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991.
Mark R. Condina Johan O. R. Gustafsson Manuela Klingler‐Hoffmann Christopher J. Bagley Shaun R. McColl Peter Hoffmann 《Proteomics》2010,10(13):2516-2530
The quality of MALDI‐TOF mass spectrometric analysis is highly dependent on the matrix and its deposition strategy. Although different matrix‐deposition methods have specific advantages, one major problem in the field of proteomics, particularly with respect to quantitation, is reproducibility between users or laboratories. Compounding this is the varying crystal homogeneity of matrices depending on the deposition strategy used. Here, we describe a novel optimised matrix‐deposition strategy for LC‐MALDI‐TOF/TOF MS using an automated instrument that produces a nebulised matrix “mist” under controlled atmospheric conditions. Comparisons of this with previously reported strategies showed the method to be advantageous for the atypical matrix, 2,5‐DHB, and improved phosphopeptide ionisation when compared with deposition strategies for CHCA. This optimised DHB matrix‐deposition strategy with LC‐MALDI‐TOF/TOF MS, termed EZYprep LC, was subsequently optimised for phosphoproteome analysis and compared to LC‐ESI‐IT‐MS and a previously reported approach for phosphotyrosine identification and characterisation. These methods were used to map phosphorylation on epidermal growth factor‐stimulated epidermal growth factor receptor to gauge the sensitivity of the proposed method. EZYprep DHB LC‐MALDI‐TOF/TOF MS was able to identify more phosphopeptides and characterise more phosphorylation sites than the other two proteomic strategies, thus proving to be a sensitive approach for phosphoproteome analysis. 相似文献
992.
Céline Arzel Johan Elmberg Matthieu Guillemain Michel Lepley Fabrice Bosca Pierre Legagneux Jean-Baptiste Nogues 《Journal of Ornithology》2009,150(1):61-73
Two frequent assumptions about the evolution of long-distance migration in birds are that they travel long distances annually
to reach food-rich areas for breeding, and that they time their migratory journey to be at staging sites when the latter provide
the best feeding conditions. These assumptions have rarely been properly tested, and there is no study in which a species’
major food types have been measured by standardized methods throughout a flyway and over a large part of the year. We here
present such data for Eurasian teal (Anas crecca), converted to a common energetic currency, and collected at wintering, spring staging and breeding sites. Teal did not time
migration to maximize local food abundance; most birds left wintering and spring staging sites before a sharp increase in
invertebrate food abundance occurred. On the other hand, hatching of ducklings coincided with a peak in invertebrate food
abundance on boreal breeding lakes. Mean overall food abundance (invertebrates and seeds combined) did not differ between
wintering sites in southern France and breeding sites in northern Sweden at the time of breeding. Our results are inconsistent
with the hypothesis that long-distance migration in dabbling ducks has evolved because adult birds gain an immediate pay-off
in increased food abundance by flying north in spring. However, our data confirm a selective advantage for breeding at higher
latitudes, because hatching of ducklings may coincide with a peak in invertebrate emergence and because longer days may increase
the duration of efficient foraging. 相似文献
993.
Shared signals -'alarm calls' from plants increase apparency to herbivores and their enemies in nature 总被引:1,自引:0,他引:1
The attraction of natural enemies of herbivores by volatile organic compounds as an induced indirect defence has been studied in several plant systems. The evidence for their defensive function originates mainly from laboratory studies with trained parasitoids and predators; the defensive function of these emissions for plants in natural settings has been rarely demonstrated. In native populations and laboratory Y-tube choice experiments with transgenic Nicotiana attenuata plants unable to release particular volatiles, we demonstrate that predatory bugs use terpenoids and green leaf volatiles (GLVs) to locate their prey on herbivore-attacked plants. By attracting predators with volatile signals, this native plant reduces its herbivore load – demonstrating the defensive function of herbivore-induced volatile emissions. However, plants producing GLVs are also damaged more by flea beetles. The implications of these conflicting ecological effects for the evolution of induced volatile emissions and for the development of sustainable agricultural practices are discussed. 相似文献
994.
995.
Judith Sitters Mariska te Beest Mehdi Cherif Reiner Giesler Johan Olofsson 《Ecosystems》2017,20(7):1266-1277
Herbivores impact nutrient availability and cycling, and the net effect of herbivory on soil nutrients is generally assumed to be positive in nutrient-rich environments and negative in nutrient-poor ones. This is, however, far from a uniform pattern, and there is a recognized need to investigate any interactive effects of herbivory and habitat fertility (i.e., plant C/N ratios) on soil nutrient availabilities. We determined long-term effects of reindeer on soil extractable nitrogen (N) and phosphorus (P) and their net mineralization rates along a fertility gradient of plant carbon (C) to N and P ratios in arctic tundra. Our results showed that reindeer had a positive effect on soil N in the more nutrient-poor sites and a negative effect on soil P in the more nutrient-rich sites, which contrasts from the general consensus. The increase in N availability was linked to a decrease in plant and litter C/N ratios, suggesting that a shift in vegetation composition toward more graminoids favors higher N cycling. Soil P availability was not as closely linked to the vegetation and is likely regulated more by herbivore-induced changes in soil physical and chemical properties. The changes in soil extractable N and P resulted in higher soil N/P ratios, suggesting that reindeer could drive the vegetation toward P-limitation. This research highlights the importance of including both the elements N and P and conducting studies along environmental gradients in order to better understand the interactive effects of herbivory and habitat fertility on nutrient cycling and primary production. 相似文献
996.
