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61.
Jean-Daniel Bontemps Jean-Christophe Herv�� Jean-Michel Leban Jean-Fran?ois Dh?te 《Trees - Structure and Function》2011,25(2):237-251
Environmental drivers of forest productivity increases have been much debated. Evidence for the suggested role of increasing
nitrogen supply is lacking over long-term time scales. Tracking the footprint of environmental factors by using long-term
growth records may thus prove decisive. We analysed growth chronologies of common beech in two areas of contrasting nutritional
status in France. Dominant height growth was used as a proxy for productivity. Growth was compared between old and young paired
stands sampled at the same sites to factor out effects of ageing and site. Growth chronologies were estimated with a statistical
modelling procedure. The environmental causality of growth changes was addressed by combining (1) a comparison of growth changes
between regions, (2) a regional comparison of growth chronologies with chronologies of environmental factors and (3) growth–environment
relationships established from climate/soil data. Historical growth increases followed very similar courses in the two areas.
Remarkably, the magnitude of change was 50% lower in the area that had reduced nutritional status and nitrogen deposition.
Historical variations in environmental factors and growth were congruent with the roles of nitrogen availability and deposition,
and of atmospheric CO2 increase. Low-frequency variations in climate and growth were not coincident. However, our analysis demonstrated the role
of climatic anomalies in short-term growth variations. Growth–environment relationships further indicated a nitrogen constraint.
These observations corroborate the enhancing role of increased nitrogen availability on forest biomass accumulation previously
reported in ecosystem experiments and process-based modelling explorations. 相似文献
62.
63.
Nicolas Chemidlin Prévost-Bouré Samuel Dequiedt Jean Thioulouse Mélanie Lelièvre Nicolas P. A. Saby Claudy Jolivet Dominique Arrouays Pierre Plassart Philippe Lemanceau Lionel Ranjard 《PloS one》2014,9(11)
Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2): i) to examine their spatial structuring; ii) to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii) to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (Landes<Burgundy≤Brittany<<South-East) using the systematic grid of French Soil Quality Monitoring Network to evaluate the communities’ composition turnovers. The relative importance of processes and filters was assessed by distance-based redundancy analysis. This study demonstrates significant community composition turnover rates for soil bacteria and fungi, which were dependent on the region. Bacterial and fungal community composition turnovers were mainly driven by environmental selection explaining from 10% to 20% of community composition variations, but spatial variables also explained 3% to 9% of total variance. These variables highlighted significant spatial autocorrelation of both communities unexplained by the environmental variables measured and could partly be explained by dispersal limitations. Although the identified filters and their hierarchy were dependent on the region and organism, selection was systematically based on a common group of environmental variables: pH, trophic resources, texture and land use. Spatial autocorrelation was also important at coarse (80 to 120 km radius) and/or medium (40 to 65 km radius) spatial scales, suggesting dispersal limitations at these scales. 相似文献
64.
Ling Chun Kong Bridget A. Holmes Aurelie Cotillard Fatiha Habi-Rachedi Rémi Brazeilles Sophie Gougis Nicolas Gausserès Patrice D. Cani Soraya Fellahi Jean-Philippe Bastard Sean P. Kennedy Joel Doré Stanislav Dusko Ehrlich Jean-Daniel Zucker Salwa W. Rizkalla Karine Clément 《PloS one》2014,9(10)
Background
Associations between dietary patterns, metabolic and inflammatory markers and gut microbiota are yet to be elucidated.Objectives
We aimed to characterize dietary patterns in overweight and obese subjects and evaluate the different dietary patterns in relation to metabolic and inflammatory variables as well as gut microbiota.Design
Dietary patterns, plasma and adipose tissue markers, and gut microbiota were evaluated in a group of 45 overweight and obese subjects (6 men and 39 women). A group of 14 lean subjects were also evaluated as a reference group.Results
Three clusters of dietary patterns were identified in overweight/obese subjects. Cluster 1 had the least healthy eating behavior (highest consumption of potatoes, confectionary and sugary drinks, and the lowest consumption of fruits that was associated also with low consumption of yogurt, and water). This dietary pattern was associated with the highest LDL cholesterol, plasma soluble CD14 (p = 0.01) a marker of systemic inflammation but the lowest accumulation of CD163+ macrophages with anti-inflammatory profile in adipose tissue (p = 0.05). Cluster 3 had the healthiest eating behavior (lower consumption of confectionary and sugary drinks, and highest consumption of fruits but also yogurts and soups). Subjects in this Cluster had the lowest inflammatory markers (sCD14) and the highest anti-inflammatory adipose tissue CD163+ macrophages. Dietary intakes, insulin sensitivity and some inflammatory markers (plasma IL6) in Cluster 3 were close to those of lean subjects. Cluster 2 was in-between clusters 1 and 3 in terms of healthfulness. The 7 gut microbiota groups measured by qPCR were similar across the clusters. However, the healthiest dietary cluster had the highest microbial gene richness, as evaluated by quantitative metagenomics.Conclusion
A healthier dietary pattern was associated with lower inflammatory markers as well as greater gut microbiota richness in overweight and obese subjects.Trial Registration
ClinicalTrials.gov NCT01314690相似文献65.
