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排序方式: 共有163条查询结果,搜索用时 15 毫秒
91.
Iain L. Mainprize Jordan D. Bean Catrien Bouwman Matthew S. Kimber Chris Whitfield 《The Journal of biological chemistry》2013,288(32):23064-23074
UDP-glucose dehydrogenase (Ugd) generates UDP-glucuronic acid, an important precursor for the production of many hexuronic acid-containing bacterial surface glycostructures. In Escherichia coli K-12, Ugd is important for biosynthesis of the environmentally regulated exopolysaccharide known as colanic acid, whereas in other E. coli isolates, the same enzyme is required for production of the constitutive group 1 capsular polysaccharides, which act as virulence determinants. Recent studies have implicated tyrosine phosphorylation in the activation of Ugd from E. coli K-12, although it is not known if this is a feature shared by bacterial Ugd proteins. The activities of Ugd from E. coli K-12 and from the group 1 capsule prototype (serotype K30) were compared. Surprisingly, for both enzymes, site-directed Tyr → Phe mutants affecting the previously proposed phosphorylation site retained similar kinetic properties to the wild-type protein. Purified Ugd from E. coli K-12 had significant levels of NAD substrate inhibition, which could be alleviated by the addition of ATP and several other nucleotide triphosphates. Mutations in a previously identified UDP-glucuronic acid allosteric binding site decreased the binding affinity of the nucleotide triphosphate. Ugd from E. coli serotype K30 was not inhibited by NAD, but its activity still increased in the presence of ATP. 相似文献
92.
Limonard GJ Thijsen SF Bossink AW Asscheman A Bouwman JJ 《FEMS immunology and medical microbiology》2012,64(1):57-60
Definitively establishing a clinical diagnosis of chronic Q fever remains challenging, as the diagnostic performance of both conventional serological tests and PCR is limited. Given the importance of an early diagnosis of chronic Q fever, there is a need for a reliable diagnostic test. We developed an enzyme-linked immunospot assay to measure Coxiella burnetii (C.?burnetii)-specific T-cell responses (Coxiella ELISPOT) to both phase I and phase II antigens and tested convalescent Q fever patients (without chronic disease, n?=?9) and patients with an established diagnosis of chronic Q fever (n?=?3). The Coxiella ELISPOT adequately identified convalescent Q fever patients from healthy controls by demonstrating C.?burnetii-specific T-cell interferon-γ production to both phase I and phase II antigens. Compared to convalescent Q fever patients, chronic Q fever patients showed a distinct Coxiella ELISPOT profile characterized by a much higher spot count for both phase I and phase II (18-fold for phase II, 8-fold higher for phase I) and a consistent shift towards more phase I reactivity. The diagnostic potential of the Coxiella ELISPOT is promising and warrants further investigation. 相似文献
93.
Jiannan Cui Coco Duizer Lieneke I. Bouwman Kristel S. van Rooijen Carlos G. P. Voogdt Jos P. M. van Putten Marcel R. de Zoete 《PLoS pathogens》2021,17(8)
The Gram-negative bacterium Campylobacter jejuni is a major cause of foodborne disease in humans. After infection, C. jejuni rapidly colonizes the mucus layer of the small and large intestine and induces a potent pro-inflammatory response characterized by the production of a large repertoire of cytokines, chemokines, and innate effector molecules, resulting in (bloody) diarrhea. The virulence mechanisms by which C. jejuni causes this intestinal response are still largely unknown. Here we show that C. jejuni releases a potent pro-inflammatory compound into its environment, which activates an NF-κB-mediated pro-inflammatory response including the induction of CXCL8, CXCL2, TNFAIP2 and PTGS2. This response was dependent on a functional ALPK1 receptor and independent of Toll-like Receptor and Nod-like Receptor signaling. Chemical characterization, inactivation of the heptose-biosynthesis pathway by the deletion of the hldE gene and in vitro engineering identified the released factor as the LOS-intermediate ADP-heptose and/or related heptose phosphates. During C. jejuni infection of intestinal cells, the ALPK1-NF-κB axis was potently activated by released heptose metabolites without the need for a type III or type IV injection machinery. Our results classify ADP-heptose and/or related heptose phosphates as a major virulence factor of C. jejuni that may play an important role during Campylobacter infection in humans. 相似文献
94.
H. Bouwman 《Ostrich》2013,84(1-2)
Bouwman, H. 2000. Perforations in the tail features of parasitic Cuckoos. Ostrich 71 (1 & 2): 126. Perforations in the tail feathers of parasitic cuckoos have been observed in both live and museum specimens. These perforations occurring in the vane of the feather, are longitudinally arranged, and in many cases evenly spaced. The position, arrangement and spacing suggest that the perforations were not caused by feather mites. Anecdotal evidence and literature suggests that these perforations are probably caused by host birds during confrontations. Quantification of perforations in terms of species, age, sex, increase in damage during the breeding season, and in damage from breeding and non-breeding areas, supports this hypothesis. The parasitic species that parasitisc birds with stronger beaks (weavers and shrikes) tended to have more damage. 相似文献
95.
