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201.
202.
E. R. Jasper Wubs Wim H. van der Putten Simon R. Mortimer Gerard W. Korthals Henk Duyts Roel Wagenaar T. Martijn Bezemer 《Ecology letters》2019,22(7):1145-1151
Recent demonstrations of the role of plant–soil biota interactions have challenged the conventional view that vegetation changes are mainly driven by changing abiotic conditions. However, while this concept has been validated under natural conditions, our understanding of the long‐term consequences of plant–soil interactions for above‐belowground community assembly is restricted to mathematical and conceptual model projections. Here, we demonstrate experimentally that one‐time additions of soil biota and plant seeds alter soil‐borne nematode and plant community composition in semi‐natural grassland for 20 years. Over time, aboveground and belowground community composition became increasingly correlated, suggesting an increasing connectedness of soil biota and plants. We conclude that the initial composition of not only plant communities, but also soil communities has a long‐lasting impact on the trajectory of community assembly. 相似文献
203.
Yukie Sato Yoshiaki Tsuda Hironori Sakamoto Martijn Egas Tetsuo Gotoh Yutaka Saito Yan‐Xuan Zhang Jian‐Zhen Lin Jung‐Tai Chao Atsushi Mochizuki 《Ecology and evolution》2019,9(4):1590-1602
When males fight for access to females, such conflict rarely escalates into lethal fight because the risks and costs involved, that is, severe injury or death, are too high. The social spider mite, Stigmaeopsis miscanthi, does exhibit lethal male fights, and this male–male aggressiveness varies among populations. To understand the evolution of lethal fighting, we investigated aggressiveness in 42 populations and phylogenetic relationships in 47 populations along the Japanese archipelago. By analysis of the male weapon morph, a proxy for aggressiveness, we confirmed the existence of a mildly aggressive (ML) form, besides the low aggression (LW) and high aggression (HG) forms reported earlier. To evaluate demographic history of these three forms, we employed the approximate Bayesian computation approach using mtCOI sequences and taking into consideration the postlast glacial expansion history of the host plant, Miscanthus sinensis. As results, hierarchical split models are more likely to explain the observed genetic pattern than admixture models, and the ML form in the subtropical region was considered the ancestral group. The inferred demographic history was consistent with the one reconstructed for the host plant in a previous study. The LW form was split from the ML form during the last glacial period (20,000–40,000 years BP), and subsequently, the HG form was split from the ML form at the end of or after the last glacial period (5,494–10,988 years BP). The results also suggest that the mite invaded Japan more than once, resulting in the present parapatric distribution of LW and HG forms in eastern Japan. 相似文献
204.
Benedetta Artegiani Lisa van Voorthuijsen Rik G.H. Lindeboom Daniëlle Seinstra Inha Heo Pablo Tapia Carmen López-Iglesias Daniel Postrach Talya Dayton Rurika Oka Huili Hu Ruben van Boxtel Johan H. van Es Johan Offerhaus Peter J. Peters Jacco van Rheenen Michiel Vermeulen Hans Clevers 《Cell Stem Cell》2019,24(6):927-943.e6
205.
Local polarity and hydrogen bonding inside the Sec14p phospholipid-binding cavity: high-field multi-frequency electron paramagnetic resonance studies 下载免费PDF全文
Smirnova TI Chadwick TG Voinov MA Poluektov O van Tol J Ozarowski A Schaaf G Ryan MM Bankaitis VA 《Biophysical journal》2007,92(10):3686-3695
Sec14p promotes the energy-independent transfer of either phosphatidylinositol (PtdIns) or phosphatidylcholine (PtdCho) between lipid bilayers in vitro and represents the major PtdIns/PtdCho transfer protein in the budding yeast Saccharomyces cerevisiae. Herein, we employ multi-frequency high-field electron paramagnetic resonance (EPR) to analyze the electrostatic and hydrogen-bonding microenvironments for series of doxyl-labeled PtdCho molecules bound by Sec14p in a soluble protein-PtdCho complex. A structurally similar compound, 5-doxyl stearic acid dissolved in a series of solvents, was used for experimental calibration. The experiments yielded two-component rigid limit 130- and 220-GHz EPR spectra with excellent resolution in the gx region. Those components were assigned to hydrogen-bonded and nonhydrogen-bonded nitroxide species. Partially resolved 130-GHz EPR spectra from n-doxyl-PtdCho bound to Sec14p were analyzed using this two-component model and allowed quantification of two parameters. First, the fraction of hydrogen-bonded nitroxide species for each n-doxyl-PtdCho was calculated. Second, the proticity profile along the phospholipid-binding cavity of Sec14p was characterized. The data suggest the polarity gradient inside the Sec14p cavity is a significant contributor to the driving molecular forces for extracting a phospholipid from the bilayer. Finally, the enhanced g-factor resolution of EPR at 130 and 220 GHz provides researchers with a spectroscopic tool to deconvolute two major contributions to the x-component of the nitroxide g-matrix: hydrogen-bond formation and local electrostatic effects. 相似文献
206.
