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261.
Energetics of Growth of a Defined Mixed Culture of Desulfovibrio vulgaris and Methanosarcina barkeri: Interspecies Hydrogen Transfer in Batch and Continuous Cultures 总被引:2,自引:0,他引:2 下载免费PDF全文
Alfred S. Traore Marie-Laure Fardeau Claude E. Hatchikian Jean Le Gall Jean-Pierre Belaich 《Applied microbiology》1983,46(5):1152-1156
Interspecies hydrogen transfer was studied in Desulfovibrio vulgaris-Methanosarcina barkeri mixed cultures. Experiments were performed under batch and continuous growth culture conditions. Lactate or pyruvate was used as an energy source. In batch culture and after 30 days of simultaneous incubation, these organisms were found to yield 1.5 mol of methane and 1.5 mol of carbon dioxide per mol of lactate fermented. When M. barkeri served as the hydrogen acceptor, growth yields of D. vulgaris were higher compared with those obtained on pyruvate without any electron acceptor other than protons. In continuous culture, all of the carbon derived from the oxidation of lactate was recovered as methane and carbon dioxide, provided the dilution rate was minimal. Increasing the dilution rate induced a gradual accumulation of acetate, causing acetate metabolism to cease at above μ = 0.05 h−1. Under these conditions all of the methane produced originated from carbon dioxide. The growth yields of D. vulgaris were measured when sulfate or M. barkeri was the electron acceptor. Two key observations resulted from the present study. First, although sulfate was substituted by M. barkeri, metabolism of D. vulgaris was only slightly modified. The coculture-fermented lactate produced equimolar quantities of carbon dioxide and methane. Second, acetogenesis and methane formation from acetate were completely separable. 相似文献
262.
Elodie Boussinet David José Nachón Aldo Sottolichio Aude Lochet Stefan Stoll Gilles Bareille Helene Tabouret Christophe Pécheyran Marie-Laure Acolas Françoise Daverat 《Journal of fish biology》2024,104(4):1054-1066
Diadromous fish have exhibited a dramatic decline since the end of the 20th century. The allis shad (Alosa alosa) population in the Gironde-Garonne-Dordogne (GGD) system, once considered as a reference in Europe, remains low despite a fishing ban in 2008. One hypothesis to explain this decline is that the downstream migration and growth dynamics of young stages have changed due to environmental modifications in the rivers and estuary. We retrospectively analysed juvenile growth and migration patterns using otoliths from adults caught in the GGD system 30 years apart during their spawning migration, in 1987 and 2016. We coupled otolith daily growth increments and laser ablation inductively-coupled plasma mass spectrometry measurements of Sr:Ca, Ba:Ca, and Mn:Ca ratios along the longest growth axis from hatching to an age of 100 days (i.e., during the juvenile stage). A back-calculation allowed us to estimate the size of juveniles at the entrance into the brackish estuary. Based on the geochemistry data, we distinguished four different zones that juveniles encountered during their downstream migration: freshwater, fluvial estuary, brackish estuary, and lower estuary. We identified three migration patterns during the first 100 days of their life: (a) Individuals that reached the lower estuary zone, (b) individuals that reached the brackish estuary zone, and (c) individuals that reached the fluvial estuary zone. On average, juveniles from the 1987 subsample stayed slightly longer in freshwater than juveniles from the 2016 subsample. In addition, juveniles from the 2016 subsample entered the brackish estuary at a smaller size. This result suggests that juveniles from the 2016 subsample might have encountered more difficult conditions during their downstream migration, which we attribute to a longer exposure to the turbid maximum zone. This assumption is supported by the microchemical analyses of the otoliths, which suggests based on wider Mn:Ca peaks that juveniles in 2010s experienced a longer period of physiological stress during their downstream migration than juveniles in 1980s. Finally, juveniles from the 2016 subsample took longer than 100 days to exit the lower estuary than we would have expected from previous studies. Adding a new marker (i.e., Ba:Ca) helped us refine the interpretation of the downstream migration for each individual. 相似文献
263.
