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191.
Aquatic Ecology - Blooms of freshwater toxic cyanobacteria are a growing environmental health problem, enhanced by anthropogenic eutrophication and climate change. A variety of techniques were... 相似文献
192.
Marcus de Melo Teixeira Anderson Messias Rodrigues Clement K. M. Tsui Luiz Gonzaga Paulo de Almeida Anne D. Van Diepeningen Bert Gerrits van den Ende Geisa Ferreira Fernandes Rui Kano Richard C. Hamelin Leila Maria Lopes-Bezerra Ana Tereza Ribeiro Vasconcelos Sybren de Hoog Zoilo Pires de Camargo Maria Sueli Soares Felipe 《Eukaryotic cell》2015,14(2):158-169
Sporotrichosis is one of the most frequent subcutaneous fungal infections in humans and animals caused by members of the plant-associated, dimorphic genus Sporothrix. Three of the four medically important Sporothrix species found in Brazil have been considered asexual as no sexual stage has ever been reported in Sporothrix schenckii, Sporothrix brasiliensis, or Sporothrix globosa. We have identified the mating type (MAT) loci in the S. schenckii (strain 1099-18/ATCC MYA-4821) and S. brasiliensis (strain 5110/ATCC MYA-4823) genomes by using comparative genomic approaches to determine the mating type ratio in these pathogen populations. Our analysis revealed the presence of a MAT1-1 locus in S. schenckii while a MAT1-2 locus was found in S. brasiliensis representing genomic synteny to other Sordariomycetes. Furthermore, the components of the mitogen-activated protein kinase (MAPK)-pheromone pathway, pheromone processing enzymes, and meiotic regulators have also been identified in the two pathogens, suggesting the potential for sexual reproduction. The ratio of MAT1-1 to MAT1-2 was not significantly different from 1:1 for all three Sporothrix species, but the population of S. brasiliensis in the outbreaks originated from a single mating type. We also explored the population genetic structure of these pathogens using sequence data of two loci to improve our knowledge of the pattern of geographic distribution, genetic variation, and virulence phenotypes. Population genetics data showed significant population differentiation and clonality with a low level of haplotype diversity in S. brasiliensis isolates from different regions of sporotrichosis outbreaks in Brazil. In contrast, S. schenckii isolates demonstrated a high degree of genetic variability without significant geographic differentiation, indicating the presence of recombination. This study demonstrated that two species causing the same disease have contrasting reproductive strategies and genetic variability patterns. 相似文献
193.
After more than a decade of soil moisture deficit,tropical rainforest trees maintain photosynthetic capacity,despite increased leaf respiration 下载免费PDF全文
Lucy Rowland Raquel L. Lobo‐do‐Vale Bradley O. Christoffersen Eliane A. Melém Bart Kruijt Steel S. Vasconcelos Tomas Domingues Oliver J. Binks Alex A. R. Oliveira Daniel Metcalfe Antonio C. L. da Costa Maurizio Mencuccini Patrick Meir 《Global Change Biology》2015,21(12):4662-4672
Determining climate change feedbacks from tropical rainforests requires an understanding of how carbon gain through photosynthesis and loss through respiration will be altered. One of the key changes that tropical rainforests may experience under future climate change scenarios is reduced soil moisture availability. In this study we examine if and how both leaf photosynthesis and leaf dark respiration acclimate following more than 12 years of experimental soil moisture deficit, via a through‐fall exclusion experiment (TFE) in an eastern Amazonian rainforest. We find that experimentally drought‐stressed trees and taxa maintain the same maximum leaf photosynthetic capacity as trees in corresponding control forest, independent of their susceptibility to drought‐induced mortality. We hypothesize that photosynthetic capacity is maintained across all treatments and taxa to take advantage of short‐lived periods of high moisture availability, when stomatal conductance (gs) and photosynthesis can increase rapidly, potentially compensating for reduced assimilate supply at other times. Average leaf dark respiration (Rd) was elevated in the TFE‐treated forest trees relative to the control by 28.2 ± 2.8% (mean ± one standard error). This mean Rd value was dominated by a 48.5 ± 3.6% increase in the Rd of drought‐sensitive taxa, and likely reflects the need for additional metabolic support required for stress‐related repair, and hydraulic or osmotic maintenance processes. Following soil moisture deficit that is maintained for several years, our data suggest that changes in respiration drive greater shifts in the canopy carbon balance, than changes in photosynthetic capacity. 相似文献
194.
