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71.
James A. McAteer Orion D. Hegre 《In vitro cellular & developmental biology. Plant》1978,14(9):795-803
Summary A method of perfusion organ culture is described in which explants cultured at the airmedium interface are bathed by a continuous
flow of nutrient medium. Morphological studies on the fetal rat lung indicate that explant development in this system is comparable
to that obtained using standard organ-culture dishes. Medium supply is easily manipulated and continuous sampling of the effluent
stream is possible without disturbing the immediate explant environment. The basic design facilitates secretory-response studies
on cultured organ explants as demonstrated by a study of glucose-stimulated insulin release by the neonatal rat pancreas.
This work was supported by U. S. Public Health Service Training Grant No. GM 00114. 相似文献
72.
Summary Insulin release and membrane potential fluctuations in response to increased extracellular potassium [K+]
o
have been measured in single perifused islets of Langerhans from normal mice. An increase in [K+]
o
from 5mm to 50mm induced a transient insulin release with a peak at about 1 min. The peak value was [K+]
o
-dependent but the half-timet
1/2 for the decline was constant at nearly 1 min. 2.5mm cobalt completely inhibited the potassium-induced stimulation of insulin release. The insulin release elicited by 28 and 50mm [K+]
o
was similar in terms of peak, total release and half-time from maximum release. Stepwise increase in [K+]
o
from 10 to 28 to 50mm resulted in a normal response to 28mm but no peak of release after the 28 to 50mm increase. The results indicate good correlation between excess voltage noise, thought to reflect calcium channel activity, and insulin release evoked by changing extracellular potassium. 相似文献
73.
Effect of bombesin upon plasma somatostatin-like immunoreactivity, insulin and glucagon in normal and chemically sympathectomized dogs 总被引:2,自引:0,他引:2
The present study was designed to determine the effects of intravenously infused bombesin (10 ng/kg/min) upon basal and postprandial plasma somatostatin-like immunoreactivity (SLI), glucagon, insulin and triglyceride levels in normal (n = 12) and chemically sympathectomized (n = 11) dogs. Basal plasma SLI, glucagon and insulin levels rose significantly during the infusion of bombesin in the normal dogs, and this was not altered by chemical sympathectomy. Bombesin infusion enhanced the postprandial SLI response, while attenuating the postprandial glucagon response by 50% and the insulin response in the early postprandial phase of the meal. Sympathectomy did not significantly alter the basal levels of these polypeptides, but augmented the postprandial plasma SLI response during the first 90 min, and reduced the postprandial glucagon response during the infusion of bombesin. The postprandial insulin response was not affected by sympathectomy. In both normal and chemically sympathectomized dogs the rise in postprandial triglyceride levels was attenuated by bombesin infusion. 相似文献
74.
Hexokinase is present in the tissues in four isoenzymic forms. Cerebral tissue contains predominantly Type I hexokinase which
is believed to be insulin-insensitive. In cerebral tissue about 60 to 70% of the hexokinase is bound to the particulate fraction.
The changes in the distribution of hexokinase Type I and Type II together with the bound and free hexokinase have been studied
in control, diabetic and diabetic animals treated with insulin. The results indicate that the presence of insulin is essential
for the normal binding of the hexokinase to the particulate fraction. In heart tissue, Type II hexokinase bound to the pellet
shows a significant decrease in diabetes, which is reversed on insulin administration. 相似文献
75.
The immune responses to several antigens were compared in the I-A mutant mouse strain B6.C-H-2bm12 and the wild-type strain C57BL/6. With a lymph node cell proliferation assay, the response to two of these antigens, beef insulin and (TG)A-L, was demonstrated to be controlled by a gene in the I-Ab region. B6.C-H-2bm12 mice failed to respond to beef insulin, while their responses to (TG)A-L, DNP-OVA and PPD were comparable with those of the wild-type strain C57BL/6. Taken together with previous studies, these data suggest that the product of a single pleiotropic I-A gene, an la molecule, functions as a histocompatibility, la, and MLR antigen, as well as a necessary component for Ir gene function. Furthermore, the data reported here demonstrate that la molecules have multiple functional “Ir determinants,” one of which has been altered in the B6.C-H-2bm12 mutant. The B6.C-H-2bm12 mice, therefore, represent a powerful analytical tool for the understanding of the cellular and molecular basis for Ir gene control of the immune response. 相似文献
76.
A review of experimental studies of the effect of zinc nutrition on insulin metabolism is presented. In addition to a short
introduction to the synthesis, secretion, and action of insulin, the effects of zinc deficiency—specifically on glucose tolerance,
insulin secretion, insulin synthesis and storage, and on total insulin-like activity—are dealt with. The concentrations of
zinc and chromium in serum, pancreas, and liver are compared to those of zinc-deficient animals and pair-fed controls.
In contrast to pair-fed controls, zinc-deficient rats had unaltered proinsulin contents after glucose stimulation, but they
showed a diminished glucose tolerance, lowered serum insulin content, and an elevated total insulin-like activity. The serum
zinc concentration of the deficient animals was greatly reduced and did not change during glucose stimulation, whereas it
rose in the case of the pair-fed controls. The serum chromium concentration increased in both groups in response to glucose
stimulation. In the pancreas of the deficient animals, the zinc concentration was reduced 60% and it increased during the
glucose tolerance test. In the liver there were no significant differences. The chromium concentrations were elevated in both
the pancreas and liver of the zinc-deficient rats by 60 and 100%, respectively, and were not influenced by glucose injection.
