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31.
Olivier Véron Jean-Philippe Blondeau Michał Grabiec Aleksandra Wolak Krzystof Dzierżęga Nadège Ollier François Goutaland Mohamed Chérif Sow Stéphane Pellerin Nadia Pellerin 《Plasmonics (Norwell, Mass.)》2013,8(1):93-103
Silver-exchanged silicate glass has been irradiated by 532-nm pulsed Nd:YAG laser in order to locally form metallic nanoparticles. The particular interest of this process is to locally control the silver nanoparticles (NPs) growth. Silver ions are exchanged with sodium ions near the glass surface after dumping of a silicate glass few minutes in silver and sodium nitrates molten salt. A low-energy density laser exposure (0.239 J/cm2) chosen at the ablation threshold allows to observe the kinetics of the silver NPs growth according to the increasing shots number. An on-line optical measurement is carried out after each shot to identify the most important steps during the irradiation process. According to this measurement, we have determined four steps highlighted by UV/Visible spectrophotometry and we have identified the influence of located surface plasmon resonance. Three combined material analysis methods were used to understand the glass/laser interaction mechanism: we outlined the material volume variations by profilometric method, the element distribution by scanning electron microscopy and finally the structural distribution of the irradiated region by a local infrared investigation. The trend for NPs formation revealed by the UV/Visible spectrophotometry is thus explained by the formation of a ring expelled from a central hole. We highlight that the on-line extinction measurement can be used to data process the NPs evolution. 相似文献
32.
Tom V. Lee Maya K. Sethi Jessica Leonardi Nadia A. Rana Falk F. R. Buettner Robert S. Haltiwanger Hans Bakker Hamed Jafar-Nejad 《PLoS genetics》2013,9(6)
The Notch signaling pathway controls a large number of processes during animal development and adult homeostasis. One of the conserved post-translational modifications of the Notch receptors is the addition of an O-linked glucose to epidermal growth factor-like (EGF) repeats with a C-X-S-X-(P/A)-C motif by Protein O-glucosyltransferase 1 (POGLUT1; Rumi in Drosophila). Genetic experiments in flies and mice, and in vivo structure-function analysis in flies indicate that O-glucose residues promote Notch signaling. The O-glucose residues on mammalian Notch1 and Notch2 proteins are efficiently extended by the addition of one or two xylose residues through the function of specific mammalian xylosyltransferases. However, the contribution of xylosylation to Notch signaling is not known. Here, we identify the Drosophila enzyme Shams responsible for the addition of xylose to O-glucose on EGF repeats. Surprisingly, loss- and gain-of-function experiments strongly suggest that xylose negatively regulates Notch signaling, opposite to the role played by glucose residues. Mass spectrometric analysis of Drosophila Notch indicates that addition of xylose to O-glucosylated Notch EGF repeats is limited to EGF14–20. A Notch transgene with mutations in the O-glucosylation sites of Notch EGF16–20 recapitulates the shams loss-of-function phenotypes, and suppresses the phenotypes caused by the overexpression of human xylosyltransferases. Antibody staining in animals with decreased Notch xylosylation indicates that xylose residues on EGF16–20 negatively regulate the surface expression of the Notch receptor. Our studies uncover a specific role for xylose in the regulation of the Drosophila Notch signaling, and suggest a previously unrecognized regulatory role for EGF16–20 of Notch. 相似文献
33.
Nadia Mhedbi-Hajri Ahmed Hajri Tristan Boureau Armelle Darrasse Karine Durand Chrystelle Brin Marion Fischer-Le Saux Charles Manceau Stéphane Poussier Olivier Pruvost Christophe Lemaire Marie-Agnès Jacques 《PloS one》2013,8(3)
Deciphering mechanisms shaping bacterial diversity should help to build tools to predict the emergence of infectious diseases. Xanthomonads are plant pathogenic bacteria found worldwide. Xanthomonas axonopodis is a genetically heterogeneous species clustering, into six groups, strains that are collectively pathogenic on a large number of plants. However, each strain displays a narrow host range. We address the question of the nature of the evolutionary processes – geographical and ecological speciation – that shaped this diversity. We assembled a large collection of X. axonopodis strains that were isolated over a long period, over continents, and from various hosts. Based on the sequence analysis of seven housekeeping genes, we found that recombination occurred as frequently as point mutation in the evolutionary history of X. axonopodis. However, the impact of recombination was about three times greater than the impact of mutation on the diversity observed in the whole dataset. We then reconstructed the clonal genealogy of the strains using coalescent and genealogy approaches and we studied the diversification of the pathogen using a model of divergence with migration. The suggested scenario involves a first step of generalist diversification that spanned over the last 25 000 years. A second step of ecology-driven specialization occurred during the past two centuries. Eventually, secondary contacts between host-specialized strains probably occurred as a result of agricultural development and intensification, allowing genetic exchanges of virulence-associated genes. These transfers may have favored the emergence of novel pathotypes. Finally, we argue that the largest ecological entity within X. axonopodis is the pathovar. 相似文献
34.
