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81.
Tidhar Turgeman Olga Lubinsky Nurit Roth-Bejerano Varda Kagan-Zur Yoram Kapulnik Hinanit Koltai Eli Zaady Shimon Ben-Shabat Ofer Guy Efraim Lewinsohn Yaron Sitrit 《Mycorrhiza》2016,26(4):287-297
The ectendomycorrhizal fungus Terfezia boudieri is known to secrete auxin. While some of the effects of fungal auxin on the plant root system have been described, a comprehensive understanding is still lacking. A dual culture system to study pre mycorrhizal signal exchange revealed previously unrecognized root–fungus interaction mediated by the fungal auxin. The secreted fungal auxin induced negative taproot gravitropism, attenuated taproot growth rate, and inhibited initial host development. Auxin also induced expression of Arabidopsis carriers AUX1 and PIN1, both of which are involved in the gravitropic response. Exogenous application of auxin led to a root phenotype, which fully mimicked that induced by ectomycorrhizal fungi. Co-cultivation of Arabidopsis auxin receptor mutants tir1-1, tir1-1 afb2-3, tir1-1 afb1-3 afb2-3, and tir1-1 afb2-3 afb3-4 with Terfezia confirmed that auxin induces the observed root phenotype. The finding that auxin both induces taproot deviation from the gravity axis and coordinates growth rate is new. We propose a model in which the fungal auxin induces horizontal root development, as well as the coordination of growth rates between partners, along with the known auxin effect on lateral root induction that increases the availability of accessible sites for colonization at the soil plane of fungal spore abundance. Thus, the newly observed responses described here of the root to Terfezia contribute to a successful encounter between symbionts. 相似文献
82.
Red and blue light triggered the opening of isolated stomata of Pisum sativum L. cv. Peleg Alvador, Vicia faba L. (unknown cultivar) and Pelargonium sp. The stimulatory effect of short irradiation with red or blue light was reversed by a subsequent short irradiation with far-red light. In Pisum the stimulatory effect of a continuous irradiation with red or blue light was also abolished by a concomitant far-red light. In leaf pieces of P. sativum blue light was more effective than red, but not in isolated guard cells. In the presence of mesophyll, DCMU inhibited stomatal opening in red light more than in blue, and thus increased the relative response to blue light. This was less evident in isolated guard cells. 相似文献
83.
Stomatal response to ATP mediated by phytochrome 总被引:2,自引:0,他引:2
External ATP stimulated stomatal opening in epidemal strips of Commelina communis L. in darkness following brief irradiation with white or red light. ATP had no effect in darkness after irradiation with far red light or in continuous light. Mg2+ stimulated stomatal response to ATP, which was shown to be taken-up by the tissue. This implies that a Mg-stimulated ATPase, that interacts with Pfr, may be involved in stomatal opening. 相似文献
84.
William B. Wood Ralph Hecht Stephen Carr Rebecca Vanderslice Nurit Wolf David Hirsh 《Developmental biology》1980,74(2):446-469
Genetic tests for parental effects were performed on 24 temperature-sensitive embryonic-lethal mutants of the nematode Caenorhabditis elegans. For 21 of these mutants, maternal expression of the wild-type allele is sufficient for embryonic survival, regardless of the embryo's genotype. For 11 of these 21 mutants, maternal expression of the wild-type allele is necessary for embryonic survival (strict maternals). For the remaining 10, either maternal or embryonic expression is sufficient for survival (partial maternals). One mutant shows a paternal effect; that is, a wild-type extragenic sperm function appears to rescue homozygous mutant embryos. Similar parental-effect tests were performed on 11 larval-lethal mutants. In 4 mutants, 1 of which blocks as late as the second larval stage after hatching, maternal contributions still can rescue mutant larvae. The remaining 3 embryonic lethals and 8 larval lethals show no parental effects; that is, zygotic expression of the wild-type allele is necessary and sufficient for embryonic survival. Temperatureshift experiments on embryonic-lethal embryos showed that all but 1 of the strict maternal mutants are temperature sensitive only before gastrulation. One of the partial maternal mutants is temperature sensitive prior to gastrulation, suggesting that some zygotic genes can function early in embryogenesis. At the nonpermissive temperature, 7 of the strict maternal mutants either show cleavage abnormalities in early divisions or stop cleavage at less than 100 cells, or both. 相似文献
85.
