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991.
992.
Schalk JA Docters van Leeuwen AE Lodder WJ de Man H Euser S den Boer JW de Roda Husman AM 《Applied and environmental microbiology》2012,78(12):4519-4521
Viable Legionella pneumophila bacteria were isolated by amoebal coculture from pluvial floods after intense rainfall and from water collected at sewage treatment plants. Several isolated L. pneumophila strains belonged to sequence types that have been previously identified in patients. 相似文献
993.
994.
Lucas Anjos de Souza Sara Adrián López de Andrade Sarah Caroline Ribeiro de Souza Marlene Aparecida Schiavinato 《Acta Physiologiae Plantarum》2012,34(2):523-531
Heavy metals (HMs) are environmental pollutants of great concern to humans because of their high potential toxicity. Lead
is a HM that is present in the soil in very small amounts, but anthropogenic activities have increased its content in some
locations, which can make these areas unproductive or inappropriate for crop production. However, there are some plants that
can grow in contaminated soils and, thus, can be useful for the removal or stabilisation of such contaminants. In addition,
plants that are not able to tolerate high concentrations of HMs in the soil can become tolerant or increase their performance
when associated with arbuscular mycorrhizal (AM) fungi. Accordingly, this study was carried out to verify whether the inoculation
of Glomus etunicatum, an AM fungus species, in Calopogonium mucunoides would influence plant tolerance to increasing concentrations of Pb in the soil. The experimental design was completely randomised,
in a 2 × 4 factorial design, and the treatments consisted of inoculation (or not) with the AM fungus, G. etunicatum, and the addition of four Pb concentrations (0, 250, 500 or 1,000 mg kg−1) to the soil. The results showed that the association of C. mucunoides with G. etunicatum promoted biomass production, and nutrient uptake (P, S and Fe) was also positively influenced by mycorrhization. The malondialdehyde
content was higher in non-mycorrhizal leaves, suggesting a reduction in the damage to membranes by lipid peroxidation in plants
associated with mycorrhizae. However, the Pb concentration in the shoots did not differ between the mycorrhizal and non-mycorrhizal
plants. The results of our study suggest that the AM symbiosis can be considered very effective in contributing to the tolerance
of C. mucunoides to Pb. 相似文献
995.
Oliveira AV Gaspar AR Francisco SC Quintela DA 《International journal of biometeorology》2012,56(2):319-332
The present experimental work is dedicated to the analysis of the effect of walking on the thermal insulation of the air layer
(I
a
) and on the convective heat transfer coefficients (h
conv
) of the human body. Beyond the standing static posture, three step rates were considered: 20, 30 and 45 steps/min. This corresponds
to walking speeds of approximately 0.23, 0.34 and 0.51 m/s, respectively. The experiments took place in a climate chamber
with an articulated thermal manikin with 16 independent parts. The indoor environment was controlled through the inner wall
temperatures since the objective of the tests was restricted to the influence of the walking movements under calm conditions.
Five set points were selected: 10, 15, 20, 25 and 30°C, and the operative temperature within the test chamber varied between
11.9 and 29.6°C. The highest and lowest I
a
values obtained were equal to 0.87 and 0.71 clo, respectively, and the reduction in insulation due to walking ranged between
9.8 and 11.5%. The convective coefficients (h
conv
) for the whole body and for the different body segments were also determined for each step rate. In the case of the whole
body, for the standing static reference posture, the mean value of h
conv
was equal to 3.3 W/m2°C and a correlation [Nu = Nu(Gr)] for natural convection is also presented in good agreement with previous results. For the other postures, the values of
h
conv
were equal to 3.7, 3.9 and 4.2 W/m2°C, respectively for 20, 30 and 45 steps/min. 相似文献
996.
Martin SL Cakmak S Hebbern CA Avramescu ML Tremblay N 《International journal of biometeorology》2012,56(4):605-619
The environmental changes caused by climate change represent a significant challenge to human societies. One part of this
challenge will be greater heat-related mortality. Populations in the northern hemisphere will experience temperature increases
exceeding the global average, but whether this will increase or decrease total temperature-related mortality burdens is debated.
Here, we use distributed lag modeling to characterize temperature-mortality relationships in 15 Canadian cities. Further,
we examine historical trends in temperature variation across Canada. We then develop city-specific general linear models to
estimate change in high- and low-temperature-related mortality using dynamically downscaled climate projections for four future
periods centred on 2040, 2060 and 2080. We find that the minimum mortality temperature is frequently located at approximately
the 75th percentile of the city’s temperature distribution, and that Canadians currently experience greater and longer lasting
risk from cold-related than heat-related mortality. Additionally, we find no evidence that temperature variation is increasing
in Canada. However, the projected increased temperatures are sufficient to change the relative levels of heat- and cold-related
mortality in some cities. While most temperature-related mortality will continue to be cold-related, our models predict that
higher temperatures will increase the burden of annual temperature-related mortality in Hamilton, London, Montreal and Regina,
but result in slight to moderate decreases in the burden of mortality in the other 11 cities investigated. 相似文献
997.
