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排序方式: 共有613条查询结果,搜索用时 109 毫秒
1.
DNA fragments of around 200 base pair (average size) have been covalently crosslinked with 8-methoxypsoralen under 365 nm UV light. The photoadduct, induced antibodies in rabbits with a titer of > 1:12,800 by direct bindng ELISA. Binding data showed that the induced antibodies are conformation-specific recognizing restricted conformational change at site of crosslinking. Human autoantibodies against DNA, bound not only to native DNA but to the photomodified DNA fragment as well. In addition, binding patterns of SLE sera obtained from different patients were remarkably similar, indicating the recognition of altered conformation of the modified polymer by naturally occurring SLE anti-DNA autoantibodies.  相似文献   
2.

The present study is aimed at exploring different scanning parameters, detectors and their orientations for time-efficient and accurate commissioning of a 6 MV clinical linear accelerator (LINAC). Beam profiles and percentage depth dose (PDD) curves were measured with a PTW dosimetry diode, a PTW Semiflex and a PinPoint ion chamber in different orientations. To acquire beam data, equidistant (step size of 0.5 mm, 1 mm, 2 mm and 3 mm) and fanline (step size of 2–0.5 mm, 2–1 mm, 3–0.5 mm and 3-1 mm) scanning modes were employed and data measurement time was recorded. Scan time per measurement point was also varied (0.2 s, 0.5 s and 1.0 s) to investigate its effect on the accuracy and acquisition time of beam data. Accuracy of the measured data was analyzed on the basis of the variation between measured data and data modeled by a treatment planning system. Beam profiles (particularly in penumbra region) were found to be sensitive to variation in scanning resolution and showed an improved accuracy with decrease in step size, while PDD curves were affected negligibly. The accuracy of beam data obtained with the PTW dosimetry diode and the PinPoint ion chamber was higher than those obtained with the PTW Semiflex ion chamber for small fields (2?×?2 cm2 and 3?×?3 cm2). However, the response of the PTW diode and the PinPoint ion chamber was significantly indifferent in these fields. Furthermore, axial orientation of the PTW Semiflex ion chamber improved accuracy of profiles and PDDs as compared to radial orientation, while such a difference was not significant for the PinPoint ion chamber. It is concluded that a scan time of 0.2 s/point with a fanline scanning resolution of 2–1 mm for beam profiles and 3 mm for PDDs are most favorable in terms of accuracy and time efficiency. For small fields (2?×?2 cm2 and 3?×?3 cm2), a PinPoint ion chamber in radial orientation or a dosimetry diode in axial orientation are recommended for both beam profiles and PDDs. If a PinPoint ion chamber and a PTW dosimetry diode are not available, a Semiflex ion chamber in axial orientation may be used for small fields.

  相似文献   
3.
M. Asif 《Hydrobiologia》1980,75(1):73-79
Periphytic diatom communities on clay tile and sterilized rock substrates were compared with those on natural substrates. Clay tiles yielded diatom communities with the least variability between replicate samples, and the greatest similarity to the natural substrate assemblage. The advantages of utilizing introduced substrate communities and problems encountered with their simulation of the natural substrate community are discussed.  相似文献   
4.
The isolation of bergenin, 2-hydroxy-4-benzyloxyacetophenone and the related dimer and stilbene from Gnetum ula is reported.  相似文献   
5.
Russian Journal of Bioorganic Chemistry - Pyridazines hold considerable interest relative to pharmacologically active molecules. The pyridazine compounds are exhibited different types of...  相似文献   
6.
Tristeza is a devastating viral disease in all the citrus growing countries throughout the world and has killed millions of citrus trees in severely affected orchards. The citrus species grafted on sour orange rootstock are affected by this disease. Predominantly, the sweet orange, grapefruit and lime trees grafted on sour orange exhibit severe symptoms like quick decline, vein clearing, pin holing, bark scaling and degeneration leading to variable symptoms. Symptomatic expression of Citrus tristeza virus (CTV) in different hosts has been attributed to virus isolates which are from severe to mild. Different serological and molecular assays have been deployed to differentiate the strains of CTV. Citrus tristeza virus is diversified towards its strains on the basis of biological, serological and molecular characterization. Phenotypic expression is due to genetic alteration and different molecular basis have now been adopted for strain differentiation. This review will give a brief idea about the different CTV isolates, their characterization based on nucleic acid and serological assays. Different methods along with salient features for strain characterization has also been reviewed. This review will also open the new aspects towards formulation of management strategies through different detection techniques.  相似文献   
7.
Plant Molecular Biology - This study focused on the key regulatory function of Physcomitrium patens GRAS12 gene underlying an increasing plant complexity, an important step in plant...  相似文献   
8.
Plant Cell, Tissue and Organ Culture (PCTOC) - Plant cells develop defence mechanisms in response to mutagen stress which leads to modulation of certain metabolic and defensive pathways. Owing to...  相似文献   
9.
Molecular Biology Reports - Heat shock phenomenon is a process by which cells express a set of proteins called heat shock proteins (HSPs) against heat stress. HSPs include several families...  相似文献   
10.
Root-knot nematodes Meloidogyne incognita (Kofoid and White) Chitwood and Rhizoctonia bataticola (Taub.) Butler, fungus, are very dangerous root damaging pathogens. Present study was planned to establish a chemical control of these root deteriorating pathogens under lab conditions as well as in field. Maximum death rate of nematode juveniles and minimum numbers of nematode eggs hatched were recorded in plates treated with Cadusafos (Rugby® 100G) @12 g/100 ml and Cartap® (4% G) @9g/100 ml. Chemical treatment of Rhizoctonia bataticola with Trifloxystrobin + Tebuconazole (Nativo®) @0.2 g/100 ml and Mancozeb + Matalaxyl (Axiom) @0.25 g/100 ml significantly controlled the mycelial growth in plates. The best treatments tested in laboratory were applied in field as protective and curative treatments. Results proved that chemical control of root-knot nematode and root rot fungi by tested chemicals at recommended time and dose is a significant management technique under field conditions.  相似文献   
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