全文获取类型
收费全文 | 81篇 |
免费 | 10篇 |
出版年
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 9篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有91条查询结果,搜索用时 457 毫秒
71.
72.
73.
DNA transfer occurs during a cell surface contact stage of F sex factor-mediated bacterial conjugation. 总被引:13,自引:9,他引:4 下载免费PDF全文
Donor bacteria containing JCFL39, a temperature-sensitive traD mutant of the F sex factor, were used at the nonpermissive temperature to accumulate stable mating pairs with recipient cells. At this stage in conjugation, extracellular F pili were removed by treatment with 0.01% sodium dodecyl sulfate. Upon then shifting to the permissive temperature for JCFL39, transfer of the F plasmid was observed. The mating pairs that were accumulated with JCFL39 at the nonpermissive temperature were readily observed by electron microscopy in wall-to-wall contact with the recipient bacteria. These results demonstrate that the traD product, which is known to be required in transferring DNA to a recipient bacterium, acts after the stage at which extracellular F pili are required. In addition, we concluded that DNA transfer takes place while donor and recipient cells are in surface contact and not necessarily through an extended F pilus as envisioned in some models of bacterial conjugation. 相似文献
74.
Using a traD overexpression plasmid, we purified the F sex factor TraD protein in milligram quantities. The purified protein has an apparent molecular weight of 82,000 and an amino acid composition rich in acidic residues. Using specific antibodies, TraD was localized to the inner membrane of F+ cells under conditions where it is produced in physiologically normal amounts. Furthermore, the protein was soluble only in the presence of detergents, but there is evidence that the carboxyl terminus is water-soluble. The purified protein shows pH-sensitive binding to DNA cellulose columns. 相似文献
75.
Histochemical and ultrastructural studies of the muscle coat of the oesophagus from ICRC/HiCri mice (with megaoesophagus) and DBA/2fNCri mice (normal oesophagus) were carried out. The striking observation from histochemical studies was the presence of smooth muscle in the abdominal segment of the oesophagus from ICRC mouse in contrast to the control strain where smooth muscle was present only in the lowermost portion adjoining the stomach. Ultrastructural studies of the oesophageal wall from 5- and 10-day-old ICRC mice revealed an apparently normal muscle coat. In 3-month-old ICRC mice the upper abdominal segment of the oesophagus showed several abnormalities of smooth muscle fibres and paucity of plexus tissue accompanied by interstitial collagen deposition. The abnormalities were more severe in 1-year-old animals and were seen throughout the abdominal segment. From this study it is suggested that the primary cause of megaoesophagus in ICRC mice is neurogenic and not myogenic. 相似文献
76.
Paulo C Carvalho Juliana SG Fischer Emily I Chen John R YatesIII Valmir C Barbosa 《BMC bioinformatics》2008,9(1):316
Background
A goal of proteomics is to distinguish between states of a biological system by identifying protein expression differences. Liu et al. demonstrated a method to perform semi-relative protein quantitation in shotgun proteomics data by correlating the number of tandem mass spectra obtained for each protein, or "spectral count", with its abundance in a mixture; however, two issues have remained open: how to normalize spectral counting data and how to efficiently pinpoint differences between profiles. Moreover, Chen et al. recently showed how to increase the number of identified proteins in shotgun proteomics by analyzing samples with different MS-compatible detergents while performing proteolytic digestion. The latter introduced new challenges as seen from the data analysis perspective, since replicate readings are not acquired. 相似文献77.
Melzer D Perry JR Hernandez D Corsi AM Stevens K Rafferty I Lauretani F Murray A Gibbs JR Paolisso G Rafiq S Simon-Sanchez J Lango H Scholz S Weedon MN Arepalli S Rice N Washecka N Hurst A Britton A Henley W van de Leemput J Li R Newman AB Tranah G Harris T Panicker V Dayan C Bennett A McCarthy MI Ruokonen A Jarvelin MR Guralnik J Bandinelli S Frayling TM Singleton A Ferrucci L 《PLoS genetics》2008,4(5):e1000072
78.
John E Moore Adrienne Shaw Jennifer L Howard James SG Dooley J Stuart Elborn 《Annals of clinical microbiology and antimicrobials》2004,3(1):1-5
Background
Although various hematologic abnormalities are seen in tuberculosis, immune thrombocytopenic purpura is a rare event.Case Presentation
We report a case of a 29 year-old male who was presented with immune thrombocytopenia-induced hemoptysis, macroscopic hematuria and generalized petechiae. The patient was found to have clinical, microbiological and radiological evidence of active pulmonary tuberculosis. The immune thrombocytopenic purpura was successfully treated with anti-tuberculous drugs combined with corticosteroids and high dose immune globulin therapy.Conclusion
Immune thrombocytopenic purpura can be one of the hematological manifestations of tuberculosis which has a global prevalence with increasing incidence secondary to HIV infection. 相似文献79.
Mateus F Santana José CF Silva Eduardo SG Mizubuti Elza F Araújo Bradford J Condon B Gillian Turgeon Marisa V Queiroz 《BMC genomics》2014,15(1)
Background
Cochliobolus heterostrophus is a dothideomycete that causes Southern Corn Leaf Blight disease. There are two races, race O and race T that differ by the absence (race O) and presence (race T) of ~ 1.2-Mb of DNA encoding genes responsible for the production of T-toxin, which makes race T much more virulent than race O. The presence of repetitive elements in fungal genomes is considered to be an important source of genetic variability between different species.Results
A detailed analysis of class I and II TEs identified in the near complete genome sequence of race O was performed. In total in race O, 12 new families of transposons were identified. In silico evidence of recent activity was found for many of the transposons and analyses of expressed sequence tags (ESTs) demonstrated that these elements were actively transcribed. Various potentially active TEs were found near coding regions and may modify the expression and structure of these genes by acting as ectopic recombination sites. Transposons were found on scaffolds carrying polyketide synthase encoding genes, responsible for production of T-toxin in race T. Strong evidence of ectopic recombination was found, demonstrating that TEs can play an important role in the modulation of genome architecture of this species. The Repeat Induced Point mutation (RIP) silencing mechanism was shown to have high specificity in C. heterostrophus, acting only on transposons near coding regions.Conclusions
New families of transposons were identified. In C. heterostrophus, the RIP silencing mechanism is efficient and selective. The co-localization of effector genes and TEs, therefore, exposes those genes to high rates of point mutations. This may accelerate the rate of evolution of these genes, providing a potential advantage for the host. Additionally, it was shown that ectopic recombination promoted by TEs appears to be the major event in the genome reorganization of this species and that a large number of elements are still potentially active. So, this study provides information about the potential impact of TEs on the evolution of C. heterostrophus.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-536) contains supplementary material, which is available to authorized users. 相似文献80.
Gabriela G Loots Patrick SG Chain Shalini Mabery Amy Rasley Emilio Garcia Ivan Ovcharenko 《BMC bioinformatics》2006,7(1):307-8