全文获取类型
收费全文 | 281篇 |
免费 | 21篇 |
专业分类
302篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 16篇 |
2016年 | 20篇 |
2015年 | 14篇 |
2014年 | 21篇 |
2013年 | 16篇 |
2012年 | 24篇 |
2011年 | 25篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 18篇 |
2007年 | 9篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有302条查询结果,搜索用时 31 毫秒
101.
Lílian Ktia Ximenes Silva Jos de Brito Loureno Júnior Aluizio Otavio Almeida da Silva Jos Silva de Sousa Andr Guimares Maciel e Silva Adriana Novaes dos Reis Moyss dos Santos Miranda Simone do Socorro Damasceno Santos Otvio Mitio Ohashi Lucieta Guerreiro Martorano Geraldo Narciso da Rocha Filho Cristian Faturi Eziquiel de Morais rica Karine Loureno Mares Alexandre Rossetto Garcia 《Animal Reproduction》2020,17(4)
Ruminant energy supplementation with vegetable oils or fats has been standing out worldwide and oil palm processing has been receiving growing interest. This study assessed the effect of supplementation with saturated and unsaturated fatty acids from the palm oil industry on the lipid profile of seminal plasma and of the sperm membrane, as well as on the morphological and functional characteristics of raw and cryopreserved buffalo semen. Twelve purebred Murrah bulls (Bubalus bubalis) were assigned to the experimental groups and fed diets for 120 days with no added lipids (CONT, four bulls), or with an extra amount of 3% lipids from crude palm oil (PALM, four bulls), or from palm oil deodorizer distillate (PODD, four bulls). Semen was collected and cryopreserved every 15 days. The lipid composition of membranes and semen quality were determined after collections. Lipid supplementation did not impact feed intake (P>0.05). Diet enrichment with PALM increased the linoleic acid (C18:2,ω6) in seminal plasma. Lipid supplementation did not increase the polyunsaturated fatty acids in the sperm membrane composition, but significantly increased the lignoceric acid (C24:0). Cryopreserved semen of the supplemented bulls presented higher progressive motility (60.2 vs. 67.9 vs. 65.2%; P<0.05) and sperm viability detected by eosin-nigrosin staining (61.1 vs. 69.4 vs. 67.8%; P<0.05). Palm oil reduced major sperm defects in both raw (12.2 vs. 9.3 vs. 13.2%; P<0.0001) and cryopreserved semen (12.4 vs. 9.4 vs. 11.2%; P<0.0001). The lipids added to the diet did not impact the population of spermatozoa with intact plasma and acrosomal membranes (PI-/PSA-), but significantly increased the percentage of spermatozoa with high mitochondrial potential (25.6 vs. 31.5 vs. 32.0%; P=0.008). The results suggest that lipid supplementation based on crude palm oil or palm oil deodorizer distillate can be safely used to feed buffalo bulls and may increase sperm attributes related to male fertility. 相似文献
102.
Population Ecology - Although empirical verifications of ecological theory are essential for the advance of our understanding of ecosystems functioning, they are often hard to obtain or even... 相似文献
103.
