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1.
Magni Olsen Kyrkjeeide Kristian Hassel Kjell Ivar Flatberg A. Jonathan Shaw Narjes Yousefi Hans K. Sten?ien 《PloS one》2016,11(2)
Spore-producing organisms have small dispersal units enabling them to become widespread across continents. However, barriers to gene flow and cryptic speciation may exist. The common, haploid peatmoss Sphagnum magellanicum occurs in both the Northern and Southern hemisphere, and is commonly used as a model in studies of peatland ecology and peatmoss physiology. Even though it will likely act as a rich source in functional genomics studies in years to come, surprisingly little is known about levels of genetic variability and structuring in this species. Here, we assess for the first time how genetic variation in S. magellanicum is spatially structured across its full distribution range (Northern Hemisphere and South America). The morphologically similar species S. alaskense was included for comparison. In total, 195 plants were genotyped at 15 microsatellite loci. Sequences from two plastid loci (trnG and trnL) were obtained from 30 samples. Our results show that S. alaskense and almost all plants of S. magellanicum in the northern Pacific area are diploids and share the same gene pool. Haploid plants occur in South America, Europe, eastern North America, western North America, and southern Asia, and five genetically differentiated groups with different distribution ranges were found. Our results indicate that S. magellanicum consists of several distinct genetic groups, seemingly with little or no gene flow among them. Noteworthy, the geographical separation of diploids and haploids is strikingly similar to patterns found within other haploid Sphagnum species spanning the Northern Hemisphere. Our results confirm a genetic division between the Beringian and the Atlantic that seems to be a general pattern in Sphagnum taxa. The pattern of strong genetic population structuring throughout the distribution range of morphologically similar plants need to be considered in future functional genomic studies of S. magellanicum. 相似文献
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The Branchiura are fish ectoparasites which include the well-known and very commonly found genus Argulus. But the Branchiura also contains the monotypic genus Dipteropeltis, about which only very little is known. In this investigation of two female paratype specimens we describe for the first time the external morphology of Dipteropeltis based on Scanning Electron Microscopy. We show that Dipteropeltis has a pre-oral spine, unique suction disc support structures, an Argulus-like mouth cone and second maxillae with a combination of features seen in both Argulus and Chonopeltis. These data are compared with data from the three remaining branchiuran genera Dolops, Chonopeltis and Argulus and discussed in a phylogenetic context based on a recently proposed phylogeny of the group. 相似文献
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NADPH-dependent reductase solubilized from microsomes by peroxidation and its activity 总被引:1,自引:0,他引:1
Johan Högberg Robert E. Larson Annika Kristoferson Sten Orrenius 《Biochemical and biophysical research communications》1974,56(3):836-842
Isolated rat liver microsomes were subjected to enzymatic or non-enzymatic lipid peroxidation . NADPH-dependent cytochrome reductase activity was released from the microsomes into the media during peroxidation. This activity could be recovered from the media by DEAE-cellulose chromatography. The recovered enzyme retained high activity for the reduction of cytochrome and a lower level of activity for the reduction of cytochrome P-450. The active fractions were capable of enzymatically supporting the peroxidation of isolated mitochondria in the presence of organically complexed Fe+3 and NADPH, and in this respect the specific activity was found to be about ten times higher than in microsomes. 相似文献
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Leander A. H. Petersen Christian Lieven Subir K. Nandy John Villadsen Sten B. Jørgensen Ib Christensen Krist V. Gernaey 《Biotechnology and bioengineering》2019,116(11):2884-2895
The methanotrophic bacterium Methylococcus capsulatus is capable of assimilating methane and oxygen into protein-rich biomass, however, the diverse metabolism of the microorganism also allows for several undesired cometabolic side-reactions to occur. In this study, the ammonia cometabolism in Methylococcus capsulatus is investigated using pulse experiments. Surprisingly Methylococcus capsulatus oxidizes ammonia to nitrate through a yet unknown mechanism and fixes molecular nitrogen even at a high dissolved oxygen tension. The observed phenomena can be modeled using 14 ordinary differential equations and 18 kinetic parameters, of which 6 were revealed by Morris screening to be identifiable from the experimental data. Monte Carlo simulations showed that the model was robust and accurate even with uncertainty in the parameter values as confirmed by statistical error analysis. 相似文献
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Nicole A. Huijgen Joop S. E. Laven Chantal T. Labee Yvonne V. Louwers Sten P. Willemsen Régine P. M. Steegers-Theunissen 《PloS one》2015,10(11)