全文获取类型
收费全文 | 1135篇 |
免费 | 71篇 |
国内免费 | 5篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 24篇 |
2021年 | 74篇 |
2020年 | 32篇 |
2019年 | 40篇 |
2018年 | 39篇 |
2017年 | 37篇 |
2016年 | 53篇 |
2015年 | 79篇 |
2014年 | 87篇 |
2013年 | 81篇 |
2012年 | 93篇 |
2011年 | 96篇 |
2010年 | 58篇 |
2009年 | 47篇 |
2008年 | 44篇 |
2007年 | 59篇 |
2006年 | 36篇 |
2005年 | 41篇 |
2004年 | 41篇 |
2003年 | 37篇 |
2002年 | 28篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 11篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有1211条查询结果,搜索用时 898 毫秒
221.
222.
Kathryn L. Hopkins Fatima Laher Kennedy Otwombe Gavin Churchyard Linda-Gail Bekker Stephen DeRosa Maphoshane Nchabeleng Koleka Mlisana James Kublin Glenda Gray 《PloS one》2014,9(8)
Background
Phambili, the Merck (MRK)-Adenovirus Type 5 (Ad5) HIV-1 gag/pol/nef subtype B vaccine study, conducted in South Africa, suspended enrollment and vaccination when companion study, Step, was found non-efficacious. Although the vaccine did not prevent HIV-1 infection or lower viral-load setpoint, immune responses recognized clades B and C HIV-1 subtypes. We investigated predictors of the vaccine-induced antigen-specific immune responses.Methods
Vaccine-induced immunogenicity was ascertained by interferon-γ ELISpot assays on the first 186 enrolled participants receiving two vaccinations. Analyses, stratified by study arm/sex, were performed on baseline demographics [sex, age, Body Mass Index (BMI), site, Adenovirus Type-5 (Ad5) titer, Herpes Simplex Virus Type-2 (HSV2) status, heavy drinking]. Multivariate logistic regression determined predictors.Results
Of the 186 participants, 53.7% (n = 100) were female, median BMI was 22.5 [IQR: 20.4–27.0], 85.5% (n = 159) were Ad5 seropositive, and 18.8% (n = 35) drank heavily. All vaccine recipients responded to both clade B (n = 87; 47%) and/or C (n = 74; 40%), p = 0.17. In multivariate analysis, female sex [Adjusted Odds Ratio (AOR): 6.478; p = 0.0159], overweight/obese BMI (AOR: 0.186; p = 0.0452), and heavy drinking (AOR: 0.270; p = 0.048) significantly predicted immune response to clade C for any antigens. A marginally significant predictor of clade C-pol antigen was female sex (AOR: 3.182; p = 0.0500).Conclusions
Sex, BMI, and heavy drinking affected vaccine-induced HIV-1 specific immune responses to clade C antigens. The role of female sex and overweight/obese BMI boosting and suppressing vaccine-induced HIV-1 specific immune responses, respectively, requires elucidation, including any effect on HIV vaccine efficacy, especially in the era of colliding epidemics (HIV and obesity). 相似文献223.
M. Isabel Ortiz-Marchena Tomás Albi Eva Lucas-Reina Fatima E. Said Francisco J. Romero-Campero Beatriz Cano M. Teresa Ruiz José M. Romero Federico Valverde 《The Plant cell》2014,26(2):565-584
Flowering is a crucial process that demands substantial resources. Carbon metabolism must be coordinated with development through a control mechanism that optimizes fitness for any physiological need and growth stage of the plant. However, how sugar allocation is controlled during the floral transition is unknown. Recently, the role of a CONSTANS (CO) ortholog (Cr-CO) in the control of the photoperiod response in the green alga Chlamydomonas reinhardtii and its influence on starch metabolism was demonstrated. In this work, we show that transitory starch accumulation and glycan composition during the floral transition in Arabidopsis thaliana are regulated by photoperiod. Employing a multidisciplinary approach, we demonstrate a role for CO in regulating the level and timing of expression of the GRANULE BOUND STARCH SYNTHASE (GBSS) gene. Furthermore, we provide a detailed characterization of a GBSS mutant involved in transitory starch synthesis and analyze its flowering time phenotype in relation to its altered capacity to synthesize amylose and to modify the plant free sugar content. Photoperiod modification of starch homeostasis by CO may be crucial for increasing the sugar mobilization demanded by the floral transition. This finding contributes to our understanding of the flowering process. 相似文献
224.