Sara Kanje Raminta Venskutonytė Julia Scheffel Johan Nilvebrant Karin Lindkvist-Petersson Sophia Hober 《Journal of molecular biology》2018,430(18):3427-3438
Presented here is an engineered protein domain, based on Protein A, that displays a calcium-dependent binding to antibodies. This protein, ZCa, is shown to efficiently function as an affinity ligand for mild purification of antibodies through elution with ethylenediaminetetraacetic acid. Antibodies are commonly used tools in the area of biological sciences and as therapeutics, and the most commonly used approach for antibody purification is based on Protein A using acidic elution. Although this affinity-based method is robust and efficient, the requirement for low pH elution can be detrimental to the protein being purified. By introducing a calcium-binding loop in the Protein A-derived Z domain, it has been re-engineered to provide efficient antibody purification under mild conditions. Through comprehensive analyses of the domain as well as the ZCa–Fc complex, the features of this domain are well understood. This novel protein domain provides a very valuable tool for effective and gentle antibody and Fc-fusion protein purification. 相似文献
997.
998.
Facilitation in plant communities: the past, the present, and the future 总被引:24,自引:11,他引:24
Rob W. Brooker Fernando T. Maestre Ragan M. Callaway Christopher L. Lortie Lohengrin A. Cavieres Georges Kunstler Pierre Liancourt Katja Tielbörger Justin M. J. Travis Fabien Anthelme Cristina Armas Lluis Coll Emmanuel Corcket Sylvain Delzon Estelle Forey Zaal Kikvidze Johan Olofsson Francisco Pugnaire Constanza L. Quiroz Patrick Saccone Katja Schiffers Merav Seifan Blaize Touzard Richard Michalet 《Journal of Ecology》2008,96(1):18-34
999.
William J. Sutherland Rosalind Aveling Thomas M. Brooks Mick Clout Lynn V. Dicks Liz Fellman Erica Fleishman David W. Gibbons Brandon Keim Fiona Lickorish Kathryn A. Monk Diana Mortimer Lloyd S. Peck Jules Pretty Johan Rockström Jon Paul Rodríguez Rebecca K. Smith Mark D. Spalding Femke H. Tonneijck Andrew R. Watkinson 《Trends in ecology & evolution》2014
1000.
Louise Ilum Sørensen Juha Mikola Minna-Maarit Kytöviita Johan Olofsson 《Ecosystems》2009,12(5):830-842
Mammal grazing is composed of three mechanisms—removal of foliar tissue (defoliation), return of nutrients via dung and urine
(fertilization), and trampling. To evaluate the relative role of these mechanisms in the effect of reindeer grazing on soil
biota in northern grasslands, we subjected experimental plots in a sub-arctic alpine meadow to defoliation, fertilization
(using NPK-solution), simulated trampling, and their factorial combinations once a year from 2002 to 2004 and measured the
response of plants and decomposers (including microbes, nematodes, collembolans, and enchytraeids) in 2004. Trampling affected
both plant and decomposer communities: the coverage of the moss Pleurozium schreberi and the sedge Carex vaginata, as well as the abundance of collembolans and enchytraeids were reduced in trampled plots. Trampling and fertilization also
interacted significantly, with fertilization increasing the abundance of bacteria and bacterial-feeding and omnivorous nematodes
in trampled plots only, and trampling decreasing fungal biomass in non-fertilized plots only. Defoliation had no overall effects
on plants or decomposers. Nematode genera were not affected by the experimental treatments, but nematode and plant communities
were significantly associated, and all decomposer biota, except collembolans, were strongly affected by the spatial heterogeneity
of the study site. Our results indicate that trampling may have larger and defoliation and fertilization smaller roles than
anticipated in explaining reindeer grazing effects in sub-arctic grasslands. However, even the effects of trampling seem to
be outweighed by the spatial heterogeneity of decomposer abundances. This suggests that in sub-arctic grasslands spatial variation
in abiotic factors can be a more important factor than grazing in controlling soil biota abundances.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Author contributions LIS was involved in planning of the study, fieldwork, lab work, analysis, and wrote the article with contributions from all
other authors; JM and MMK conceived the study and contributed to the data analyses; MMK further contributed to the field work
and JM refined the final appearance of the text; JO started and was responsible for managing the field experiment, collecting
the plant data and gave advice on statistical analysis. 相似文献