全文获取类型
收费全文 | 1255篇 |
免费 | 74篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 21篇 |
2021年 | 45篇 |
2020年 | 20篇 |
2019年 | 31篇 |
2018年 | 45篇 |
2017年 | 33篇 |
2016年 | 38篇 |
2015年 | 74篇 |
2014年 | 65篇 |
2013年 | 82篇 |
2012年 | 102篇 |
2011年 | 94篇 |
2010年 | 68篇 |
2009年 | 68篇 |
2008年 | 83篇 |
2007年 | 76篇 |
2006年 | 45篇 |
2005年 | 46篇 |
2004年 | 47篇 |
2003年 | 40篇 |
2002年 | 36篇 |
2001年 | 19篇 |
2000年 | 19篇 |
1999年 | 19篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1972年 | 1篇 |
1965年 | 1篇 |
1954年 | 2篇 |
排序方式: 共有1329条查询结果,搜索用时 15 毫秒
91.
Merima Bublin Maria Kostadinova Julian E. Fuchs Daniela Ackerbauer Adolfo H. Moraes Fabio C. L. Almeida Nina Lengger Christine Hafner Christof Ebner Christian Radauer Klaus R. Liedl Ana Paula Valente Heimo Breiteneder 《PloS one》2015,10(11)
Fish allergy is associated with moderate to severe IgE-mediated reactions to the calcium binding parvalbumins present in fish muscle. Allergy to multiple fish species is caused by parvalbumin-specific cross-reactive IgE recognizing conserved epitopes. In this study, we aimed to produce cross-reactive single chain variable fragment (scFv) antibodies for the detection of parvalbumins in fish extracts and the identification of IgE epitopes. Parvalbumin-specific phage clones were isolated from the human ETH-2 phage display library by three rounds of biopanning either against cod parvalbumin or by sequential biopanning against cod (Gad m 1), carp (Cyp c 1) and rainbow trout (Onc m 1) parvalbumins. While biopanning against Gad m 1 resulted in the selection of clones specific exclusively for Gad m 1, the second approach resulted in the selection of clones cross-reacting with all three parvalbumins. Two clones, scFv-gco9 recognizing all three parvalbumins, and scFv-goo8 recognizing only Gad m 1 were expressed in the E. coli non-suppressor strain HB2151 and purified from the periplasm. scFv-gco9 showed highly selective binding to parvalbumins in processed fish products such as breaded cod sticks, fried carp and smoked trout in Western blots. In addition, the scFv-gco9-AP produced as alkaline phosphatase fusion protein, allowed a single-step detection of the parvalbumins. In competitive ELISA, scFv-gco9 was able to inhibit binding of IgE from fish allergic patients’ sera to all three β-parvalbumins by up to 80%, whereas inhibition by scFv-goo8 was up to 20%. 1H/15N HSQC NMR analysis of the rGad m 1:scFv-gco9 complex showed participation of amino acid residues conserved among these three parvalbumins explaining their cross-reactivity on a molecular level. In this study, we have demonstrated an approach for the selection of cross-reactive parvalbumin-specific antibodies that can be used for allergen detection and for mapping of conserved epitopes. 相似文献
92.
