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排序方式: 共有198条查询结果,搜索用时 109 毫秒
111.
The tetraspanin CD63 regulates ESCRT-independent and -dependent endosomal sorting during melanogenesis 总被引:3,自引:0,他引:3
van Niel G Charrin S Simoes S Romao M Rochin L Saftig P Marks MS Rubinstein E Raposo G 《Developmental cell》2011,21(4):708-721
Cargo sorting to intraluminal vesicles (ILVs) of multivesicular endosomes is required for lysosome-related organelle (LRO) biogenesis. PMEL-a component of melanocyte LROs (melanosomes)-is sorted to ILVs in an ESCRT-independent manner, where it is proteolytically processed and assembled into functional amyloid fibrils during melanosome maturation. Here we show that the tetraspanin CD63 directly participates in ESCRT-independent sorting of the PMEL luminal domain, but not of traditional ESCRT-dependent cargoes, to ILVs. Inactivating CD63 in cell culture or in mice impairs amyloidogenesis and downstream melanosome morphogenesis. Whereas CD63 is required for normal PMEL luminal domain sorting, the disposal of the remaining PMEL transmembrane fragment requires functional ESCRTs but not CD63. In the absence of CD63, the PMEL luminal domain follows this fragment and is targeted for ESCRT-dependent degradation. Our data thus reveal a tight interplay regulated by CD63 between two distinct endosomal ILV sorting processes for a single cargo during LRO biogenesis. 相似文献
112.
Se-Young Oh Caroline G. Balch Rachael L. Cliff Bhawani S. Sharma Herman J. Boermans H. V. L. N. Swamy V. Margaret Quinton Niel A. Karrow 《Mycotoxin Research》2013,29(4):235-243
In this study, the modulation of key enzymes involved in epigenetic regulation was assessed in immortalized bovine macrophages (BoMacs) following in vitro exposure to the following Penicillium mycotoxins: citrinin (CIT), ochratoxin A (OTA), patulin (PAT), mycophenolic acid (MPA), penicillic acid (PA), or a combination of one of the above with OTA at the concentration that inhibits BoMac proliferation by 25 % (IC25). Real-time PCR analysis of the genes coding DNA methyltransferases (DNMTs), histone demethylases (JMJD-3 and UTX), as well as the class-1 histone deacetylases (HDAC?1, ?2, and ?3) and histone acetylase (Bmi-1) was assessed following 6 h of mycotoxin exposure. A change in the expression of JMJD-3 as well as HDAC-3, MPA (p?=?0.1) and PA (p?=?0.08), by at least one of the treatments was observed at their respective IC25. The expression of JMJD-3 was significantly induced by PA, but synergistically suppressed by CIT?+?OTA. The combination of CIT?+?OTA also synergistically suppressed the expression of DNMT-3a and DNMT-3b. The combination of PAT?+?OTA reduced DNMT-3a expression, while PA?+?OTA reduced DNMT-3b expression. Lastly, MPA and PA slightly reduced HDAC-3 expression, while OTA in combination with CIT, PAT, MPA or PA synergistically suppressed HDAC-3 expression. The results of this study demonstrate that Penicillium mycotoxin exposure, specifically OTA and other mycotoxin combinations, can alter the expression of BoMac enzymes that are involved in epigenetic regulation. These findings suggest a potential novel regulatory mechanism by which mycotoxins can modulate macrophage function. 相似文献
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115.
MHC II in Dendritic Cells is Targeted to Lysosomes or T Cell-Induced Exosomes Via Distinct Multivesicular Body Pathways 总被引:1,自引:0,他引:1
Sonja I. Buschow Esther N. M. Nolte-'t Hoen Guillaume van Niel Maaike S. Pols Toine ten Broeke Marjolein Lauwen Ferry Ossendorp Cornelis J. M. Melief Graça Raposo Richard Wubbolts Marca H. M. Wauben Willem Stoorvogel 《Traffic (Copenhagen, Denmark)》2009,10(10):1528-1542
Dendritic cells (DCs) express major histocompatibility complex class II (MHC II) to present peptide antigens to T cells. In immature DCs, which bear low cell surface levels of MHC II, peptide-loaded MHC II is ubiquitinated. Ubiquitination drives the endocytosis and sorting of MHC II to the luminal vesicles of multivesicular bodies (MVBs) for lysosomal degradation. Ubiquitination of MHC II is abrogated in activated DCs, resulting in an increased cell surface expression. We here provide evidence for an alternative MVB sorting mechanism for MHC II in antigen-loaded DCs, which is triggered by cognately interacting antigen-specific CD4+ T cells. At these conditions, DCs generate MVBs with MHC II and CD9 carrying luminal vesicles that are secreted as exosomes and transferred to the interacting T cells. Sorting of MHC II into exosomes was, in contrast to lysosomal targeting, independent of MHC II ubiquitination but rather correlated with its incorporation into CD9 containing detergent-resistant membranes. Together, these data indicate two distinct MVB pathways: one for lysosomal targeting and the other for exosome secretion. 相似文献
116.
