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排序方式: 共有131条查询结果,搜索用时 234 毫秒
1.
Jacky L. Snoep Mark R. de Graef Adrie H. Westphal Arie de Kok M. Joost Teixeira de Mattos Oense M. Neijssel 《FEMS microbiology letters》1993,114(3):279-283
Abstract The effect of NADH on the activity of the purified pyruvate dehydrogenase complexes (PDHc) of Enterococcus (Ec.) faecalis, Lactococcus lactis, Azotobacter vinelandii and Escherichia coli was determined in vitro. It was found that the PDHc of E. coli and L. lactis was active only at relatively low NADH/NAD ratios, whereas the PDHc of Ec. faecalis was inhibited only at high NADH/NAD ratios. The PDHc of Azotobacter vinelandii showed an intermediate sensitivity. The organisms were grown in chemostat culture under conditions that led to different intracellular NADH/NAD ratios and the PDHc activities in vivo could be calculated from the specific rates of product formation. Under anaerobic growth conditions, only Ec. faecelis expressed PDHc activity in vivo. The activities in vivo of the complexes of the different organisms were in good agreement with their properties determined in vitro. The physiological consequences of these results are discussed. 相似文献
2.
Mieke M. E. Huijbers Jenny W. Wu Adrie H. Westphal Willem J. H. van Berkel 《Biotechnology journal》2019,14(5)
Thermus thermophilus proline dehydrogenase ( TtProDH) catalyzes the first step in proline catabolism. The thermostable flavoenzyme consists of a distorted triosephosphate isomerase (TIM) barrel and three N‐terminal helices: αA, αB, and αC. Using maltose‐binding protein (MBP) fused constructs, it has been recently demonstrated that helix αC is crucial for TtProDH catalysis and for tetramerization through positioning of helix α8. Here, the structural features that determine the thermostability of TtProDH are reported. Selective disruption of two ion pairs in the dimerization interface of several MBP‐TtProDH variants result in the formation of monomers. The newly created monomers have improved catalytic properties but their melting temperatures are decreased by more than 20 °C. Sequence comparison suggests that one of the ion‐pairs involved in dimerization is unique for ProDHs from Thermus species. In summary, intermolecular ion‐pairs improve the thermostability of TtProDH and a trade‐off is made between thermostability and catalytic activity. 相似文献
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Marion Venot Lise Weis Christophe Clec’h Michael Darmon Bernard Allaouchiche Dany Goldgran-Tolédano Maité Garrouste-Orgeas Christophe Adrie Jean-Fran?ois Timsit Elie Azoulay 《PloS one》2015,10(5)
IntroductionWhether diabetes mellitus increases the risk of acute kidney injury (AKI) during sepsis is controversial.ResultsFirst, we compared 451 patients with severe sepsis or septic shock and diabetes to 3,277 controls with severe sepsis or septic shock and without diabetes. Then, we compared 318 cases (with diabetes) to 746 matched controls (without diabetes). Diabetic patients did not have a higher frequency of AKI (hazard ratio [HR], 1.18; P = 0.05]) or RRT (HR, 1.09; P = 0.6). However, at discharge, diabetic patients with severe sepsis or septic shock who experienced acute kidney injury during the ICU stay and were discharged alive more often required RRT (9.5% vs. 4.8%; P = 0.02), had higher serum creatinine values (134 vs. 103 µmoL/L; P<0.001) and had less often recovered a creatinine level less than 1.25 fold the basal creatinine (41.1% vs. 60.5%; P<0.001).ConclusionsIn patients with severe sepsis or septic shock, diabetes is not associated with occurrence of AKI or need for RRT but is an independent risk factor for persistent renal dysfunction in patients who experience AKI during their ICU stay. 相似文献
4.
Melissa Richard-Greenblatt Horacio Bach John Adamson Sandra Pe?a-Diaz Wu Li Adrie J. C. Steyn Yossef Av-Gay 《The Journal of biological chemistry》2015,290(38):23064-23076
Ergothioneine (EGT) is synthesized in mycobacteria, but limited knowledge exists regarding its synthesis, physiological role, and regulation. We have identified Rv3701c from Mycobacterium tuberculosis to encode for EgtD, a required histidine methyltransferase that catalyzes first biosynthesis step in EGT biosynthesis. EgtD was found to be phosphorylated by the serine/threonine protein kinase PknD. PknD phosphorylates EgtD both in vitro and in a cell-based system on Thr213. The phosphomimetic (T213E) but not the phosphoablative (T213A) mutant of EgtD failed to restore EGT synthesis in a ΔegtD mutant. The findings together with observed elevated levels of EGT in a pknD transposon mutant during in vitro growth suggests that EgtD phosphorylation by PknD negatively regulates EGT biosynthesis. We further showed that EGT is required in a nutrient-starved model of persistence and is needed for long term infection of murine macrophages. 相似文献
5.
