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951.
Large proteins are usually expressed in a eukaryotic system while smaller ones are expressed in prokaryotic systems. For proteins that require glycosylation, mammalian cells, fungi or the baculovirus system is chosen. The least expensive, easiest and quickest expression of proteins can be carried out in Escherichia coli. However, this bacterium cannot express very large proteins. Also, for S–S rich proteins, and proteins that require post-translational modifications, E. coli is not the system of choice. The two most utilized yeasts are Saccharomyces cerevisiae and Pichia pastoris. Yeasts can produce high yields of proteins at low cost, proteins larger than 50 kD can be produced, signal sequences can be removed, and glycosylation can be carried out. The baculoviral system can carry out more complex post-translational modifications of proteins. The most popular system for producing recombinant mammalian glycosylated proteins is that of mammalian cells. Genetically modified animals secrete recombinant proteins in their milk, blood or urine. Similarly, transgenic plants such as Arabidopsis thaliana and others can generate many recombinant proteins. 相似文献
952.
J. A. P. Marcelino S. Gouli R. Giordano V. V. Gouli B. L. Parker M. Skinner 《Journal of Applied Entomology》2009,133(2):82-89
Stands of eastern hemlock [(Tsuga canadensis (L.) Carrière] in the northeastern United States are in decline, in part from the attack of elongate hemlock scale, Fiorinia externa Ferris (Hemiptera: Diaspididae). From 2001 to the present, a natural epizootic has been observed in populations of F. externa. Initially discovered at the Mianus River Gorge Preserve in Bedford, New York, the epizootic has also been detected in Pennsylvania, New Jersey and Connecticut. Understanding and assessing the identity of the pathogenic micro‐organisms responsible for this natural mortality is crucial for developing biological controls for this pest. We have isolated and taxonomically and genetically identified entomopathogens, phytopathogens and endophytic fungi associated with F. externa. Isolates of the following were obtained: Colletotrichum sp., Lecanicillium lecanii, Beauveria bassiana, Metarhiziopsis microspora, Myriangium sp., Mycosphaerella sp. anamorph, Nectria sp., Botrytis sp., Phialophora sp. and Fusarium sp. 相似文献
953.
Szymon Zubek Katarzyna Turnau Merope Tsimilli-Michael Reto J. Strasser 《Mycorrhiza》2009,19(2):113-123
Three endangered plant species, Plantago atrata and Pulsatilla slavica, which are on the IUCN red list of plants, and Senecio umbrosus, which is extinct in the wild in Poland, were inoculated with soil microorganisms to evaluate their responsiveness to inoculation
and to select the most effective microbial consortium for application in conservation projects. Individuals of these taxa
were cultivated with (1) native arbuscular mycorrhizal fungi (AMF) isolated from natural habitats of the investigated species,
(2) a mixture of AMF strains available in the laboratory, and (3) a combination of AMF lab strains with rhizobacteria. The
plants were found to be dependent on AMF for their growth; the mycorrhizal dependency for P. atrata was 91%, S. umbrosus-95%, and P. slavica-65%. The applied inocula did not significantly differ in the stimulation of the growth of P. atrata and S. umbrosus, while in P. slavica, native AMF proved to be the less efficient. We therefore conclude that AMF application can improve the ex situ propagation
of these three threatened taxa and may contribute to the success of S. umbrosus reintroduction. A multilevel analysis of chlorophyll a fluorescence transients by the JIP test permitted an in vivo evaluation of plant vitality in terms of biophysical parameters
quantifying photosynthetic energy conservation, which was found to be in good agreement with the results concerning physiological
parameters. Therefore, the JIP test can be used to evaluate the influence of AMF on endangered plants, with the additional
advantage of being applicable in monitoring in a noninvasive way the acclimatization of reintroduced species in nature. 相似文献
954.