Sodium- and potassium-activated adenosine triphosphatases (Na,K-ATPase) is the ubiquitous active transport system that maintains
the Na+ and K+ gradients across the plasma membrane by exchanging three intracellular Na+ ions against two extracellular K+ ions. In addition to the two cation binding sites homologous to the calcium site of sarcoplasmic and endoplasmic reticulum
calcium ATPase and which are alternatively occupied by Na+ and K+ ions, a third Na+-specific site is located close to transmembrane domains 5, 6 and 9, and mutations close to this site induce marked alterations
of the voltage-dependent release of Na+ to the extracellular side. In the absence of extracellular Na+ and K+, Na,K-ATPase carries an acidic pH-activated, ouabain-sensitive “leak” current. We investigated the relationship between the
third Na+ binding site and the pH-activated current. The decrease (in E961A, T814A and Y778F mutants) or the increase (in G813A mutant)
of the voltage-dependent extracellular Na+ affinity was paralleled by a decrease or an increase in the pH-activated current, respectively. Moreover, replacing E961
with oxygen-containing side chain residues such as glutamine or aspartate had little effect on the voltage-dependent affinity
for extracellular Na+ and produced only small effects on the pH-activated current. Our results suggest that extracellular protons and Na+ ions share a high field access channel between the extracellular solution and the third Na+ binding site. 相似文献
66.
Mousset C Giraud A Provot O Hamze A Bignon J Liu JM Thoret S Dubois J Brion JD Alami M 《Bioorganic & medicinal chemistry letters》2008,18(11):3266-3271
A series of benzil derivatives related to combretastatin A-4 (CA-4) have been synthesized by oxidation of diarylalkynes promoted by PdI(2) in DMSO. Using this new protocol, 14 benzils were prepared in good to excellent yields and their biological activity has been delineated. Several benzils exhibited excellent antiproliferative activity: for example, 4j and 4k bearing the greatest resemblance to CA-4 and AVE-8062, respectively, were found to inhibit cell growth at the nanomolar level (20-50nM) on four human tumor cell lines. Flow cytometric analysis indicates that these compounds act as antimitotics and arrest the cell cycle in G(2)/M phase. A cell-based assay indicated that compounds 4j and 4k displayed a similar inhibition of tubulin assembly with an IC(50) value similar to CA-4. These results clearly demonstrated that the Z-double bond of CA-4 can be replaced by a 1,2-diketone unit without significant loss of cytotoxicity and inhibition of tubulin assembly potency. 相似文献
67.
Human breast epithelial xenografts: An immunocytochemical and ultrastructural study of differentiation and lactogenic response 总被引:1,自引:0,他引:1
Jean-Daniel Dubois Michael J. O'Hare Paul Monaghan Jiri Bartek Robert Norris Barry A. Gusterson 《Differentiation; research in biological diversity》1987,35(1):72-82
Fragments of ductal and lobular epithelium ('organoids') produced by collagenase digestion of reduction-mammoplasty specimens were injected into athymic 'nude' mice. These heterospecific tissues were accepted without rejection, and the presence of xenografts was confirmed by cytology, immunocytochemistry and chromatin staining. Lactation, as confirmed by immunocytochemical and ultrastructural criteria, was observed in the grafted human epithelium during murine pregnancy at both intra- and extra-mammary sites. 相似文献
68.
Proteomics has changed the way proteins are analyzed in living systems. This approach has been applied to blood products and protein profiling has evolved in parallel with the development of techniques. The identification of proteins belonging to red blood cell, platelets or plasma was achieved at the end of the last century. Then, the questions on the applications emerged. Hence, several studies have focused on problems related to blood banking and products, such as the aging of blood products, identification of biomarkers, related diseases and the protein-protein interactions. More recently, a mass spectrometry-based proteomics approach to quality control has been applied in order to offer solutions and improve the quality of blood products. The current challenge we face is developing a closer relationship between transfusion medicine and proteomics. In this article, these issues will be approached by focusing first on the proteome identification of blood products and then on the applications and future developments within the field of proteomics and blood products. 相似文献
69.
Transport and pharmacological properties of nine different human Na, K-ATPase isozymes 总被引:12,自引:0,他引:12
Crambert G Hasler U Beggah AT Yu C Modyanov NN Horisberger JD Lelièvre L Geering K 《The Journal of biological chemistry》2000,275(3):1976-1986
Na,K-ATPase plays a crucial role in cellular ion homeostasis and is the pharmacological receptor for digitalis in man. Nine different human Na,K-ATPase isozymes, composed of 3 alpha and beta isoforms, were expressed in Xenopus oocytes and were analyzed for their transport and pharmacological properties. According to ouabain binding and K(+)-activated pump current measurements, all human isozymes are functional but differ in their turnover rates depending on the alpha isoform. On the other hand, variations in external K(+) activation are determined by a cooperative interaction mechanism between alpha and beta isoforms with alpha2-beta2 complexes having the lowest apparent K(+) affinity. alpha Isoforms influence the apparent internal Na(+) affinity in the order alpha1 > alpha2 > alpha3 and the voltage dependence in the order alpha2 > alpha1 > alpha3. All human Na,K-ATPase isozymes have a similar, high affinity for ouabain. However, alpha2-beta isozymes exhibit more rapid ouabain association as well as dissociation rate constants than alpha1-beta and alpha3-beta isozymes. Finally, isoform-specific differences exist in the K(+)/ouabain antagonism which may protect alpha1 but not alpha2 or alpha3 from digitalis inhibition at physiological K(+) levels. In conclusion, our study reveals several new functional characteristics of human Na,K-ATPase isozymes which help to better understand their role in ion homeostasis in different tissues and in digitalis action and toxicity. 相似文献