全文获取类型
收费全文 | 561篇 |
免费 | 26篇 |
专业分类
587篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 19篇 |
2020年 | 19篇 |
2019年 | 11篇 |
2018年 | 31篇 |
2017年 | 23篇 |
2016年 | 28篇 |
2015年 | 33篇 |
2014年 | 44篇 |
2013年 | 48篇 |
2012年 | 46篇 |
2011年 | 41篇 |
2010年 | 21篇 |
2009年 | 29篇 |
2008年 | 34篇 |
2007年 | 27篇 |
2006年 | 11篇 |
2005年 | 17篇 |
2004年 | 20篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有587条查询结果,搜索用时 15 毫秒
151.
Matthew K. Nock Irving Hwang Nancy Sampson Ronald C. Kessler Matthias Angermeyer Annette Beautrais Guilherme Borges Evelyn Bromet Ronny Bruffaerts Giovanni de Girolamo Ron de Graaf Silvia Florescu Oye Gureje Josep Maria Haro Chiyi Hu Yueqin Huang Elie G. Karam Norito Kawakami Viviane Kovess Daphna Levinson Jose Posada-Villa Rajesh Sagar Toma Tomov Maria Carmen Viana David R. Williams 《PLoS medicine》2009,6(8)
Background
Suicide is a leading cause of death worldwide. Mental disorders are among the strongest predictors of suicide; however, little is known about which disorders are uniquely predictive of suicidal behavior, the extent to which disorders predict suicide attempts beyond their association with suicidal thoughts, and whether these associations are similar across developed and developing countries. This study was designed to test each of these questions with a focus on nonfatal suicide attempts.Methods and Findings
Data on the lifetime presence and age-of-onset of Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) mental disorders and nonfatal suicidal behaviors were collected via structured face-to-face interviews with 108,664 respondents from 21 countries participating in the WHO World Mental Health Surveys. The results show that each lifetime disorder examined significantly predicts the subsequent first onset of suicide attempt (odds ratios [ORs] = 2.9–8.9). After controlling for comorbidity, these associations decreased substantially (ORs = 1.5–5.6) but remained significant in most cases. Overall, mental disorders were equally predictive in developed and developing countries, with a key difference being that the strongest predictors of suicide attempts in developed countries were mood disorders, whereas in developing countries impulse-control, substance use, and post-traumatic stress disorders were most predictive. Disaggregation of the associations between mental disorders and nonfatal suicide attempts showed that these associations are largely due to disorders predicting the onset of suicidal thoughts rather than predicting progression from thoughts to attempts. In the few instances where mental disorders predicted the transition from suicidal thoughts to attempts, the significant disorders are characterized by anxiety and poor impulse-control. The limitations of this study include the use of retrospective self-reports of lifetime occurrence and age-of-onset of mental disorders and suicidal behaviors, as well as the narrow focus on mental disorders as predictors of nonfatal suicidal behaviors, each of which must be addressed in future studies.Conclusions
This study found that a wide range of mental disorders increased the odds of experiencing suicide ideation. However, after controlling for psychiatric comorbidity, only disorders characterized by anxiety and poor impulse-control predict which people with suicide ideation act on such thoughts. These findings provide a more fine-grained understanding of the associations between mental disorders and subsequent suicidal behavior than previously available and indicate that mental disorders predict suicidal behaviors similarly in both developed and developing countries. Future research is needed to delineate the mechanisms through which people come to think about suicide and subsequently progress from ideation to attempts. Please see later in the article for Editors'' Summary 相似文献152.
Pérez-Bello D Suárez VM Bolaños CP López JM Pérez GP López-Canovas L Higginson-Clarke D Rodríguez-Tanty C Riverón AM 《Preparative biochemistry & biotechnology》2003,33(4):253-268
In the present work, a comparative study of 5-FdUrd, thy-, and metabolic in vivo labeling methods for plasmid and chromosomal DNA in E. coli DH5alpha cells was performed in order to achieve the best thymidine substitution method by 5-BrdUrd. According to the colorimetric immunoenzymatic results, we found that the minimal detectable labeled DNA (MDLD) was 312pg with the 5-FdUrd and thy- methods for 5-BrdUrd labeled plasmid DNA. 5-BrdUrd replaced about 96% of the total thymidine by 5-FdUrd methods; for the thy- and metabolic labeling methods, the MDLD value was 1,25 ng for denatured 5-BrdUrd chromosomal DNA. Pyrimidine nucleoside analogues were also evaluated as immunochemical markers for their in vivo introduction into DNA. 相似文献
153.
