全文获取类型
收费全文 | 298篇 |
免费 | 21篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 17篇 |
2014年 | 23篇 |
2013年 | 18篇 |
2012年 | 17篇 |
2011年 | 24篇 |
2010年 | 14篇 |
2009年 | 8篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 11篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有319条查询结果,搜索用时 27 毫秒
141.
Systematic Parasitology - Two new species of parasitic copepods of the genus Colobomatus Hesse, 1873 (Cyclopoida) are proposed based on specimens collected from the squirrelfishes (Holocentridae)... 相似文献
142.
Bruno Henrique dos Santos Ferreira Angélica Guerra Maxwell da Rosa Oliveira Letícia Koutchin Reis André Aptroot Danilo Bandini Ribeiro Letícia Couto Garcia 《Plant Species Biology》2021,36(3):523-534
Optimal sexual reproduction in relation to fire effects varies in Fabaceae species. Calliandra species have a large investment in reproduction. We investigated the consequences of fire during the fruiting period of Calliandra parviflora Benth., by checking fruit exposure to fire, pre-dispersal seed predator infestation, and the effect of fruit burning on germination. We conducted this study in a floodable savanna in central Brazil, where we collected burnt and unburnt fruits. We measured the fruit and seed mass, and counted the number of damaged and undamaged seeds and live larvae per fruit. We analyzed the seed germination percentage from burnt and unburnt fruits. The burnt fruits presented greater mass than the unburnt fruits, despite their seed mass being similar. The number of damaged seeds per fruit was only slightly higher in burnt compared to unburnt fruits (p = 0.047). The number of larvae on pre-dispersal seeds per fruit varied from 0 to 4 and did not differ between burnt and unburnt fruits. The germination percentage of unburnt fruit seeds (mean = 22 ± 17%), was significantly higher than that of burnt fruit (mean = 3.0 ± 2.0%, p < 0.001). Fire during fruiting or pre-dispersion decreases seed germination from 22 to 3%, but it does not hurt vegetative regeneration or resprout capacity of C. parviflora, which is a facultative seeder. Hence, we suggest that C. parviflora has potential for post-fire restoration in floodable open grassy savannas, in the ecotone between Cerrado and Pantanal, because this species may sprout quickly after first post-fire rains. 相似文献
143.
Elisabeth Couto Sven Sandin Marie L?f Giske Ursin Hans-Olov Adami Elisabete Weiderpass 《PloS one》2013,8(2)
Background
A Mediterranean diet has a recognized beneficial effect on health and longevity, with a protective influence on several cancers. However, its association with breast cancer risk remains unclear.Objective
We aimed to investigate whether adherence to a Mediterranean dietary pattern influences breast cancer risk.Design
The Swedish Women’s Lifestyle and Health cohort study includes 49,258 women aged 30 to 49 years at recruitment in 1991–1992. Consumption of foods and beverages was measured at enrollment using a food frequency questionnaire. A Mediterranean diet score was constructed based on the consumption of alcohol, vegetables, fruits, legumes, cereals, fish, the ratio of unsaturated to saturated fat, and dairy and meat products. Relative risks (RR) for breast cancer and specific tumor characteristics (invasiveness, histological type, estrogen/progesterone receptor status, malignancy grade and stage) associated with this score were estimated using Cox regression controlling for potential confounders.Results
1,278 incident breast cancers were diagnosed. Adherence to a Mediterranean dietary pattern was not statistically significantly associated with reduced risk of breast cancer overall, or with specific breast tumor characteristics. A RR (95% confidence interval) for breast cancer associated with a two-point increment in the Mediterranean diet score was 1.08 (1.00–1.15) in all women, and 1.10 (1.01–1.21) and 1.02 (0.91–1.15) in premenopausal and postmenopausal women, respectively. When alcohol was excluded from the Mediterranean diet score, results became not statistically significant.Conclusions
Adherence to a Mediterranean dietary pattern did not decrease breast cancer risk in this cohort of relatively young women. 相似文献144.
