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131.
Bustanji Y Taha MO Yousef AM Al-Bakri AG 《Journal of enzyme inhibition and medicinal chemistry》2006,21(2):163-171
Berberine was investigated as an inhibitor of human protein tyrosine phosphatase 1B (h-PTP 1B) in an attempt to explain its anti-hyperglycemic activitiy. The investigation included simulated docking experiments to fit berberine within the binding pocket of h-PTP 1B. Berberine was found to readily fit within the binding pocket of h-PTP 1B in a low energy orientation characterized with optimal electrostatic attractive interactions bridging the isoquinolinium positively charged nitrogen atom of berberine and the negatively charged acidic residue of ASP 48 of h-PTP 1B. Experimentally, berberine was found to potently competitively inhibit recombinant h-PTP 1B in vitro (Ki value = 91.3 nM). Our findings strongly suggest that h-PTP 1B inhibition is at least one of the reasons for the reported anti-hyperglycemic activities of berberine. 相似文献
132.
Moukha-Chafiq O Taha ML Lazrek HB Vasseur JJ Clercq ED 《Nucleosides, nucleotides & nucleic acids》2006,25(8):849-860
A useful route to obtain trisubstituted pyrazolo[3,4-d]pyrimidines 14-17 is described. Those later were coupled with the alkylating agents 18-20 as in ACV, HBG, and iso-DHPG to give, after deprotection, the desired acylonucleosides 33-44. Almost all of the new compounds were evaluated for their inhibitory effects against the replication of various DNA viruses in culture. 相似文献
133.
Oxidized LDL immune complexes induce release of sphingosine kinase in human U937 monocytic cells 总被引:3,自引:0,他引:3
Hammad SM Taha TA Nareika A Johnson KR Lopes-Virella MF Obeid LM 《Prostaglandins & other lipid mediators》2006,79(1-2):126-140
The transformation of macrophages into foam cells is a critical event in the development of atherosclerosis. The most studied aspect of this process is the uptake of modified LDL through the scavenger receptors. Another salient aspect is the effect of modified LDL immune complexes on macrophages activation and foam cell formation. Macrophages internalize oxidized LDL immune complexes (oxLDL-IC) via the Fc-gamma receptor and transform into activated foam cells. In this study we examined the effect of oxLDL-IC on sphingosine kinase 1 (SK1), an enzyme implicated in mediating pro-survival and inflammatory responses through the generation of the signaling molecule sphingosine-1-phosphate (S1P). Intriguingly, oxLDL-IC, but not oxLDL alone, induced an immediate translocation and release of SK1 into the conditioned medium as evidenced by fluorescence confocal microscopy. Immunoblot analysis of cell lysates and conditioned medium revealed a decrease in intracellular SK1 protein levels accompanied by a concomitant increase in extracellular SK1 levels. Furthermore, measurement of S1P formation showed that the activity of cell-associated SK decreased in response to oxLDL-IC compared to oxLDL alone, whereas the activity of SK increased extracellularly. Blocking oxLDL-IC binding to Fc-gamma receptors resulted in decreased levels of extracellular S1P. The data also show that cell survival of human U937 cells exposed to oxLDL-IC increased compared to oxLDL alone. Exogenously added S1P further increased cell survival induced by oxLDL-IC. Taken together, these findings indicate that S1P may be generated extracellularly in response to modified LDL immune complexes and may therefore promote cell survival and prolong cytokine release by activated macrophages. 相似文献
134.
Nor-ent-kaurane diterpenes and hydroxylactones from Antennaria geyeri and Anaphalis margaritacea 总被引:1,自引:0,他引:1
Ahmed AA Hussein TA Mahmoud AA Farag MA Paré PW Wojcińska M Karchesy J Mabry TJ 《Phytochemistry》2004,65(18):2539-2543
In a study of Pacific Northwest plants of the Asteraceae family, a nor-ent-kaurane diterpene and a known diterpene, both displaying antibacterial activities, were isolated together with scopoletin and sitosterol-3-O-beta-glucopyranoside from the aerial parts of Antennaria geyeri. Anaphalis margaritacea afforded two hydroxylactones. The structures were established by one and two dimensional NMR techniques, IR and CIMS. 相似文献
135.
Moukha-chafiq O Taha ML Mouma A Lazrek HB Vasseur JJ De Clercq E 《Nucleosides, nucleotides & nucleic acids》2003,22(5-8):967-972
The chemical synthesis and biological evaluation of some acyclic alpha-[6-(1'-carbamoylalkylthio)-1H-pyrazolo[3,4-d]pyrimidin-4-yl]thioalkylamide nucleosides are described. 相似文献
136.