Fbio H. Takagui Patrik Viana Lucas Baumgrtner Jamille A. Bitencourt Vladimir Pavan Margarido Roberto Laridondo Lui Eliana Feldberg Jose Luis Olivan Birindelli Fernanda Simes Almeida Lucia Giuliano-Caetano 《Genetics and molecular biology》2021,44(4)
Doradinae (Siluriformes: Doradidae) is the most species-rich subfamily among thorny catfishes, encompassing over 77 valid species, found mainly in Amazon and Platina hydrographic basins. Here, we analyzed seven Doradinae species using combined methods (e.g., cytogenetic tools and Mesquite ancestral reconstruction software) in order to scrutinize the processes that mediated the karyotype diversification in this subfamily. Our ancestral reconstruction recovered that 2n=58 chromosomes and simple nucleolar organizer regions (NOR) are ancestral features only for Wertheimerinae and the most clades of Doradinae. Some exceptions were found in Trachydoras paraguayensis (2n=56), Trachydoras steindachneri (2n=60), Ossancora punctata (2n=66) and Platydoras hancockii whose karyotypes showed a multiple NOR system. The large thorny catfishes, such as Pterodoras granulosus, Oxydoras niger and Centrodoras brachiatus share several karyotype features, with subtle variations only regarding their heterochromatin distribution. On the other hand, a remarkable karyotypic variability has been reported in the fimbriate barbells thorny catfishes. These two contrasting karyoevolution trajectories emerged from a complex interaction between chromosome rearrangements (e.g., inversions and Robertsonian translocations) and mechanisms of heterochromatin dispersion. Moreover, we believe that biological features, such as microhabitats preferences, populational size, low vagility and migratory behavior played a key role during the origin and maintenance of chromosome diversity in Doradinae subfamily. 相似文献
154.
Gregorio M. Toral Riad E. Baouab Mónica Martinez-Haro Inés S. Sánchez-Barbudo Juli Broggi Josue Martínez-de la Puente Duarte Viana Rafael Mateo Jordi Figuerola 《PloS one》2015,10(5)
Levels of exposure to pesticides in rice fields can be significant depending on the environmental policies practiced. The aim of European Union integrated management policy is to reduce pesticide use and impact on environment. Rice fields provide an alternative breeding habitat for many waterbirds that are exposed to the pesticides used and therefore can be valuable indicators of their risk for wildlife. To evaluate integrated management success we examined exposure of Black-winged Stilts (Himantopus himantopus) to cholinesterase-inhibiting pesticides in rice fields under different types of management by measuring plasma cholinesterase activity. Cholinesterase activity was lower in birds sampled in (a) 2008 after a period of intense pesticide application, than in (b) 2005-2007 and 2011 in rice fields subject to integrated management in Doñana (SW Spain) and (c) in control natural wetlands in Spain and Morocco. During 2009 and 2010, cholinesterase activity was lower in rice fields in Doñana than in rice fields in Larache and Sidi Allal Tazi (NW Morocco). Our results suggest that integrated management successfully reduced the exposure of Black-winged Stilts to pesticides in most of the years. Care should be taken to implement mosquito and pest crop controls on time and with environmentally friendly products in order to reduce its impact on wildlife. 相似文献
155.
Camila Magalh?es Silveira Erica Rosanna Siu James C. Anthony Luis Paulo Saito Arthur Guerra de Andrade Andressa Kutschenko Maria Carmen Viana Yuan-Pang Wang Silvia S. Martins Laura Helena Andrade 《PloS one》2014,9(10)
Background
Research conducted in high-income countries has investigated influences of socioeconomic inequalities on drinking outcomes such as alcohol use disorders (AUD), however, associations between area-level neighborhood social deprivation (NSD) and individual socioeconomic status with these outcomes have not been explored in Brazil. Thus, we investigated the role of these factors on drink-related outcomes in a Brazilian population, attending to male-female variations.Methods
A multi-stage area probability sample of adult household residents in the São Paulo Metropolitan Area was assessed using the WHO Composite International Diagnostic Interview (WMH-CIDI) (n = 5,037). Estimation focused on prevalence and correlates of past-year alcohol disturbances [heavy drinking of lower frequency (HDLF), heavy drinking of higher frequency (HDHF), abuse, dependence, and DMS-5 AUD] among regular users (RU); odds ratio (OR) were obtained.Results
Higher NSD, measured as an area-level variable with individual level variables held constant, showed an excess odds for most alcohol disturbances analyzed. Prevalence estimates for HDLF and HDHF among RU were 9% and 20%, respectively, with excess odds in higher NSD areas; schooling (inverse association) and low income were associated with male HDLF. The only individual-level association with female HDLF involved employment status. Prevalence estimates for abuse, dependence, and DSM-5 AUD among RU were 8%, 4%, and 8%, respectively, with excess odds of: dependence in higher NSD areas for males; abuse and AUD for females. Among RU, AUD was associated with unemployment, and low education with dependence and AUD.Conclusions
Regular alcohol users with alcohol-related disturbances are more likely to be found where area-level neighborhood characteristics reflect social disadvantage. Although we cannot draw inferences about causal influence, the associations are strong enough to warrant future longitudinal alcohol studies to explore causal mechanisms related to the heterogeneous patterns of association and male-female variations observed herein. Hopefully, these findings may help guide future directions for public health. 相似文献156.
