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1.
We sought to determine whether the orexigenic hormone, ghrelin, is involved in the intrinsic regulation of food choice in rats. Ghrelin would seem suited to serve such a role given that it signals hunger information from the stomach to brain areas important for feeding control, including the hypothalamus and reward system (e.g. ventral tegmental area, VTA). Thus, in rats offered a choice of palatable foods (sucrose pellets and lard) superimposed on regular chow for 2 weeks, we explored whether acute central delivery of ghrelin (intracerebroventricular (ICV) or intra-VTA) is able to redirect their dietary choice. The major unexpected finding is that, in rats with high baseline lard intake, acute ICV ghrelin injection increased their chow intake over 3-fold, relative to vehicle-injected controls, measured at both 3 hr and 6 hr after injection. Similar effects were observed when ghrelin was delivered to the VTA, thereby identifying the VTA as a likely contributing neurobiological substrate for these effects. We also explored food choice after an overnight fast, when endogenous ghrelin levels are elevated, and found similar effects of dietary choice to those described for ghrelin. These effects of fasting on food choice were suppressed in models of suppressed ghrelin signaling (i.e. peripheral injection of a ghrelin receptor antagonist to rats and ghrelin receptor (GHSR) knock-out mice), implicating a role for endogenous ghrelin in the changes in food choice that occur after an overnight fast. Thus, in line with its role as a gut-brain hunger hormone, ghrelin appears to be able to acutely alter food choice, with notable effects to promote “healthy” chow intake, and identify the VTA as a likely contributing neurobiological substrate for these effects. 相似文献
2.
Wenbo Zhang Xuemei Xu Raymond Kao Tina Mele Peter Kvietys Claudio M. Martin Tao Rui 《PloS one》2014,9(9)
Myocardial contractile dysfunction in sepsis is associated with the increased morbidity and mortality. Although the underlying mechanisms of the cardiac depression have not been fully elucidated, an exaggerated inflammatory response is believed to be responsible. Nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome is an intracellular platform that is involved in the maturation and release of interleukin (IL)-1β. The aim of the present study is to evaluate whether sepsis activates NLRP3 inflammasome/caspase-1/IL-1β pathway in cardiac fibroblasts (CFs) and whether this cytokine can subsequently impact the function of cardiomyocytes (cardiac fibroblast-myocyte cross-talk). We show that treatment of CFs with lipopolysaccharide (LPS) induces upregulation of NLRP3, activation of caspase-1, as well as the maturation (activation) and release of IL-1β. In addition, the genetic (small interfering ribonucleic acid [siRNA]) and pharmacological (glyburide) inhibition of the NLRP3 inflammasome in CFs can block this signaling pathway. Furthermore, the inhibition of the NLRP3 inflammasome in cardiac fibroblasts ameliorated the ability of LPS-chalenged CFs to impact cardiomyocyte function as assessed by intracellular cyclic adenosine monophosphate (cAMP) responses in cardiomyocytes. Salient features of this the NLP3 inflammasome/ caspase-1 pathway were confirmed in in vivo models of endotoxemia/sepsis. We found that inhibition of the NLRP3 inflammasome attenuated myocardial dysfunction in mice with LPS and increased the survival rate in mice with feces-induced peritonitis. Our results indicate that the activation of the NLRP3 inflammasome in cardiac fibroblasts is pivotal in the induction of myocardial dysfunction in sepsis. 相似文献
3.
4.
