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R.L. Hbert C. Lamoureux P. Sirois P. Braquet G.E. Plante 《Prostaglandins & other lipid mediators》1987,33(2)
Recent experiments indicate that prostaglandin E2 potentiates the vasodilatory properties of leukotrienes in the skin microcirculation. The present experiments were undertaken to study the effect of leukotriene D4 and prostaglandin E2 on renal hemodynamics and urinary electrolytes in the dog. Experiments were performed in three groups of anesthetized Mongrel dogs: the first group was studied under hydropenia, whereas the two remaining groups were studied during water diuresis with (Group 3) or without indomethacin (Group 2). LTD4 (100ng/min) and PGE2 (3ug/min) were infused in the left renal artery to minimize systemic effects of these compounds. LTD4 alone failed to influence urinary sodium excretion in all 3 groups. In Group 1, urinary sodium increased from 77 ± 6 to 393 ± 74uEq/min during PGE2, and further increased to 511 ± 52uEq/min during LTD4 + PGE2. No change occured in the contralateral right kidney. In this group, glomerular filtration as well as renal plasma flow were not statistically influenced. In Group 2, the same phenomenon was observed for urinary sodium. The combined infusion of LTD4 + PGE2 increased urinary sodium without significant changes in glomerular filtration and renal plasma flow. Finally, in Group 3, indomethacin was shown to reduce the natriuretic effects of LTD4 and PGE2: during PGE2 alone, urinary sodium increased from 90 ± 14 to 260 ± 66uEq/min, and only rose from 80 ± 10 to 175 ± 19uEq/min during the combined infusion of LTD4 and PGE2. In groups 2 and 3, free water clearance was utilized as an index of sodium chloride reabsorption in the thick ascending limb: this parameter increased from 2.35 ± 0.25 to 4.70 ± 0.30ml/min, while urinary volume was increasing from 3.55 ± 0.25 to 10.05 ± 0.65ml/min, during LTD4 + PGE2. Indomethacin, administered in Group 3, (3mg/kg/hr) again abolished the effect of combined PGE2 + LTD4. These results indicate a potentiating effect of leukotriene D4 on the PGE2-induced natriuresis in the anesthetized dog. These phenomena occured in the absence of significant changes in renal hemodynamics, therefore suggesting a direct tubular effect of these arachidonic acid metabolites. Finally, the water diuresis experiments suggest a proximal site of action of PGE2 and LTD4. 相似文献
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Guinea pig alveolar eosinophils and macrophages produce leukotriene B4 but no peptido-leukotriene 总被引:2,自引:0,他引:2
K Hirata K Maghni P Borgeat P Sirois 《Journal of immunology (Baltimore, Md. : 1950)》1990,144(5):1880-1885
The metabolism of arachidonic acid (AA) was investigated in purified guinea pig alveolar eosinophils and macrophages. Alveolar eosinophils produced 12S-hydroxy-5,8,10-heptadecatraenoic acid (HHT) and small amounts only of 5-lipoxygenase products when stimulated by AA (10 microM) or ionophore A23187 (2 microM). However, when the cell suspensions were stimulated with both AA and A23187, the cells produced HHT, leukotriene (LT) B4, and 5S-hydroxy-6,8,11,14-eicosatetraenoic acid, whereas LTC4, D4, and E4 were undetectable. Similarly, alveolar macrophages stimulated with A23187 produced HHT, 5-hydroxy-6,8,11,14-eicosatetraenoic acid, and LTB4 but no peptido-leukotrienes. When LTA4 was added to suspensions of eosinophils and macrophages, only LTB4 was formed, whereas in parallel experiments, intact human platelets incubated with LTA4 produced LTC4. These data suggest that guinea pig alveolar eosinophils and macrophages contain both cyclooxygenase and 5-lipoxygenase, but do not produce peptido-leukotrienes, probably lacking LTA4 glutathione transferase activity. These studies demonstrate that guinea pig eosinophils differ from eosinophils of other animal species which have been shown to be major sources of leukotriene C4. The present data imply that eosinophils and macrophages are not the source of peptido-leukotrienes in anaphylactic guinea pig lungs. 相似文献