These studies show clearly that nutritional zinc deficiency influences insulin metabolism and action. 相似文献
77.
Eight Billroth II resected patients and 8 normal controls were given two oral glucose loads, one ingested within 2 min, and the other ingested slowly over 80 min. In the Billroth II resected group, the integrated plasma GIP release was significantly higher after the fast than after the slow glucose ingestion. In this group the integrated plasma GIP release was also significantly higher than in the control group, but only after the fast glucose ingestion. These findings indicate that the rate of glucose delivery into the intestine may be of importance in the plasma GIP response to oral glucose. 相似文献
78.
Hideki Oyama Jeanne Martin Karl Sussman Gordon C. Weir Alan Permutt 《Regulatory peptides》1981,1(6):387-396
Catfish pancreatic somatostatin, which contains eight additional amino acids on the amino terminus of a tetradecapeptide with considerable homology to tetradecapeptide somatostatin (SRIF), is a naturally occurring homology of the hypothalamic peptide. The purpose of these studies was to determibe the biological activity of this somatostatin homolog. Inhibition of 125I-labelled tyr1-SRIF binding to bovine pituitart plasma membranes by catfish pancreatic somatostatin was approximately 33% that of SRIF. Pancreatic somatostatin has full biological activity measured by inhibition of growth hormone release from isolated rat pituitary cells, but 0.01–0.1% the potency of SRIF. Pancreatic somatostatin at 100 ng/ml produced a 50–60% inhibition of insulin and glucagon secretion from perfused rat pancreas, while SRIF produced comparable inhibition at 10 ng/ml. This report demonstrates that a larger molecular form and natural homolog of SRIF, isolated from fish pancreas, has the same (but reduced) biological activities in rat assay systems as somatostatin originally isolated from sheep hypothalamus. 相似文献
79.
This study was designed to document whether the reported distribution of insulin receptors in small groups of receptor sites randomly distributed in the glycocalyx of adipocytes and isolated adipocyte plasma membranes was a naturally occurring phenomena or due to artifacts. Possible artifacts include: (1) oligomeric forms of ferritin in the ferritin-insulin preparation, (2) an uneven distribution of the glycocalyx on the plasma membrane, or (3) ligand-induced aggregation of occupied receptor complexes. Biogel A 1.5m chromatography of the ferritin-insulin conjugate revealed the ferritin in the ferritin-insulin complex to consist of 55% monomers, 15% dimers, and 30% oligomers. The monomer peak was purified (> 95%) for use in these studies. Cationic ferritin, a glycocalyx marker, when incubated with paraformaldehyde-fixed plasma membranes, was found to be uniformly distributed on the surface of the plasma membrane indicative of uniformly distributed glycocalyx. The ability to demonstrate and inhibit ligand-induced aggregation on the isolated plasma membrane was established with a multivalent ligand, ferritin-concanavalin A. More than 66% of the ferritin-concanavalin A receptors were found in large clusters of 5 or more and 34% as singletons or clusters of up to 4 when incubated at 24°C with fresh membranes. Only 38% of the ferritin-concanavalin A receptors were in large clusters; 62% were singletons or clusters up to 4 on membranes prefixed with paraformaldehyde before incubation. The distribution of the monomeric ferritin-insulin was similar on both adipocytes and purified adipocyte plasma membranes and was consistent with earlier reports with ferritin-insulin. The quantitative distribution of the monomeric ferritin-insulin as singletons or in groups of 2–6 was comparable between the intact cells and isolated membranes incubated at 24°C. The binding of 500 μUnits monomeric ferritin-insulin per ml to the isolated plasma membranes was studied under incubation conditions similar to those used with ferritin-concanavalin A. Under all three conditions, fresh membranes at 24°C and 0–4°C and prefixed membranes at 24°C, the pattern of distribution of the monomeric ferritin-insulin as singletons or groups of 2–6 was identical, indicating that the ligand was not causing aggregation into clusters as did the concanavalin A. Thus, the occurrence of insulin receptors in small groups appears to be a natural phenomenon in the plasma membrane structure of adipocytes. 相似文献
80.
Harvey R. Herschman Dennis S. Passovoy Rebecca M. Pruss Aharon Aharonov 《Journal of cellular biochemistry》1978,8(3):263-268
The growth-promoting activities of fetal bovine serum, cortisol, phorbol myristate acetate, prostaglandin F2α, insulin, epidermal growth factor, and fibroblast growth factor were evaluated on four murine embryo cell lines (Swiss 3T3, Balb 3T3, M2, and C3H10T1/2). Each cell had an unique response spectrum to this collection of reported mitogens. Phorbol myristate acetate and prostaglandin F2α were active only on selected cell lines; cortisol was inactive on all four lines. Serum, epidermal growth factor, and fibroblast growth factor were able to stimulate cell division in all four lines, albeit to varying degrees for the different target cells. 相似文献