Fabyano Fonseca e Silva José Marcelo Soriano Viana Vinícius Ribeiro Faria Marcos Deon Vilela de Resende 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2013,126(7):1749-1761
The objectives of this study were to implement a Bayesian framework for mixed models analysis in crop species breeding and to exploit alternatives for informative prior elicitation. Bayesian inference for genetic evaluation in annual crop breeding was illustrated with the first two half-sib selection cycles in a popcorn population. The Bayesian framework was based on the Just Another Gibbs Sampler software and the R2jags package. For the first cycle, a non-informative prior for the inverse of the variance components and an informative prior based on meta-analysis were used. For the second cycle, a non-informative prior and an informative prior defined as the posterior from the non-informative and informative analyses of the first cycle were used. Regarding the first cycle, the use of an informative prior from the meta-analysis provided clearly distinct results relative to the analysis with a non-informative prior only for the grain yield. Regarding the second cycle, the results for the expansion volume and grain yield showed differences among the three analyses. The differences between the non-informative and informative prior analyses were restricted to variance components and heritability. The correlations between the predicted breeding values from these analyses were almost perfect. 相似文献
157.
L.G.B. Siqueira C.A.A. Torres P.L.J. Monteiro Jr. L.S.A. Camargo J.H.M. Viana 《Theriogenology》2009,72(7):949-958
The objective was to investigate the influence of corpora lutea physical and functional characteristics on pregnancy rates in bovine recipients synchronized for fixed-time embryo transfer (FTET). Crossbred (Bos taurus taurus × Bos taurus indicus) nonlactating cows and heifers (n = 259) were treated with the following protocol: 2 mg estradiol benzoate (EB) plus an intravaginal progesterone device (CIDR 1.9 g progesterone; Day 0); 400 IU equine chorionic gonadotropin (eCG; Day 5); prostaglandin F2α (PGF2α) and CIDR withdrawal (Day 8); and 1 mg EB (Day 9). Ovarian ultrasonography and blood sample collections were performed on Day 17. Of the 259 cattle initially treated, 197 (76.1%) were suitable recipients; they received a single, fresh, quality grade 1 or 2 in vivo-derived (n = 90) or in vitro-produced (n = 87) embryo on Day 17. Pregnancy rates (23 d after embryo transfer) were higher for in vivo-derived embryos than for in vitro-produced embryos (58.8% vs. 31.0%, respectively; P < 0.001). Mean (±SD) plasma progesterone (P4) concentration was higher in cattle that became pregnant than that in nonpregnant cattle (5.2 ± 5.0 vs. 3.8 ± 2.4 ng/mL; P = 0.02). Mean pixel values (71.8 ± 1.3 vs. 71.2 ± 1.1) and pixel heterogeneity (14.8 ± 0.3 vs. 14.5 ± 0.5) were similar between pregnant and nonpregnant recipients (P > 0.10). No significant relationship was detected between pregnancy outcome and plasma P4, corpus luteum area, or corpus luteum echotexture. Embryo type, however, affected the odds of pregnancy. In conclusion, corpus luteum-related traits were poor predictors of pregnancy in recipients. The type of embryo, however, was a major factor affecting pregnancy outcome. 相似文献
158.
159.
Cassius de Souza Yuri Vieira Faria Lincoln de Oliveira Sant’Anna Vanilda Gon?alves Viana Sérgio Henrique Seabra M?nica Cristina de Souza Ver?nica Viana Vieira Raphael Hirata Júnior Lílian de Oliveira Moreira Ana Luíza de Mattos-Guaraldi 《Memórias do Instituto Oswaldo Cruz》2015,110(2):242-248
Corynebacterium striatum is a potentially pathogenic microorganismthat causes nosocomial outbreaks. However, little is known about its virulencefactors that may contribute to healthcare-associated infections (HAIs). Weinvestigated the biofilm production on abiotic surfaces of multidrug-resistant (MDR)and multidrug-susceptible (MDS) strains of C. striatum ofpulsed-field gel electrophoresis types I-MDR, II-MDR, III-MDS and IV-MDS isolatedduring a nosocomial outbreak in Rio de Janeiro, Brazil. The results showed thatC. striatum was able to adhere to hydrophilic and hydrophobicabiotic surfaces. The C. striatum 1987/I-MDR strain, predominantlyisolated from patients undergoing endotracheal intubation procedures, showed thegreatest ability to adhere to all surfaces. C. striatum boundfibrinogen to its surface, which contributed to biofilm formation. Scanning electronmicroscopy showed the production of mature biofilms on polyurethane catheters by allpulsotypes. In conclusion, biofilm production may contribute to the establishment ofHAIs caused by C. striatum. 相似文献
160.
John M. Wentworth Naiara G. Bediaga Megan A. S. Penno Esther Bandala-Sanchez Komal N. Kanojia Konstantinos A. Kouremenos Jennifer J. Couper Leonard C. Harrison ENDIA Study Group 《Metabolomics : Official journal of the Metabolomic Society》2018,14(10):130