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71.
Jean Velours Alain Dautant Bndicte Salin Isabelle Sagot Daniel Brthes 《The international journal of biochemistry & cell biology》2009,41(10):1783-1789
The mitochondrial F1F0-ATP synthase adopts supramolecular structures. The interaction domains between monomers involve components belonging to the F0 domains. In Saccharomyces cerevisiae, alteration of these components destabilizes the oligomeric structures, leading concomitantly to the appearance of monomeric species of ATP synthase and anomalous mitochondrial morphologies in the form of onion-like structures. The mitochondrial ultrastructure at the cristae level is thus modified. Electron microscopy on cross-sections of wild type mitochondria display many short cristae with narrowed intra-cristae space, whereas yeast mutants defected in supramolecular ATP synthases assembly present a low number of large lamellar cristae of constant thickness and traversing the whole organelle. The growth of these internal structures leads finally to mitochondria with sphere-like structures with a mean diameter of 1 μm that are easily identified by epifluorescence microscopy. As a result, ATP synthase is an actor of the mitochondrial ultrastructure in yeast. This paper reviews the ATP synthase components whose modifications lead to anomalous mitochondrial morphology and also provides a schema showing the formation of the so-called onion-like structures. 相似文献
72.
Giulieri S Jaton K Cometta A Trellu LT Greub G 《FEMS immunology and medical microbiology》2012,64(1):92-97
Molecular diagnosis using real-time polymerase chain reaction (PCR) may allow earlier diagnosis of rickettsiosis. We developed a duplex real-time PCR that amplifies (1) DNA of any rickettsial species and (2) DNA of both typhus group rickettsia, that is, Rickettsia prowazekii and Rickettsia typhi. Primers and probes were selected to amplify a segment of the 16S rRNA gene of Rickettsia spp. for the pan-rickettsial PCR and the citrate synthase gene (gltA) for the typhus group rickettsia PCR. Analytical sensitivity was 10 copies of control plasmid DNA per reaction. No cross-amplification was observed when testing human DNA and 22 pathogens or skin commensals. Real-time PCR was applied to 16 clinical samples. Rickettsial DNA was detected in the skin biopsies of three patients. In one patient with severe murine typhus, the typhus group PCR was positive in a skin biopsy from a petechial lesion and seroconversion was later documented. The two other patients with negative typhus group PCR suffered from Mediterranean and African spotted fever, respectively; in both cases, skin biopsy was performed on the eschar. Our duplex real-time PCR showed a good analytical sensitivity and specificity, allowing early diagnosis of rickettsiosis among three patients, and recognition of typhus in one of them. 相似文献
73.
Llorenç Milà i Canals Christian Bauer Jochen Depestele Alain Dubreuil Ruth Freiermuth Knuchel Gérard Gaillard Ottar Michelsen Ruedi Müller-Wenk Bernt Rydgren 《The International Journal of Life Cycle Assessment》2007,12(1):5-15
Background, Aim and Scope
Land use by agriculture, forestry, mining, house-building or industry leads to substantial impacts, particularly on biodiversity
and on soil quality as a supplier of life support functions. Unfortunately there is no widely accepted assessment method so
far for land use impacts. This paper presents an attempt, within the UNEP-SETAC Life Cycle Initiative, to provide a framework
for the Life Cycle Impact Assessment (LCIA) of land use.
Materials and Methods:
This framework builds from previous documents, particularly the SETAC book on LCIA (Lindeijer et al. 2002), developing essential
issues such as the reference for occupation impacts; the impact pathways to be included in the analysis; the units of measure
in the impact mechanism (land use interventions to impacts); the ways to deal with impacts in the future; and bio-geographical
differentiation.
Results:
The paper describes the selected impact pathways, linking the land use elementary flows (occupation; transformation) and parameters
(intensity) registered in the inventory (LCI) to the midpoint impact indicators and to the relevant damage categories (natural
environment and natural resources). An impact occurs when the land properties are modified (transformation) and also when
the current man-made properties are maintained (occupation).