Guilherme Kemeron Maciel Salazar Joseir Saturnino Cristino Alexandre Vilhena Silva-Neto Altair Seabra Farias Joo Arthur Alcntara Vinícius Azevedo Machado Felipe Murta Vanderson Souza Sampaio Fernando Val Andr Sachett Paulo Srgio Bernarde Marcus Lacerda Fan Hui Wen Wuelton Monteiro Jacqueline Sachett 《PLoS neglected tropical diseases》2021,15(9)
In the Brazilian Amazon, long distances, low healthcare coverage, common use of ineffective or deleterious self-care practices, and resistance to seeking medical assistance have an impact on access to antivenom treatment. This study aimed to estimate snakebite underreporting, and analyze barriers that prevent victims from obtaining healthcare in communities located in 15 municipalities on the banks of the Solimões, Juruá and Purus Rivers, in the remote Western Brazilian Amazon. Information on the participants’ demographics, previous snakebites, access to healthcare, time taken to reach medical assistance, use of self-care practices, and the reason for not accessing healthcare were collected through semi-structured interviews. In the case of deaths, information was collected by interviewing parents, relatives or acquaintances. A total of 172 participants who reported having suffered snakebites during their lifetime were interviewed. A total of 73 different treatment procedures was reported by 65.1% of the participants. Participants living in different river basins share few self-care procedures that use traditional medicine, and 91 (52.9%) participants reported that they had access to healthcare. Living in communities along the Juruá River [OR = 12.6 (95% CI = 3.2–49.7; p<0.001)] and the use of traditional medicine [OR = 11.6 (95% CI = 3.4–39.8; p<0.001)] were variables that were independently associated to the lack of access to healthcare. The main reasons for not accessing healthcare were the pprioritization of traditional treatments (70.4%), and the failure to recognize the situation as being potentially severe (50.6%). Four deaths from complications arising from the snakebite were reported, and three of these were from communities on the banks of the Juruá River. Only one of these received medical assistance. We found an unexpectedly high underreporting of snakebite cases and associated deaths. Snakebite victims utilized three main different healing systems: 1) self-care using miscellaneous techniques; 2) official medical healthcare generally combined with traditional practices; and 3) self-care using traditional practices combined with Western medicines. To mitigate snakebite burden in the Brazilian Amazon, an innovative intervention that would optimize timely delivery of care, including antivenom distribution among existing community healthcare centers, is needed. 相似文献
104.
Arpita Chatterjee Saikat Saha Anirban Chakraborty Anabela Silva-Fernandes Santi M. Mandal Andreia Neves-Carvalho Yongping Liu Raj K. Pandita Muralidhar L. Hegde Pavana M. Hegde Istvan Boldogh Tetsuo Ashizawa Arnulf H. Koeppen Tej K. Pandita Patricia Maciel Partha S. Sarkar Tapas K. Hazra 《PLoS genetics》2015,11(1)
DNA strand-breaks (SBs) with non-ligatable ends are generated by ionizing radiation, oxidative stress, various chemotherapeutic agents, and also as base excision repair (BER) intermediates. Several neurological diseases have already been identified as being due to a deficiency in DNA end-processing activities. Two common dirty ends, 3’-P and 5’-OH, are processed by mammalian polynucleotide kinase 3’-phosphatase (PNKP), a bifunctional enzyme with 3’-phosphatase and 5’-kinase activities. We have made the unexpected observation that PNKP stably associates with Ataxin-3 (ATXN3), a polyglutamine repeat-containing protein mutated in spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph Disease (MJD). This disease is one of the most common dominantly inherited ataxias worldwide; the defect in SCA3 is due to CAG repeat expansion (from the normal 14–41 to 55–82 repeats) in the ATXN3 coding region. However, how the expanded form gains its toxic function is still not clearly understood. Here we report that purified wild-type (WT) ATXN3 stimulates, and by contrast the mutant form specifically inhibits, PNKP’s 3’ phosphatase activity in vitro. ATXN3-deficient cells also show decreased PNKP activity. Furthermore, transgenic mice conditionally expressing the pathological form of human ATXN3 also showed decreased 3’-phosphatase activity of PNKP, mostly in the deep cerebellar nuclei, one of the most affected regions in MJD patients’ brain. Finally, long amplicon quantitative PCR analysis of human MJD patients’ brain samples showed a significant accumulation of DNA strand breaks. Our results thus indicate that the accumulation of DNA strand breaks due to functional deficiency of PNKP is etiologically linked to the pathogenesis of SCA3/MJD. 相似文献
105.
