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91.
OBJECTIVES: Peptide YY is an abundant distal gut hormone which regulates secretion, motility, and possibly epithelial proliferation in the gut. Though messenger RNA for the peptide YY Y1 receptor subtype occurs in the basal colonic crypts of humans, peptide YY receptors themselves have not been clearly localized within the adult human gastrointestinal tract. Using an antiserum directed against the C-terminus of the Y1 receptor we determined the actual extent of Y1 receptor protein expression in the human colon in order to identify areas targeted for peptide YY effects and suggest additional physiological roles for PYY in the human gut. RESULTS: Y1 receptor protein expression was seen throughout the colonic epithelium along its basolateral aspect. There was an unexpected dense distribution of Y1 receptor immunoreactivity in varicose fibers within the mucosa. Staining was also noted in nerve fibers of the muscularis mucosae, in the submucous and myenteric plexuses, and in nerves in the muscularis propria. CONCLUSIONS: Widespread distribution of Y1 receptors in the colonic epithelium and mucosal nerve fibers suggests diverse regulatory roles for peptide YY in modulating epithelial function as well as secretomotor reflexes in response to lumenal peptide YY-release signals. 相似文献
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Effects of polyamines on in vitro phosphorylation and acetylation of histones of the cerebral cortex of rats of various ages 总被引:3,自引:0,他引:3
phosphorylation and acetylation of histones and their modulation by spermine and spermidine were studied using slices of cerebral cortex of female rats of various ages. Phosphorylation and acetylation of individual histones decrease with increasing age. Spermine and spermidine have stimulatory effects on both the modifications of specific histones in immature rats. These effects decrease with increasing age. Such changes in covalent modifications of histones may alter gene expression and contribute to the aging process. 相似文献
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The induction of acetylcholinesterase (AChE) was studied in the cerebral hemisphere and cerebellum of immature (9-), adult (29-) and old (65-week) female rats. The specific activity of AChE of the cerebral hemisphere of normal rats is highest at 9 weeks and decreases thereafter. There is no such change in the cerebellum. Ovariectomy decreases its activity in the cerebral hemisphere of adult, and cerebellum of immature and adult rats, but not of old rats. Administration of estradiol to ovariectomized rats increases the activity in the cerebral hemisphere and cerebellum of immature and adult rats but not of old rats. The magnitude of stimulation, which is actinomycin D-sensitive, is highest in immature rats. 相似文献
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The possibility of methylation, acetylation and phosphorylation of the bases of DNA has been studied in vitro by incubating nuclei of the liver and cerebral hemisphere of young (18 wk) and old (120 wk) rats with radioactive donors, [3H]S approximately adenosyl methylmethionine, [3H]-acetyl approximately CoA and [32P]-gamma-ATP for methylation, acetylation and phosphorylation of the bases, respectively. Nuclei were also incubated with S approximately adenosyl homocysteine to inhibit methylation with sodium butyrate to stimulate acetylation and with alkaline phosphatase to remove phosphate groups incorporated into the bases. DNA was then extensively purified and incorporation of each type of label was estimated. The data show that both methylation and acetylation of DNA of old rats were significantly higher than those of young rats, and phosphorylation is lower in old rats. Such modifications may prevent base pairing between the two strands of DNA, alter its conformation and binding of trans-acting factors at specific sites, and thereby alter gene expression. 相似文献
98.
1. Parallel determinations of the oxygen consumption by skin slices with glucose or galactose as substrate and of the concentration of DNA of the skin of various ages of rats were carried out to study the metabolic changes of the skin with age. 2. Both the oxygen consumption and the DNA content of the skin decreased rapidly till the attainment of maturity; thereafter the rate of decrease in oxygen consumption was lower whereas the concentration of DNA was constant. The decrease in the oxygen consumption during the early developmental period is thus due to the loss of cells, but the decrease in the older rats may be due to a decline in the activity of the cells of the skin as a result of aging. 3. The uptake of glucose by the skin decreased with increasing age. 相似文献
99.
The induction of soluble cytoplasmic (c-), and particulate mitochondrial (m-) and nuclear (n-) isoenzymes of tyrosine aminotransferase (TAT) by hydrocortisone in the liver of 6-, 35- and 76- week old rats was studied. In contrast to the earlier reports, both the particulate isoenzymes (m- &; n-TAT) are induced by hydrocortisone. This induction is actinomycin D sensitive. The degree and pattern of induction of the three isoenzymes of TAT vary with age. The possibility of separate regulatory mechanisms for the synthesis of the three isoenzymes is discussed. 相似文献
100.