Maria A. Guimar?es Rosimeire N. de Oliveira Leiz M. C. Véras David F. Lima Yuri D. M. Campelo Stefano Augusto Campos Selma A. S. Kuckelhaus Pedro L. S. Pinto Peter Eaton Ana C. Mafud Yvonne P. Mascarenhas Silmara M. Allegretti Josué de Moraes Aleksandar Loli? Tatjana Verbi? José Roberto S. A. Leite 《PLoS neglected tropical diseases》2015,9(3)
Schistosomiasis is a serious disease currently estimated to affect more that 207 million people worldwide. Due to the intensive use of praziquantel, there is increasing concern about the development of drug-resistant strains. Therefore, it is necessary to search for and investigate new potential schistosomicidal compounds. This work reports the in vivo effect of the alkaloid epiisopiloturine (EPI) against adults and juvenile worms of Schistosoma mansoni. EPI was first purified its thermal behavior and theoretical solubility parameters charaterised. In the experiment, mice were treated with EPI over the 21 days post-infection with the doses of 40 and 200 mg/kg, and 45 days post-infection with single doses of 40, 100 and 300 mg/kg. The treatment with EPI at 40 mg/kg was more effective in adult worms when compared with doses of 100 and 300 mg/kg. The treatment with 40 mg/kg in adult worms reduced parasite burden significantly, lead to reduction in hepatosplenomegaly, reduced the egg burden in faeces, and decreased granuloma diameter. Scanning electron microscopy revealed morphological changes to the parasite tegument after treatment, including the loss of important features. Additionally, the in vivo treatment against juvenile with 40 mg/kg showed a reduction of the total worm burden of 50.2%. Histopathological studies were performed on liver, spleen, lung, kidney and brain and EPI was shown to have a DL50 of 8000 mg/kg. Therefore EPI shows potential to be used in schistosomiasis treatment. This is the first time that schistosomicidal in vivo activity of EPI has been reported. 相似文献
93.
Louise E. Bird Heather Rada Anil Verma Raphael Gasper James Birch Matthew Jennions Jan L?we Isabel Moraes Raymond J. Owens 《Journal of visualized experiments : JoVE》2015,(95)
The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and the inherent instability of many membrane proteins once solubilized in detergents. A protocol is described that combines ligation independent cloning of membrane proteins as GFP fusions with expression in Escherichia coli detected by GFP fluorescence. This enables the construction and expression screening of multiple membrane protein/variants to identify candidates suitable for further investment of time and effort. The GFP reporter is used in a primary screen of expression by visualizing GFP fluorescence following SDS polyacrylamide gel electrophoresis (SDS-PAGE). Membrane proteins that show both a high expression level with minimum degradation as indicated by the absence of free GFP, are selected for a secondary screen. These constructs are scaled and a total membrane fraction prepared and solubilized in four different detergents. Following ultracentrifugation to remove detergent-insoluble material, lysates are analyzed by fluorescence detection size exclusion chromatography (FSEC). Monitoring the size exclusion profile by GFP fluorescence provides information about the mono-dispersity and integrity of the membrane proteins in different detergents. Protein: detergent combinations that elute with a symmetrical peak with little or no free GFP and minimum aggregation are candidates for subsequent purification. Using the above methodology, the heterologous expression in E. coli of SED (shape, elongation, division, and sporulation) proteins from 47 different species of bacteria was analyzed. These proteins typically have ten transmembrane domains and are essential for cell division. The results show that the production of the SEDs orthologues in E. coli was highly variable with respect to the expression levels and integrity of the GFP fusion proteins. The experiment identified a subset for further investigation. 相似文献
94.
Gesilda F. Neves José R. F. Silva Renato B. Moraes Thiago S. Fernandes Bruno M. Tenorio Romildo A. Nogueira 《Acta biotheoretica》2014,62(2):133-143
The production, distribution and use of electricity can generate low frequency electric and magnetic fields (50–60 Hz). Considering that some studies showed adverse effects on pancreatic β-cells exposed to these fields; the present study aimed to analyze the effects of 60 Hz electric fields on membrane potential during the silent and burst phases in pancreatic β-cells using a mathematical model. Sinusoidal 60 Hz electric fields with amplitude ranging from 0.5 to 4 mV were applied on pancreatic β-cells model. The sinusoidal electric field changed burst duration, inter-burst intervals (silent phase) and spike sizes. The parameters above presented dose-dependent response with the voltage amplitude applied. In conclusion, theoretical analyses showed that a 60 Hz electric field with low amplitudes changes the membrane potential in pancreatic β-cells. 相似文献
95.
