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131.
Molecular Analysis of a Salmonella Enterica Group E1 Rfb Gene Cluster: O Antigen and the Genetic Basis of the Major Polymorphism 总被引:9,自引:0,他引:9 下载免费PDF全文
Salmonella enterica is highly polymorphic for the O antigen, a surface polysaccharide that is subject to intense selection by the host immune system. This polymorphism is used for serotyping Salmonella isolates. The genes encoding O antigen biosynthesis are located in the rfb gene cluster. We report here the cloning and sequence of the 19-kb rfb region from strain M32 (serovar anatum, group E1) and compare it with that of strain LT2 (serovar typhimurium, group B). Genes for biosynthetic pathways common to both strains are conserved and have very similar sequences. In contrast, the five genes for CDP-abequose synthesis, present in strain LT2, are absent in strain M32; three open reading frames (ORFs) of strain LT2, thought to include genes for transferases, are not present in strain M32 but are replaced by three different ORFs with little or low level of similarity. Both rfb gene clusters are low in G + C content, indicating that they were transferred from a common ancestral species with low G + C content to S. enterica relatively recently (in the evolutionary sense). We discuss the recombination and lateral transfer events which may have been involved in the evolution of the polymorphism. 相似文献
132.
Five clones of axenic Entamoeba histolytica (HMI) grown as discrete colonies in semisolid agar medium were adapted in liquid medium and labelled as HMI-C121, HMI-C131, HMI-C143, HMI-C144 and HMI-C145. The clone HMI-C121 was more cytotoxic to the cultured Baby Hamster Kidney (BHK) cells while all other clones were significantly (P less than 0.001) less cytotoxic as compared to the cloned HMI-C121 and uncloned E. histolytica (HMI). The uncloned Indian axenic E. histolytica (KCG:0986:11) as well as E. histolytica (NIH:200) cultures were significantly (P less than 0.001) less cytotoxic to cultured BHK cells. No difference in the electromobility of maleate NADP oxidoreductase (ME) or glucophosphate isomerase (GPI) isoenzyme in the lysates of all the cloned and uncloned cultures of E. histolytica was observed. The clones HMI-C121, HMI-C131, HMI-G143 and HMI-C144 had three bands of hexokinase (HK) while all uncloned cultures and one of clones, HMI-C145 had only two bands. Though cloned and uncloned cultures had a single PGM band, the relative electromobility (rf) of phosphoglucomutase (PGM) for clone HMI-C131, HMI-C143 HMI-C144 was relatively less (rf 0.075) and these were also significantly (P less than 0.001) less cytotoxic to BHK cells as compared to clone HMI-C121. It is felt that axenic E. histolytica culture consists of several populations (clones) and expression of isoenzymes pattern or cytotoxic potentials would depend upon the population which predominantly multiples and outgrows other populations in the culture system. 相似文献
133.
Structure and sequence of the rfb (O antigen) gene cluster of Salmonella serovar typhimurium (strain LT2) 总被引:68,自引:0,他引:68
X.-M. Jiang B. Neal F. Santiago S. J. Lee L. K. Romana P. R. Reeves 《Molecular microbiology》1991,5(3):695-713
The rfb gene cluster of Salmonella LT2 has been cloned and sequenced. The genes rfbA, rfbB, rfbD, rfbF, rfbG, rfbK, rfbM and rfbP were located individually and the gene rfbL was located outside the cluster. Approximately 16 open reading frames were found in the region which is essential for the expression of O antigen. The gene products of rfbB and rfbG were found to have homology with the group of dehydrogenase and related enzymes described previously. Analysis of the G + C ratio of the rfb cluster extended the area of low-G + C composition previously found in the sequence of rfbJ to the whole rfb gene cluster. Three to five segments with discrete G + C contents and codon adaptation indices are present in the rfb region, indicating a heterogeneous origin of these segments. Potential promoters were found near the start of the rfb region, supporting the possibility that the rfb gene cluster is an operon. 相似文献
134.
1. Crude gammadelta-dioxovalerate was synthesized from laevulinate by two different methods and was purified by Sephadex chromatography. Some analytical reactions of the compound are described. 2. gammadelta-Dioxovalerate is a substrate for glyoxalase I and the GSH derivative formed by this enzyme is hydrolysed by glyoxalase II to form d-alpha-hydroxyglutarate. The K(m) of glyoxalase I for gammadelta-dioxovalerate is 1.0x10(-3)m at pH5.8.3. The u.v.-absorption spectrum of thiol ester, synthesized enzymically from gammadelta-dioxovalerate and GSH by glyoxalase I, is almost identical with that for S-lactoylglutathione. Some optical properties of this thiol ester were measured. 4. Attempts to show reversibility of the glyoxalase system reactions with d-alpha-hydroxyglutarate as substrate were unsuccessful. 5. The possible metabolic role of the gammadelta-dioxovalerate reaction is discussed. It is suggested that one of the metabolic functions of the glyoxalase system may be to provide a mechanism for the entry of this compound into the tricarboxylic acid cycle. 相似文献
135.
136.