Khelifi-Touhami F Taha RA Badary OA Lezzar A Hamada FM 《Journal of biochemical and molecular toxicology》2003,17(6):324-328
The effects of three natural phenolic acids (caffeic, ferulic, and p-coumaric) on the rat thyroid gland were examined in a 3-week oral-treatment study. Forty male Wistar albino rats, divided into groups of 10 rats each and fed iodine-rich diet, were administered by gastrointestinal tube saline (control), caffeic acid, ferulic acid, or p-coumaric acid at a dose level of 0.25 micromol/kg/day for 3 weeks. The mean absolute and relative thyroid weights in caffeic, ferulic, or p-coumaric acid groups were significantly increased to 127 and 132%, 146 and 153%, or 189 and 201% compared to control value, respectively. Histological examination of the thyroids of p-coumaric acid group revealed marked hypertrophy and/or hyperplasia of the follicles. Caffeic or ferulic groups showed slight to moderate thyroid gland enlargement. Thyroid lesions in p-coumaric acid group were associated with significant increases in cellular proliferation as indicated by [(3)H]thymidine incorporation. In addition, the goitrogenic effect of p-coumaric acid was further confirmed by significant decreases (50%) in serum tri-iodothyronine (T(3)) and thyroxine (T(4)), and a parallel increase (90%) in serum thyroid stimulating hormone (TSH) compared to control group. These results indicate that administration of p-coumaric acid at relatively high doses induces goiter in rats. 相似文献
137.
138.
Recent trends using natural polymeric nanofibers as supports for enzyme immobilization and catalysis
Rumysa S. Khan Anjum H. Rather Taha U. Wani Sami-ullah Rather Touseef Amna M. Shamshi Hassan Faheem A. Sheikh 《Biotechnology and bioengineering》2023,120(1):22-40
All the disciplines of science, especially biotechnology, have given continuous attention to the area of enzyme immobilization. However, the structural support made by material science intervention determines the performance of immobilized enzymes. Studies have proven that nanostructured supports can maintain better catalytic performance and improve immobilization efficiency. The recent trends in the application of nanofibers using natural polymers for enzyme immobilization have been addressed in this review article. A comprehensive survey about the immobilization strategies and their characteristics are highlighted. The natural polymers, e.g., chitin, chitosan, silk fibroin, gelatin, cellulose, and their blends with other synthetic polymers capable of immobilizing enzymes in their 1D nanofibrous form, are discussed. The multiple applications of enzymes immobilized on nanofibers in biocatalysis, biosensors, biofuels, antifouling, regenerative medicine, biomolecule degradation, etc.; some of these are discussed in this review article. 相似文献
139.
Using simulated data, we compared five methods of phylogenetic tree
estimation: parsimony, compatibility, maximum likelihood, Fitch-
Margoliash, and neighbor joining. For each combination of substitution
rates and sequence length, 100 data sets were generated for each of 50
trees, for a total of 5,000 replications per condition. Accuracy was
measured by two measures of the distance between the true tree and the
estimate of the tree, one measure sensitive to accuracy of branch lengths
and the other not. The distance-matrix methods (Fitch- Margoliash and
neighbor joining) performed best when they were constrained from estimating
negative branch lengths; all comparisons with other methods used this
constraint. Parsimony and compatibility had similar results, with
compatibility generally inferior; Fitch- Margoliash and neighbor joining
had similar results, with neighbor joining generally slightly inferior.
Maximum likelihood was the most successful method overall, although for
short sequences Fitch- Margoliash and neighbor joining were sometimes
better. Bias of the estimates was inferred by measuring whether the
independent estimates of a tree for different data sets were closer to the
true tree than to each other. Parsimony and compatibility had particular
difficulty with inaccuracy and bias when substitution rates varied among
different branches. When rates of evolution varied among different sites,
all methods showed signs of inaccuracy and bias.
相似文献
140.
Of 700 animal feed samples, 32 (4.5%) harbored Salmonella. The highest percentage of contamination was found in sheep feed and local protein. A total of 17 Salmonella serotypes were identified. The most frequent serotypes were Salmonella meleagridis. S. bornum, S. montevideo, and S. drypool. S. bornum was isolated for the first time in Iraq and from both local feed and its ingredients. The common somatic group found was that of Salmonella group C; then came groups E, G, B, and D. Three serotypes (S. enteritidis, S. california, and S. muenchen) seemed to form a link of infection among feed, food, patients, and carriers. 相似文献