Cadhla Firth Rafal Tokarz Darlene B. Simith Marcio R. T. Nunes Meera Bhat Elizabeth S. T. Rosa Daniele B. A. Medeiros Gustavo Palacios Pedro F. C. Vasconcelos W. Ian Lipkin 《Journal of virology》2012,86(24):13756-13766
Hantaviruses are important contributors to disease burden in the New World, yet many aspects of their distribution and dynamics remain uncharacterized. To examine the patterns and processes that influence the diversity and geographic distribution of hantaviruses in South America, we performed genetic and phylogeographic analyses of all available South American hantavirus sequences. We sequenced multiple novel and previously described viruses (Anajatuba, Laguna Negra-like, two genotypes of Castelo dos Sonhos, and two genotypes of Rio Mamore) from Brazilian Oligoryzomys rodents and hantavirus pulmonary syndrome cases and identified a previously uncharacterized species of Oligoryzomys associated with a new genotype of Rio Mamore virus. Our analysis indicates that the majority of South American hantaviruses fall into three phylogenetic clades, corresponding to Andes and Andes-like viruses, Laguna Negra and Laguna Negra-like viruses, and Rio Mamore and Rio Mamore-like viruses. In addition, the dynamics and distribution of these viruses appear to be shaped by both the geographic proximity and phylogenetic relatedness of their rodent hosts. The current system of nomenclature used in the hantavirus community is a significant impediment to understanding the ecology and evolutionary history of hantaviruses; here, we suggest strict adherence to a modified taxonomic system, with species and strain designations resembling the numerical system of the enterovirus genus. 相似文献
195.
Cláudio de Oliveira Cunha Luiz Fernando Goda Zuleta Luiz Gonzaga Paula de Almeida Luciane Prioli Ciapina Wardsson Lustrino Borges Rosa Maria Pitard José Ivo Baldani Rosangela Straliotto Sérgio Miana de Faria Mariangela Hungria Benildo Sousa Cavada Fábio Martins Mercante Ana Tereza Ribeiro de Vasconcelos 《Journal of bacteriology》2012,194(23):6675-6676
The genus Burkholderia represents a challenge to the fields of taxonomy and phylogeny and, especially, to the understanding of the contrasting roles as either opportunistic pathogens or bacteria with biotechnological potential. Few genomes of nonpathogenic strains, especially of diazotrophic symbiotic bacteria, have been sequenced to improve understanding of the genus. Here, we contribute with the complete genome sequence of Burkholderia phenoliruptrix strain BR3459a (CLA1), an effective diazotrophic symbiont of the leguminous tree Mimosa flocculosa Burkart, which is endemic to South America. 相似文献
196.
Neves MP Cravo S Lima RT Vasconcelos MH Nascimento MS Silva AM Pinto M Cidade H Corrêa AG 《Bioorganic & medicinal chemistry》2012,20(1):25-33
Thirty-one 2'-hydroxychalcones were prepared via solid-phase synthesis by base-catalyzed aldol condensation of substituted 2'-hydroxyacetophenones and benzaldehydes. Chalcones were tested for their growth inhibitory activity in three human tumor cell lines (MCF-7, NCI-H460 and A375-C5) using the SRB assay. Results revealed that several of the tested compounds caused a pronounced dose-dependent growth inhibitory effect on the tumor cell lines studied in the low micromolar range. To gain further insight on the cellular mechanism of action of this class of compounds, studies of their effect on cell cycle profile as well as on induction of cellular apoptosis were also carried out. Generally, the tested chalcones interfered with the cell cycle profile and increased the percentage of apoptotic MCF-7 cells. The results here presented may help to identify new chalcone-like structures with optimized cell growth inhibitory activity which may be further tested as potential antitumor agents. 相似文献
197.
LS Tavares JV Rettore RM Freitas WF Porto AP Duque Jde L Singulani ON Silva Mde L Detoni EG Vasconcelos SC Dias OL Franco Mde O Santos 《Peptides》2012,37(2):294-300
Antimicrobial peptides (AMPs) are compounds that act in a wide range of physiological defensive mechanisms developed to counteract bacteria, fungi, parasites and viruses. These molecules have become increasingly important as a consequence of remarkable microorganism resistance to common antibiotics. This report shows Escherichia coli expressing the recombinant antimicrobial peptide Pg-AMP1 previously isolated from Psidium guajava seeds. The deduced Pg-AMP1 open reading frame consists in a 168bp long plus methionine also containing a His6 tag, encoding a predicted 62 amino acid residue peptide with related molecular mass calculated to be 6.98kDa as a monomer and 13.96kDa at the dimer form. The recombinant Pg-AMP1 peptide showed inhibitory activity against multiple Gram-negative (E. coli, Klebsiella pneumonia and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Staphylococcus epidermides) bacteria. Moreover, theoretical structure analyses were performed in order to understand the functional differences between natural and recombinant Pg-AMP1 forms. Data here reported suggest that Pg-AMP1 is a promising peptide to be used as a biotechnological tool for control of human infectious diseases. 相似文献
198.
