全文获取类型
收费全文 | 800篇 |
免费 | 51篇 |
专业分类
851篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 24篇 |
2020年 | 18篇 |
2019年 | 18篇 |
2018年 | 29篇 |
2017年 | 33篇 |
2016年 | 34篇 |
2015年 | 42篇 |
2014年 | 42篇 |
2013年 | 61篇 |
2012年 | 74篇 |
2011年 | 58篇 |
2010年 | 38篇 |
2009年 | 30篇 |
2008年 | 40篇 |
2007年 | 46篇 |
2006年 | 36篇 |
2005年 | 29篇 |
2004年 | 25篇 |
2003年 | 24篇 |
2002年 | 19篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1938年 | 1篇 |
1874年 | 1篇 |
排序方式: 共有851条查询结果,搜索用时 15 毫秒
81.
Solano AF Leipnitz G De Bortoli GM Seminotti B Amaral AU Fernandes CG Latini AS Dutra-Filho CS Wajner M 《Free radical research》2008,42(8):707-715
The present work investigated the in vitro effects of isovaleric acid (IVA) and isovalerylglycine (IVG), which accumulate in isovaleric acidemia (IVAcidemia), on important parameters of oxidative stress in supernatants and mitochondrial preparations from brain of 30-day-old rats. IVG, but not IVA, significantly increased TBA-RS and chemiluminescence values in cortical supernatants. Furthermore, the addition of free radical scavengers fully prevented IVG-induced increase of TBA-RS. IVG also decreased GSH concentrations, whereas IVA did not modify this parameter in brain supernatants. Furthermore, IVG did not alter lipid peroxidation or GSH concentrations in mitochondrial preparations, indicating that the generation of oxidants by IVG was dependent on cytosolic mechanisms. On the other hand, IVA significantly induced carbonyl formation both in supernatants and purified mitochondrial preparations from rat brain, with no effect observed for IVG. Therefore, it is presumed that oxidative damage may be at least in part involved in the pathophysiology of the neuropathology of IVAcidemia. 相似文献
82.
PJS Amaral LFM Finotelo EHC De Oliveira A Pissinatti CY Nagamachi JC Pieczarka 《BMC evolutionary biology》2008,8(1):169
Background
Chromosomal painting, using whole chromosome probes from humans and Saguinus oedipus, was used to establish karyotypic divergence among species of the genus Cebus, including C. olivaceus, C. albifrons, C. apella robustus and C. apella paraguayanus. Cytogenetic studies suggested that the species of this genus have conservative karyotypes, with diploid numbers ranging from 2n = 52 to 2n = 54. 相似文献83.
Comparative mitochondrial and chloroplast genomics of a genetically distinct form of Sargassum contributing to recent “Golden Tides” in the Western Atlantic 下载免费PDF全文
Linda A. Amaral‐Zettler Nicholas B. Dragone Jeffrey Schell Beth Slikas Leslie G. Murphy Clare E. Morrall Erik R. Zettler 《Ecology and evolution》2017,7(2):516-525
Over the past 5 years, massive accumulations of holopelagic species of the brown macroalga Sargassum in coastal areas of the Caribbean have created “golden tides” that threaten local biodiversity and trigger economic losses associated with beach deterioration and impact on fisheries and tourism. In 2015, the first report identifying the cause of these extreme events implicated a rare form of the holopelagic species Sargassum natans (form VIII). However, since the first mention of S. natans VIII in the 1930s, based solely on morphological characters, no molecular data have confirmed this identification. We generated full‐length mitogenomes and partial chloroplast genomes of all representative holopelagic Sargassum species, S. fluitans III and S. natans I alongside the putatively rare S. natans VIII, to demonstrate small but consistent differences between S. natans I and VIII (7 bp differences out of the 34,727). Our comparative analyses also revealed that both S. natans I and S. natans VIII share a very close phylogenetic relationship with S. fluitans III (94‐ and 96‐bp differences of 34,727). We designed novel primers that amplified regions of the cox2 and cox3 marker genes with consistent polymorphic sites that enabled differentiation between the two S. natans forms (I and VIII) from each other and both from S. fluitans III in over 150 Sargassum samples including those from the 2014 golden tide event. Despite remarkable gene synteny and sequence conservation, the three Sargassum forms differ in morphology, ecology, and distribution patterns, warranting more extensive interrogation of holopelagic Sargassum genomes as a whole. 相似文献
84.
