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Aurélie Lieutaud Robert van Lis Simon Duval Line Capowiez Daniel Muller Régine Lebrun Sabrina Lignon Marie-Laure Fardeau Marie-Claire Lett Wolfgang Nitschke Barbara Schoepp-Cothenet 《The Journal of biological chemistry》2010,285(27):20433-20441
We characterized the aro arsenite oxidation system in the novel strain Ralstonia sp. 22, a β-proteobacterium isolated from soil samples of the Salsigne mine in southern France. The inducible aro system consists of a heterodimeric membrane-associated enzyme reacting with a dedicated soluble cytochrome c554. Our biochemical results suggest that the weak association of the enzyme to the membrane probably arises from a still unknown interaction partner. Analysis of the phylogeny of the aro gene cluster revealed that it results from a lateral gene transfer from a species closely related to Achromobacter sp. SY8. This constitutes the first clear cut case of such a transfer in the Aro phylogeny. The biochemical study of the enzyme demonstrates that it can accommodate in vitro various cytochromes, two of which, c552 and c554, are from the parent species. Cytochrome c552 belongs to the sox and not the aro system. Kinetic studies furthermore established that sulfite and sulfide, substrates of the sox system, are both inhibitors of Aro activity. These results reinforce the idea that sulfur and arsenic metabolism are linked. 相似文献
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Hajaij M Carron A Deleuze J Gaven B Setier-Rio ML Vigo G Thiéry I Nielsen-LeRoux C Lagneau C 《Microbial ecology》2005,50(4):475-487
We studied the persistence of Bacillus thuringiensis serovar israelensis (Bti) in a typical breeding site of the mosquito Ochlerotatus caspius in a particularly sensitive salt marsh ecosystem following two Bti-based larvicidal applications (Vectobac 12AS, 1.95 L/ha). The treated area was composed of four larval biotopes that differed in terms of the most representative plant species (Sarcocornia fruticosa, Bolboschoenus maritimus, Phragmites australis, and Juncus maritimus) and the physical and chemical characteristics of the soil. We sampled water, soil, and plants at various times before and after the applications (from spring to autumn, 2001) and quantified the spores of B. thuringiensis (Bt) and Bacillus species. The B. cereus group accounted for between 0% and 20% of all Bacillus spp. before application depending on the larval biotope. No Bti were found before application. The variation in the quantity of bacilli during the mosquito breeding season depended more on the larval biotope than on the season or the larvicidal application. More bacilli were found in soil (10(4)-10(6) spores/g) than on plant samples (10(2)-10(4) spores/g). The abundance in water (10(5) to 10(7) spores/L) appeared to be correlated to the water level of the breeding site. The number of Bti spores increased just after application, after declining; no spores were detected in soil or water 3 months after application. However, low numbers of Bti spores were present on foliage from three of the four studied plant strata. In conclusion, the larvicidal application has very little impact on Bacillus spp. flora after one breeding season (two applications). 相似文献
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Nadia Khelifi Emna Ben Romdhane Abdeljabbar Hedi Anne Postec Marie-Laure Fardeau Moktar Hamdi Jean-Luc Tholozan Bernard Ollivier Agnès Hirschler-Réa 《Extremophiles : life under extreme conditions》2010,14(3):297-304
A novel thermophilic anaerobic and microaerophilic bacterium (optimal growth in the presence of 5–10% O2), strain Nad S1T was isolated from the terrestrial hot spring of Hammam Sidi Jdidi, Nabeul, Tunisia. Cells were motile rods having a Gram-positive cell wall structure. Strain Nad S1T grew optimally at 55°C (range 37–70°C). Optimum pH for growth was 6.5–7.0. It was halotolerant growing with NaCl up to 7% (optimum concentration 1.5–3.0%). It grew chemoorganotrophically on various carbohydrates, organic-acids and amino-acids as energy sources, or chemolithotrophically on H2 using nitrate, as terminal electron acceptor. Beside oxygen (under microaerobic conditions) and nitrate, nitrite was also used. Nitrate was completely reduced to N2. No fermentation occurred. The genomic DNA G + C content was 41.8 mol%. Based on 16S rRNA gene sequence analysis, strain Nad S1T belongs to the Bacillaceae family within the class ‘Bacilli’. Because of its phylogenetic and phenotypic characteristics, we propose this isolate to be assigned as a novel genus and a novel species within the domain Bacteria, Microaerobacter geothermalis gen. nov., sp. nov. The type strain is Nad S1T (=DSM 22679T =JCM 16213T). 相似文献
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Naimi A Martinez AS Specq ML Mrac A Diss B Mathieu M Sourdaine P 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2009,152(2):189-196
The Pacific oyster Crassostrea gigas is a successive not systematic protandric hermaphrodite. Searching for an ortholog to Dmrt1, a conserved sex determinism factor, we have identified the first complete cDNA of a DM factor in Lophotrochozoa which we have called Cg-DMl (Crassostrea gigas DMRT-like). It is 359aa long, with the DM domain common to all the family factors, and one DMA domain specific to members such as Dmrt4 and Dmrt5. Its gene presents one intron of 598 bp. Real time PCR and in situ hybridization have shown that Cg-DMl was expressed in both sexes, with a significantly higher expression in male than in female gonads at the end of the adult gametogenetic cycle and that a significant peak of expression was observed in spat between 1 and 2 months of age. These results suggest that Cg-DMl may be involved in the development of the gonad and may constitute preliminary clues for future work in order to better understand DM protein evolution. 相似文献
167.
Corinne Vacher Jean-Jacques Daudin Dominique Piou Marie-Laure Desprez-Loustau 《Biological invasions》2010,12(9):3249-3259
The diversification of species and their interactions during the course of evolution has produced ecological networks with
a complex topology. This topology influences the current functioning of ecosystems. It is therefore important to investigate
whether the species introduced recently by human activities have merged seamlessly into recipient ecological networks by developing
interactions quantitatively and qualitatively similar to those of native species, or whether their establishment has altered
the topology of the networks. We tackled this issue in the case of a well resolved interaction network between 51 forest tree
taxa and 154 pathogenic fungal species. We found that alien and native species with similar phylogenetic histories and life-history
strategies had similar types and numbers of interactions. Our results also suggest that the clustered architecture of the
network has not been altered by the integration of alien species. It therefore seems that a few centuries have been sufficient
for the network to assimilate the newly introduced species. This rapid integration was unexpected for a plant-pathogen network,
because selection acts continually on plants, favouring the emergence of defences against new pathogens and impeding the development
of new interactions. However, it was recently shown that perturbation of the structure of ecological networks might be overlooked
if species interactions are not quantified. The tree-parasitic fungus network considered in this study is binary. We might
therefore end up with different results by using quantitative data. 相似文献
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