Fernanda A. H. Batista Leandro S. Goto Wanius Garcia Derminda I. de Moraes Mario de Oliveira Neto Igor Polikarpov Marcia R. Cominetti Heloísa S. Selistre-de-Araújo Leila M. Beltramini Ana Paula Ulian Araújo 《European biophysics journal : EBJ》2010,39(8):1193-1205
Lectins have been classified into a structurally diverse group of proteins that bind carbohydrates and glycoconjugates with
high specificity. They are extremely useful molecules in the characterization of saccharides, as drug delivery mediators,
and even as cellular surface makers. In this study, we present camptosemin, a new lectin from Camptosema ellipticum. It was characterized as an N-acetyl-d-galactosamine-binding homo-tetrameric lectin, with a molecular weight around 26 kDa/monomers. The monomers were stable over
a wide range of pH values and exhibited pH-dependent oligomerization. Camptosemin promoted adhesion of breast cancer cells
and hemagglutination, and both activities were inhibited by its binding of sugar. The stability and unfolding/folding behavior
of this lectin was characterized using fluorescence and far-UV circular dichroism spectroscopies. The results indicate that
chemical unfolding of camptosemin proceeds as a two-state monomer-tetramer process. In addition, small-angle X-ray scattering
shows that camptosemin behaves as a soluble and stable homo-tetramer molecule in solution. 相似文献
96.
Tatiane M. M. G. de Castro Gilberto J. de Moraes 《Experimental & applied acarology》2010,50(2):133-139
Life cycle and behaviour of Cunaxatricha tarsospinosa Castro & Den Heyer from rubber trees in Brazil were studied, with Tenuipalpus heveae Baker offered as prey. The study was conducted at 25.4 ± 0.2°C, 83 ± 5% RH and 12:12 h L:D photophase. The egg stage was
the longest immature stage, lasting 17.1 ± 1.3 days (mean ± SE); total juvenile development was completed in 33.2 ± 2.8 days.
Lifetime fecundity was 12.0 ± 2.2 eggs. Intrinsic rate of population increase was low, suggesting that T. heveae may not be a good prey for the predator. All specimens of C. tarsospinosa collected in the field for this study were females, no males were found. Concurrently, only females were obtained in the
laboratory. This seems to be the first report of thelytokous parthenogenesis for cunaxids. Similar to earlier reports for
some Cunaxinae and Coleoscirinae, prey were captured when predators were actively searching for them. 相似文献
97.
Rogério P. Mateus Luciana P.B. Machado Evandro M. Moraes Fábio M. Sene 《Biochemical Systematics and Ecology》2010
Drosophila antonietae and Drosophila gouveai are allopatric, cactophilic, cryptic and endemic of South America species, which aedeagus morphology is considered the main diagnostic character. In this work, single close populations from the edge distributions of each species, located in an “introgressive corridor”, were analyzed regarding temporal isozenzymatic genetic variability. Isocitrate dehydrogenase (Idh) appeared as a diagnostic locus between D. antonieate and D. gouveai because each population was fixed for different alleles. Moreover, several polymorphic loci showed accentuated divergence in the allele frequency, as evidenced by Nei’s I (0.3188) and D (1.1432), and also by Reynolds’ genetic distance and identity (1.3207 and 0.7331, respectively). Our results showed that, in spite of the very similar external morphology, related evolutionary histories, close distributions, and events of introgression in the studied area, these cryptic species have high allozymatic differentiation, and this is discussed here. 相似文献
98.