Renato Sathler-Avelar Danielle Marquete Vitelli-Avelar Armanda Moreira Mattoso-Barbosa Marcelo Perdig?o-de-Oliveira Ronaldo Peres Costa Silvana Maria Elói-Santos Matheus de Souza Gomes Laurence Rodrigues do Amaral Andréa Teixeira-Carvalho Olindo Assis Martins-Filho Edward J. Dick Jr Gene B. Hubbard Jane F. VandeBerg John L. VandeBerg 《PLoS neglected tropical diseases》2016,10(1)
Background
Cynomolgus macaques (Macaca fascicularis) represent a feasible model for research on Chagas disease since natural T. cruzi infection in these primates leads to clinical outcomes similar to those observed in humans. However, it is still unknown whether these clinical similarities are accompanied by equivalent immunological characteristics in the two species. We have performed a detailed immunophenotypic analysis of circulating leukocytes together with systems biology approaches from 15 cynomolgus macaques naturally infected with T. cruzi (CH) presenting the chronic phase of Chagas disease to identify biomarkers that might be useful for clinical investigations.Methods and Findings
Our data established that CH displayed increased expression of CD32+ and CD56+ in monocytes and enhanced frequency of NK Granzyme A+ cells as compared to non-infected controls (NI). Moreover, higher expression of CD54 and HLA-DR by T-cells, especially within the CD8+ subset, was the hallmark of CH. A high level of expression of Granzyme A and Perforin underscored the enhanced cytotoxicity-linked pattern of CD8+ T-lymphocytes from CH. Increased frequency of B-cells with up-regulated expression of Fc-γRII was also observed in CH. Complex and imbricate biomarker networks demonstrated that CH showed a shift towards cross-talk among cells of the adaptive immune system. Systems biology analysis further established monocytes and NK-cell phenotypes and the T-cell activation status, along with the Granzyme A expression by CD8+ T-cells, as the most reliable biomarkers of potential use for clinical applications.Conclusions
Altogether, these findings demonstrated that the similarities in phenotypic features of circulating leukocytes observed in cynomolgus macaques and humans infected with T. cruzi further supports the use of these monkeys in preclinical toxicology and pharmacology studies applied to development and testing of new drugs for Chagas disease. 相似文献85.
Vinolo MA Rodrigues HG Festuccia WT Crisma AR Alves VS Martins AR Amaral CL Fiamoncini J Hirabara SM Sato FT Fock RA Malheiros G dos Santos MF Curi R 《American journal of physiology. Endocrinology and metabolism》2012,303(2):E272-E282
The aim of this study was to investigate whether treatment with tributyrin (Tb; a butyrate prodrug) results in protection against diet-induced obesity and associated insulin resistance. C57BL/6 male mice fed a standard chow or high-fat diet were treated with Tb (2 g/kg body wt, 10 wk) and evaluated for glucose homeostasis, plasma lipid profile, and inflammatory status. Tb protected mice against obesity and obesity-associated insulin resistance and dyslipidemia without food consumption being affected. Tb attenuated the production of TNFα and IL-1β by peritoneal macrophages and their expression in adipose tissue. Furthermore, in the adipose tissue, Tb reduced the expression of MCP-1 and infiltration by leukocytes and restored the production of adiponectin. These effects were associated with a partial reversion of hepatic steatosis, reduction in liver and skeletal muscle content of phosphorylated JNK, and an improvement in muscle insulin-stimulated glucose uptake and Akt signaling. Although part of the beneficial effects of Tb are likely to be secondary to the reduction in body weight, we also found direct protective actions of butyrate reducing TNFα production after LPS injection and in vitro by LPS- or palmitic acid-stimulated macrophages and attenuating lipolysis in vitro and in vivo. The results, reported herein, suggest that Tb may be useful for the treatment and prevention of obesity-related metabolic disorders. 相似文献
86.
87.
