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71.
72.
Gonadotropin-releasing hormone stimulation of pituitary gonadotrope cells produces an increase in intracellular calcium 总被引:4,自引:0,他引:4
Gonadotropin-releasing hormone (GnRH) stimulates pituitary gonadotrope cells to release luteinizing hormone (LH). Previous studies have indicated a role for Ca+2 in this process; however, the present study provides the first measurements of an increased intracellular Ca+2 concentration. Pituitary cell cultures enriched for gonadotropes were loaded with quin 2, a fluorescent Ca+2-sensitive molecule. Subsequent addition of GnRH to these cells produced a rapid (within 10 sec) increase in fluorescence (indicating an increase in intracellular free Ca+2). In contrast, two GnRH analogs, des1 GnRH (a very low-affinity binder to the GnRH receptor) and Ac[D-pCl-Phe1,2] DTrp3 DLys6 DAla10-GnRH (a pure GnRH antagonist) produced no such Ca+2 change, thus showing a correlation between increased intracellular Ca+2 and LH release. A functional relationship between increased Ca+2 and LH release was suggested by experiments in which LH release was inhibited from cells loaded with high levels of intracellular quin 2 (in order to chelate intracellular Ca+2). Since this inhibition was completely reversed by addition of the Ca+2 ionophore A23187, quin 2 was not toxic at the concentrations used and apparently inhibited LH release by buffering intracellular Ca+2. The results presented here are consistent with the hypothesis that GnRH-stimulated LH release is mediated by increased intracellular Ca+2 and support the notion that the rate-limiting step in GnRH-stimulated LH release is distal to Ca+2 mobilization. 相似文献
73.
Serotonin (5HT) stimulates phosphoinositide turnover in a number of tissues, but it is not known whether this effect is due to activation of a 5HT receptor which is coupled to phosphoinositide hydrolysis or if the effect is secondary to 5HT stimulated arachidonate metabolism or to the release of another neurotransmitter. In the present study we show that neither indomethacin nor BW 755C inhibits 5HT stimulated phosphoinositide hydrolysis in rat cerebral cortex, suggesting that neither cyclooxygenase nor lipoxygenase activity is required for the response to 5HT. Proteinase inhibitors do not potentiate the response to 5HT, suggesting that 5HT's effect is not due to stimulation of release of a peptide neurotransmitter. Tetrodotoxin does not inhibit the effect of 5HT and 5HT's effect is additive with that of KCl and veratrine. These data suggest that 5HT stimulated phosphoinositide hydrolysis is not dependent upon release of another neurotransmitter. 相似文献
74.
Robert A. Gelman Kathleen M. Conn John D. Termine 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,630(2):220-224
Phosphoproteins retard the rate at which collagen molecules undergo self-assembly into fibrils. The inhibition appears to be dependent on the amount of phosphoprotein present, with increasing phosphoprotein concentrations resulting in greater inhibition. Prior treatment of the phosphoprotein with calcium markedly increases the resultant inhibitory effect. Dentin phosphoproteins are considerably more effective than phosvitin in retarding collagen self-assembly, with retardation times for these hard tissue extracellular matrix proteins being 25–30 times greater than control values. 相似文献
75.
A microsomal fraction from seedlings of Sorghum bicolor (Linn) Moench has been shown to catalyze the conversion of L-tyrosine to p-hydroxymandelonitrile via p-hydroxyphenylacetaldoxime. This transformation is consistent with the general pathway for cyanogenic glycoside biosynthesis proposed on the basis of in vivo experiments. When the microsomal fraction was combined with a protein fraction from the soluble portion of the cell and uridine diphosphate glucose, it was possible to demonstrate the synthesis of the cyanogenic glycoside dhurrin from L-tyrosine. 相似文献
76.
H. J. Conn 《Biotechnic & histochemistry》1930,5(2):39-48
The staining of bacteria is naturally of later origin than the use of dyes in histological work, as the systematic study of bacteria did not begin until after 1870. The use of dyes in this study followed very promptly after that date, however. 相似文献
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Andrew S. Felts Alice L. Rodriguez Ryan D. Morrison Anna L. Blobaum Frank W. Byers J. Scott Daniels Colleen M. Niswender P. Jeffrey Conn Craig W. Lindsley Kyle A. Emmitte 《Bioorganic & medicinal chemistry letters》2018,28(10):1679-1685
Based on previous work that established fused heterocycles as viable alternatives for the picolinamide core of our lead series of mGlu5 negative allosteric modulators (NAMs), we designed a novel series of 6-(pyrimidin-5-ylmethyl)quinoline-8-carboxamide mGlu5 NAMs. These new quinoline derivatives also contained carbon linkers as replacements for the diaryl ether oxygen atom common to our previously published chemotypes. Compounds were evaluated in a cell-based functional mGlu5 assay, and an exemplar analog 27 was >60-fold selective versus the other seven mGlu receptors. Selected compounds were also studied in metabolic stability assays in rat and human S9 hepatic fractions and exhibited a mixture of P450- and non-P450-mediated metabolism. 相似文献