Purification,Characterization and Antibacterial Activity of l‐amino Acid Oxidase from Cerastes cerastes 下载免费PDF全文
Ziad‐Meziane Hanane‐Fadila Laraba‐Djebari Fatima 《Journal of biochemical and molecular toxicology》2014,28(8):347-354
Antibiotic resistance presents a real problem in which new antibacterial molecules from natural secretions could be beneficial in the development of new drugs. In this study, Cerastes cerastes venom was investigated for its antibacterial activity against Gram‐positive and Gram‐negative bacteria. The antibacterial activity was evaluated by measuring the halo inhibition and minimum inhibitory concentration (MIC). An l ‐amino acid oxidase (CcLAAO) was purified from this venom using three chromatographic steps; its homogeneity (60 kDa) was confirmed by SDS‐PAGE. LC–MS/MS analysis of CcLAAO showed similarities with other LAAO enzymes from Echis ocellatus and Viridovipera stejnegeri venoms. CcLAAO presents an antibacterial activity against three bacterial strains (Staphylococcus aureus, Methicillin‐resistant S. aureus, and Pseudomonas aeruginosa) with MIC values of 10, 10, and 20 μg/mL, respectively. However, no effect was observed against Escherichia coli and yeast strains. Kinetic parameters of CcLAAO evaluated on l ‐leucine at pH 8.0 and 20°C were Km = 0.06 mmol and Vmax = 164 mmol/min. 相似文献
225.
Batool Ossareh-Nazari Carlos A. Ni?o Mario H. Bengtson Joong-Won Lee Claudio A.P. Joazeiro Catherine Dargemont 《The Journal of cell biology》2014,204(6):909-917
Autophagy, the process by which proteins or organelles are engulfed by autophagosomes and delivered for vacuolar/lysosomal degradation, is induced to ensure survival under starvation and other stresses. A selective autophagic pathway for 60S ribosomal subunits elicited by nitrogen starvation in yeast—ribophagy—was recently described and requires the Ubp3-Bre5 deubiquitylating enzyme. This discovery implied that an E3 ligases act upstream, whether inhibiting the process or providing an initial required signal. In this paper, we show that Ltn1/Rkr1, a 60S ribosome-associated E3 implicated in translational surveillance, acts as an inhibitor of 60S ribosomal subunit ribophagy and is antagonized by Ubp3. The ribosomal protein Rpl25 is a relevant target. Its ubiquitylation is Ltn1 dependent and Ubp3 reversed, and mutation of its ubiquitylation site rendered ribophagy less dependent on Ubp3. Consistently, the expression of Ltn1—but not Ubp3—rapidly decreased after starvation, presumably to allow ribophagy to proceed. Thus, Ltn1 and Ubp3-Bre5 likely contribute to adapt ribophagy activity to both nutrient supply and protein translation. 相似文献
226.
Fatima A. Haggar Gavin Pereira David Preen C. D'Arcy Holman Kristjana Einarsdottir 《PloS one》2014,9(12)
Objective
To investigate obstetric and perinatal outcomes among female survivors of adolescent and young adult (AYA) cancers and their offspring.Methods
Using multivariate analysis of statewide linked data, outcomes of all first completed pregnancies (n = 1894) in female survivors of AYA cancer diagnosed in Western Australia during the period 1982–2007 were compared with those among females with no cancer history. Comparison pregnancies were matched by maternal age-group, parity and year of delivery.Results
Compared with the non-cancer group, female survivors of AYA cancer had an increased risk of threatened abortion (adjusted relative risk 2.09, 95% confidence interval 1.51–2.74), gestational diabetes (2.65, 2.08–3.57), pre-eclampsia (1.32, 1.04–1.87), post-partum hemorrhage (2.83, 1.92–4.67), cesarean delivery (2.62, 2.22–3.04), and maternal postpartum hospitalization>5 days (3.01, 1.72–5.58), but no excess risk of threatened preterm delivery, antepartum hemorrhage, premature rupture of membranes, failure of labor to progress or retained placenta. Their offspring had an increased risk of premature birth (<37 weeks: 1.68, 1.21–2.08), low birth weight (<2500 g: 1.51, 1.23–2.12), fetal growth restriction (3.27, 2.45–4.56), and neonatal distress indicated by low Apgar score (<7) at 1 minute (2.83, 2.28–3.56), need for resuscitation (1.66, 1.27–2.19) or special care nursery admission (1.44, 1.13–1.78). Congenital abnormalities and perinatal deaths (intrauterine or ≤7 days of birth) were not increased among offspring of survivors.Conclusion
Female survivors of AYA cancer have moderate excess risks of adverse obstetric and perinatal outcomes arising from subsequent pregnancies that may require additional surveillance or intervention. 相似文献227.
