全文获取类型
收费全文 | 502篇 |
免费 | 40篇 |
专业分类
542篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 21篇 |
2021年 | 33篇 |
2020年 | 15篇 |
2019年 | 29篇 |
2018年 | 23篇 |
2017年 | 18篇 |
2016年 | 22篇 |
2015年 | 37篇 |
2014年 | 40篇 |
2013年 | 39篇 |
2012年 | 51篇 |
2011年 | 24篇 |
2010年 | 22篇 |
2009年 | 15篇 |
2008年 | 23篇 |
2007年 | 26篇 |
2006年 | 18篇 |
2005年 | 23篇 |
2004年 | 15篇 |
2003年 | 14篇 |
2002年 | 12篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有542条查询结果,搜索用时 15 毫秒
41.
V Baral A Chaoui Y Watanabe M Goossens T Attie-Bitach S Marlin V Pingault N Bondurand 《PloS one》2012,7(7):e41927
Waardenburg syndrome (WS) is a rare auditory-pigmentary disorder that exhibits varying combinations of sensorineural hearing loss and pigmentation defects. Four subtypes are clinically defined based on the presence or absence of additional symptoms. WS type 2 (WS2) can result from mutations within the MITF or SOX10 genes; however, 70% of WS2 cases remain unexplained at the molecular level, suggesting that other genes might be involved and/or that mutations within the known genes escaped previous screenings. The recent identification of a deletion encompassing three of the SOX10 regulatory elements in a patient presenting with another WS subtype, WS4, defined by its association with Hirschsprung disease, led us to search for deletions and point mutations within the MITF and SOX10 regulatory elements in 28 yet unexplained WS2 cases. Two nucleotide variations were identified: one in close proximity to the MITF distal enhancer (MDE) and one within the U1 SOX10 enhancer. Functional analyses argued against a pathogenic effect of these variations, suggesting that mutations within regulatory elements of WS genes are not a major cause of this neurocristopathy. 相似文献
42.
Asma Awadi Hichem Ben Slimen Steve Smith Jonas Kahlen Mohamed Makni Franz Suchentrunk 《Comptes rendus biologies》2018,341(6):315-324
Toll-like receptors (TLRs) are a major group of proteins that recognize molecular components of infectious agents, known as pathogen associated molecular patterns (PAMPs). The structure of these genes is similar and characterized by the presence of an ectodomain, a signal transmembrane segment and a highly conserved cytoplasmic domain. The latter domain is homologous to the human interleukin-1 receptor (IL1R) and human IL-18 receptor (IL-18R) and designated TIR domain. The latter domain of the TLR genes was suggested to be very conservative and its evolution is driven by purifying selection. Variability and evolution of the TIR sequences of TLR2 gene were studied in three hare populations from Tunisia with different ecological characteristics (NT–North Tunisia with Mediterranean, CT–Central Tunisia with semi-arid, and ST–South Tunisia with arid climate). Sequencing of a 372 bp fragment of TIR2 revealed 25 alleles among 110 hares. Twenty variable nucleotide positions were detected, of which 7 were non-synonymous. The highest variability was observed in CT, with 16 polymorphic positions. In ST, only 4 polymorphic nucleotide positions were detected with all diversity values lower than those recorded for the other two populations. By using several approaches, no positive selection was detected. However, evidence of purifying selection was found at two positions. The logistic models of the most common TIR2 protein variant that we run to examine whether its occurrence was affected by climatic variation independent of the geographic sample location suggested only a longitudinal effect. Finally, the mapping of the non-synonymous mutations to the inferred tertiary protein structure showed that they were all localized in the different loop regions. Among all non-synonymous substitutions, three were suggested to be deleterious as evidenced by PROVEAN analysis. The observed patterns of variability characterized by low genetic diversity in ST might suggest that the TIR region was more affected, than other markers, by genetic drift or/and that these patterns were shaped by different selective pressures under different ecological conditions. Notably, this low diversity was not detected by other (putatively neutral) microsatellite markers analysed in the course of other studies. But low diversity was also found for two MHC class II adaptive immune genes. As expected from functionally important regions, the evolution of the TIR2 domain is mainly driven by purifying selection. However, the occurrence of deleterious non-synonymous substitutions might highlight the flexible evolution of the TIR genes and/or their interactions with other proteins. 相似文献
43.