To investigate the diversity of root endophytes in Rhododendron fortunei, fungal strains were isolated from the hair roots of plants from four habitats in subtropical forests of China. In total,
220 slow-growing fungal isolates were isolated from the hair roots of R. fortunei. The isolates were initially grouped into 17 types based on the results of internal transcribed spacer-restriction fragment
length polymorphism (ITS-RFLP) analysis. ITS sequences were obtained for representative isolates from each RFLP type and compared
phylogenetically with known sequences of ericoid mycorrhizal endophytes and selected ascomycetes or basidiomycetes. Based
on phylogenetic analysis of the ITS sequences in GenBank, 15 RFLP types were confirmed as ascomycetes, and two as basidiomycetes;
nine of these were shown to be ericoid mycorrhizal endophytes in experimental cultures. The only common endophytes of R. fortunei were identified as Oidiodendron maius at four sites, although the isolation frequency (3–65%) differed sharply according to habitat. Phialocephala fortinii strains were isolated most abundantly from two habitats which related to the more acidic soil and pine mixed forests. A number
of less common mycorrhizal RFLP types were isolated from R. fortunei at three, two, or one of the sites. Most of these appeared to have strong affinities for some unidentified root endophytes
from Ericaceae hosts in Australian forests. We concluded that the endophyte population isolated from R. fortunei is composed mainly of ascomycete, as well as a few basidiomycete strains. In addition, one basidiomycete strain was confirmed
as a putative ericoid mycorrhizal fungus. 相似文献
955.
Extreme environments have for long been considered to be populated almost exclusively by prokaryotic organisms and therefore monopolized by bacteriologists. Solar salterns are natural hypersaline environments characterized by extreme concentrations of NaCl, often high concentrations of other ions, high uv irradiation and in some cases extremes in pH. In 2000 fungi were first reported to be active inhabitants of solar salterns. Since then many new species and species previously known only as food contaminants have been discovered in hypersaline environments around the globe. The eukaryotic microorganism most studied for its salt tolerance is Saccharomyces cerevisiae. However, S. cerevisiae is rather salt sensitive and not able to adapt to hypersaline conditions. In contrast, some species like Debaryomyces hansenii, Hortaea werneckii, and Wallemia ichthyophaga have been isolated globally from natural hypersaline environments. We believe that all three are more suitable model organisms to study halotolerance in eukaryotes than S. cerevisiae. Furthermore, they belong to different and distant taxonomic groups and have developed different strategies to cope with the same problems of ion toxicity and loss of water. 相似文献
956.
A survey for natural entomopathogenic fungi of two spotted spider mite (Tetranychus urticae) adults was made in Erzurum, Turkey, during the period 2006. Tetranychus urticae (65.8%) infected with a strain of the fungus Cladosporium cladosporioides were found. Thirteen isolates of C.
cladosporioides were assessed against T. urticae, in a single dose (8 × 106 conidia ml −1), laboratory bioassay on bean leaflets. The total mortality percentage caused by C. cladosporioides isolates varied from 50.95 to 74.76% and LT50 values ranged from 2.34 to 3.90 days. The results revealed that isolates of C. cladosporioides were effective against two spotted spider mite. This is the first record of natural infection of T. urticae by C.
cladosporioides. 相似文献
957.