Haanstra JR Kerkhoven EJ van Tuijl A Blits M Wurst M van Nuland R Albert MA Michels PA Bouwman J Clayton C Westerhoff HV Bakker BM 《Molecular microbiology》2011,79(1):94-108
Awareness is growing that drug target validation should involve systems analysis of cellular networks. There is less appreciation, though, that the composition of networks may change in response to drugs. If the response is homeostatic (e.g. through upregulation of the target protein), this may neutralize the inhibitory effect. In this scenario the effect on cell growth and survival would be less than anticipated based on affinity of the drug for its target. Glycolysis is the sole free-energy source for the deadly parasite Trypanosoma brucei and is therefore a possible target pathway for anti-trypanosomal drugs. Plasma-membrane glucose transport exerts high control over trypanosome glycolysis and hence the transporter is a promising drug target. Here we show that at high inhibitor concentrations, inhibition of trypanosome glucose transport causes cell death. Most interestingly, sublethal concentrations initiate a domino effect in which network adaptations enhance inhibition. This happens via (i) metabolic control exerted by the target protein, (ii) decreases in mRNAs encoding the target protein and other proteins in the same pathway, and (iii) partial differentiation of the cells leading to (low) expression of immunogenic insect-stage coat proteins. We discuss how these 'anti-homeostatic' responses together may facilitate killing of parasites at an acceptable drug dosage. 相似文献
96.
Hu C Wei H van den Hoek AM Wang M van der Heijden R Spijksma G Reijmers TH Bouwman J Wopereis S Havekes LM Verheij E Hankemeier T Xu G van der Greef J 《PloS one》2011,6(5):e19423
Background
Lipids are known to play crucial roles in the development of life-style related risk factors such as obesity, dyslipoproteinemia, hypertension and diabetes. The first selective cannabinoid-1 receptor blocker rimonabant, an anorectic anti-obesity drug, was frequently used in conjunction with diet and exercise for patients with a body mass index greater than 30 kg/m2 with associated risk factors such as type II diabetes and dyslipidaemia in the past. Less is known about the impact of this drug on the regulation of lipid metabolism in plasma and liver in the early stage of obesity.Methodology/Principal Findings
We designed a four-week parallel controlled intervention on apolipoprotein E3 Leiden cholesteryl ester transfer protein (ApoE*3Leiden.CETP) transgenic mice with mild overweight and hypercholesterolemia. A liquid chromatography–linear ion trap-Fourier transform ion cyclotron resonance-mass spectrometric approach was employed to investigate plasma and liver lipid responses to the rimonabant intervention. Rimonabant was found to induce a significant body weight loss (9.4%, p<0.05) and a significant plasma total cholesterol reduction (24%, p<0.05). Six plasma and three liver lipids in ApoE*3Leiden.CETP transgenic mice were detected to most significantly respond to rimonabant treatment. Distinct lipid patterns between the mice were observed for both plasma and liver samples in rimonabant treatment vs. non-treated controls. This study successfully applied, for the first time, systems biology based lipidomics approaches to evaluate treatment effects of rimonabant in the early stage of obesity.Conclusion
The effects of rimonabant on lipid metabolism and body weight reduction in the early stage obesity were shown to be moderate in ApoE*3Leiden.CETP mice on high-fat diet. 相似文献97.
Claudine Nieuwoudt Rialet Pieters Laura P. Quinn Henrik Kylin Anders R. Borgen Henk Bouwman 《Soil & Sediment Contamination》2011,20(2):188-204
Polycyclic aromatic hydrocarbons (PAHs) are of global concern due to their ubiquitous presence, toxicity, and carcinogenicity. No data on PAHs in soils from South Africa have been published, even though it has the largest economy and industrial base in Africa. During this initial assessment, the levels of PAHs were determined in soils and sediments collected from central South Africa, specifically targeting industrial, residential, and agricultural areas. Analysis was performed by gas chromatography/mass spectrometry (GC/MS). The total concentration of PAHs (Σt-PAH) ranged between 44 and 39,000 ng/g, dw and the concentration of carcinogenic PAHs (Σc-PAH) ranged between 19 and 19,000 ng/g, dw. Pyrogenic processes were the most likely sources, with minimal petrogenic contributions. PAH levels were in the same range as levels reported from other countries, and the majority of the sites did not exceed Canadian environmental quality guidelines. Based on assumptions for dermal contact and ingestion of PAH-contaminated soil, we provisionally calculated only a small increase in cancer risk, but additional PAH inhalation could add considerably to this risk. Our data indicates a need for more analysis in industrial and residential areas, and should include air. 相似文献
98.