Hélène Peyriere Amandine Cournil Marie-Laure Casanova Stéphanie Badiou Jean-Paul Cristol Jacques Reynes 《PloS one》2015,10(11)
Objective
The objective of this prospective observational study was to describe the evolution of tubular proteinuria detected in HIV-infected patients, and to evaluate the impact of tenofovir disoproxil fumarate (TDF) discontinuation.Methods
Proteinuria and estimated glomerular filtration rate (eGFR) were followed during a median duration of 32 months, in 81 HIV-infected patients with tubular proteinuria and eGFR ≥ 60 ml/min/1.73 m2 (determined using the Chronic Kidney Disease Epidemiology (CKD-EPI) Collaboration equation). Tubular proteinuria was defined by urine protein to creatinine ratio (uPCR) ≥200 mg/g and albumin to protein ratio (uAPR) <0.4.Results
Twenty per cent of patients had persistence of tubular proteinuria: TDF continuation was the main factor associated with this persistence [OR 9.0; 95%CI: 1.9–41.4; p = 0.01]. Among the 23 patients who discontinued TDF, uPCR returned below the threshold of 200 mg/g in 11 patients. Overall, eGFR decreased with a mean rate of decline of 3.8 ml/min/1.73m2/year. The decline in eGFR was lesser after discontinuation of TDF (5.8 ml/min/1.73m2/year during TDF exposure versus 3 ml/min/1.73m2/year after TDF discontinuation; p = 0.01).Conclusions
The continuation of TDF was the main factor associated with the persistence of proteinuria. Moreover, proteinuria was normalized in only half of the patients who discontinued TDF. The clinical significance of TDF-related low level of proteinuria as a factor associated with renal disease progression and bone loss remains poorly understood. 相似文献264.
Médéric Jeanne Hélène Demory Aubin Moutal Marie-Laure Vuillaume Sophie Blesson Rose-Anne Thépault Sylviane Marouillat Judith Halewa Saskia M. Maas M. Mahdi Motazacker Grazia M.S. Mancini Marjon A. van Slegtenhorst Avgi Andreou Helene Cox Julie Vogt Jason Laufman Natella Kostandyan Davit Babikyan Frédéric Laumonnier 《American journal of human genetics》2021,108(5):951-961
265.
Oscar R. Huanel Wendy A. Nelson Vanessa Robitzch Stéphane Mauger Sylvain Faugeron Maren Preuss Giuseppe C. Zuccarello Marie-Laure Guillemin 《Journal of phycology》2020,56(6):1575-1590
Molecular studies have reported the coexistence of two species of Agarophyton in New Zealand: the newly described A.transtasmanicum with an apparently restricted distribution to some sites in the North Island, and the more widespread A.chilense. Here, we compared the distribution, genetic diversity, and structure of both Agarophyton species throughout the archipelago using sequences of the nuclear Internal Transcribed Spacer 2 (ITS2) marker. Agarophyton chilense’s distribution was continuous and extensive along the North and South Islands, Stewart Island, and Chatham Island, and the genetic clusters were mostly concordant with boundaries between biogeographic regions. In contrast, specimens of A.transtasmanicum were collected in four sites broadly distributed in both the North and South Islands, with no clear spatial structure of the genetic diversity. Populations, where the species co-occurred, tended to display similar levels in genetic diversity for the two species. Demographic inferences supported a postglacial demographic expansion for two A.chilense genetic clusters, one present in the South Island and the eastern coast of the North Island, and the other present in northern South Island. A third genetic cluster located on the western coast of the North Island had a signature of long-term demographic stability. For A.transtasmanicum, the skyline plot also suggested a postglacial demographic expansion. Last, we developed a new molecular tool to quickly and easily distinguish between the two Agarophyton species, which could be used to ease future fine-scale population studies, especially in areas where the two species coexist. 相似文献
266.
267.
Lattanzi FA Ostler U Wild M Morvan-Bertrand A Decau ML Lehmeier CA Meuriot F Prud'homme MP Schäufele R Schnyder H 《Journal of experimental botany》2012,63(6):2363-2375
This work assessed the central carbohydrate metabolism of actively photosynthesizing leaf blades of a C3 grass (Lolium perenne L.). The study used dynamic (13)C labelling of plants growing in continuous light with contrasting supplies of nitrogen ('low N' and 'high N') and mathematical analysis of the tracer data with a four-pool compartmental model to estimate rates of: (i) sucrose synthesis from current assimilation; (ii) sucrose export/use; (iii) sucrose hydrolysis (to glucose and fructose) and resynthesis; and (iv) fructan synthesis and sucrose resynthesis from fructan metabolism. The contents of sucrose, fructan, glucose, and fructose were almost constant in both treatments. Labelling demonstrated that all carbohydrate pools were turned over. This indicated a system in metabolic steady state with equal rates of synthesis and degradation/consumption of the individual pools. Fructan content was enhanced by nitrogen deficiency (55 and 26% of dry mass at low and high N, respectively). Sucrose content was lower in nitrogen-deficient leaves (2.7 versus 6.7%). Glucose and fructose contents were always low (<1.5%). Interconversions between sucrose, glucose, and fructose were rapid (with half-lives of individual pools ranging between 0.3 and 0.8 h). Futile cycling of sucrose through sucrose hydrolysis (67 and 56% of sucrose at low and high N, respectively) and fructan metabolism (19 and 20%, respectively) was substantial but seemed to have no detrimental effect on the relative growth rate and carbon-use efficiency of these plants. The main effect of nitrogen deficiency on carbohydrate metabolism was to increase the half-life of the fructan pool from 27 to 62 h and to effectively double its size. 相似文献
268.