Fonseca FV Fonseca de Souza AL Mariano AC Entringer PF Gondim KC Meyer-Fernandes JR 《Experimental parasitology》2006,112(2):76-84
In this work we describe the ability of living Trypanosoma rangeli to hydrolyze extracellular ATP. In these intact parasites whose viability was assessed before and after the reactions by motility and by Trypan blue dye exclusion, there was a low level of ATP hydrolysis in the absence of any divalent metal (1.53+/-0.12 nmol P(i)/h x 10(7) cells). The ATP hydrolysis was stimulated by MgCl(2) and the Mg-dependent ecto-ATPase activity was 5.24+/-0.64 nmol P(i)/h x 10(7) cells. The Mg-dependent ecto-ATPase activity was linear with cell density and with time for at least 60 min. This stimulatory effect on the ATP hydrolysis was also observed when MgCl(2) was replaced by MnCl(2), but not by CaCl(2), SrCl(2), and ZnCl(2). The apparent K(m) for Mg-ATP2- was 0.53+/-0.11 mM. The optimum pH for the T. rangeli Mg-dependent ecto-ATPase activity lies in the alkaline range. This ecto-ATPase activity was insensitive to inhibitors of other ATPase and phosphatase activities, such as oligomycin, sodium azide, bafilomycin A1, ouabain, furosemide, vanadate, molybdate, sodium fluoride, tartrate, and levamizole. To confirm that this Mg-dependent ATPase was an ecto-ATPase, we used an impermeant inhibitor, DIDS (4, 4'-diisothiocyanostylbene 2'-2'-disulfonic acid) as well as suramin, an antagonist of P2 purinoreceptors and inhibitor of some ecto-ATPases. These two reagents inhibited the Mg(2+)-dependent ATPase activity in a dose-dependent manner. This ecto-ATPase activity was stimulated by carbohydrates involved in the attachment/invasion of salivary glands of Rhodnius prolixus and by lipophorin, an insect lipoprotein circulating in the hemolymph. 相似文献
199.
Campos PP Andrade SP Moro L Ferreira MA Vasconcelos AC 《Histology and histopathology》2006,21(12):1263-1270
The integration of implanted material to host organism requires spatial and temporal organization of several cellular processes, such as proliferation, differentiation and apoptosis. Despite the clinical relevance of these processes, there is little information regarding the sequence of such events in synthetic matrices. Here, we present a combination of techniques used to characterize the fibrovascular response in subcutaneous polyether-polyurethane sponge implants in mice at days 4, 7, 10 and 14 postimplantation. The AgNOR technique was modified and used as a surrogate marker for proliferating and activated cells invading the implant. The number of AgNOR-stained cells increased progressively from day 4 (606+/-76) to day 14 (2146+/-71) postimplantation. The number of TUNEL-positive (apoptotic index) cells also increased progressively from day 4 (459+/-40) to day 14 (1157+/-119) postimplantation. However, the ratio of TUNEL-labeled/proliferating cells had its highest peak in the early phase of the process remaining stable until day 14. Using Picrosirius staining it was shown that thin collagen increased from day 4, peaking at day 10 and falling markedly at day 14, whereas dense collagen increased progressively during the whole period. These experiments hold potential to investigate not only distinct phases of tissue repair induced by synthetic matrices but also to study underlying mechanisms involved. 相似文献
200.
Martin Saker Cristiana Moreira Joana Martins Brett Neilan Vitor Manuel Vasconcelos 《Applied microbiology and biotechnology》2009,85(2):237-252
Cyanobacteria are prokaryotic photosynthetic living organisms that inhabit our planet for over three billion years. With a
worldwide distribution, they can be found in all types of environments: fresh, brackish and saltwater as well as terrestrial.
Though beneficial in the development of life on earth, they also constitute a serious risk to our ecosystems since they can
biologically produce harmful secondary metabolites named cyanotoxins. When studying cyanobacteria and their cyanotoxins, several
methodologies have been applied with an increasing relevance to molecular methods. Therefore, the aim of this review is to
describe alternative molecular methods that can be used as alternative methods for the identification of cyanobacteria. More
traditional chemotaxonomic methods are discussed briefly as are the standard and somewhat dated techniques for assessing genome
content for taxonomic classification schemes. The use of DNA amplification technology has been applied to the systematics
and phylogeny of many bacterial groups, and the optimisation of methods for rapid identification and classification of cyanobacteria
are presented. Together with novel methods developed for these photosynthetic microorganisms, the generated DNA profiles have
been utilised to study cyanobacterial bloom population diversity and prediction of strain toxigenicity. Finally, the genotypes
found were applied to a variety of phylogenetic analyses; trees were reconstructed and compared to the current morphological
system of classification. The ecology and diversity of the cyanobacteria is discussed with respect to the derived molecular
phylogenies and systematics. 相似文献