Jean-Paul Pais de Barros Thomas Gautier Wahib Sali Christophe Adrie Hélène Choubley Emilie Charron Caroline Lalande Naig Le Guern Valérie Deckert Mehran Monchi Jean-Pierre Quenot Laurent Lagrost 《Journal of lipid research》2015,56(7):1363-1369
Quantitation of plasma lipopolysaccharides (LPSs) might be used to document Gram-negative bacterial infection. In the present work, LPS-derived 3-hydroxymyristate was extracted from plasma samples with an organic solvent, separated by reversed phase HPLC, and quantitated by MS/MS. This mass assay was combined with the limulus amebocyte lysate (LAL) bioassay to monitor neutralization of LPS activity in biological samples. The described HPLC/MS/MS method is a reliable, practical, accurate, and sensitive tool to quantitate LPS. The combination of the LAL and HPLC/MS/MS analyses provided new evidence for the intrinsic capacity of plasma lipoproteins and phospholipid transfer protein to neutralize the activity of LPS. In a subset of patients with systemic inflammatory response syndrome, with documented infection but with a negative plasma LAL test, significant amounts of LPS were measured by the HPLC/MS/MS method. Patients with the highest plasma LPS concentration were more severely ill. HPLC/MS/MS is a relevant method to quantitate endotoxin in a sample, to assess the efficacy of LPS neutralization, and to evaluate the proinflammatory potential of LPS in vivo. 相似文献
6.
Vanessa Gonzalez‐Covarrubias Marian Beekman Hae‐Won Uh Adrie Dane Jorne Troost Iryna Paliukhovich Frans M. van der Kloet Jeanine Houwing‐Duistermaat Rob J. Vreeken Thomas Hankemeier Eline P. Slagboom 《Aging cell》2013,12(3):426-434
Middle‐aged offspring of nonagenarians, as compared to their spouses (controls), show a favorable lipid metabolism marked by larger LDL particle size in men and lower total triglyceride levels in women. To investigate which specific lipids associate with familial longevity, we explore the plasma lipidome by measuring 128 lipid species using liquid chromatography coupled to mass spectrometry in 1526 offspring of nonagenarians (59 years ± 6.6) and 675 (59 years ± 7.4) controls from the Leiden Longevity Study. In men, no significant differences were observed between offspring and controls. In women, however, 19 lipid species associated with familial longevity. Female offspring showed higher levels of ether phosphocholine (PC) and sphingomyelin (SM) species (3.5–8.7%) and lower levels of phosphoethanolamine PE (38:6) and long‐chain triglycerides (TG) (9.4–12.4%). The association with familial longevity of two ether PC and four SM species was independent of total triglyceride levels. In addition, the longevity‐associated lipid profile was characterized by a higher ratio of monounsaturated (MUFA) over polyunsaturated (PUFA) lipid species, suggesting that female offspring have a plasma lipidome less prone to oxidative stress. Ether PC and SM species were identified as novel longevity markers in females, independent of total triglycerides levels. Several longevity‐associated lipids correlated with a lower risk of hypertension and diabetes in the Leiden Longevity Study cohort. This sex‐specific lipid signature marks familial longevity and may suggest a plasma lipidome with a better antioxidant capacity, lower lipid peroxidation and inflammatory precursors, and an efficient beta‐oxidation function. 相似文献
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A genomic library was constructed from DNA of a domestic cat and screened with a human HLA-DR probe at low stringency. Several positive clones were isolated, and the DNA sequence of one of these clones was determined. Comparison with class II gene sequences from other species suggested that the feline gene is a DPA homologue (FLA-DPA) showing 84% similarity with HLA-DP1 in the exon encoding the second domain. The FLA-DPA gene that was isolated is a pseudogene, as two frame-shift mutations are present: one in the exon encoding the second domain, causing premature termination of translation, and one in the exon encoding the transmembrane region. The latter mutation and the further deletion of two codons in the transmembrane exon show a remarkable resemblance to the same exon of the human pseudogene, HLA-DPA2. Hence, both pseudogenes evolved from the same ancestral gene. The inactivation of this DPA gene could therefore have occurred prior to the major mammalian divergence. 相似文献
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