Successful phytoremediation of crude-oil contaminated soil at an oil exploration and production company by plants-bacterial synergism 总被引:1,自引:0,他引:1
Kaneez Fatima Asma Imran Imran Amin Qaiser M. Khan 《International journal of phytoremediation》2018,20(7):675-681
Phytoremediation is a promising approach for the cleanup of soil contaminated with petroleum hydrocarbons. This study aimed to develop plant-bacterial synergism for the successful remediation of crude oil-contaminated soil. A consortia of three endophytic bacteria was augmented to two grasses, Leptochloa fusca and Brachiaria mutica, grown in oil-contaminated soil (46.8 g oil kg?1 soil) in the vicinity of an oil exploration and production company. Endophytes augmentation improved plant growth, crude oil degradation, and soil health. Maximum oil degradation (80%) was achieved with B. mutica plants augmented with the endophytes and it was significantly (P < 0.05) higher than the use of plants or bacteria individually. Moreover, endophytes showed more persistence, the abundance and expression of alkB gene in the rhizosphere as well as in the endosphere of the tested plants than in unvegetated soil. A positive relationship (r = 0.70) observed between gene expression and crude oil reduction indicates that catabolic gene expression is important for hydrocarbon mineralization. This investigation showed that the use of endophytes with appropriate plant is an effective strategy for the cleanup of oil-contaminated soil under field conditions. 相似文献
44.
Asma Ben Ghnaya Gilbert Charles Michel Branchard 《Plant Cell, Tissue and Organ Culture》2008,92(1):25-30
The present work describes a procedure that allows for the easy and rapid induction of caulogenesis in four cultivars of Brassica napus L. from transversal Thin Cell Layers (tTCLs). In order to investigate the regeneration ability of this crop, the effects
of genotype, explant source and culture medium were examined on shoot regeneration. The tTCL explants were excised from hypocotyl
and petiole of 2-week-old seedlings and cultured on a solid basal MS medium supplemented with α-naphthaleneacetic acid (NAA:
0.1–0.4 mg l−1), 6-benzylamino-purine (BAP: 1–4 mg l−1) and sucrose (20–40 g l−1). A significant genotypic effect was observed between the four cvs; Jumbo and Drakkar displayed higher capacities to produce
shoots than Pactol and Cossair. Regeneration commenced earlier and the percentage of shoot-producing explants as well as the
number of shoots per regenerating explant was greater. The comparison between the regeneration ability of different explants
showed that the hypocotyls exhibited a high rate of shoot organogenesis when they were cultured on MS medium supplemented
with 3 mg l−1 BAP, 0.3 mg l−1 NAA and 30 g l−1 sucrose. Adventitious shoot buds developed from 46% of the tTCLs, with a mean of 7.5 buds. Furthermore, the method was fast
with shoot formation occurring by 7 days culture. Plantlets regenerated from all shoots and developed normally. The regenerated
plants were fertile and identical to source plants. 相似文献
45.
AbstractA study was undertaken to compare the patterns of spatial variability, epiphytic percentage cover, and distribution of epiphytic fauna and flora between the two adjacent seagrasses Cymodocea nodosa and the invasive species Halophila stipulucea. Samples were taken at six stations separated by 600?m and exposed to different current conditions. The stations G2 and G5 were affected by a high current tide, while G4 was directly exposed to the northern marine currents. The station G3 was situated in the middle of a Posidonia oceanica bed and was less exposed to hydrodynamism, whereas the other stations were relatively protected. Results indicate that for both H. stipulacea and C. nodosa, shoot density and epiphytic cover biomass decreased when exposed to high levels of hydrodynamic activity. In terms of epiphytic leaf assemblages, our results showed significant differences for the two host plants in their mean cover and for the six stations at the largest and smallest spatial scale. Our observations highlight the dominance of Rhodophyta and the low number of epiphytic species and the epiphytic cover on H. stipulacea compared to C. nodosa. In addition, results indicate the absence of two taxa Hydrozoans and Annelida in the epiphytic assemblage of H. stipulacea leaves. 相似文献
46.