Julie In Valeriy Lukyanenko Jennifer Foulke-Abel Ann L. Hubbard Michael Delannoy Anne-Marie Hansen James B. Kaper Nadia Boisen James P. Nataro Chengru Zhu Edgar C. Boedeker Jorge A. Girón Olga Kovbasnjuk 《PloS one》2013,8(7)
Life-threatening intestinal and systemic effects of the Shiga toxins produced by enterohemorrhagic Escherichia coli (EHEC) require toxin uptake and transcytosis across intestinal epithelial cells. We have recently demonstrated that EHEC infection of intestinal epithelial cells stimulates toxin macropinocytosis, an actin-dependent endocytic pathway. Host actin rearrangement necessary for EHEC attachment to enterocytes is mediated by the type 3 secretion system which functions as a molecular syringe to translocate bacterial effector proteins directly into host cells. Actin-dependent EHEC attachment also requires the outer membrane protein intimin, a major EHEC adhesin. Here, we investigate the role of type 3 secretion in actin turnover occurring during toxin macropinocytosis. Toxin macropinocytosis is independent of EHEC type 3 secretion and intimin attachment. EHEC soluble factors are sufficient to stimulate macropinocytosis and deliver toxin into enterocytes in vitro and in vivo; intact bacteria are not required. Intimin-negative enteroaggregative Escherichia coli (EAEC) O104:H4 robustly stimulate Shiga toxin macropinocytosis into intestinal epithelial cells. The apical macropinosomes formed in intestinal epithelial cells move through the cells and release their cargo at these cells’ basolateral sides. Further analysis of EHEC secreted proteins shows that a serine protease EspP alone is able to stimulate host actin remodeling and toxin macropinocytosis. The observation that soluble factors, possibly serine proteases including EspP, from each of two genetically distinct toxin-producing strains, can stimulate Shiga toxin macropinocytosis and transcellular transcytosis alters current ideas concerning mechanisms whereby Shiga toxin interacts with human enterocytes. Mechanisms important for this macropinocytic pathway could suggest new potential therapeutic targets for Shiga toxin-induced disease. 相似文献
35.
Aleksandar Zocevic Fabien Vorimore Nadia Vicari Julien Gasparini Lisa Jacquin Konrad Sachse Simone Magnino Karine Laroucau 《PloS one》2013,8(3)
Recent evidence of the occurrence of atypical Chlamydiaceae strains in pigeons, different from the established Chlamydiaceae, requires the development of a specific and rapid detection tool to investigate their prevalence and significance. Here is described a new real-time PCR assay that allows specific detection of atypical Chlamydiaceae from pigeons. The assay has been used to assess the dissemination of these strains in field samples collected from Parisian pigeon populations in 2009. The results suggest a limited dissemination compared to the usually higher prevalence of Chlamydia psittaci that is the main species associated with avian chlamydiosis. 相似文献
36.
Yara Koréissi-Dembélé Nadia Fanou-Fogny Diego Moretti Stephan Schuth Romain A. M. Dossa Ines Egli Michael B. Zimmermann Inge D. Brouwer 《PloS one》2013,8(10)
Low iron and high phytic acid content make fonio based meals a poor source of bioavailable iron. Phytic acid degradation in fonio porridge using whole grain cereals as phytase source and effect on iron bioavailability when added to iron fortified fonio meals were investigated. Grains, nuts and seeds collected in Mali markets were screened for phytic acid and phytase activity. We performed an iron absorption study in Beninese women (n = 16), using non-dephytinised fonio porridge (FFP) and dephytinised fonio porridge (FWFP; 75% fonio-25% wheat), each fortified with 57Fe or 58Fe labeled FeSO4. Iron absorption was quantified by measuring the erythrocyte incorporation of stable iron isotopes. Phytic acid varied from 0.39 (bambara nut) to 4.26 g/100 g DM (pumpkin seed), with oilseeds values higher than grains and nuts. Phytase activity ranged from 0.17±1.61 (fonio) to 2.9±1.3 phytase unit (PU) per g (whole wheat). Phytic acid was almost completely degraded in FWFP after 60 min of incubation (pH≈5.0, 50°C). Phytate∶iron molar ratios decreased from 23.7∶1 in FFP to 2.7∶1 in FWFP. Iron fortification further reduced phytate∶iron molar ratio to 1.9∶1 in FFP and 0.3∶1 in FWFP, respectively. Geometric mean (95% CI) iron absorption significantly increased from 2.6% (0.8–7.8) in FFP to 8.3% (3.8–17.9) in FWFP (P<0.0001). Dephytinisation of fonio porridge with intrinsic wheat phytase increased fractional iron absorption 3.2 times, suggesting it could be a possible strategy to decrease PA in cereal-based porridges. 相似文献
37.