Isolation and characterization of a biosurfactant‐producing Fusarium sp. BS‐8 from oil contaminated soil 下载免费PDF全文
Muneer A. Qazi Tayyaba Kanwal Muniba Jadoon Safia Ahmed Nighat Fatima 《Biotechnology progress》2014,30(5):1065-1075
This study reports characterization of a biosurfactant‐producing fungal isolate from oil contaminated soil of Missa Keswal oil field, Pakistan. It was identified as Fusarium sp. BS‐8 on the basis of macroscopic and microscopic morphology, and 18S rDNA gene sequence homology. The biosurfactant‐producing capability of the fungal isolates was screened using oil displacement activity, emulsification index assay, and surface tension (SFT) measurement. The optimization of operational parameters and culture conditions resulted in maximum biosurfactant production using 9% (v/v) inoculum at 30°C, pH 7.0, using sucrose and yeast extract, as carbon and nitrogen sources, respectively. A C:N ratio of 0.9:0.1 (w/w) was found to be optimum for growth and biosurfactant production. At optimal conditions, it attained lowest SFT (i.e., 32 mN m?1) with a critical micelle concentration of ≥ 1.2 mg mL?1. During 5 L shake flask fermentation experiments, the biosurfactant productivity was 1.21 g L?1 pure biosurfactant having significant emulsifying index (E24, 70%) and oil‐displacing activity (16 mm). Thin layer chromatography and Fourier transform infrared spectrometric analyses indicated a lipopeptide type of the biosurfactant. The Fusarium sp. BS‐8 has substantial potential of biosurfactant production, yet it needs to be fully characterized with possibility of relatively new class of biosurfactants. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1065–1075, 2014 相似文献
228.
Carla Oliveira-Ribeiro Maria Inês Fernandes Pimentel Liliane de Ftima Antonio Oliveira rica de Camargo Ferreira e Vasconcellos Fatima Conceio-Silva Armando de Oliveira Schubach Aline Fagundes Cintia Xavier de Mello Eliame Mouta-Confort Luciana de Freitas Campos Miranda Claudia Maria Valete-Rosalino Ana Cristina da Costa Martins Raquel de Vasconcellos Carvalhaes de Oliveira Leonardo Pereira Quintella Marcelo Rosandiski Lyra 《PLoS neglected tropical diseases》2021,15(9)
BackgroundTreatment of cutaneous leishmaniasis (CL) remains challenging since the drugs currently used are quite toxic, thus contributing to lethality unrelated to the disease itself but to adverse events (AE). The main objective was to evaluate different treatment regimens with meglumine antimoniate (MA), in a reference center in Rio de Janeiro, Brazil.MethodologyA historical cohort of 592 patients that underwent physical and laboratory examination were enrolled between 2000 and 2017. The outcome measures of effectiveness were epithelialization and complete healing of cutaneous lesions. AE were graded using a standardized scale. Three groups were evaluated: Standard regimen (SR): intramuscular (IM) MA 10–20 mg Sb5+/kg/day during 20 days (n = 46); Alternative regimen (AR): IM MA 5 mg Sb5+/kg/day during 30 days (n = 456); Intralesional route (IL): MA infiltration in the lesion(s) through subcutaneous injections (n = 90). Statistical analysis was performed through Fisher exact and Pearson Chi-square tests, Kruskal-Wallis, Kaplan-Meier and log-rank tests.ResultsSR, AR and IL showed efficacy of 95.3%, 84.3% and 75.9%, with abandonment rate of 6.5%, 2.4% and 3.4%, respectively. IL patients had more comorbidities (58.9%; p = 0.001), were mostly over 50 years of age (55.6%), and had an evolution time longer than 2 months (65.6%; p = 0.02). Time for epithelialization and complete healing were similar in IL and IM MA groups (p = 0.9 and p = 0.5; respectively). Total AE and moderate to severe AE that frequently led to treatment interruption were more common in SR group, while AR and IL showed less toxicity.Conclusions/SignificanceAR and IL showed less toxicity and may be good options especially in CL cases with comorbidities, although SR treatment was more effective. IL treatment was an effective and safe strategy, and it may be used as first therapy option as well as a rescue scheme in patients initially treated with other drugs. 相似文献
229.
Rocío Joo Andrea Snchez-Tapia Sara Mortara Yanina Bellini Saibene Heather Turner Dorothea Hug Peter Natalia Soledad Morandeira Matt Bannert Batool Almazrouq Elizabeth Hare Laura Acin Juan Pablo Narvez-Gmez Marcela Alfaro Crdoba Federico Marini Rita Giordano Silvia Caneln Anicet Ebou Adithi R. Upadhya Joselyn Chvez Janani Ravi 《PLoS computational biology》2022,18(7)
Conferences are spaces to meet and network within and across academic and technical fields, learn about new advances, and share our work. They can help define career paths and create long-lasting collaborations and opportunities. However, these opportunities are not equal for all. This article introduces 10 simple rules to host an inclusive conference based on the authors’ recent experience organizing the 2021 edition of the useR! statistical computing conference, which attracted a broad range of participants from academia, industry, government, and the nonprofit sector. Coming from different backgrounds, career stages, and even continents, we embraced the challenge of organizing a high-quality virtual conference in the context of the Coronavirus Disease 2019 (COVID-19) pandemic and making it a kind, inclusive, and accessible experience for as many people as possible. The rules result from our lessons learned before, during, and after the organization of the conference. They have been written mainly for potential organizers and selection committees of conferences and contain multiple practical tips to help a variety of events become more accessible and inclusive. We see this as a starting point for conversations and efforts towards building more inclusive conferences across the world. * Translated versions of the English abstract and the list of rules are available in 10 languages in S1 Text: Arabic, French, German, Italian, Japanese, Korean, Portuguese, Spanish, Tamil, and Thai. 相似文献