Bárbara Santos Pires da Silva Eloísa Bonfá Júlio César Bertacini de Moraes Carla Gonçalves Schain Saad Ana Cristina de Medeiros Ribeiro Célio Roberto Gonçalves Jozélio Freire de Carvalho 《Biologicals》2010,38(5):567-569
The objective of this study was to evaluate the influence of anti-tumor necrosis factor (anti-TNF) in juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS) or psoriatic arthritis (PsA). Sixty-two patients were investigated: 7 JIA; 37 AS; and 18 PsA. Caucasian race accounted for 79% and 29% were female. Mean age was 40.4 ± 12.6years. None of the patients had a history of diabetes, and none had used oral hypoglycemic agents or insulin. Treatment was with adalimumab, infliximab and etanercept. Glucose, inflammatory markers and prednisone dose were assessed at baseline, as well as after three and six months of treatment. The mean erythrocyte sedimentation rate was significantly lower at three months and six months than at baseline (13.7 ± 18.0 and 18 ± 22.5 vs. 27.9 ± 23.4 mm; p = 0.001). At baseline, three months and six months, we found the following: mean C-reactive protein levels were comparable (22.1 ± 22.7, 14.5 ± 30.7 and 16.0 ± 23.8 mg/L, respectively; p = 0.26); mean glucose levels remained unchanged (90.8 ± 22.2 mg/dl, 89.5 ± 14.6 mg/dl and 89.8 ± 13.6 mg/dl, respectively; p = 0.91); and mean prednisone doses were low and stable (3.9 ± 4.9 mg/day, 3.7 ± 4.8 mg/day and 2.6 ± 4.0 mg/day, respectively; p = 0.23). During the first six months of treatment, anti-TNF therapy does not seem to influence glucose metabolism in JIA, AS or PsA. 相似文献
99.
Chulvi-Medrano I García-Massó X Colado JC Pablos C de Moraes JA Fuster MA 《Journal of strength and conditioning research / National Strength & Conditioning Association》2010,24(10):2723-2730
The objective of this study was to compare the production of force and paraspinal muscle activity between deadlifts carried out in a standard way and with different instability devices (Bosu and T-Bow). Deadlifts involve the performance of muscle activities with dynamic and isometric characteristics. Thirty-one subjects participated voluntarily in the study. Initially, they performed an isometric test for 5 seconds in each condition. After that, they performed a set of 5 repetitions with 70% of the maximum isometric force obtained in each one of the previously evaluated conditions. During the isometric tests, records of electromyographic activity and force production were obtained, whereas during the dynamic tests, only the electromyographic activity was registered. The subjects produced more force and muscle activity on the stable surface than under the other conditions during the isometric test (p < 0.05), and the same differences in muscle activity were observed during the dynamic test (p < 0.05). These data show that the performance of deadlifts under stable conditions favors a higher production of maximum strength and muscle activity. Therefore, we conclude that the use of instability devices in deadlift training does not increase performance, nor does it provide greater activation of the paraspinal muscles, leading us to question their value in the performance of other types of exercises. 相似文献
100.
The present paper aims to increase the knowledge on the sand fly fauna in the cerrado areas of Maranh?o state in urban, rural and forest environments. The research was carried out from October 2007 to September 2008, between 18:00h and 06:00h, in the municipality of Chapadinha, northeast Maranh?o. For insect sampling, CDC light traps were set up in peridomicile and domicile areas of urban and rural zones as well as in Cerrado and Gallery forests. The total of 1,401 specimens belonging to 17 species were sampled, all within the genus Lutzomyia. Lutzomyia longipalpis (Lutz & Neiva) (52.5%), Lu. evandroi (Costa Lima & Antunes) (18.3%), Lu. whitmani (Antunes & Coutinho) (12.1%), Lu. lenti (Mangabeira) (4.7%) and Lu. termitophila (Martins, Falc?o & Silva) (4.0%) were the most frequently collected. From an epidemiological viewpoint, five from all of the collected species are vectors of leishmaniasis: Lu. longipalpis, Lu. whitmani, Lu. flaviscutellata (Mangabeira), Lu. gomezi (Nitzulescu) and Lu. chagasi (Costa Lima). Lutzomyia chagasi was registered for the first time in Maranh?o state and Lu. saulensis (Floch & Abonnenc), Lu. monstruosa (Floch & Abonnenc) and Lu. gomezi were found for the first time in the eastern part of the state, since they had been reported only in the Amazonian region of Maranh?o. Regarding to the studied environments, the urban chicken house had the highest number of specimens collected (801), while the Gallery Forest was the most diverse (15 species). This study demonstrates that the northeast cerrado exhibits a mixed sand fly fauna characterized by an extremely important species vectors assortment involved in the epidemiological cycle of leishmaniasis in Maranh?o state. 相似文献