Christian Mitri Laurent Soustelle Bérénice Framery Jo?l Bockaert Marie-Laure Parmentier Yves Grau 《PLoS biology》2009,7(6)
For all animals, the taste sense is crucial to detect and avoid ingesting toxic molecules. Many toxins are synthesized by plants as a defense mechanism against insect predation. One example of such a natural toxic molecule is l-canavanine, a nonprotein amino acid found in the seeds of many legumes. Whether and how insects are informed that some plants contain l-canavanine remains to be elucidated. In insects, the taste sense relies on gustatory receptors forming the gustatory receptor (Gr) family. Gr proteins display highly divergent sequences, suggesting that they could cover the entire range of tastants. However, one cannot exclude the possibility of evolutionarily independent taste receptors. Here, we show that l-canavanine is not only toxic, but is also a repellent for Drosophila. Using a pharmacogenetic approach, we find that flies sense food containing this poison by the DmX receptor. DmXR is an insect orphan G-protein–coupled receptor that has partially diverged in its ligand binding pocket from the metabotropic glutamate receptor family. Blockade of DmXR function with an antagonist lowers the repulsive effect of l-canavanine. In addition, disruption of the DmXR encoding gene, called mangetout (mtt), suppresses the l-canavanine repellent effect. To avoid the ingestion of l-canavanine, DmXR expression is required in bitter-sensitive gustatory receptor neurons, where it triggers the premature retraction of the proboscis, thus leading to the end of food searching. These findings show that the DmX receptor, which does not belong to the Gr family, fulfills a gustatory function necessary to avoid eating a natural toxin. 相似文献
269.
Cyrille Violle Eric Garnier Jérémie Lecoeur Catherine Roumet Cécile Podeur Alain Blanchard Marie-Laure Navas 《Oecologia》2009,160(4):747-755
Although of primary importance to explain plant community structure, general relationships between plant traits, resource
depletion and competitive outcomes remain to be quantified across species. Here, we used a comparative approach to test whether
instantaneous measurements of plant traits can capture both the amount of resources depleted under plant cover over time (competitive
effect) and the way competitors perceived this resource depletion (competitive response). We performed a large competition
experiment in which phytometers from a single grass species were transplanted within 18 different monocultures grown in a
common-garden experiment, with a time-integrative quantification of light and water depletion over the phytometers’ growing
season. Resource-capturing traits were measured on both phytometers (competitive response traits) and monocultures (competitive
effect traits). The total amounts of depleted light and water availabilities over the season strongly differed among monocultures;
they were best estimated by instantaneous measurements of height and rooting depth, respectively, performed when either light
or water became limiting. Specific leaf area and leaf water potential, two competitive response traits measured at the leaf
level, were good predictors of changes in phytometer performance under competition, and reflected the amount of light and
water, respectively, perceived by plants throughout their lifespan. Our results demonstrated the relevance of instantaneous
measures of plant traits as indicators of resource depletion over time, validating the trait-based approach for competition
ecology.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
270.
Marie-Laure Desprez-Loustau Régis Courtecuisse Cécile Robin Claude Husson Pierre-Arthur Moreau Dominique Blancard Marc-André Selosse Brigitte Lung-Escarmant Dominique Piou Ivan Sache 《Biological invasions》2010,12(1):157-172
A first comprehensive inventory of alien fungi and fungal-like organisms (in Stramenopila) recorded in France since 1800 was
established, comprising 227 species, with 64.7% plant pathogens, 29.5% saprotrophic species, 3.5% ectomycorrhizal fungi, 1.3%
animal parasites and 0.9% mycopathogenic fungi. Using this and a previously built European dataset, correlates of invasion
success in fungi (sensu lato) were investigated, especially for pathogenic species occurring in wild environments (mostly forest tree pathogens). Several
common features were demonstrated at the two spatial scales. Some taxonomic/phylogenetic orders were shown to be over-represented
in alien fungi and Stramenopila pseudo-fungi, e.g. Peronosporales and to have faster spread, e.g. Erysiphales. Residence time
and economic variables, especially imports, were important explaining variables of the levels of invasion. The influence of
climatic factors was also suggested. 相似文献