Fábio M. Maciel Cristiane M. C. Salles Claudio A. Retamal Valdirene M. Gomes Olga L. T. Machado 《Acta Physiologiae Plantarum》2011,33(5):1867-1875
Jasmonates are signaling molecules that play key roles in wound response and regulate the biosynthesis of many defensive proteins,
including proteases. In this study, we investigate the effects of wounding and methyl jasmonate (MJ) application on the protein
expression pattern of Ricinus communis L. leaves and on proteolytic activity. Gelatin zymography demonstrated that both MJ and mechanical wounding induce alterations
in the proteolytic pattern of castor bean leaves (R. communis L.). Expression of two cysteine proteases (38 and 29 kDa) was induced by the treatments employed; however, MJ induced a higher
protease level than mechanical wounding during the stress period (24, 48, and 72 h). The increase in protease activity mirrors
the decline in soluble protein content and rubisco degradation that may indicate initiation of senescence in castor plants.
The 29 kDa protease has an acidic optimal pH; whereas the 38 kDa protease has a neutral optimum activity. Both proteases were
almost completely inhibited by E-64 and cystatin. The significant induction of these proteins by MJ suggests a possible role
of cysteine proteases in leaf senescence as well as their involvement in regulating both the wound response and MJ in castor
bean plants. 相似文献
106.
Correlation between CAG Repeat Length and Clinical Features in Machado-Joseph Disease 总被引:16,自引:3,他引:16 下载免费PDF全文
Patrícia Maciel Claudia Gaspar Anita L. DeStefano Isabel Silveira Paula Coutinho Joo Radvany David M. Dawson Lewis Sudarsky Joo Guimares Jose E. L. Loureiro Marjan M. Nezarati Lee I. Corwin Iscia Lopes-Cendes Karen Rooke Roger Rosenberg Patrick MacLeod Lindsay A. Farrer Jorge Sequeiros Guy A. Rouleau 《American journal of human genetics》1995,57(1):54-61
Machado-Joseph disease (MJD) is associated with the expansion of a CAG trinucleotide repeat in a novel gene on 14q32.1. We confirmed the presence of this expansion in 156 MJD patients from 33 families of different geographic origins: 15 Portuguese Azorean, 2 Brazilian, and 16 North American of Portuguese Azorean descent. Normal chromosomes contain between 12 and 37 CAG repeats in the MJD gene, whereas MJD gene carriers have alleles within the expanded range of 62–84 CAG units. The distribution of expanded alleles and the gap between normal and expanded allele sizes is either inconsistent with a premutation hypothesis or most (if not all) of the alleles we studied descend from a common ancestor. There is a strong correlation between the expanded repeat size and the age at onset of the disease as well as the clinical presentation. There is mild instability of the CAG tract length with transmission of the expanded alleles; both increase and decrease in size between parents and progeny occur, with larger variations in male than in female transmissions. Together, these effects can partly explain the variability of age at onset and of phenotypic features in MJD; however, other modifying factors must exist. 相似文献
107.
da Silva Edson Filisbino Freire Novo Evlyn Márcia Leão de Moraes Lobo Felipe de Lucia Barbosa Claudio Clemente Faria Noernberg Mauricio Almeida Rotta Luiz Henrique da Silva Cairo Carolline Tressmann Maciel Daniel Andrade Flores Júnior Rogério 《Limnology》2021,22(1):57-68
Limnology - Optical water types (OWTs) can represent diverse ranges of Chlorophyll-a (Chl-a), total suspended matter (TSM), and colored dissolved organic matter (CDOM) concentrations, which make... 相似文献
108.
