全文获取类型
收费全文 | 594篇 |
免费 | 33篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 18篇 |
2020年 | 15篇 |
2019年 | 16篇 |
2018年 | 22篇 |
2017年 | 19篇 |
2016年 | 36篇 |
2015年 | 50篇 |
2014年 | 39篇 |
2013年 | 65篇 |
2012年 | 54篇 |
2011年 | 67篇 |
2010年 | 27篇 |
2009年 | 20篇 |
2008年 | 24篇 |
2007年 | 27篇 |
2006年 | 26篇 |
2005年 | 18篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有627条查询结果,搜索用时 31 毫秒
141.
José C. Ramalho M. C. Rebelo M. Emília Santos M. Luísa Antunes M. Antonieta Nunes 《Plant and Soil》1995,172(1):87-96
Calcium deficiency was induced in hydroponically grown 1.5-years-old coffee plants with 12–14 pairs of leaves. Calcium was given in the form of Ca(NO3)2: 5, 2.5, 0.1, 0.01 and 0 mM. After 71 days of Ca-treatment root and shoot as well as total biomass were decreased by severe Ca-deficiency. However, a stronger decrease was observed for shoot growth as revealed by the increase in the root/shoot ratio. New leaves were affected showing decreases in the total leaf area and in Leaf Area Duration (LAD). After 91 days of deficiency, leaf protein concentration decreased (by about 45%) in the top leaves while nitrate reductase activity (NRA) and NO3 content showed no significant changes. Total nitrogen and mineral concentrations (P, K, Ca, Mg and Na) were also determined in leaves and roots. With the decrease in calcium concentration in Ca-deficiency conditions, we observed concomitant increases in the concentrations of K+, Mg2+ and Na+ in leaves (maximal changes of 32% for K+, 96% for Mg2+ and 438% for Na+) and in roots (108% for K+, 86% for Mg2+ and 38% for Na+). Accordingly, the ratio between elements changed, including the ratio N/P, showing a non-equilibrium in the balance of nutrients. Significant correlations were obtained between Ca2+ concentration and some photosynthetic parameters. Ca-deficiency conditions would increase the loss of energy as expressed by the rise in aE and decrease the photochemical efficiency, which confirms the importance of this element in the stabilization of chlorophyll and in the maintenance of good photochemical efficiency at PS II level.Abbreviations Chl
Chlorophyll
- Fv/Fm
ratio of variable to maximal fluorescence
- LAD
leaf area duration
- LHC II
light harvesting complex of PS II
- NRA
nitrate reductase activity
- PC
photosynthetic capacity
- PS II
photosystem II
- P680
reaction center of PS II
- qN
non-photochemical quenching
- qE
high-energy dependent quenching
- qp
photochemical quenching
- SLA
specific leaf area 相似文献
142.
Silvio Renato Oliveira Menegassi Gabriel Ribas Pereira Carolina Bremm Celso Koetz Flávio Guiselli Lopes Eduardo Custódio Fiorentini Concepta McManus Eduardo Antunes Dias Marcela Kuczynski da Rocha Rubia Branco Lopes Júlio Otávio Jardim Barcellos 《International journal of biometeorology》2016,60(11):1787-1794
143.
144.
Cell wall targeted in planta iron accumulation enhances biomass conversion and seed iron concentration in Arabidopsis and rice 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Plant biotechnology journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Haibing Yang Hui Wei Guojie Ma Mauricio S. Antunes Stefan Vogt Joseph Cox Xiao Zhang Xiping Liu Lintao Bu S. Charlotte Gleber Nicholas C. Carpita Lee Makowski Michael E. Himmel Melvin P. Tucker Maureen C. McCann Angus S. Murphy Wendy A. Peer 《Plant biotechnology journal》2016,14(10):1998-2009
Conversion of nongrain biomass into liquid fuel is a sustainable approach to energy demands as global population increases. Previously, we showed that iron can act as a catalyst to enhance the degradation of lignocellulosic biomass for biofuel production. However, direct addition of iron catalysts to biomass pretreatment is diffusion‐limited, would increase the cost and complexity of biorefinery unit operations and may have deleterious environmental impacts. Here, we show a new strategy for in planta accumulation of iron throughout the volume of the cell wall where iron acts as a catalyst in the deconstruction of lignocellulosic biomass. We engineered CBM‐IBP fusion polypeptides composed of a carbohydrate‐binding module family 11 (CBM11) and an iron‐binding peptide (IBP) for secretion into Arabidopsis and rice cell walls. CBM‐IBP transformed Arabidopsis and rice plants show significant increases in iron accumulation and biomass conversion compared to respective controls. Further, CBM‐IBP rice shows a 35% increase in seed iron concentration and a 40% increase in seed yield in greenhouse experiments. CBM‐IBP rice potentially could be used to address iron deficiency, the most common and widespread nutritional disorder according to the World Health Organization. 相似文献
145.