Discussion:
The size of impact is the difference between the effect on land quality from the studied case of land use and a suitable reference
land use on the same area (dynamic reference situation). The impact depends not only on the type of land use (including coverage
and intensity) but is also heavily influenced by the bio-geographical conditions of the area. The time lag between the land
use intervention and the impact may be large; thus land use impacts should be calculated over a reasonable time period after
the actual land use finishes, at least until a new steady state in land quality is reached.
Conclusions:
Guidance is provided on the definition of the dynamic reference situation and on methods and time frame to assess the impacts
occurring after the actual land use. Including the occupation impacts acknowledges that humans are not the sole users of land.
Recommendations and Perspectives:
The main damages affected by land use that should be considered by any method to assess land use impacts in LCIA are: biodiversity
(existence value); biotic production potential (including soil fertility and use value of biodiversity); ecological soil quality
(including life support functions of soil other than biotic production potential). Bio-geographical differentiation is required
for land use impacts, because the same intervention may have different consequences depending on the sensitivity and inherent
land quality of the environment where it occurs. For the moment, an indication of how such task could be done and likely bio-geographical
parameters to be considered are suggested. The recommendation of indicators for the suggested impact categories is a matter
of future research. 相似文献
74.
75.
Incubation of horse-heart oxymyoglobin or metmyoglobin with excess H2O2 causes formation of myoglobin(IV), followed by haem degradation. At the time when haem degradation is observed, hydroxyl radicals (.OH) can be detected in the reaction mixture by their ability to degrade the sugar deoxyribose. Detection of hydroxyl radicals can be decreased by transferrin or by OH scavengers (mannitol, arginine, phenylalanine) but not by urea. Neither transferrin nor any of these scavengers inhibit the haem degradation. It is concluded that intact oxymyoglobin or metmyoglobin molecules do not react with H2O2 to form OH detectable by deoxyribose, but that H2O2 eventually leads to release of iron ions from the proteins. These released iron ions can react to form OH outside the protein or close to its surface. Salicylate and the iron chelator desferrioxamine stabilize myoglobin and prevent haem degradation. The biological importance of OH generated using iron ions released from myoglobin by H2O2 is discussed in relation to myocardial reoxygenation injury. 相似文献
76.
Mustapha Arkoun Laëtitia Jannin Philippe Laîné Philippe Etienne Céline Masclaux-Daubresse Sylvie Citerne Maria Garnica José-Maria Garcia-Mina Jean-Claude Yvin Alain Ourry 《Plant and Soil》2013,362(1-2):79-92
Background and aims
Urea is the major nitrogen (N) form supplied as fertilizer in agriculture. However, urease, a nickel-dependent enzyme, allows plants to use external or internally generated urea as a nitrogen source. Since a urease inhibitor is frequently applied in conjunction with urea fertilizer, the N-metabolism of plants may be affected. The aim of this study was to determine physiological and molecular effects of nickel deficiency and a urease inhibitor on urea uptake and assimilation in oilseed rape.Methods
Plants were grown on hydroponic solution with urea as the sole N source under three treatments: plants treated with nickel (+Ni) as a control, without nickel (?Ni) and with nickel and phenylphosphorodiamidate (+Ni+PPD). Urea transport and assimilation were investigated.Results
The results show that Ni-deficiency or PPD supply led to reduced growth and reduced 15N-uptake from urea. This effect was more pronounced in PPD-treated plants, which accumulated high amounts of urea and ammonium. Thus, Ni-deficiency or addition of PPD, limit the availability of N and decreased shoot and root amino acid content. The up-regulation of BnDUR3 in roots indicated that this gene is a component of the stress response to nitrogen-deficiency. A general decline of glutamine synthetase (GS) activity and activation of glutamate dehydrogenase (GDH) and increases in its expression level were observed in control plants. At the same time, in (?N) or (+Ni+PPD) treated plants, no increases in GS or GDH activities and expression level were found.Conclusions
Overall results showed that plants require Ni as a nutrient (while most widely used nutrient solutions are devoid of Ni), whether they are grown with or without a urea supply, and that urease inhibitors may have deleterious effects at least in hydroponic grown oilseed rape. 相似文献77.