Characterization of calf liver glucosidase I and its inhibition by basic sugar analogs 总被引:4,自引:0,他引:4
Glucosidase I, the enzyme catalyzing the first step of N-linked oligosaccharide processing, has been purified from calf liver crude membranes [H. Hettkamp, G. Legler, and E. Bause, (1984) Eur. J. Biochem. 142, 85-90]. Binding experiments with concanavalin A-Sepharose suggest that glucosidase I is a glycoprotein with high-mannose carbohydrate chain(s). The enzyme has a subunit molecular mass of approximately 83 kDa and specifically hydrolyzes the terminal alpha-1,2-linked glucose residue from the natural Glc3-Man9-GlcNAc2 oligosaccharide. Studies with a variety of substrates modified in the aglycon moiety suggest that the Glc2 branch rather than the more distant domains of the substrate molecule are important for binding and hydrolysis. Glucosidase I does not require metal ions for activity and is strongly inhibited by 1-deoxynojirimycin (dNM) and its N-alkyl derivatives. Ki values range from 0.07 microM for N-methyl-dNM to 1.0 microM for dNM, measured at the pH-optimum of enzyme activity. The pH dependence of inhibition indicates that the cationic form of the inhibitors is the active species. Comparison of the Ki for N-decanoyl-dNM (approximately 70 microM) with that of N-decyl-dNM (approximately 0.4 microM) suggests that electrostatic interactions at the catalytic site of the enzyme are important for inhibitor binding. 1-Deoxymannojirimycin, previously assumed to be a specific mannosidase inhibitor, as well as its N-methyl and N-5-carboxypentyl derivatives, inhibit glucosidase I with Ki values around 190, 17, and 100 microM, respectively. This apparent lack of specificity shows that in vivo experiments on N-glycoprotein processing as well as the interpretation of results with these mannosidase inhibitors may give misleading results when these compounds are used in the millimolar range. 相似文献
5.
Penicillium citrinum cultures have been germinated on an H2O-based medium, resuspended on a D2O-based medium and treated with [l,2-13C2] acetate. The resulting citrinin (1) has been analysed by2H and13C nuclear magnetic resonance spectroscopy and information about the metabolism of hydrogen in citrinin biosynthesis has been deduced. 相似文献
6.
Roger J. Kemble Tina L. Barsby Stephen A. Yarrow 《Molecular & general genetics : MGG》1988,213(2-3):202-205
Summary
Brassica napus cybrid plants which contain novel nucleus-mitochondria-chloroplast combinations have been constructed, via protoplast fusion. Such fusions resulted in mitochondrial DNA plasmids being lost (at a frequency of 12.5%) or, more surprisingly, being transferred from mitochondria of one protoplast population to mitochondria of the other population (at a frequency of 6.1%). Mitochondria containing their new DNA complement became the dominant organelle population in regenerated plants and were faithfully maternally inherited through successive sexnal generations. No concomitant alterations in mitochondrial chromosome organization or nuclear chromosome number occurred. Protoplast fusion can, therefore, cure plant mitochondria of extrachromosomal DNA and, more importantly, be used to transform plant mitochondria with naturally occurring mitochondrial plasmids. The potential for mitochondrial transformation with recombinant vectors is discussed. 相似文献
7.
Allison A. Welder Tina Machu Steven W. Leslie Richard E. Wilcox June Bradlaw Daniel Acosta 《In vitro cellular & developmental biology. Plant》1988,24(8):771-777
Summary Primary mycolardial cell cultures and freshly isolated cardiac cells in suspension resprensent two isolated, whole cell models
for investigating cellular transsarcolemmal45Ca++ exchange in response to a receptor-coupled stimulus. Studies were performed to characterize beta-adrenergic receptor binding,
beta-adrenergic receptor mediated cellular calcium (45Ca++) exchange, and viability in purified primary myocardial cell cultures and freshly isolated cardiac cells in suspension obtained
from 3-to 3-d-old Sprague-Dawley rats. In addition, beta-adrenergic receptor binding was characterized in whole-heart crude
membrane preparations. All three preparations had saturable beta-adrenergic binding sites with the antagonist [125I]iodopindolol ([125I]IPIN). The suspensions had a significantly lower B
max
(42±6 fmol/mg protein) than the membranes and cultures (77±8 and 95±10 fmol/mg protein, respectively). The K
D
of the cultures (218±2.0 pM) was significantly higher than that for the suspensions (107 ±1.3 pM) and membranes (93±1.3 pM). Viability was significantly lower in the suspensions (57%) when compared to 94% viability in myocardial cell cultures after
3 h of incubation in Kreb's Henseleit buffer. Incubation of the cultures with 5.0×10−7
M isoproterenol resulted in a significant increase in45Ca++ exchange as early as 15 s. In contrast,45Ca++ exchange into the suspensions was not increased. Although both primary cell cultures and cardiac cells in suspension possess
saturable beta-adrenergic receptors, only the monolayer cultures exhibited functional beta-adrenergic receptor-mediated45Ca++ exchange. Of the two intact cell models investigated, these data suggest that primary myocardial cell cultures are more suitable
than cell suspensions for investigating beta-adrenergic receptor binding and functions in the postnatal rat heart.
