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101.
Dietary phosphate deprivation increases 1,25-dihyroxyvitamin D3 synthesis in rat kidney in vitro 总被引:8,自引:0,他引:8
A sensitive radioreceptor assay has been used to measure in vitro 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) synthesis in vitamin D-replete rats. Incubation of kidney cortical slices with 25-hydroxyvitamin D3 produced a product which co-migrated on high performance liquid chromatography with authentic 1,25(OH)2D3 in two different solvent systems and displaced 1,25(OH)2D3 from its intestinal receptor. In addition, mass spectral analysis of the product produced a mass fragmentation consistent with that of authentic 1,25(OH)2D3. Endogenous renal cortical 1,25(OH)2D3 content in phosphate-deprived rats averaged 1.1 +/- 0.3 pmol/g (n = 11), which was significantly greater than the renal cortical 1,25(OH)2D3 content of age-matched rats eating a normal diet which averaged 0.44 +/- 0.21 pmol/g (n = 8, p less than 0.001). After incubation, net 1,25(OH)2D3 synthesis in renal slices from phosphate-deprived rats averaged 51 pmol/g/h, about 13-fold greater than the mean of 3.8 pmol/g/h observed in renal slices from rats eating the normal diet. These results indicate that the elevated plasma 1,25(OH)2D3 levels observed in rats during dietary phosphate deprivation are due to increased renal synthesis of the hormone. 相似文献
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Crimi E Sica V Williams-Ignarro S Zhang H Slutsky AS Ignarro LJ Napoli C 《Free radical biology & medicine》2006,40(3):398-406
Oxidative stress defines an imbalance in production of oxidizing chemical species and their effective removal by protective antioxidants and scavenger enzymes. Evidence of massive oxidative stress is well established in adult critical illnesses characterized by tissue ischemia-reperfusion injury and by an intense systemic inflammatory response such as during sepsis and acute respiratory distress syndrome. Oxidative stress could exacerbate organ injury and thus overall clinical outcome. We searched MEDLINE databases (January 1966 to June 2005). For interventional studies, we accepted only randomized trials. Several small clinical trials have been performed in order to reduce oxidative stress by supplementation of antioxidants alone or in combination with standard therapies. These studies have reported controversial results. Newer large multicenter trials with antioxidant supplementation should be performed, considering administration at an early stage of illness and a wider population of critically ill patients. 相似文献
106.
Highly Branched Phenotype of the Petunia dad1-1 Mutant Is Reversed by Grafting 总被引:10,自引:1,他引:10 下载免费PDF全文
Napoli C 《Plant physiology》1996,111(1):27-37
The recessive dad1-1 allele conditions a highly branched growth habit resulting from a proliferation of first- and second-order branches. Unlike the wild-type parent, which has lateral branching delayed until the third or fourth leaf node distal to the cotyledons, dad1-1 initiates lateral branching from each cotyledon axil. In addition to initiating lateral branching sooner than the wild type, dad1-1 sustains branching through more nodes on the main shoot axis than the wild type. In keeping with a propensity for branching at basal nodes, dad1-1 produces second-order branches at the proximal-most nodes on first-order branches and small shoots from accessory buds at basal nodes on the main shoot axis. Additional traits associated with the mutation are late flowering, adventitious root formation, shortened internodes, and mild leaf chlorosis. Graft studies show that a dad1-1 scion, when grafted onto wild-type stock, is converted to a phenotype resembling the wild type. Furthermore, a small wild-type interstock fragment inserted between a mutant root stock and a mutant scion is sufficient to convert the dad1-1 scion from mutant to a near wild-type appearance. The recessive dad1-1 phenotype combines traits associated with cytokinin overexpression, auxin overexpression, and gibberellin limitation, which suggests a complex interaction of hormones in establishing the mutant phenotype. 相似文献
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AA Bozzo CA Soñez I Monedero Cobeta A Rolando MC Romanini D Cots 《Biotechnic & histochemistry》2014,89(4):296-303
The model of chronic intermittent stress by immobilization during pregnancy may produce alterations in the mechanisms that maintain adrenal gland homeostasis. In earlier investigations using this model, significant variations in plasma prolactin and corticosterone levels, and adrenal gland weights were observed. We hypothesized that chronic stress causes changes in apoptosis in the adrenal glands of pregnant rats. We identified and quantified apoptotic cells in the adrenal cortex and examined their ultrastructural characteristics using transmission electron microscopy. Adrenal glands of pregnant rats at gestation days 12, 17 and 21 were studied for control and experimental (stressed) rats. Immunolabelling techniques, stereological analysis and image quantification of adrenal gland sections were combined to determine differences in apoptosis in the different cell populations of the adrenal cortex. The apoptotic index of the experimental rats showed a significant reduction at gestation day 17, while at days 12 and 21 there were no differences from controls. Moreover, the apoptotic index of the reticular zones in control and experimental animals showed a significant increase compared to the glomerular and fascicular zones at the three gestation times studied. Chronic stress by immobilization reduced the caspase-dependent apoptotic index at gestation day 17, which may be related to variations in plasma concentrations of estrogens and prolactin. 相似文献
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25,26-dihydroxyvitamin D3 is not a major intermediate in 25-hydroxyvitamin D3-26,23-lactone formation 总被引:1,自引:0,他引:1
Structural similarities between 25S,26-dihydroxyvitamin D3 and 25-hydroxyvitamin D3-26,23-lactone and their concomitant multifold increase in the plasma of animals treated with pharmacological doses of vitamin D3 suggest a precursor-product relationship. However, a single dose of 25S,26-[3H]dihydroxyvitamin D3 given to rats treated chronically with pharmacological amounts of vitamin D3 did not result in detectable plasma 25-[3H]hydroxyvitamin D3-26,23-lactone. Multiple doses of synthetic 25S,26-dihydroxyvitamin D3 given to vitamin D3-deficient rats treated chronically with pharmacological amounts of vitamin D2 also did not result in detectable plasma 25-hydroxyvitamin D3-26,23-lactone. Furthermore, homogenates prepared from vitamin d-deficient chickens, dosed with 1,25-dihydroxyvitamin D3, converted 25-[3H]hydroxyvitamin D3 to 25-[3H]hydroxyvitamin D3-26,23-lactone. But these same homogenates did not convert 25S,26-[3H]dihydroxyvitamin D3 to 25-[3H]hydroxyvitamin D3-26,23-lactone. These data indicate that 25,26-dihydroxyvitamin D3 is not an intermediate in 25-hydroxyvitamin D326, 23-lactone formation. 相似文献