Martin J. MacInnis Eric A. Carter Michael G. Freeman Bidur Prasad Pandit Ashmita Siwakoti Ankita Subedi Utsav Timalsina Nadia Widmer Ghan Bahadur Thapa Michael S. Koehle Jim L. Rupert 《PloS one》2013,8(10)
Background
Each year, thousands of pilgrims travel to the Janai Purnima festival in Gosainkunda, Nepal (4380 m), ascending rapidly and often without the aid of pharmaceutical prophylaxis.Methods
During the 2012 Janai Purnima festival, 538 subjects were recruited in Dhunche (1950 m) before ascending to Gosainkunda. Through interviews, subjects provided demographic information, ratings of AMS symptoms (Lake Louise Scores; LLS), ascent profiles, and strategies for prophylaxis.Results
In the 491 subjects (91% follow-up rate) who were assessed upon arrival at Gosainkunda, the incidence of AMS was 34.0%. AMS was more common in females than in males (RR = 1.57; 95% CI = 1.23, 2.00), and the AMS incidence was greater in subjects >35 years compared to subjects ≤35 years (RR = 1.63; 95% CI = 1.36, 1.95). There was a greater incidence of AMS in subjects who chose to use garlic as a prophylactic compared to those who did not (RR = 1.69; 95% CI = 1.26, 2.28). Although the LLS of brothers had a moderate correlation (intraclass correlation = 0.40, p = 0.023), sibling AMS status was a weak predictor of AMS.Conclusions
The incidence of AMS upon reaching 4380 m was 34% in a large population of Nepalese pilgrims. Sex, age, and ascent rate were significant factors in the development of AMS, and traditional Nepalese remedies were ineffective in the prevention of AMS. 相似文献38.
Abdel-Magied Nadia Elkady Ahmed A. Abdel Fattah Salma M. 《Biological trace element research》2020,193(2):410-413
Biological Trace Element Research - This report explains the employing of a combination test of traditional cell culture with a quantitative real-time PCR for assessment of the antiviral effect of... 相似文献
39.
Nadia M. S. Arafa Mona Abdel-Rahman Manal F. El-khadragy Rami B. Kassab 《Neurochemical research》2013,38(1):174-185
The neuroprotective effect of Nigella sativa (NS) on amino acid neurotransmitters alteration in pentylenetetrazole (PTZ) and ciprofloxacin (CFX) treated rats in different brain regions was examined. The oral administration of NS induced an elevation in aspartate and glutamate contents, whereas the levels of GABA and glycine were decreased. Furthermore, the treated groups with PTZ and CFX caused a decrease in aspartate, glutamate and total antioxidant capacity levels, while the concentrations of GABA and glycine were increased after 14 days. Moreover, the pre- and post-treatment with NS in PTZ and CFX treated rats return the levels of these parameters near control values. So, it could be concluded that the treatment with CFX induced imbalance between the excitatory and the inhibitory amino acids which may lead to the initiation of epileptic seizures and the treatment with NS was found to ameliorate these neurological defects which reflect its potent antiepileptic activity. 相似文献
40.
Alistair N. Hume Anne John Nadia A. Akawi Aydah M. Al-Awadhi Sarah S. Al-Suwaidi Lihadh Al-Gazali Bassam R. Ali 《Molecular and cellular biochemistry》2013,373(1-2):247-257
Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant disease characterised by vascular dysplasia and increased bleeding that affect 1 in 5,000 people world-wide. Pathology is linked to mutations in genes encoding components of the heteromeric transforming growth factor-beta receptor (TGF-beta) and SMAD signalling pathway. Indeed HHT1 and HHT2 result from mutations in the genes encoding endoglin and activin-like kinase 1 (ALK1), TGF-beta receptor components. However, the fundamental cellular defects underlying HHT is poorly understood. Previously using confocal microscopy and N-glycosylation analysis, we found evidence that defective trafficking of endoglin from the endoplasmic reticulum (ER) to the plasma membrane is a mechanism underlying HHT1 in some patients. In this study, we used confocal microscopy to investigate whether a similar mechanism contributes to HHT2 pathology. To do this we expressed wild-type ALK1 and a number of HHT2 patient mutant variants as C-terminally tagged EGFP fusion proteins and tested their localisation in HeLa cells. We found that wild-type ALK1–EGFP was targeted predominantly to the plasma membrane, as evidenced by its colocalisation with the co-expressed HA-tagged endoglin. However, we found that in the majority of cases analysed the HHT2 patient mutant protein was retained within the ER as indicated by their colocalisation with the ER resident marker (calnexin) and lack of colocalisation with cell surface associated HA-endoglin. We conclude that defective trafficking and retention in the ER of mutant ALK1 protein is a possible mechanism of HHT2 in some patients. 相似文献