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排序方式: 共有113条查询结果,搜索用时 15 毫秒
1.
Claudia T Guimaraes Christiano C Simoes Maria Marta Pastina Lyza G Maron Jurandir V Magalhaes Renato CC Vasconcellos Lauro JM Guimaraes Ubiraci GP Lana Carlos FS Tinoco Roberto W Noda Silvia N Jardim-Belicuas Leon V Kochian Vera MC Alves Sidney N Parentoni 《BMC genomics》2014,15(1)
Background
Aluminum (Al) toxicity is an important limitation to food security in tropical and subtropical regions. High Al saturation on acid soils limits root development, reducing water and nutrient uptake. In addition to naturally occurring acid soils, agricultural practices may decrease soil pH, leading to yield losses due to Al toxicity. Elucidating the genetic and molecular mechanisms underlying maize Al tolerance is expected to accelerate the development of Al-tolerant cultivars.Results
Five genomic regions were significantly associated with Al tolerance, using 54,455 SNP markers in a recombinant inbred line population derived from Cateto Al237. Candidate genes co-localized with Al tolerance QTLs were further investigated. Near-isogenic lines (NILs) developed for ZmMATE2 were as Al-sensitive as the recurrent line, indicating that this candidate gene was not responsible for the Al tolerance QTL on chromosome 5, qALT5. However, ZmNrat1, a maize homolog to OsNrat1, which encodes an Al3+ specific transporter previously implicated in rice Al tolerance, was mapped at ~40 Mbp from qALT5. We demonstrate for the first time that ZmNrat1 is preferentially expressed in maize root tips and is up-regulated by Al, similarly to OsNrat1 in rice, suggesting a role of this gene in maize Al tolerance. The strongest-effect QTL was mapped on chromosome 6 (qALT6), within a 0.5 Mbp region where three copies of the Al tolerance gene, ZmMATE1, were found in tandem configuration. qALT6 was shown to increase Al tolerance in maize; the qALT6-NILs carrying three copies of ZmMATE1 exhibited a two-fold increase in Al tolerance, and higher expression of ZmMATE1 compared to the Al sensitive recurrent parent. Interestingly, a new source of Al tolerance via ZmMATE1 was identified in a Brazilian elite line that showed high expression of ZmMATE1 but carries a single copy of ZmMATE1.Conclusions
High ZmMATE1 expression, controlled either by three copies of the target gene or by an unknown molecular mechanism, is responsible for Al tolerance mediated by qALT6. As Al tolerant alleles at qALT6 are rare in maize, marker-assisted introgression of this QTL is an important strategy to improve maize adaptation to acid soils worldwide.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-153) contains supplementary material, which is available to authorized users. 相似文献2.
3.
4.
Thermodynamic benchmark study using Biacore technology 总被引:1,自引:0,他引:1
Navratilova I Papalia GA Rich RL Bedinger D Brophy S Condon B Deng T Emerick AW Guan HW Hayden T Heutmekers T Hoorelbeke B McCroskey MC Murphy MM Nakagawa T Parmeggiani F Qin X Rebe S Tomasevic N Tsang T Waddell MB Zhang FF Leavitt S Myszka DG 《Analytical biochemistry》2007,364(1):67-77
A total of 22 individuals participated in this benchmark study to characterize the thermodynamics of small-molecule inhibitor-enzyme interactions using Biacore instruments. Participants were provided with reagents (the enzyme carbonic anhydrase II, which was immobilized onto the sensor surface, and four sulfonamide-based inhibitors) and were instructed to collect response data from 6 to 36 degrees C. van't Hoff enthalpies and entropies were calculated from the temperature dependence of the binding constants. The equilibrium dissociation and thermodynamic constants determined from the Biacore analysis matched the values determined using isothermal titration calorimetry. These results demonstrate that immobilization of the enzyme onto the sensor surface did not alter the thermodynamics of these interactions. This benchmark study also provides insights into the opportunities and challenges in carrying out thermodynamic studies using optical biosensors. 相似文献
5.