Subhajit Basu Deepti D Deobagkar SG Prabhu Matondkar Irene Furtado 《Microbial ecology》2013,65(4):934-954
A massive algal bloom of the dinoflagellate Noctiluca miliaris (green) was located in the Northern Arabian Sea by IRS-P4-2 (OCM-II) for microbiological studies, during two consecutive cruises of February-March 2009. Culturable bacterial load during bloom were ~2–3-fold higher in comparison to non-bloom waters and ranged from 3.20?×?105 to 6.84?×?105?cfu?ml?1. An analysis of the dominant heterotrophs associated with Noctiluca bloom resulted in phylogenetic and a detailed metabolic characterization of 70 bacterial isolates from an overlapping active and declining bloom phase location near north-central Arabian Sea. The active phase flora was dominated by Gram-positive forms (70.59 %), a majority of which belonged to Bacillus (35.29 %) of Firmicutes. As the bloom declined, Gram-negative forms (61.11 %) emerged dominant, and these belonged to a diverse γ-proteobacterial population consisting of Shewanella (16.67 %) and equal fractions of a Cobetia–Pseudomonas-Psychrobacter–Halomonas population (36.11 %). A Unifrac-based principal coordinate analysis of partial 16S rDNA sequences showed significant differences among the active and declining phase flora and also with reported endocytic flora of Noctiluca (red). A nonparametric multidimensional scaling (NMDS) of antibiogram helped differentiation among closely related strains. The organic matter synthesized by N. miliaris appears to be quickly utilized and remineralized as seen from the high efficiency of isolates to metabolize various complex and simple C/N substrates such as carbohydrates, proteins/amino acids, lipids, sulfide production from organic matter, and solubilize phosphates. The ability of a large fraction of these strains (50–41.67 %) to further aerobically denitrify indicates their potential for nitrogen removal from these high-organic microniches of the Noctiluca bloom in the Arabian Sea, also known for high denitrification activity. The results indicate that culturable euphotic bacterial associates of Noctiluca are likely to play a critical role in the biogeochemical ramifications of these unique seasonally emerging tropical open-water blooms of the Northern Arabian Sea. 相似文献
145.
Andrew N. Gillison David E. Bignell Kenneth R. W. Brewer Erick C. M. Fernandes David T. Jones Douglas Sheil Peter H. May Allan D. Watt Reginaldo Constantino Eduardo G. Couto Kurniatun Hairiah Paul Jepson Agus P. Kartono Ibnu Maryanto Germano G. Neto Meine van Noordwijk Elton A. Silveira Francis-Xavier Susilo Stephen A. Vosti Paulo C. Nunes 《Biodiversity and Conservation》2013,22(9):1909-1930
Multi-taxon surveys were conducted in species-rich, lowland palaeotropical and neotropical forested landscapes in Sumatra, Indonesia and Mato Grosso, Brazil. Gradient-directed transects (gradsects) were sampled across a range of forested land use mosaics, using a uniform protocol to simultaneously record vegetation (vascular plant species, plant functional types (PFTs) and vegetation structure), vertebrates (birds, mammals) and invertebrates (termites), in addition to measuring site and soil properties, including carbon stocks. At both sites similar correlations were detected between major components of structure (mean canopy height, woody basal area and litter depth) and the diversities of plant species and PFTs. A plant species to PFT ratio [spp.:PFTs] was the best overall predictor of animal diversity, especially termite species richness in Sumatra. To a notable extent vegetation structure also correlated with animal diversity. These surrogates demonstrate generic links between habitat structural elements, carbon stocks and biodiversity. They may also offer practical low-cost indicators for rapid assessment in tropical forest landscapes. 相似文献
146.
Gonçalo M. Rosa Henrique Couto Refaly Ernest Franco Andreone 《Marine and Freshwater Behaviour and Physiology》2013,45(6):467-471
Hydrothelphusa vencesi is an endemic Madagascan freshwater crab whose ecology and behaviour are largely unknown. We report here on an episode of the feeding habits of two individuals of H. vencesi on a giant fire millipede (Aphistogoniulus infernalis) and on a cicada (Malagasia inflata) in south-east Madagascar. This represents a first report on the diet of this species and an example of its opportunistic feeding behaviour, shedding some light on the possible trophic link between an aquatic and a terrestrial system. 相似文献
147.
The use and practicability of microwave-assisted staining procedures in routine histopathology has been well established for more than 17 years. In the study reported here, we aimed to examine an alternative approach that would shorten the duration of dewaxing and clearing steps of hematoxylin and eosin (H & E) staining of paraffin sections by using a microwave oven. Although xylene is one of the most popular dewaxing and clearing agents, its flammability restricts its use in a microwave oven; thus we preferred 1,1,1 trichloroethane, which is not flammable, as the dewaxing and clearing agent in the present study. In Group I and Group II (control groups), intestine was processed with xylene and 1,1,1 trichloroethane, respectively. The sections were then stained with H & E according to the conventional staining protocol at room temperature and subdivided into two groups according to the duration of dewaxing and clearing in xylene. In Groups III and IV (experimental groups) similar tissues were processed with xylene and 1,1,1 trichloroethane, respectively; however, sections from these groups were divided into four subgroups to study the period required for dewaxing and clearing in 1,1,1 trichloroethane, then stained with H & E in the microwave oven at 360 W for 30 sec. Our conventional H & E staining procedure, which includes dewaxing, staining and clearing of sections, requires approximately 90 min, while our method using 1,1,1 trichloroethane and microwave heating required only 2 min. Our alternative method for H & E staining not only reduced the procedure time significantly, but also yielded staining quality equal or superior to those stained the conventional way. Our results suggest that 1,1,1 trichloroethane can be used effectively and safely as a dewaxing and clearing agent for H & E staining in a microwave oven. 相似文献
148.