Solange S. Magalhães Luís Alves Marco Sebastião Bruno Medronho Zaida L. Almeida Tiago Q. Faria Rui M.M. Brito Maria J. Moreno Filipe E. Antunes 《Biotechnology progress》2016,32(5):1276-1282
The use of enzymes in laundry and dish detergent products is growing. Such tendency implies dedicated studies to understand surfactant‐enzyme interactions. The interactions between surfactants and enzymes and their impact on the catalytic efficiency represent a central problem and were here evaluated using circular dichroism, dynamic light scattering, and enzyme activity determinations. This work focuses on this key issue by evaluating the role of the ethyleneoxide (EO) groups of anionic surfactants on the structure and activity of a commercial lipase, and by focusing on the protein/surfactant interactions at a molecular level. The conformational changes and enzymatic activity of the protein were evaluated in the presence of sodium dodecyl sulfate (SDS also denoted as SLE0S) and of sodium lauryl ether sulfate with two EO units (SLE2S). The results strongly suggest that the presence of EO units in the surfactant polar headgroup determines the stability and the activity of the enzyme. While SDS promotes enzyme denaturation and consequent loss of activity, SLE2S preserves the enzyme structure and activity. The data further highlights that the electrostatic interactions among the protein groups are changed by the presence of the adsorbed anionic surfactants being such absorption mainly driven by hydrophobic interactions. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1276–1282, 2016 相似文献
146.
Raimundo Fernandes de Araújo Júnior Vinícius Barreto Garcia Renata Ferreira de Carvalho Leit?o Gerly Anne de Castro Brito Emilio de Castro Miguel Paulo Marcos Matta Guedes Aurigena Antunes de Araújo 《PloS one》2016,11(2)
Aim
To evaluate the anti-inflammatory, anti-oxidant and antifibrotic effects of carvedilol (CARV) in rats with ethanol-induced liver injury.Methods
Liver injury was induced by gavage administration of alcohol (7 g/kg) for 28 consecutive days. Eighty Wistar rats were pretreated with oral CARV at 1, 3, or 5 mg/kg or with saline 1 h before exposure to alcohol. Liver homogenates were assayed for interleukin (IL)-1β, IL-10, and tumor necrosis factor (TNF)-α level as well as for myeloperoxidase (MPO) activity and malonyldialdehyde (MDA) and glutathione (GSH) levels. Serum aspartate aminotransferase (AST) activity and liver triglyceride (TG) levels were also assayed. Immunohistochemical analyses of cyclooxygenase 2 (COX-2), receptor activator of nuclear factor kappa-B/ligand (RANK/RANKL), suppressor of cytokine signalling (SOCS1), the Kupffer cell marker IBA-1 (ionized calcium-binding adaptor molecule 1), intercellular adhesion molecule 1 (ICAM-1), superoxide dismutase (SOD-1), and glutathione peroxidase (GPx-1) expression were performed. Confocal microscopy analysis of IL-1β and NF-κB expression and real-time quantitative PCR analysis for TNFα, PCI, PCIII, and NF-κB were performed.Results
CARV treatment (5 mg/kg) during the alcohol exposure protocol was associated with reduced steatosis, hepatic cord degeneration, fibrosis and necrosis, as well as reduced levels of AST (p < 0.01), ALT (p < 0.01), TG (p < 0.001), MPO (p < 0.001), MDA (p < 0.05), and proinflammatory cytokines (IL-1β and TNF-α, both p < 0.05), and increased levels of the anti-inflammatory cytokine IL-10 (p < 0.001) and GSH (p < 0.05), compared to the alcohol-only group. Treatment with CARV 5 mg/kg also reduced expression levels of COX-2, RANK, RANKL, IBA-1, and ICAM-1 (all p < 0.05), while increasing expression of SOCS1, SOD-1, and GPx-1 (all p < 0.05) and decreasing expression of IL-1β and NF-κB (both, p < 0.05). Real-time quantitative PCR analysis showed that mRNA production of TNF-α, procollagen type I (PCI), procollagen type III (PCIII), and NF-κB were decreased in the alcohol-CARV 5 mg/kg group relative to the alcohol-only group.Conclusions
CARV can reduce the stress oxidative, inflammatory response and fibrosis in ethanol-induced liver injury in a rat model by downregulating signalling of Kuppfer cells and hepatic stellate cells (HSCs) through suppression of inflammatory cytokines. 相似文献147.