Miller JR Herberg JT Tomilo M McCroskey MC Feilmeier BJ 《Analytical biochemistry》2007,365(1):132-143
The rise in bacterial resistance to antibiotics demonstrates the medical need for new antibacterial agents. One approach to this problem is to identify new antibacterials that act through validated drug targets such as bacterial DNA gyrase. DNA gyrase uses the energy of ATP hydrolysis to introduce negative supercoils into plasmid and chromosomal DNA and is essential for DNA replication. Inhibition of the ATPase activity of DNA gyrase is the mechanism by which coumarin-class antibiotics such as novobiocin inhibit bacterial growth. Although ATPase inhibitors exhibit potent antibacterial activity against gram-positive pathogens, no gyrase ATPase activity from a gram-positive organism is described in the literature. To address this, we developed and optimized an enzyme-coupled phosphate assay and used this assay to characterize the ATPase kinetics of Streptococcus pneumoniae gyrase. The S. pneumoniae enzyme exhibits cooperativity with ATP and requires organic potassium salts. We also studied inhibition of the enzyme by novobiocin. Apparent inhibition constants for novobiocin increased linearly with ATP concentration, indicative of an ATP-competitive mechanism. Similar binding affinities were measured by isothermal titration calorimetry. These results reveal unique features of the S. pneumoniae DNA gyrase ATPase and demonstrate the utility of the assay for screening and kinetic characterization of ATPase inhibitors. 相似文献
6.
Sidders B Withers M Kendall SL Bacon J Waddell SJ Hinds J Golby P Movahedzadeh F Cox RA Frita R Ten Bokum AM Wernisch L Stoker NG 《Genome biology》2007,8(12):R265-13
We describe an analysis, applicable to any spotted microarray dataset produced using genomic DNA as a reference, that quantifies prokaryotic levels of mRNA on a genome-wide scale. Applying this to Mycobacterium tuberculosis, we validate the technique, show a correlation between level of expression and biological importance, define the complement of invariant genes and analyze absolute levels of expression by functional class to develop ways of understanding an organism's biology without comparison to another growth condition. 相似文献
7.
José MC Ribeiro Bruno Arcà Fabrizio Lombardo Eric Calvo My Van Phan Prafulla K Chandra Stephen K Wikel 《BMC genomics》2007,8(1):1-27
Background
The number of completely sequenced plastid genomes available is growing rapidly. This array of sequences presents new opportunities to perform comParative analyses. In comParative studies, it is often useful to compare across wide phylogenetic spans and, within angiosperms, to include representatives from basally diverging lineages such as the genomes reported here: Nuphar advena (from a basal-most lineage) and Ranunculus macranthus (a basal eudicot). We report these two new plastid genome sequences and make comparisons (within angiosperms, seed plants, or all photosynthetic lineages) to evaluate features such as the status of ycf15 and ycf68 as protein coding genes, the distribution of simple sequence repeats (SSRs) and longer dispersed repeats (SDR), and patterns of nucleotide composition.Results
The Nuphar [GenBank:NC_008788] and Ranunculus [GenBank:NC_008796] plastid genomes share characteristics of gene content and organization with many other chloroplast genomes. Like other plastid genomes, these genomes are A+T-rich, except for rRNA and tRNA genes. Detailed comparisons of Nuphar with Nymphaea, another Nymphaeaceae, show that more than two-thirds of these genomes exhibit at least 95% sequence identity and that most SSRs are shared. In broader comparisons, SSRs vary among genomes in s of abundance and length and most contain repeat motifs based on A and T nucleotides.Conclusion
SSR and SDR abundance varies by genome and, for SSRs, is proportional to genome size. Long SDRs are rare in the genomes assessed. SSRs occur less frequently than predicted and, although the majority of the repeat motifs do include A and T nucleotides, the A+T bias in SSRs is less than that predicted from the underlying genomic nucleotide composition. In codon usage third positions show an A+T bias, however variation in codon usage does not correlate with differences in A+T-richness. Thus, although plastome nucleotide composition shows "A+T richness", an A+T bias is not apparent upon more in-depth analysis, at least in these aspects. The pattern of evolution in the sequences identified as ycf15 and ycf68 is not consistent with them being protein-coding genes. In fact, these regions show no evidence of sequence conservation beyond what is normal for non-coding regions of the IR. 相似文献8.
9.
van Beers JJ Raijmakers R Alexander LE Stammen-Vogelzangs J Lokate AM Heck AJ Schasfoort RB Pruijn GJ 《Arthritis research & therapy》2010,12(6):R219
Introduction
Rheumatoid arthritis (RA) frequently involves the loss of tolerance to citrullinated antigens, which may play a role in pathogenicity. Citrullinated fibrinogen is commonly found in inflamed synovial tissue and is a frequent target of autoantibodies in RA patients. To obtain insight into the B-cell response to citrullinated fibrinogen in RA, its autoepitopes were systematically mapped using a new methodology. 相似文献10.
Andréia S Lessa Bruno D Paredes Juliana V Dias Adriana B Carvalho Luiz Fernando Quintanilha Christina M Takiya Bernardo R Tura Guilherme FM Rezende Antonio C Campos de Carvalho Célia MC Resende Regina CS Goldenberg 《BMC veterinary research》2010,6(1):1-10