Aung Swe Rajesh Jeewon Stephen B. Pointing Kevin D. Hyde 《Biodiversity and Conservation》2009,18(6):1695-1714
Nematode-trapping fungi are ubiquitous in terrestrial habitats in dung, soils, litter and woody debris and they also occur
in freshwater, but only one species has been found in marine habitats. The purpose of this study was therefore to investigate
whether nematode-trapping fungi occurred in mangrove habitats. To achieve this we assessed the diversity of nematode-trapping
fungi on decaying litter from mangroves, freshwater and terrestrial habitats (22 sites) in Hong Kong. Composite samples (n = 1,320) of decaying litter (wood and leaves) were examined and a total of 31 species of nematode-trapping fungi belonging
to four genera, Arthrobotrys, Monacrosporium, and Dactylella were recorded. Twenty-nine species reported in this study are new records for Hong Kong and 16 species are new records from
mangrove habitats worldwide. Nematode trapping fungi are therefore present in marine environments. Commonly encountered taxa
were Arthrobotrys oligospora and Monacrosporium thaumasium which are abundant in all habitats. A. oligospora, M. thaumasium and Arthrobotrys musiformis were frequent (F > 10%). Twenty-six species were rare (0.16–9.32%). Species richness and diversity was higher in terrestrial than in freshwater
and mangrove habitats (ANOVA, P < 0.001). A higher mean diversity was observed on decaying leaves as compared to decaying wood in all habitats (P < 0.001). Based on Shannon diversity index, it was also observed that taxa characterized by adhesive nets were more frequent
in all habitats. This can be explained by the fact that these taxa may have a better competitive saprotrophic ability which
would allow them to compete favourably in nutrient limited environments. Abiotic factors that could be linked to differences
in species diversity between decaying wood and leaves are also discussed. 相似文献
958.
Jeff R. Powell Jeri L. Parrent Miranda M. Hart John N. Klironomos Matthias C. Rillig Hafiz Maherali 《Proceedings. Biological sciences / The Royal Society》2009,276(1676):4237-4245
The diversity of functional and life-history traits of organisms depends on adaptation as well as the legacy of shared ancestry. Although the evolution of traits in macro-organisms is well studied, relatively little is known about character evolution in micro-organisms. Here, we surveyed an ancient and ecologically important group of microbial plant symbionts, the arbuscular mycorrhizal (AM) fungi, and tested hypotheses about the evolution of functional and life-history traits. Variation in the extent of root and soil colonization by AM fungi is constrained to a few nodes basal to the most diverse groups within the phylum, with relatively little variation associated with recent divergences. We found no evidence for a trade-off in biomass allocated to root versus soil colonization in three published glasshouse experiments; rather these traits were positively correlated. Partial support was observed for correlated evolution between fungal colonization strategies and functional benefits of the symbiosis to host plants. The evolution of increased soil colonization was positively correlated with total plant biomass and shoot phosphorus content. Although the effect of AM fungi on infection by root pathogens was phylogenetically conserved, there was no evidence for correlated evolution between the extent of AM fungal root colonization and pathogen infection. Variability in colonization strategies evolved early in the diversification of AM fungi, and we propose that these strategies were influenced by functional interactions with host plants, resulting in an evolutionary stasis resembling trait conservatism. 相似文献
959.
T. I. Ivanova N. P. Kuz’mina S. V. Petrova A. P. Chevychelov A. P. D’yachkovskii 《Contemporary Problems of Ecology》2009,2(1):27-32
Specific features of soil microbial colonies in industry-affected mountainous-taiga permafrost landscapes in the El’kon uranium ore district on the territory of South Yakutia are revealed: a high number of ecological trophic groups of microorganisms (2.0 × 103 ?7.6 × 107 cells/g), comparable to the density of microbes in meadow steppe soils of Central Yakutia and a special nature of their distribution over the soil profile depending on the uranium content of the soil. In the soil of a uranium-contaminated pit, the number of individuals in all examined groups of microorganisms increases with a decrease in uranium content to 161 ppm. In the remaining samples of this pit, the disappearance of microorganisms or their decline by one or two orders of magnitude with increasing uranium content of the soil is observed. A different situation is with microorganisms in the soil of native landscape: Their numbers remain there high over the entire soil profile. Estimated correlations between the number of individuals of the main ecological trophic groups of microorganisms and factors such as uranium content, temperature, and humidity of soil shows that the relationship with the concentration of this radionuclide was strongly negative (r = ?0.6) in the radiation-contaminated alluvial soil, while a strict relationship between the number of microorganisms and soil temperature was revealed for the uncontaminated soil (r = ±1). 相似文献
960.