Mutation detection in Machado-Joseph disease using repeat expansion detection. 总被引:3,自引:0,他引:3 下载免费PDF全文
K. Lindblad A. Lunkes P. Maciel G. Stevanin C. Zander T. Klockgether T. Ratzlaff A. Brice G. A. Rouleau T. Hudson G. Auburger M. Schalling 《Molecular medicine (Cambridge, Mass.)》1996,2(1):77-85
BACKGROUND: Several neurological disorders have recently been explained through the discovery of expanded DNA repeat sequences. Among these is Machado-Joseph disease, one of the most common spinocerebellar ataxias (MJD/SCA3), caused by a CAG repeat expansion on chromosome 14. A useful way of detecting repeat sequence mutations is offered by the repeat expansion detection method (RED), in which a thermostable ligase is used to detect repeat expansions directly from genomic DNA. We have used RED to detect CAG expansions in families with either MJD/SCA3 or with previously uncharacterized spinocerebellar ataxia (SCA). MATERIALS AND METHODS: Five MJD/SCA3 families and one SCA family where linkage to SCA1-5 had been excluded were analyzed by RED and polymerase chain reaction (PCR). RESULTS: An expansion represented by RED products of 180-270 bp segregated with MJD/SCA3 (p < 0.00001) in five families (n = 60) and PCR products corresponding to 66-80 repeat copies were observed in all affected individuals. We also detected a 210-bp RED product segregating with disease (p < 0.01) in a non-SCA1-5 family (n = 16), suggesting involvement of a CAG expansion in the pathophysiology. PCR analysis subsequently revealed an elongated MJD/SCA3 allele in all affected family members. CONCLUSIONS: RED products detected in Machado-Joseph disease families correlated with elongated PCR products at the MJD/SCA3 locus. We demonstrate the added usefulness of RED in detecting repeat expansions in disorders where linkage is complicated by phenotyping problems in gradually developing adult-onset disorders, as in the non-SCA1-5 family examined. The RED method is informative without any knowledge of flanking sequences. This is particularly useful when studying diseases where the mutated gene is unknown. We conclude that RED is a reliable method for analyzing expanded repeat sequences in the genome. 相似文献
109.
Maciel EA de Carvalho AL Nascimento SF de Matos RB Gouveia EL Reis MG Ko AI 《PLoS neglected tropical diseases》2008,2(1):e154
Background
Leptospirosis, a spirochaetal zoonotic disease, is the cause of epidemics associated with high mortality in urban slum communities. Infection with pathogenic Leptospira occurs during environmental exposures and is traditionally associated with occupational risk activities. However, slum inhabitants reside in close proximity to environmental sources of contamination, suggesting that transmission during urban epidemics occurs in the household environment.Methods and Findings
A survey was performed to determine whether Leptospira infection clustered within households located in slum communities in the city of Salvador, Brazil. Hospital-based surveillance identified 89 confirmed cases of leptospirosis during an outbreak. Serum samples were obtained from members of 22 households with index cases of leptospirosis and 52 control households located in the same slum communities. The presence of anti-Leptospira agglutinating antibodies was used as a marker for previous infection. In households with index cases, 22 (30%) of 74 members had anti-Leptospira antibodies, whereas 16 (8%) of 195 members from control households had anti-Leptospira antibodies. Highest titres were directed against L. interrogans serovars of the Icterohaemorrhagiae serogroup in 95% and 100% of the subjects with agglutinating antibodies from case and control households, respectively. Residence in a household with an index case of leptospirosis was associated with increased risk (OR 5.29, 95% CI 2.13–13.12) of having had a Leptospira infection. Increased infection risk was found for all age groups who resided in a household with an index case, including children <15 years of age (P = 0.008).Conclusions
This study identified significant household clustering of Leptospira infection in slum communities where recurrent epidemics of leptospirosis occur. The findings support the hypothesis that the household environment is an important transmission determinant in the urban slum setting. Prevention therefore needs to target sources of contamination and risk activities which occur in the places where slum inhabitants reside. 相似文献110.
Mariani Carla Prudente Batista Eliane de Fatima Duarte Michele Delarmelina dos Reis Borba Emilie Zingler João Mangussi-Gomes Beatriz Taynara Araújo dos Santos Olivia Laquis de Moraes Sylvia Asaka Yamashita Hayashida Edmund C. Baracat Francisco de Assis da Rocha Neves Gustavo Arantes Rosa Maciel Tania Aparecida Sartori Sanchez Bachega Gustavo Barcelos Barra Adriana Lofrano-Porto 《Gene》2014