Protein secretion in Pseudomonas aeruginosa: characterization of seven xcp genes and processing of secretory apparatus components by prepilin peptidase 总被引:22,自引:0,他引:22
Marc Bally Alain Filloux Mohammed Akrim Geneviéve Ball ree Lazdunski Jan Tommassen 《Molecular microbiology》1992,6(9):1121-1131
The xcp genes are required for the secretion of most extracellular proteins by Pseudomonas aeruginosa. The products of these genes are essential for the transport of exoproteins across the outer membrane after they have reached the periplasm via a signal sequence-dependent pathway. To date, analysis of three xcp genes has suggested the conservation of this secretion pathway in many Gram-negative bacteria. Furthermore, the xcpA gene was shown to be identical to pilD, which encodes a peptidase involved in the processing of fimbrial (pili) subunits, suggesting a connection between pili biogenesis and protein secretion. Here the nucleotide sequences of seven other xcp genes, designated xcpR to -X, are presented. The N-termini of four of the encoded Xcp proteins display similarity to the N-termini of type IV pili, suggesting that XcpA is involved in the processing of these Xcp proteins. This could indeed be demonstrated in vivo. Furthermore, two other proteins, XcpR and XcpS, show similarity to the PilB and PilC proteins required for fimbriae assembly. Since XcpR and PilB display a canonical nucleotide-binding site, ATP hydrolysis may provide energy for both systems. 相似文献
78.
Molecular analysis of the modulatory factors of the response to HBsAg in mice as an approach to HBV vaccine enhancement 总被引:1,自引:0,他引:1
Philippe Bouige Sylvio Iscaki Alain Cosson Jacques Pillot 《FEMS immunology and medical microbiology》1996,13(1):71-79
Abstract Mice were injected with immune complexes containing the recombinant hepatitis B surface antigen (HBsAg) vaccine (S + preS2) bound to different monoclonal antibodies (mAbs), in order to determine whether an enhancement of the response to a human vaccine could be obtained and observed. Enhancement and indifference were observed, as well as a decrease in immunogenicity. N relationship could be established between any effect and affinity or isotypy of the bound mAbs. The preS2 region was rendered more immunogenic when an IgG2a mAb was bound to the S region of the HBsAg. The response to the S region was not modulated, whereas immunogenicity of the preS2 collinear region was decreased by antibody shielding. The mAb which was the most efficient as an enhancer of the antibody response also increased binding of the complexed immunogen to antigen presenting cells. The binding of a human mAb to the sole S region, but not to the preS2 region, should be tested as a potentiating agent of the anti-preS2 human immune response. 相似文献
79.
80.
Alain Dejean Arthur Compin Maurice Leponce Frédéric Azémar Camille Bonhomme Stanislas Talaga Laurent Pelozuelo Yann Hénaut Bruno Corbara 《Comptes rendus biologies》2018,341(3):200-207
In an inundated Mexican forest, 89 out of 92 myrmecophytic tank bromeliads (Aechmea bracteata) housed an associated ant colony: 13 sheltered Azteca serica, 43 Dolichoderus bispinosus, and 33 Neoponera villosa. Ant presence has a positive impact on the diversity of the aquatic macroinvertebrate communities (n = 30 bromeliads studied). A Principal Component Analysis (PCA) showed that the presence and the species of ant are not correlated to bromeliad size, quantity of water, number of wells, filtered organic matter or incident radiation. The PCA and a generalized linear model showed that the presence of Azteca serica differed from the presence of the other two ant species or no ants in its effects on the aquatic invertebrate community (more predators). Therefore, both ant presence and species of ant affect the composition of the aquatic macroinvertebrate communities in the tanks of A. bracteata, likely due to ant deposition of feces and other waste in these tanks. 相似文献