Amira Moussa Jihène Rejeb Asma Omezzine Lamia Rebhi Imen Boumaiza Slim Kacem Nabila Ben Rejeb Essia Boughzala Ahmed Ben Abdelaziz Ali Bouslama 《Biochemical genetics》2014,52(5-6):269-282
Haptoglobin (Hp) polymorphism generates three common human genotypes (Hp1-1, Hp2-1, and Hp2-2), having functional differences, related to the risk of development of cardiovascular diseases. These functions are a consequence of hemoglobin binding that leads to the synthesis of an antioxidant like ferritin. We explored the association of Hp polymorphism with significant coronary stenosis (SCS) and its severity within 400 Tunisian patients, using genotyping, biochemical parameters, and the Gensini score. After adjustments for age and gender, Hp2-2 was associated with the highest ferritin but the lowest Hp concentrations. After adjustments for confounding parameters, the OR of SCS associated with Hp2-2 was 1.74 (95% CI 1.18–2.58; p = 0.005). This effect was enhanced within diabetics (OR 1.90, 95% CI 1.11–3.24; p = 0.018), obese subjects (OR 1.98, 95% CI 1.10–4.86; p = 0.034), and smokers (OR 4.17, 95% CI 1.54–1.29; p = 0.005). The Hp2-2 genotype is associated with an increase in SCS especially in diabetics, the obese, and smokers. 相似文献
47.
R Shaheen E Faqeih HE Shamseldin RR Noche A Sunker MJ Alshammari T Al-Sheddi N Adly MS Al-Dosari SG Megason M Al-Husain F Al-Mohanna FS Alkuraya 《American journal of human genetics》2012,91(2):330-336
Primordial dwarfism (PD) is a phenotype characterized by profound growth retardation that is prenatal in onset. Significant strides have been made in the last few years toward improved understanding of the molecular underpinning of the limited growth that characterizes the embryonic and postnatal development of PD individuals. These include impaired mitotic mechanics, abnormal IGF2 expression, perturbed DNA-damage response, defective spliceosomal machinery, and abnormal replication licensing. In three families affected by a distinct form of PD, we identified a founder truncating mutation in POC1A. This gene is one of two vertebrate paralogs of POC1, which encodes one of the most abundant proteins in the Chlamydomonas centriole proteome. Cells derived from the index individual have abnormal mitotic mechanics with multipolar spindles, in addition to clearly impaired ciliogenesis. siRNA knockdown of POC1A in fibroblast cells recapitulates this ciliogenesis defect. Our findings highlight a human ciliopathy syndrome caused by deficiency of a major centriolar protein. 相似文献
48.
49.
Mehwish Iqtedar Mehral Aslam Muhammad Akhyar Asma Shehzaad Roheena Abdullah Afshan Kaleem 《Preparative biochemistry & biotechnology》2013,43(2):136-142
AbstractBiosynthesis of metal nanoparticles is an area of interest among researchers because of its eco-friendly approach. Current study focuses at biosynthesis of silver nanoparticles (AgNPs) and optimization of physico-chemical conditions to obtain mono-dispersed and stable AgNPs having antimicrobial activity. Initially Bacillus mojavensis BTCB15 produced silver nanoparticles (AgNPs) of 105?nm. Silver nanoparticles (AgNPs) were characterized by particle size analyzer, UV-Vis Spectroscopy, Fourier transforms infrared spectroscopy (FTIR), Atomic force microscopy (AFM), and X-ray diffraction (XRD). Whereas, under optimal conditions of temperature 55?°C, pH 8, addition of surfactant Tween 20, and metal ion K2SO4, about 104% size reduction was achieved with average size of 2.3nm. Molecular characterization revealed 98% sequence homology with Bacillus mojavensis. AgNPs exhibited antibacterial activity at concentrations ranging from 0.5 to 2.5?µg/µl against Escherichia coli BTCB03, Klebsiella pneumonia BTCB04, Acinetobacter sp. BTCB05, and Pseudomonas aeruginosa BTCB01 but none against Staphylococcus aureus BTCB02. Highest antibacterial activity was observed at 0.27?µg/µl and lowest at 0.05?µg/µl of AgNPs indicated by zone of inhibition. Conclusively, under optimum conditions, Bacillus mojavensis BTCB15 was able to produce AgNPs of 2.3?nm size and had antibacterial activity against multi drug resistant pathogens. 相似文献
50.
Aurélien Sokal Pascal Chappert Giovanna Barba-Spaeth Anais Roeser Slim Fourati Imane Azzaoui Alexis Vandenberghe Ignacio Fernandez Annalisa Meola Magali Bouvier-Alias Etienne Crickx Asma Beldi-Ferchiou Sophie Hue Laetitia Languille Marc Michel Samia Baloul France Noizat-Pirenne Marine Luka Matthieu Mahévas 《Cell》2021,184(5):1201-1213.e14