问题 问答题

何谓血沉简述血沉加快的机制。

答案

参考答案:抗凝血液在血沉管内垂直静置1小时末红细胞下沉的速率称为红细胞沉降率,简称血沉。血沉加快的根本原因在血浆而不是红细胞本身。伎血沉加快的具体因素有:①血浆纤维蛋白原显著增加,它是带正电荷的颗粒,能中和红细胞表面的负电荷,且该物质又是亲水胶质,可破坏红细胞的水化膜,使红细胞叠连加速,血沉加快;②A/G比值减小时,血液胶体状态不稳定,加速红细胞的叠连作用而使血沉加快;③某些传染病时红细胞吸附血液中的抗体,与抗原发生免疫反应使红细胞凝集而加速血沉;④胆囊炎或胆道阻塞时,因胆固醇降低红细胞表面电荷而使血沉加快。

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Current Group, a Germantown-based technology firm, has taken over an ordinary looking house in Bethesda and turned it into a laboratory for smart-grid technology, the system the company believes will bring the nation’s electricity grids into the digital age.

In the front yard stands a utility pole hooked up to a special transformer that connects the power lines to high-speed Internet. Hundreds of sensors attached to the lines monitor how power flows through the home. That information is then sent back to the utility company.

The process lets a utility more efficiently manage the distribution of electricity by allowing two-way communication between consumers and energy suppliers via the broadband network on the power lines. Based on data they receive from hundreds of homes, utilities can monitor usage and adjust output and pricing in response to demand. Consumers can be rewarded with reduced rates by cutting back on consumption during peak periods. And computerized substations can talk to each other so overloaded circuits hand off electricity to those that have not fully loaded, helping to prevent blackouts.

Some utility companies have launched initiatives to give consumers data about their energy consumption habits in an effort to lower energy bills. Smart-grid technology takes such programs further by automating electricity distribution, which would make grids more reliable and efficient.

By partnering with utilities, the company hopes to tap into $4.5 billion in stimulus grants intended to encourage smart-grid development. When he announced the funding, President Obama pointed to a project in Boulder, Colo. , as an example of a successful smart-grid experiment. Current is one of the companies working on the project.

Current’s chief executive Tom Casey believes the technology will help utility companies better distribute electricity produced by renewable resources, such as solar panels or wind farms. " A smart grid’s system can be paired up with the renewable resources so that when the renewable source is varying, the overall load can be varied as well, " Casey told the House Select Committee on Energy Independence and Global Warming. " This will reduce or eliminate the need for backup coal or gas-based power generation plants. \

What benefit can the smart-grid technology bring()

A. Substations can talk to each other through computers

B. The consumers and energy suppliers can have direct communication

C. Consumers can be rewarded for using less electricity

D. The electricity supply of a certain area can be adjusted accordingly