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To purify and characterize the isoform of prostaglandin endoperoxide synthase (rPGSi) induced by human chorionic gonadotropin in granulosa cells of rat preovulatory follicles, solubilized cell extracts were subjected to anionic exchange chromatography, column fractions were resolved by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and rPGSi was visualized by immunoblotting and silver staining techniques. Immunoreactive rPGSi and peroxidase activity co-eluted at pH 6.5 and 6.0. Amino-terminal amino acid sequence of three immunoreactive rPGSi bands (Mr = 72,000, 70,000, and 59,000) were identical, Mr = 59,000 being a proteolytic fragment. Alignment of the amino-terminal sequences of rPGSi with those of ovine PGS (oPGS) indicated that only 15 of 26 residues were identical (58% identity). In contrast, rPGSi was closely related to the deduced amino acid sequence of PGS-related cDNA clones isolated from chicken and mouse cell lines, with 77% (20/26 residues) and 96% (25/26 residues) identity, respectively. Whereas tryptic digests of oPGS generated fragments of Mr = 38,000 and Mr = 33,000, only a small peptide appeared cleaved from the carboxyl terminus of rPGSi. Peroxidase activity of partially purified rPGSi exhibited lower apparent Km and maximal velocity than that of oPGS. Collectively, these results document the existence of a novel rat PGS isoform (based on purification, enzymatic activity, and amino-terminal amino acid sequence) which is hormonally induced and obligatory for a known biological process, ovulation. 相似文献
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Scotopic vision is the result of a cascade of light-dependent biochemical events in rod outer segments (ROS) involving mainly a cGMP-modulation of sodium current. This modification of ionic currents induces changes of membrane potential which generates electroretinographic (ERG) waves. As (i) ERG disturbances are commonly recorded in hypoxic and inflammatory retinal diseases (ii) leukotrienes (LTs), a very potent mediators of inflammation, disturb ionic exchanges in several artificial or natural membrane systems, we undertook the investigation of the effects of LTs on ERG record in mammalian isolated retina. LTB4, LTC4 and LTD4, all induced a dose-dependent marked reduction of the b wave amplitude of ERG. This effect is correlated with a significant decrease in the survival time of the retina. The analysis of the modification of ERG indicates that LTs exhibit a real toxic effect since b wave is mainly affected while P III wave is unchanged. Comparatively with other nervous cells, this phenomenon may be attributed to an increase in Na+ permeability of ROS. It is suggested that LTs may be involved in the development of inflammatory or ischemic retinal diseases. 相似文献
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Mbikay M Croissandeau G Sirois F Anini Y Mayne J Seidah NG Chrétien M 《Developmental biology》2007,306(2):584-598
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Questions: What was the tree species composition of forests prior to European settlement at the northern hardwood range limit in eastern Québec, Canada? What role did human activities play in the changes in forest composition in this region? Location: Northern range limit of northern hardwoods in the Lower St. Lawrence region of eastern Québec, Canada. Methods: We used early land survey records (1846–1949) of public lands to reconstruct pre‐settlement forest composition. The data consist of ranked tree species enumerations at points or for segments along surveyed lines, with enumerations of forest cover types and notes concerning disturbances. An original procedure was developed to weigh and combine these differing data types (line versus point observations; taxa versus cover enumerations). Change to present‐day forest composition was evaluated by comparing survey records with forest decadal surveys conducted by the government of Québec over the last 30 years (1980–2009). Results: Pre‐settlement dominance of conifers was strong and uniform across the study area, whereas dominance of maple and birches was patchy. Cedar and spruce were less likely to dominate with increasing altitude, whereas maple displayed the reverse trend. Frequency of disturbances, especially logging and fire, increased greatly after 1900. Comparison of survey records and modern plots showed general increases for maple (mentioned frequency increased by 39%), poplar (36%) and paper birch (31%). Considering only taxa ranked first by surveyors, cedar displayed the largest decrease (19%), whereas poplar (15%) and maple (9%) increased significantly. Conclusions: These changes in forest composition can be principally attributed to clear‐cutting and colonization fire disturbances throughout the 20th century, and mostly reflected the propensity of taxa to expand (maples/aspen) or decline (cedar/spruce) with increased disturbance frequency. Québec's land survey archives provide an additional data source to reconstruct and validate our knowledge of North America's pre‐settlement temperate and sub‐boreal forests. 相似文献