J. M. Wilson † P. Reis-Santos A.-V. Fonseca † J. C. Antunes ‡ P. D. Bouça J. Coimbra ‡ 《Journal of fish biology》2007,70(4):1239-1253
In the present study, glass eels Anguilla anguilla in the Minho River estuary (41·5° N, 8·5° W) decreased in size (standard length, L S and mass, M ) from the beginning (autumn) to the end of the sampling season (summer). On the other hand elvers increased in L S and M from spring to summer and were significantly larger than glass eels in paired comparisons. Branchial Na+ /K+ -ATPase and vacuolar (V-type) proton ATPase ( in vitro activities), two important ion transporting pumps, did not show significant seasonal changes in either glass eels or elvers although in glass eels Na+ /K+ -ATPase (activity) expression was significantly higher than in elvers. In a single month comparison Na+ /K+ -ATPase branchial mRNA expression was also higher in glass eels as was the protein level expression of both Na+ /K+ -ATPase and NKCC (Na+ :K+ :2Cl− co-transporter). Immunofluorescence microscopy indicated apical CFTR Cl− channel labelling in Na+ /K+ -ATPase positive chloride cell in glass eels which was absent in elvers. Whole body sodium concentration and percentage water did not show significant seasonal differences in either glass eels or elvers although there were significant differences between these two groups during some months. 相似文献
148.
149.
L. Caetano. M. Antunes Sarah K. Andersen Alfredo Menendez Ellen T. Arena Jun Han Rosana B. R. Ferreira Christoph H. Borchers B. Brett Finlay 《Journal of bacteriology》2011,193(18):4719-4725
During the colonization of hosts, bacterial pathogens are presented with many challenges that must be overcome for colonization to occur successfully. This requires the bacterial sensing of the surroundings and adaptation to the conditions encountered. One of the major impediments to the pathogen colonization of the mammalian gastrointestinal tract is the antibacterial action of bile. Salmonella enterica serovar Typhimurium has specific mechanisms involved in resistance to bile. Additionally, Salmonella can successfully multiply in bile, using it as a source of nutrients. This accomplishment is highly relevant to pathogenesis, as Salmonella colonizes the gallbladder of hosts, where it can be carried asymptomatically and promote further host spread and transmission. To gain insights into the mechanisms used by Salmonella to grow in bile, we studied the changes elicited by Salmonella in the chemical composition of bile during growth in vitro and in vivo through a metabolomics approach. Our data suggest that phospholipids are an important source of carbon and energy for Salmonella during growth in the laboratory as well as during gallbladder infections of mice. Further studies in this area will generate a better understanding of how Salmonella exploits this generally hostile environment for its own benefit. 相似文献
150.
Lídia Nogueira Mirco Solé Sérgio Siqueira Paulo Roberto Antunes de Mello Affonso Christine Strüssmann Iracilda Sampaio 《Genetics and molecular biology》2016,39(1):49-53
Scinax (Anura: Hylidae) is a species-rich genus of amphibians (113 spp.), divided into five species groups by morphological features. Cladistic analyses however revealed only two monophyletic clades in these groups: Scinax catharinae and Scinax ruber. Most species from the S. catharinae clade are found in Atlantic rainforest, except for Scinax canastrensis,S. centralis, S. luizotavioi, S. machadoi,S. pombali and S. skaios. In the present work, specimens of Scinax collected in Chapada dos Guimarães, central Brazil, were morphologically compatible with species from theS. catharinae group. On the other hand, genetic analysis based on mitochondrial (16S and 12S) and nuclear (rhodopsin) sequences revealed a nucleotide divergence of 6 to 20% between Scinax sp. and other congeners from the Brazilian savannah (Cerrado). Accordingly, Bayesian inference placed Scinax sp. in the S. catharinae clade with high support values. Hence, these findings strongly indicate the presence of a new species in the S. catharinae clade from the southwestern portion of the Brazilian savannah. To be properly validated as a novel species, detailed comparative morphological and bioacustic studies with other taxa from Brazil such asS. canastrensis, S. centralis, S. luizotavioi, S. machadoi, S. pombali and S. skaios are required. 相似文献