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1.
Jet injection can be used to introduce genes into the cells of differentiated tissues of living animals and organ cultures. When a solution of plasmid DNA is jet injected into a selected tissue or organ, cells lying in or near the path of the jet injection are transfected with the DNA and the introduced gene(s) are expressed. Since there is minimal morbidity from each jet injection, multiple injections can be performed at the same or nearby sites. Both mRNA and protein expression from transfected genes can be quantitated using standard methods. In addition, the technique is an efficient means of DNA immunization. Methodology for using jet injection to transfer plasmid DNA into the cells of skin, fat, mammary gland, and muscle are described.  相似文献   
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We consider the imaging in scanning microscopes employing point and slit-shaped detectors in both the bright-field and fluorescent mode. In particular we consider the three-dimensional aspects of the imaging and show inter alia that acceptable, albeit asymmetrical, images result from a slit detector system at low levels of defocus. The situation becomes worse as the defocus is increased although acceptable extended-focus and isometric images are still possible in some cases.  相似文献   
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Nanocomposites made from polypropylene and as-received graphite were prepared by solid-state shear pulverization (SSSP) as a function of graphite loading (0.3-8.4 wt%). X-ray diffraction indicates that SSSP employing harsh pulverization conditions yields substantial graphite exfoliation at 0.3-2.7 wt% graphite content with less exfoliation being achieved at higher graphite content. With increasing graphite content, thermal degradation temperature and non-isothermal onset crystallization temperature increase substantially (by as much as 35 and 23 °C relative to neat polypropylene) while isothermal crystallization half-time decreases dramatically. In contrast, Young’s modulus and tensile yield strength exhibit maxima (∼100% and ∼60% increases, respectively, relative to neat polypropylene) at 2.7 wt% graphite content, with all nanocomposites retaining high elongation at break values except at the highest filler loading. Electrical conductivity measurements indicate percolation of graphite at 2.7 wt% and higher graphite content, consistent with rheology measurements showing the presence of a solid-like response of melt-state shear storage modulus as a function of frequency. Significant tunability of graphite exfoliation and property enhancements is demonstrated as a function of SSSP processing.  相似文献   
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早期的OSS非常专有化和封闭,在功能上是垂直的,一种OSS只专注于一种功能,与其他的OSS没有直接的交互。现代OSS则具有开放和模块化的结构、开放的接口、不同组建模块之间的交互和流程自动化等特点。在网络环境日益复杂、网络规模和用户数量不断扩大以及市场不断变化的情况下,国内的运营商面临严峻的挑战。惠普公司的电信网运营支撑系统解决方案为电信运营商提供了一种选择。  相似文献   
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James G. Hewlett   《Energy Policy》2005,33(18):2293-2297
One issue addressed in almost all electric power restructuring/de-regulation plans in both the United States (US) and the United Kingdom (UK) was the recovery of operating nuclear power plant's spent fuel disposal costs and the expenditures to decommission the units when they are retired. Prior to restructuring, in theory at least, in both countries, electricity consumers were paying for the back end costs from operating nuclear power plants. Moreover, in virtually all cases in the US, states included special provisions to insure that consumers would continue to do so after power markets were de-regulated. When power markets in the UK were initially restructured/de-regulated and nuclear power privatized, the shareholders of British Energy (BE) were initially responsible for these costs. However, after electricity prices fell and BE collapsed, the British government shifted many of the costs to future taxpayers, as much as a century forward. If this was not done, the book value of BE's equity would have been about −3.5 billion pounds. That is, BE's liabilities would have been about −3.5 billion pounds greater than their assets. It is difficult to see how BE could remain viable under such circumstances.  相似文献   
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