E Michelini M Donati R Aldini L Cevenini L Mezzanotte P Nardini C Foschi IB Zvi M Cevenini M Montagnani A Marangoni A Roda R Cevenini 《Analytical biochemistry》2012,421(1):92-96
Human bones, recovered from excavations, are an important biological archive of information. In particular, the analysis of the collagen fraction is useful for paleodietary reconstruction, via light stable isotopes, and for (14)C dating. Generally, collagen extraction procedures do not prevent loss of integrity of proteins. As a consequence, information about the state-of-remains preservation is unavailable. Here we describe a "soft" nondestructive CH(3)COOH-based method to recover collagen from archaeological bones, and also to obtain material for successive isotopic analyses. Our isotopic measurements on the extracts indicate that the CH(3)COOH-based method of extraction may be routinely employed in the context of paleodiet studies. In addition, we propose that biochemical characterization by denaturant electrophoresis and Western blot on CH(3)COOH extracts may be used as a bone collagen quality indicator. 相似文献
998.
We have investigated the inhibition by SulA of the assembly of Escherichia coli FtsZ. Using quantitative GTPase and fluorescence assays, we found that SulA inhibition resulted in an increase in the apparent critical concentration for FtsZ assembly. The increase in apparent critical concentration was always less than the total amount of SulA added, suggesting that the association of SulA and FtsZ was of modest affinity. Isothermal titration calorimetry gave a value of 0.78 μM for the dissociation constant of the FtsZ-SulA complex, similar in magnitude to the 0.72 μM critical concentration of FtsZ protofilament assembly at steady state. We modeled the reaction as an equilibrium competition between (a) FtsZ subunits assembling onto protofilaments or (b) binding SulA. When FtsZ was assembled in GMPCPP or in EDTA, the inhibition by SulA was reduced. The reduced inhibition could be explained by a 3- and 10-fold weaker binding of SulA to FtsZ. The mutant D212G, which has no GTPase activity and therefore minimal subunit cycling, was shown here to assemble one-stranded protofilaments, and the assembly was blocked by SulA. We also assayed the SulA and FtsZ proteins from Pseudomonas. The SulA inhibition was stronger than with the E. coli proteins, and the model indicated a 5-fold higher affinity of Pseudomonas SulA for FtsZ. 相似文献
999.
The increase in multidrug resistant bacteria has sparked an interest in the development of novel antibiotics. Antimicrobial peptides that operate by crossing the cell membrane may also have the potential to deliver drugs to intracellular targets. Buforin 2 (BF2) is an antimicrobial peptide that shares sequence identity with a fragment of histone subunit H2A and whose bactericidal mechanism depends on membrane translocation and DNA binding. Previously, novel histone-derived antimicrobial peptides (HDAPs) were designed based on properties of BF2, and DesHDAP1 and DesHDAP3 showed significant antibacterial activity. In this study, their DNA binding, permeabilization, and translocation abilities were assessed independently and compared to antibacterial activity to determine whether they share a mechanism with BF2. To investigate the importance of proline in determining the peptides' mechanisms of action, proline to alanine mutants of the novel peptides were generated. DesHDAP1, which shows significant similarities to BF2 in terms of secondary structure, translocates effectively across lipid vesicle and bacterial membranes, while the DesHDAP1 proline mutant shows reduced translocation abilities and antimicrobial potency. In contrast, both DesHDAP3 and its proline mutant translocate poorly, though the DesHDAP3 proline mutant is more potent. Our findings suggest that a proline hinge can promote membrane translocation in some peptides, but that the extent of its effect on permeabilization depends on the peptide's amphipathic properties. Our results also highlight the different antimicrobial mechanisms exhibited by histone-derived peptides and suggest that histones may serve as a source of novel antimicrobial peptides with varied properties. 相似文献
1000.
Romi H Cohen I Landau D Alkrinawi S Yerushalmi B Hershkovitz R Newman-Heiman N Cutting GR Ofir R Sivan S Birk OS 《American journal of human genetics》2012,90(5):893-899
Meconium ileus, intestinal obstruction in the newborn, is caused in most cases by CFTR mutations modulated by yet-unidentified modifier genes. We now show that in two unrelated consanguineous Bedouin kindreds, an autosomal-recessive phenotype of meconium ileus that is not associated with cystic fibrosis (CF) is caused by different homozygous mutations in GUCY2C, leading to a dramatic reduction or fully abrogating the enzymatic activity of the encoded guanlyl cyclase 2C. GUCY2C is a transmembrane receptor whose extracellular domain is activated by either the endogenous ligands, guanylin and related peptide uroguanylin, or by an external ligand, Escherichia coli (E. coli) heat-stable enterotoxin STa. GUCY2C is expressed in the human intestine, and the encoded protein activates the CFTR protein through local generation of cGMP. Thus, GUCY2C is a likely candidate modifier of the meconium ileus phenotype in CF. Because GUCY2C heterozygous and homozygous mutant mice are resistant to E. coli STa enterotoxin-induced diarrhea, it is plausible that GUCY2C mutations in the desert-dwelling Bedouin kindred are of selective advantage. 相似文献