Niel van Wyk Riaan den Haan Willem H. van Zyl 《Applied microbiology and biotechnology》2010,87(5):1813-1820
The processive endoglucanase Cel9A of the moderately thermophilic actinomycete Thermobifida fusca was functionally produced in Saccharomyces cerevisiae. Recombinant Cel9A displayed activity on both soluble (carboxymethylcellulose) and insoluble (Avicel) cellulose substrates
confirming its processive endoglucanase activity. High-performance anionic exchange chromatography analyses of soluble sugars
released from Avicel revealed a cellobiose/glucose ratio of 2.5 ± 0.1. Growth by the recombinant strain on amorphous cellulose
was possible due to the sufficient amount of glucose cleaved from the cellulose chain. This is the first confirmed report
of S. cerevisiae growing on a cellulosic substrate as sole carbohydrate source while only expressing one recombinant gene. To improve the
cellulolytic capability of S. cerevisiae and to investigate the level of synergy among cellulases produced by a recombinant host, the cel9A gene was co-expressed with four cellulase-coding genes of Trichoderma reesei: two endoglucanases cel5A (egII) and cel7B (egI), and two cellobiohydrolases cel6A (cbhII) and cel7A (cbhI). Synergy, especially between the Cel9A and the two cellobiohydrolases, resulted in a higher cellulolytic capability of the
recombinant host. 相似文献
117.
Frederic Cedrone Sebastien Niel Sanja Roca Tej Bhatnagar Nadra Ait-abdelkader Claudia Torre Holger Krumm Andrea Maichele Manfred T. Reetz Jacques C. Baratti 《Biocatalysis and Biotransformation》2003,21(6):357-364
An efficient and genetically stable expression system for the directed evolution of epoxide hydrolase from Aspergillus niger (ANEH) has been constructed. Error prone polymerase chain reaction (PCR) with defined mutation rates was used to create biodiversity in two libraries of mutants. Screening for activity allowed the isolation of clones with improved properties. One of these clones shows an expression level 3.4 higher than the original wild type clone in E. coli SG13009 and a 3.3 fold increased catalytic efficiency on 4-(p-nitrophenoxy)-1,2-epoxybutane. In addition, a screening assay for determining the enantioselectivity in the kinetic resolution of styrene oxide has been established using mass spectrometry. 相似文献
118.
Hydrogenomics of the Extremely Thermophilic Bacterium Caldicellulosiruptor saccharolyticus
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Harmen J. G. van de Werken Marcel R. A. Verhaart Amy L. VanFossen Karin Willquist Derrick L. Lewis Jason D. Nichols Heleen P. Goorissen Emmanuel F. Mongodin Karen E. Nelson Ed W. J. van Niel Alfons J. M. Stams Donald E. Ward Willem M. de Vos John van der Oost Robert M. Kelly Serv W. M. Kengen 《Applied microbiology》2008,74(21):6720-6729
119.
High prevalence of human Torque teno virus in streams crossing the city of Manaus, Brazilian Amazon 总被引:1,自引:0,他引:1
Aims: Torque teno virus (TTV) is a human DNA virus chronically infecting most healthy individuals worldwide and can be transmitted by faecal–oral route. The occurrence of TTV was evaluated in the streams crossing the city of Manaus (Brazilian Amazon) over a 1-year period, four times a year.
Methods and Results: Fifty-two water samples were collected from 13 different locations. Viruses were concentrated from two litres of water by adsorption to negative membrane filters followed by ultrafiltration. TTV DNA was detected by PCR assays designed to detect all five TTV genomic groups. By conventional PCR, 19/52 (37%) samples were positive. By real-time PCR, TTV DNA could be detected in 48/52 (92%) samples. Viral loads ranged from 1300 to 746 000 genome equivalent per 100 ml of river water. Eleven distinct nucleotide sequences were obtained.
Conclusions: Our results show the wide distribution and diversity of TTV among Manaus urban micro basins.
Significance and Impact of the Study: The data presented here may contribute to substantiate TTV as a sensitive indicator of human contamination. 相似文献
Methods and Results: Fifty-two water samples were collected from 13 different locations. Viruses were concentrated from two litres of water by adsorption to negative membrane filters followed by ultrafiltration. TTV DNA was detected by PCR assays designed to detect all five TTV genomic groups. By conventional PCR, 19/52 (37%) samples were positive. By real-time PCR, TTV DNA could be detected in 48/52 (92%) samples. Viral loads ranged from 1300 to 746 000 genome equivalent per 100 ml of river water. Eleven distinct nucleotide sequences were obtained.
Conclusions: Our results show the wide distribution and diversity of TTV among Manaus urban micro basins.
Significance and Impact of the Study: The data presented here may contribute to substantiate TTV as a sensitive indicator of human contamination. 相似文献
120.
Mangeney N Niel P Paul G Faubert E Hue S Dupeyron C Louarn F Leluan G 《Journal of applied microbiology》2000,88(3):504-511
Thirty-eight different strains of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae (ESBL Kp), isolated from urine and pus samples of 38 patients hospitalized in a medium- and long-stay neurology department between 1 January 1992 and 31 December 1996, were analysed by antibiotic resistance phenotyping, DNA macrorestriction by pulsed-field electrophoresis and isoelectric focusing of beta-lactamases. An epidemiological survey was conducted to identify risk factors for infection by ESBL Kp in this setting. The 38 isolates were distributed into 13 antibiotypes, three of which predominated (13, six and six isolates). The DNA macrorestriction pattern identified 15 genotypes, four of which predominated (11, six, four and four isolates). A combination of the two typing methods revealed several epidemic clones that emerged consecutively. Two main types of ESBL (SHV-2 and CTX-1) were identified by isoelectric focusing, the former predominating. The case-control study showed that the length of hospital stay, degree of malnutrition and dependency, and urinary sphincter status were the main factors significantly associated with ESBL Kp isolation. 相似文献