Freek G. Bouwman Jolanda M. A. Boer Sandra Imholz Ping Wang W. M. Monique Verschuren Martijn E. T. Dollé Edwin C. M. Mariman 《Genes & nutrition》2014,9(6)
Weight gain, when it leads to overweight or obesity, is nowadays one of the major health problems. ACE, FTO, AKR1C2, TIMP4 and MMP2 genes have been implicated in previous studies on weight regulation. This study investigated the contribution of polymorphisms in these five candidate genes to the risk of weight gain over a 10-year time period. Two groups were selected from participants of the Doetinchem cohort study who were followed over a 10-year period: A stable weight group (±2 kg/10 year; n = 259) and a weight gainers group who increased their body weight by roughly 10 % (>8 kg/10 year; n = 237). Starting BMI was between 20 and 35 kg/m2 and baseline age between 20 and 45 years. Selected SNPs and insert/deletion in candidate genes were measured in each group. In men, the allelic distribution of FTO rs9939609 (χ2p = 0.005), ACE rs4340 (χ2p = 0.006) and AKR1C2 rs12249281 (χ2p = 0.019) differed between the weight stable and weight gainers group. Interaction between FTO rs9939609 and ACE rs4340 was observed. In women, the allelic distribution of MMP2 rs1132896 differed between the weight stable and weight gainers group (χ2p = 0.00001). The A-allele of FTO was associated with a 1.99× higher risk of gaining weight in men (OR 1.99, p = 0.020), while in women, the C-allele of MMP2 was associated with a 2.50× higher risk of weight gain (OR 2.50, p = 0.001) over the 10-year period. We found that FTO in men and MMP2 in women are associated with weight gain over a 10-year follow-up period.
Electronic supplementary material
The online version of this article (doi:10.1007/s12263-014-0434-2) contains supplementary material, which is available to authorized users. 相似文献99.
Kim M. Bouwman Ilhan Tomris Hannah L. Turner Roosmarijn van der Woude Tatiana M. Shamorkina Gerlof P. Bosman Barry Rockx Sander Herfst Joost Snijder Bart L. Haagmans Andrew B. Ward Geert-Jan Boons Robert P. de Vries 《PLoS pathogens》2021,17(2)
Receptor binding studies on sarbecoviruses would benefit from an available toolkit of recombinant spike proteins, or domains thereof, that recapitulate receptor binding properties of native viruses. We hypothesized that trimeric Receptor Binding Domain (RBD) proteins would be suitable candidates to study receptor binding properties of SARS-CoV-1 and -2. Here we created monomeric and trimeric fluorescent RBD proteins, derived from adherent HEK293T, as well as in GnTI-/- mutant cells, to analyze the effect of complex vs high mannose glycosylation on receptor binding. The results demonstrate that trimeric, complex glycosylated proteins are superior in receptor binding compared to monomeric and immaturely glycosylated variants. Although differences in binding to commonly used cell lines were minimal between the different RBD preparations, substantial differences were observed when respiratory tissues of experimental animals were stained. The RBD trimers demonstrated distinct ACE2 expression profiles in bronchiolar ducts and confirmed the higher binding affinity of SARS-CoV-2 over SARS-CoV-1. Our results show that complex glycosylated trimeric RBD proteins are attractive to analyze sarbecovirus receptor binding and explore ACE2 expression profiles in tissues. 相似文献
100.
Freek G. Bouwman Mireille M.E. van Ginneken Jean-Paul Noben Erik Royackers Ellen de Graaf-Roelfsema Inge D. Wijnberg Johannes H. van der Kolk Edwin C.M. Mariman Eric van Breda 《Comparative biochemistry and physiology. Part D, Genomics & proteomics》2010,5(1):55-64
The major aim of the present study was to investigate the proteome of standardbred horses at different stages of training and intensified training. We searched for biomarkers using small skeletal muscle biopsies of live animals. 2D gel electrophoresis and mass spectrometry were successfully applied to investigate training-induced differential expression of equine muscle biopsy proteins. Despite the poor resolution of the equine genome and proteome, we were able to identify the proteins of 20 differential spots representing 16 different proteins. Evaluation of those proteins complies with adaptation of the skeletal muscle after normal training involving structural changes towards a higher oxidative capacity, an increased capacity to take up long-chain fatty acids, and to store energy in the form of glycogen. Intensified training leads to additional changed spots. Alpha-1-antitrypsin was found increased after intensified training but not after normal training. This protein may thus be considered as a marker for overtraining in horses and also linked to overtraining in human athletes. 相似文献