Collares T Campos VF De Leon PM Cavalcanti PV Amaral MG Dellagostin OA Deschamps JC Seixas FK 《Journal of biosciences》2011,36(4):613-620
Transgenic animals have been successfully produced by mass gene transfer techniques such as sperm-mediated gene transfer (SMGT). The aim of this work was to demonstrate transgene transmission by SMGT in chickens using dimethylsulfoxide (DMSO) or N,N-dimethylacetamide (DMAc) as transfectants after seminal plasma removal to prevent DNase activity. Sperm samples were prepared by repetitive washes, and after each wash sperm motility, seminal plasma proteins, exogenous DNA integrity and its uptake by spermatozoa were evaluated. Laying hens were inseminated using spermatozoa transfected with pEGFP-N1 vector in the presence of DMSO or DMAc. Transgene transmission in newborn chicks was evaluated by in vivo enhanced green fluorescent protein (EGFP) expression, RT-PCR and PCR analysis. DNA internalization was limited to sperm samples washed twice. The presence of DMSO or DMAc during transfection had no effect on fertilization or hatching rates. PCR analysis detected the presence of EGFP DNA in 38% of newborn chicks from the DMSO group and 19% from the DMAc group. EGFP mRNA was detected in 21% of newborn chicks from the DMSO group, as against 8.5% from the DMAc group. However, in vivo expression of EGFP was only observed in a single animal from the DMSO group. Our data revealed that the plasmid DNA-DMSO combination coupled with sperm washes can be an efficient method for transfection in chickens. 相似文献
88.
Hugo Teixeira Gomes Patrícia Monah Cunha Bartos Clovis Oliveira Silva Lourdes Isabel Velho do Amaral Jonny Everson Scherwinski-Pereira 《Plant Growth Regulation》2014,74(2):199-208
In this study, the different stages of somatic embryogenesis (SE) of the African oil palm (Elaeis guineensis Jacq.) were characterized biochemically. The total soluble sugars, starch, total free amino acids, and total proteins were extracted, identified and quantified at various stages of embryogenesis: zygotic embryos (initial explants), primary calluses, embryogenic calluses, calluses with pro-embryos, globular embryos, differentiated somatic embryos, and regenerated plants. It was found that at the onset of induction of SE, the level of soluble sugars in the tissues of the explants fell by half. During this period, the total soluble sugars present in the cultures consisted basically of glucose and fructose. In the process of regeneration and maturation, the concentrations of soluble sugars gradually increased, reaching the highest values in the last two stages of development. At this stage, the disaccharide sucrose accounts for more than 80 % of the composition of total soluble sugars in the explants. Compared to starch, we found that the concentrations thereof in developing tissues are inversely proportional to that of soluble sugars virtually throughout embryogenic development. As for free amino acids, we found that after 30 days of induction until formation of the embryogenic calluses, there is an accentuated synthesis of total free amino acids in the explant tissue. In this stage, there was a significant increase in the levels of alanine and serine in the tissues. However, after the formation of the embryogenic calluses, the levels of total free amino acids present in the cultures become stabile and remain constant until the end of cultivation. Similar results were found for total protein, which also showed a significant increase at the onset of induction, undergoing slight changes during the remainder of the cultivation. 相似文献
89.
We investigated the efficacy of Ocimum basilicum (OB) essential oils for treating depression related behavioral, biochemical and histopathological changes caused by exposure to chronic unpredictable mild stress (CUMS) in mice and to explore the mechanism underlying the pathology. Male albino mice were divided into four groups: controls; CUMS; CUMS plus fluoxetine, the antidepressant administered for pharmacological validation of OB; and CUMS plus OB. Behavioral tests included the forced swim test (FST), elevated plus-maze (EPM) and the open ?eld test (OFT); these tests were performed at the end of the experiment. We assessed serum corticosterone level, protein, gene and immunoexpression of brain-derived neurotropic factor (BDNF) and glucocorticoid receptors (GRs) as well as immunoexpression of glial fibrillary acidic protein (GFAP), Ki67, caspase-3 in the hippocampus. CUMS caused depression in the mice as evidenced by prolonged immobility in the FST, prolonged time spent in the open arms during the EPM test and reduction of open field activity in the OFT. OB ameliorated the CUMS induced depressive status. OB significantly reduced the corticosterone level and up-regulated protein and gene expressions of BDNF and GR. OB reduced CUMS induced hippocampal neuron atrophy and apoptosis, and increased the number of the astrocytes and new nerve cells. OB significantly increased GFAP-positive cells as well as BDNF and GR immunoexpression in the hippocampus. 相似文献
90.
Amaral Joo Henrique Fernandes Melack John Michael Barbosa Pedro Maia Borges Alberto V. Kasper Daniele Corts Alicia Cortes Zhou Wencai MacIntyre Sally Forsberg Bruce Rider 《Ecosystems》2022,25(4):911-930
Ecosystems - Extensive floodplains and numerous lakes in the Amazon basin are well suited to examine the role of floodable lands within the context of the sources and processing of carbon within... 相似文献