This research was supported by The University of Texas Research Institute, a grant from the Texas Advanced Research Technology
Program awarded to S. W. Leslie and R. E. Wilcox, and contract 223-86-2109 from the Food and Drug Administration. 相似文献
8.
Tina Pallesen Annette Vangsted Lars Drivsholm Henrik Clausen Jesper Zeuthen Håkan Wallin 《Glycoconjugate journal》1992,9(6):331-335
We here report an enzyme linked immunosorbent assay (ELISA) and a scintillation proximity assay (SPA) for detection of the ganglioside FucGM1 in sera from small cell lung cancer (SCLC) patients. The SPA was more sensitive and reproducible than the ELISA. In this assay, monoclonal antibodies specific for FucGM1 were bound to SPA particles and incubated with labelled FucGM1 and 100 µl test-serum overnight, and counted in a -counter. The sensitivity was 0.2 ng. Seven out of twenty sera from SCLC patients were positive, whereas none of twenty sera from healthy individuals were positive for FucGM1. The SPA was more sensitive than the previously reported HPTLC as well as a direct ELISA.Abbreviations MAb
monoclonal antibody
- SPA
scintillation proximity assay
- HPTLC
high performance thin layer chromatography
- SCLC
small cell lung cancer
- FucGM1
Fuc1-2Gal1-3GalNAc1-4(NeuAc2-3)-Gal1-4Glc1-1Cer
- ELISA
enzyme linked immunosorbent assay
- FCS
foetal calf serum
- PBS
phosphate buffered saline 相似文献
9.
K M Osiecki-Newman D Fabbro T Dinur S Boas S Gatt G Legler R J Desnick G A Grabowski 《Enzyme》1986,35(3):147-153
Two sepharose-bound 1-deoxynojirimycin N-alkyl derivatives, N-(9-carboxynonyl)- and N-(11-carboxyundecyl)-deoxynojirimycin, were used for the affinity purification of acid beta-glucosidase (beta-Glc) from normal and type-1 Ashkenazi Jewish Gaucher disease (AJGD) sources. The capacities of these nondegradable inhibitor supports were 0.5 and 0.75 mg of normal beta-Glc/ml of settled gel, respectively. The purified normal enzyme (14-18% yield) had a specific activity of 1.6 X 10(6) nmol/h/mg protein and was homogeneous as evidenced by a single protein species of Mr = 67,000 on sodium dodecylsulfate-polyacrylamide gel electrophoresis and reverse phase high-performance liquid chromatography (HPLC). Microsequencing demonstrated a single N terminus, and the sequence of the first 22 N-terminal amino acids was colinear with that predicted from the beta-Glc cDNA. Amino acid composition analyses of beta-Glc revealed a high content (35%) of hydrophobic amino acids. The N-decyl-deoxynojirimycin support facilitated the purification of the residual enzyme from type-1 AJGD spleen to about 7,500-fold in four steps with a yield of about 11%. These new affinity supports provided improved stability, capacity and/or specificity compared to other affinity or HPLC methods for purifying this lysosomal glycosidase. 相似文献
10.
Corticosteroid-induced abnormality in fetal mice and H-2 haplotype: Evidence of a cytoplasmic effect
Different strains of H-2 congenic mice have different susceptibilities to corticosteroid-induced fetal loss and cleft palate. Applying this knowledge, we tested the null hypothesis, which assumes that there are no statistically significant differences in the frequency of abnormality among various types of treated backcross offspring and, thus, no evidence of a cytoplasmic effect. In the present study this null hypothesis was frequently, but not consistently, rejected. Therefore, there was some evidence of a cytoplasmic effect. One possible explanation of these results is seen when one considers the phenotypic effects of “gene-gene interaction” between variant H-2 genotypes and an invariant mitochondrial genotype. 相似文献