Preimplantation genetic diagnosis (PGD) purpose is to assess the genetic status of 3 day-old embryos. PGD offers thus to couples "at-risk" of a genetic disorder an earlier option to prenatal diagnosis (PND). At the beginning, PGD's indications, patients and law were very closed to PND, but PGD specificities are gradually raising. Particularly, indications vary considerably in countries where the absence of law authorizes all the practices. Some of these applications are moreover raising serious ethical issues. Even in France, where this activity is particularly supervised, the recent modification to the law marks this evolution. 相似文献
137.
138.
Presicce GA Senatore EM Bella A De Santis G Barile VL De Mauro GJ Terzano GM Stecco R Parmeggiani A 《Theriogenology》2004,61(7-8):1343-1355
The primary objective was to elucidate ovarian follicular dynamics and hormonal profiles in nulliparous heifer (HE; n = 11 ) and mixed-parity (MP; n=10 ) Mediterranean Italian water buffaloes (Bubalus bubalis) following an estrus synchronization protocol. Both groups received a progesterone releasing intravaginal device (PRID) implant for 10 days; a luteolytic dose of synthetic prostaglandin was given 7 days after PRID insertion. Daily ultrasound monitoring and collection of blood to determine plasma concentrations estradiol and progesterone started 1 day after PRID removal and lasted for 55 and 65 days in HE and MP buffaloes, respectively. Data analysis was restricted to the first 5 days after PRID removal and to one estrus cycle following induced ovulation. The HE buffaloes were not inseminated and only one ovulated within 5 days after PRID removal; the remainder ovulated between 8 and 48 days after PRID removal (except one in which ovulation was never detected). All HP buffaloes were inseminated 72, 96 and 120 h after PRID removal; seven buffaloes ovulated within 5 days after PRID removal and two were pregnant. Mean diameter of the largest follicle was significantly smaller in HE than MP buffaloes the first 4 days after PRID removal. There was a parity by time interaction ( P=0.0047 ) for plasma progesterone concentrations; progesterone was higher in HE than MP buffaloes 1 day after PRID removal, but the converse was true 2 days after PRID removal. After induced ovulation, HE buffaloes exhibited a one-wave ( n=5; length of cycle, 8-12 days), two-wave ( n=4; range: 20-26 days) or three-wave cycle ( n=1; 25 days). In contrast, all non-pregnant MP buffaloes ( n=8 ) had a two-wave cycle (range: 19-25 days). For buffaloes with two-wave cycles, the growth rate and diameter of the largest follicle was significantly smaller in HE than MP buffaloes for both the first follicular wave (1.3mm versus 1.7 mm per day and 10.5 mm versus 13.3 mm, respectively) and the second follicular wave (1.0 mm versus 1.3 mm per day and 11.0 mm versus 13.8 mm). In conclusion, there were many significant morphological and endocrine differences between HE and MP buffaloes. 相似文献
139.
Cristiana Barbati Marta Vomero Tania Colasanti Marco Diociaiuti Fulvia Ceccarelli Sara Ferrigno Annacarla Finucci Francesca Miranda Lucia Novelli Carlo Perricone Francesca Romana Spinelli Simona Truglia Fabrizio Conti Guido Valesini Cristiano Alessandri 《Arthritis research & therapy》2018,20(1):273
Background
Rheumatoid arthritis (RA) is associated with a high prevalence of atherosclerosis. Recently increased levels of microparticles (MPs) have been reported in patients with RA. MPs could represent a link between autoimmunity and endothelial dysfunction by expressing tumor necrosis factor alpha (TNFα), a key cytokine involved in the pathogenesis of RA, altering endothelial apoptosis and autophagy. The aim of this study was to investigate TNFα expression on MPs and its relationship with endothelial cell fate.Methods
MPs were purified from peripheral blood from 20 healthy controls (HC) and from 20 patients with RA, before (time (T)0) and after (T4) 4-month treatment with etanercept (ETA). Surface expression of TNFα was performed by flow cytometry analysis. EA.hy926 cells, an immortalized endothelial cell line, were treated with RA-MPs purified at T0 and at T4 and also, with RA-MPs in vitro treated with ETA. Apoptosis and autophagy were then evaluated.Results
RA-MPs purified at T0 expressed TNFα on their surface and this expression significantly decreased at T4. Moreover, at T0 RA-MPs, significantly increased both apoptosis and autophagy levels on endothelial cells, in a dose-dependent manner. RA-MPs did not significantly change these parameters after 4 months of in vivo treatment with ETA.Conclusions
Our data demonstrate that MPs isolated from patients with RA exert a pathological effect on endothelial cells by TNFα expressed on their surface. In vivo and in vitro treatment with ETA modulates this effect, suggesting anti-TNF therapy protects against endothelial damage in patients with RA.140.
Alex Reichenbach Romana Stark Mathieu Mequinion Raphael R.G. Denis Jeferson F. Goularte Rachel E. Clarke Sarah H. Lockie Moyra B. Lemus Greg M. Kowalski Clinton R. Bruce Cheng Huang Ralf B. Schittenhelm Randall L. Mynatt Brian J. Oldfield Matthew J. Watt Serge Luquet Zane B. Andrews 《Cell reports》2018,22(7):1745-1759