STUDIES ON THE ECOLOGICAL AND PHYSIOLOGICAL SIGNIFICANCE OF AMPHICARPY IN GYMNARRHENA MICRANTHA (COMPOSITAE) 总被引:1,自引:0,他引:1
The 2 types of fruit (aerial and subterranean) borne by the dwarf desert annual Gymnarrhena micrantha were compared with regard to their responses to factors affecting their formation, dispersal, germination and seedling mortality. The 2 types of fruit differed markedly in several respects. In comparison with the subterranean fruits, the aerial ones are much smaller and more numerous, but the formation of the inflorescence in which they develop is more dependent on a favorable supply of soil moisture. The aerial fruits are dispersed by wind, after becoming detached by a complex series of hygroscopic movements which involve several organs and tissues, while the subterranean fruits never leave the dead parent plant, germinating right through its tissues. Germination of the subterranean fruits starts after a shorter incubation period and is less temperature-dependent in both light and dark. Light stimulated germination of both types of fruit, increasing their germination rates and final percentages, but not affecting the duration of the incubation period. In the subterranean fruits, the rate of germination was equally stimulated by light over the entire temperature range, with a well-defined optimum at 15 C in both light and dark. In the aerial fruits, the same optimum was found only in the light, rates in darkness increasing with decreasing temperatures. In the aerial fruits, alternations of light and dark were more favorable to germination than either continuous light or dark, the full effect being obtained with a single 8-hr or 16-hr light period, provided it was preceded by 16 or 8 hr of darkness, respectively. Similar reactions to combinations of light and dark were not observed in the subterranean fruits. Seedlings developing from the subterranean fruits were much larger, but grew at a relatively much slower rate than those from aerial fruits. The former were distinctly more tolerant of unfavorable soil-moisture regimes, such as low moisture supply and drought. It was concluded that the 2 types of fruit serve 2 distinct functions in the biology of the plant. The aerial fruits are adapted to the function of increasing the distribution of the species within suitable habitats, while the subterranean fruits are adapted to increasing the probability of the survival of the species. 相似文献
86.
Purification of human tumor cell autocrine motility factor and molecular cloning of its receptor. 总被引:11,自引:0,他引:11
H Watanabe P Carmi V Hogan T Raz S Silletti I R Nabi A Raz 《The Journal of biological chemistry》1991,266(20):13442-13448
Tumor autocrine motility factor (AMF) has been detected in and purified from serum-free conditioned medium of human HT-1080 fibrosarcoma cells. Under nonreducing conditions, AMF migrates in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a single band of 55 kDa but under reducing conditions as a band of 64 kDa. Two-dimensional polyacrylamide gel electrophoresis of the purified AMF resolved two groups of polypeptides with isoelectric points of 6.1 and 6.2 (majors), 6.35 and 6.4 (minors). Purified AMF stimulated HT-1080 cell migration in a dose-dependent fashion. The motility stimulation of the fibrosarcoma cells with AMF is associated with the phosphorylation of the AMF receptor, a 78-kDa cell surface glycoprotein (gp78), suggesting protein kinase participation in migratory signal transduction. The gene encoding gp78 was cloned from an HT-1080 fibrosarcoma complementary DNA library. The deduced sequence encodes a polypeptide of 323 amino acids. The nucleotide and predicted amino acid sequence of the gp78 reveals significant homology with the human suppressor/oncogene p53 protein. 相似文献
87.
Effects of carbanilates on the growth and development of cell suspension cultures of Acer pseudoplatanus 总被引:1,自引:0,他引:1
David Macherel Françoise Nurit Anne-Marie Lescure Michel Tissut 《Physiologia plantarum》1986,66(3):536-542
The effects of three isopropyl carbanilate derivatives (propham, chlorpropham, 3,4-diCl isopropyl carbanilate) were studied on Acer pseudoplatanus L. cell suspension cultures (Lamport's strain). At 0.1 m M , three types of effects were observed: the 3,4-diCl derivative rapidly killed the cells; chlorpropham inhibited mitosis, but the cells remained alive without any significant increase in fresh or dry matter; and propham strongly inhibited mitosis, but not cell growth.