Couto SG Cristina Nonato M Costa-Filho AJ 《Biochemical and biophysical research communications》2011,(3):487-492
Dihydroorotate dehydrogenases (DHODHs) are enzymes that catalyze the fourth step of the de novo synthesis of pyrimidine nucleotides. In this reaction, DHODH converts dihydroorotate to orotate, using a flavine mononucleotide as a cofactor. Since the synthesis of nucleotides has different pathways in mammals as compared to parasites, DHODH has gained much attention as a promising target for drug design. Escherichia coli DHODH (EcDHODH) is a family 2 DHODH that interacts with cell membranes in order to promote catalysis. The membrane association is supposedly made via an extension found in the enzyme’s N-terminal. In the present work, we used site directed spin labeling (SDSL) to specifically place a magnetic probe at positions 2, 5, 19, and 21 within the N-terminal and thus monitor, by using Electron Spin Resonance (ESR), dynamics and structural changes in this region in the presence of a membrane model system. Overall, our ESR spectra show that the N-terminal indeed binds to membranes and that it experiences a somewhat high flexibility that could be related to the role of this region as a molecular lid controlling the entrance of the enzyme’s active site and thus allowing the enzyme to give access to quinones that are dispersed in the membrane and that are necessary for the catalysis. 相似文献
149.
Alexandre Alonso Alves Lúcio Mauro da Silva Guimarães Agnaldo Rodrigues de Melo Chaves Fábio Murilo DaMatta Acelino Couto Alfenas 《Acta Physiologiae Plantarum》2011,33(5):1831-1839
One of the most important diseases of eucalyptus plantations is caused by the rust fungus Puccinia psidii. While the genetic basis of rust resistance has been addressed recently, little is known about the physiological aspects
of Eucalyptus–P. psidii interaction. In order to fill this gap, we undertook a study investigating the effects of P. psidii infection on photosynthetic processes of two E. urophylla clones with contrasting resistance to the pathogen. Our results show that gas exchange and chlorophyll a fluorescence parameters were virtually unaffected in the resistant clone. In the susceptible clone, photosynthetic rates
were chiefly constrained by biochemical limitations to carbon fixation. Photosynthesis was impaired only in symptomatic tissues
since the reductions in photosynthetic rates were proportional to the diseased leaf area. Rust infection provoked chronic
photoinhibition to photosynthesis in the susceptible clone. Overall, differences in the ability for light capture, use and
dissipation may play a significant role in explaining the clonal differences in Eucalyptus in response to P. psidii infection. To our knowledge, this is the first report of the effect of rust infection on gas exchange and chlorophyll a fluorescence parameters in Eucalyptus. 相似文献
150.
Sisti F Fernández J Higgins SC Casabuono A Couto A Mills KH Hozbor D 《Microbiology and immunology》2011,55(12):847-854
The present authors have previously obtained the Bordetella bronchiseptica mutant BbLP39, which contains a deep-rough lipopolysaccharide (LPS) instead the wild type smooth LPS with O antigen. This mutant was found to be altered in the expression of some proteins and in its ability to colonize mouse lungs. Particularly, in BbLP39 the expression of pertactin is decreased. To differentiate the contribution of each bacterial component to the observed phenotype, here mice defective in the LPS sensing receptor TLR4 (TLR4-defective mice) were used. In contrast to wild-type mice, infection of TLR4-defective mice with BbLP39 resulted in lung infection, which persisted for more than 10 days post-challenge. Comparative analysis of the immune responses induced by purified mutant and wild type LPSs showed that the mutant LPS induced significantly higher degrees of expression of TNF-α and IL-10 mRNA than did the wild type. UV matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometry analysis revealed that both LPSs had the same penta-acylated lipid A structure. However, the lipid A from BbLP39 contained pyrophosphate instead of phosphate at position 1. This structural difference, in addition to the lack of O-antigen in BbLP39, may explain the functional differences between BbLP39 and wild type strains. 相似文献