ability of LPA4 to inhibit osteoblastic differentiation of stem cells, LPA4‐deficient mice have increased trabecular bone volume, number, and thickness. J. Cell. Biochem. 109: 794–800, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
828.
Dominique F. Bonafoux Sheri L. Bonar Michael Clare Ann M. Donnelly Jeanette L. Glaenzer Julia A. Guzova He Huang Nandidni N. Kishore Francis J. Koszyk Patrick J. Lennon Adam Libby Sumathy Mathialagan David S. Oburn Sharon A Rouw Cynthia D. Sommers Catherine S. Tripp Lori J. Vanella Richard Weier Serge G. Wolfson Horng-Chih Huang 《Bioorganic & medicinal chemistry》2010,18(1):403-414
Series of aminopyridinecarboxamide-based inhibitors were synthesized and tested against human recombinant IKK-2 and in IL-1β stimulated synovial fibroblasts. The 2-amino-5-chloropyridine-4-carboxamides were identified as the most potent inhibitors with improved cellular activity. 相似文献
829.
Manolis A. Fousteris Undine Schubert Daniela Roell Julia Roediger Nikolaos Bailis Sotiris S. Nikolaropoulos Aria Baniahmad Athanassios Giannis 《Bioorganic & medicinal chemistry》2010,18(19):6960-6969
Here, the synthesis and the evaluation of novel 20-aminosteroids on androgen receptor (AR) activity is reported. Compounds 11 and 18 of the series inhibit both the wild type and the T877A mutant AR-mediated transactivation indicating AR antagonistic function. Interestingly, minor structural changes such as stereoisomers of the amino lactame moiety exhibit preferences for antagonism among wild type and mutant AR. Other tested nuclear receptors are only weakly or not affected. In line with this, the prostate cancer cell growth of androgen-dependent but not of cancer cells lacking expression of the AR is inhibited. Further, the expression of the prostate specific antigen used as a diagnostic marker is also repressed. Finally steroid 18 enhances cellular senescence that might explain in part the growth inhibition mediated by this derivative. Steroids 11 and 18 are the first steroids that act as complete AR antagonists and exhibit AR specificity. 相似文献
830.
Krishna Saxena Ulrich Schieborr Oliver Anderka Elke Duchardt-Ferner Bettina Elshorst Santosh Lakshmi Gande Julia Janzon Denis Kudlinzki Sridhar Sreeramulu Matthias K. Dreyer K. Ulrich Wendt Corentin Herbert Philippe Duchaussoy Marc Bianciotto Pierre-Alexandre Driguez Gilbert Lassalle Pierre Savi Moosa Mohammadi Fran?oise Bono Harald Schwalbe 《The Journal of biological chemistry》2010,285(34):26628-26640
Fibroblast growth factor (FGF) signaling regulates mammalian development and metabolism, and its dysregulation is implicated in many inherited and acquired diseases, including cancer. Heparan sulfate glycosaminoglycans (HSGAGs) are essential for FGF signaling as they promote FGF·FGF receptor (FGFR) binding and dimerization. Using novel organic synthesis protocols to prepare homogeneously sulfated heparin mimetics (HM), including hexasaccharide (HM6), octasaccharide (HM8), and decasaccharide (HM10), we tested the ability of these HM to support FGF1 and FGF2 signaling through FGFR4. Biological assays show that both HM8 and HM10 are significantly more potent than HM6 in promoting FGF2-mediated FGFR4 signaling. In contrast, all three HM have comparable activity in promoting FGF1·FGFR4 signaling. To understand the molecular basis for these differential activities in FGF1/2·FGFR4 signaling, we used NMR spectroscopy, isothermal titration calorimetry, and size-exclusion chromatography to characterize binding interactions of FGF1/2 with the isolated Ig-domain 2 (D2) of FGFR4 in the presence of HM, and binary interactions of FGFs and D2 with HM. Our data confirm the existence of both a secondary FGF1·FGFR4 interaction site and a direct FGFR4·FGFR4 interaction site thus supporting the formation of the symmetric mode of FGF·FGFR dimerization in solution. Moreover, our results show that the observed higher activity of HM8 relative to HM6 in stimulating FGF2·FGFR4 signaling correlates with the higher affinity of HM8 to bind and dimerize FGF2. Notably FGF2·HM8 exhibits pronounced positive binding cooperativity. Based on our findings we propose a refined symmetric FGF·FGFR dimerization model, which incorporates the differential ability of HM to dimerize FGFs. 相似文献