Ultrastructural analysis indicated that no observable changes in mitochondrial or plastid density occurred during the cytoplasmic expansion in the presence of propham. Size increase was also accompanied by vacuolar expansion and morphological changes of the nuclei. In Acer cell cultures, isopropyl carbanilates clearly show selective inhibition of mitosis only when the phenyl ring is not substituted by chlorine. 相似文献
Ultrastructural analysis indicated that no observable changes in mitochondrial or plastid density occurred during the cytoplasmic expansion in the presence of propham. Size increase was also accompanied by vacuolar expansion and morphological changes of the nuclei. In Acer cell cultures, isopropyl carbanilates clearly show selective inhibition of mitosis only when the phenyl ring is not substituted by chlorine. 相似文献
88.
Foam cell‐derived 4‐hydroxynonenal induces endothelial cell senescence in a TXNIP‐dependent manner
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Yael Riahi Nurit Kaiser Guy Cohen Ihab Abd‐Elrahman Galia Blum Oz M. Shapira Tomer Koler Maya Simionescu Anca V. Sima Neven Zarkovic Kamelija Zarkovic Marica Orioli Giancarlo Aldini Erol Cerasi Gil Leibowitz Shlomo Sasson 《Journal of cellular and molecular medicine》2015,19(8):1887-1899
Vascular endothelial cell (VEC) senescence is considered an early event in the development of atherosclerotic lesions. Stressful stimuli, in particular oxidative stress, have been linked to premature senescence in the vasculature. Foam cells are a major source of reactive oxygen species and may play a role in the induction of VEC senescence; hence, we investigated their involvement in the induction of VEC senescence in a co‐culture transwell system. Primary bovine aortic endothelial cells, exposed to the secretome of THP‐1 monocyte‐derived foam cells, were analysed for the induction of senescence. Senescence associated β‐galactosidase activity and the expression of p16 and p21 were increased, whereas phosphorylated retinoblastoma protein was reduced. This senescent phenotype was mediated by 4‐hydroxnonenal (4‐HNE), a lipid peroxidation product secreted from foam cells; scavenging of 4‐HNE in the co‐culture medium blunted this effect. Furthermore, both foam cells and 4‐HNE increased the expression of the pro‐oxidant thioredoxin‐interacting protein (TXNIP). Molecular manipulation of TXNIP expression confirmed its involvement in foam cell‐induced senescence. Previous studies showed that peroxisome proliferator‐activated receptor (PPAR)δ was activated by 4‐hydroalkenals, such as 4‐HNE. Pharmacological interventions supported the involvement of the 4‐HNE‐PPARδ axis in the induction of TXNIP and VEC senescence. The association of TXNIP with VEC senescence was further supported by immunofluorescent staining of human carotid plaques in which the expression of both TXNIP and p21 was augmented in endothelial cells. Collectively, these findings suggest that foam cell‐released 4‐HNE activates PPARδ in VEC, leading to increased TXNIP expression and consequently to senescence. 相似文献
89.
Akbal-Delibas B Hashmi I Shehu A Haspel N 《Journal of bioinformatics and computational biology》2012,10(3):1242002
Detection of protein complexes and their structures is crucial for understanding their role in the basic biology of organisms. Computational docking methods can provide researchers with a good starting point for the analysis of protein complexes. However, these methods are often not accurate and their results need to be further refined to improve interface packing. In this paper, we introduce a refinement method that incorporates evolutionary information into a novel scoring function by employing Evolutionary Trace (ET)-based scores. Our method also takes Van der Waals interactions into account to avoid atomic clashes in refined structures. We tested our method on docked candidates of eight protein complexes and the results suggest that the proposed scoring function helps bias the search toward complexes with native interactions. We show a strong correlation between evolutionary-conserved residues and correct interface packing. Our refinement method is able to produce structures with better lRMSD (least RMSD) with respect to the known complexes and lower energies than initial docked structures. It also helps to filter out false-positive complexes generated by docking methods, by detecting little or no conserved residues on false interfaces. We believe this method is a step toward better ranking and prediction of protein complexes. 相似文献
90.
Ninette Amariglio Abraham Hirshberg Bernd W Scheithauer Yoram Cohen Ron Loewenthal Luba Trakhtenbrot Nurit Paz Maya Koren-Michowitz Dalia Waldman Leonor Leider-Trejo Amos Toren Shlomi Constantini Gideon Rechavi 《PLoS medicine》2009,6(2)