Sebolai OM Pohl CH Botes PJ Strauss CJ van Wyk PW Botha A Kock JL 《Canadian journal of microbiology》2007,53(6):809-812
Using immunofluorescence confocal laser scanning microscopy, immunogold transmission electron microscopy and gas chromatography--mass spectrometry, we demonstrated the presence of 3-hydroxy fatty acids in Cryptococcus neoformans. Our results suggest that these oxylipins accumulate in capsules where they are released as hydrophobic droplets through tubular protuberances into the surrounding medium. 相似文献
207.
Ann Margaret Grøndahl Ellen Margrete Skancke Cecilie Marie Mejdell Johan Høgset Jansen 《Acta veterinaria Scandinavica》2007,49(1):16
Over a period of two years, growth rate and health were measured for dairy calves allowed to suckle their mothers up to 6–8
weeks of age. Thirty-one calves were weighted weekly, and the mean daily growth rate was 1.2 ± 0.03 kg from birth up to 13
weeks of age. Illness in calves and young stock was not observed. In the cows, the mean incidences of ketosis, displaced abomasum,
puerperal paresis, mastitis, teat injury and retained placenta were 0, 0, 8, 22, 1 and 1%, respectively, during a 6-year period.
The mean daily gain of 56 growing bulls was 1.4 kg when slaughtered at 15 months of age, which is higher than the mean daily
gain of 0.95 kg in the population. Probiotics, hormones and vaccines were not used, and antibiotics were only used for treating
illness. The present study indicates many advantages and few problems when dairy calves are penned together with the cows
and allowed natural feeding up to 6–8 weeks of age. This production system was easy to manage, preferred by the farmer, and
may satisfy the public concern regarding the practice of immediate separation of cow and calf in commercial milk production. 相似文献
208.
209.
van Platerink CJ Janssen HG Haverkamp J 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,846(1-2):147-154
A fast at-line method was developed for the identification of ACE inhibiting (ACEI) peptides in protein hydrolysates. The method consists of activity measurements of fractions collected from a two-dimensional HPLC fractionation of the peptide mixture followed by MS identification of the peptides in the inhibiting fractions. The inhibition assay is based on the inhibiting effect of ACEI peptides on the hydrolytic scission of the substrate Hippuric acid-His-Leu (HHL) during the ACE-catalysed hydrolysis reaction. A fast LC method was developed for the quantification of Hippuric acid (H) and Hippuric acid-Histidine-Leucine (HHL), allowing a large number of fractions to be analysed within a reasonable time period. The method is sensitive and uses only standard laboratory equipment. The limit of detection is 0.34 microM for the known ACEI peptide IPP. This is sufficiently sensitive for the identification of only moderately active peptides and/or ACEI peptides present at low concentrations. The relative standard deviation of the inhibition assay was 12% measured over a time period of 2 months. The IC50 value of IPP measured with the assay was 5.6 microM, which is comparable to the values of 5 microM and 5.15 microM reported in literature for the standard Matsui method. The assay was successfully applied in the identification of ACEI peptides in enzymatically hydrolysed caseinate samples. Two new, not earlier published ACEI peptides were identified; MAP (beta-casein f102-104) and ITP (alpha-s2-casein f119-121) with IC50 values of 3.8 microM and 50 microM, respectively. 相似文献
210.
Increased production of bacteriocin ST4SA byEnterococcus mundtii ST4SA in modified corn steep liquor
Johan C. J. Coetzee Svetoslav D. Todorov Johann F. Görgens Leon M. T. Dicks 《Annals of microbiology》2007,57(4):617-622
Enterococcus mundtii ST4SA produces a broad-spectrum bacteriocin (bacST4SA), active against Gram-positive and Gramnegative bacteria. Growth in corn steep liquor (CSL) with a sugar content of 5.0 and 10.0 g/l yielded bacST4SA levels of 12800 AU/ml. A four-fold increase in bacST4SA production (51200 AU/ml) was recorded in CSL with a sugar content of 7.5 g/l supplemented with 6.5 g/l yeast extract (CSL-YE). Poor growth and low levels of bacST4SA production were observed when cells were grown in CSL-YE controlled at pH 5.5. Fermentation at pH 7.5 yielded 25600 AU/ml after 6 h, but the activity levels decreased to approximately 1000 AU/ml during the next 6 h. Adjustment of the culture pH from 6.5 to 5.5 after 6 h of fermentation extended bacST4SA activity (51200 AU/ml) over 8 h. Activity then decreased to 25600 AU/ml and was maintained this level for 10 h. Optimal levels of bacST4SA production (102400 AU/ml) were obtained after 6 h of fermentation in CSL-YE supplemented with 7.5 g/l glucose at the start of the fermentation. This level of production was maintained by changing the culture pH from 6.5 after 6 h of fermentation to pH 5.5. This study proved that bacST4SA could be produced at high levels in an inexpensive industrial medium byE. mundtii ST4SA. 相似文献