标准键盘接口（MicroDin）常称为AT键盘接口，其接口共有（）个插针

Microbubbles: A new technique to treat disease involves the careful injection of tiny, drug-coated bubbles in the bloodstream.

A Thilo Hoelscher, a neurologist at the University of Califomia, San Diego, is a man with a plan. His plan is to deal with strokes by blowing bubbles at them. The bubbles in question would be small enough to inject into blood vessels leading to the affected part of the brain. When they got to the blood clot that caused the stroke, they would be jiggled into action by the application of ultrasound. The result would be myriads of tiny jackhammers chipping away at the clot before it had a chance to cause too much permanent damage.

B What makes this approach particularly interesting is that Dr Hoelscher wants to start treating stroke patients as soon as they are heaved into an ambulance, rather than waiting until they arrive in the emergency room. He plans to start a feasibility study before the end of the year in which some of San Diego's ambulances will be equipped with portable ultrasonic transducers. Andrei Alexandrov, a pioneer in therapeutic-ultrasound research who now directs the stroke centre at the University of Alabama, is pursuing a similar approach. He is designing an easy-to-use ultrasound helmet that an emergency-room nurse can attach before administering a vial of microbubbles. Both schemes are examples of a new idea in medicine, Which is to use tiny bubbles of gas not merely to highlight organs during ultrasonic scanning, as has been done for several years, but also as a form. of treatment. With clinical trials now getting under way, experts think it will take around five years for these new therapies to reach patients.

C Microbubbles are not just any old bubbles. They contain a chemically stable gas, such as perfluoropropane, instead of air. This gas is encapsulated in a fatty shell rather like a very small balloon. Even the largest microbubbles being tested for medical use are only five microns across, less than the diameter of a red blood cell. More advanced bubbles are only a few hundred nanometres across and can move easily through the lining of a blood vessel. They may also, crucially, be able to cross the blood-brain barrier, a tightly sealed layer of cells that protects the brain from dangerous chemicals including many drugs. If you put such a drug in the surface layer of a microbubble, you might be able to smuggle it into the brain.

D Having got into the brain (or anywhere else), a well-designed microbubble should also be able find a particular target. That is because the fatty layer can include molecules such as antibodies, which link up with proteins found on the surfaces of only one type of cell. A bubble with such an antibody in it would thus stick only to that type of cell. This sort of approach is being tested by Mark Borden and Paul Dayton, who work at another of the University of California's campuses, in Davis. They have demonstrated in rats that bubbles with an appropriate outer layer can be equipped with molecules that stick specifically to diseased cells. These molecules are initially hidden under a polymer layer to prevent the immune system from destroying the bubbles. When the bubble arrives at its target, however, it is blasted with ultrasound in a way that exposes the molecule and makes the bubble stick.

E The two researchers can also use sound waves to steer bubbles towards a target, as if those bubbles were surfing a wave in the sea. Moreover, they can slow the bubbles down when they arrive where they are wanted. Once the bubbles have stuck good and fast to their targets, turning up the ultrasound still further will burst them, so that they release their payloads precisely where they can do most good. The result is smaller, better-aimed doses of drugs, which should mean fewer side-effects. In principle, such paytoads could be small-molecule drugs such as those used for cancer chemotherapy. They could be therapeutic prot

目前，ATX是PC机中最流行的主权形状参数。ATX主板系列包括四种尺寸规范其中尺寸最大的是( )。

A．ATX

B．Mini-ATX

C．Micro-AXT

D．Flex-ATX

目前，ATX是PC机中最流行的主权形状参数。ATX主板系列包括四种尺寸规范其中尺寸最大的是( )。

A．ATX

B．Mini-ATX

C．Micro-AXT

D．Flex-ATX

数字钟电路子项目一：数字钟电路原理图绘制（40分） 数字钟电路的电路原理图如图5-73所示。 图5-73 数字钟电路原理图 任务一：新建项目文件（2分） 新建一个项目文件“数字钟电路.PrjPCB”。 任务二：新建原理图（2分） 新建原理图文件“数字钟电路.SchDoc”。 任务三：设置工作环境（8分） 图纸设置。方向为水平放置；大小为标准风格A4；工作区颜色为70号色；边框颜色为6号色。 栅格设置。捕捉网格为10mil；可视网格为10mil；电气网格：为8mil；字体设置：系统字体宋体，字号为10，字形为粗体。 标题栏设置。标题栏设置：图纸标题栏采用“ANSI”形式，字体为楷体，字号为小二。 任务四：加载集成库（6分） 加载库“Miscellaneous Connectors .Intlib”和“Miscellaneous Devices .Intlib”，“Philips Microcontroller 8-Bit.IntLib”。 任务五：查找并放置元件（12分） 放置数字钟电路原理图中所需的接口、单片机、电阻、电容、电解电容和数码管等元件，元件所在库见表5-4，同时修改元件属性。 表5-4 数字钟电路元件 Library Ref （元件库名称） Library （库） Designator （元件标识） Footprint （封装） Comment （注释） Value （值） P80C52SBPN Philips Microcontroller 8-Bit.IntLib U1 SOT129-1 AT89S52 Res2 Miscellaneous Devices.IntLib R1-R5 AXIAL-0.3 10K Cap C1-C2 RAD-0.1 30pF Cap C5 RAD-0.1 104 Cap Pol1 C3 CAPR5-4X5 10uF Cap Pol1 C4 CAPR5-4X5 100uF XTAL Y1 RAD-0.2 12M SW-PB S1-S5 DPST-4 Dpy Blue-CC DS1-DS4 H Dpy Blue-CC Header 2 Miscellaneous Connectors.IntLib P1 HDR1X2 Header 2 Header 9 P2 HDR1X9 8*10K 任务六：绘制导线（6分） 连接元件。 任务七：编译原理图（2分） 编译原理图，直至Messages信息框中无“Error”信息。 任务八：生产网络表（2分） 生成“数字钟电路.NET”网络表文件。 子项目二：数字钟电路PCB制作（60分） 任务一：新建PCB文件（10分） 利用向导新建一个PCB文件“数字钟电路.PcbDoc”，要求： （1）单位选择“Imperical”。 （2）设置电路板形状为方形，电路板尺寸3600mil×2300mil，放置尺寸的层为机械层4，导线宽度20mil，与板边缘保持的距离为100mil，并且只显示尺寸标注，如图5-81所示。 （3）选择电路板层。信号层为2层，内部电源层为0。 （4）选择过孔风格。只显示通孔。 （5）选择元件和布线逻辑。选择通孔元件。 任务二：设置环境参数（4分） 测量单位：“Imperial”；网格：50mil 任务三：加载网络表并手工布局（16分） 手工布局PCB板。 任务四：设置布线规则（10分） 设置布线规则：要求电源线宽30mil，地线线宽40mil，一般导线20mil如图5-84所示；布线层：顶层和底层；布线拐角模式：“Rounded”模式。 任务五：自动布线（8分） 局部布置地线；然后再全局布线。 任务六：放置泪滴（4分） 给电路图中所有焊盘补泪滴。 任务七：覆铜（8分） 给电路板顶层和底层都覆铜，并且与地线相连。

目前，ATX是PC机中最流行的主板形状参数。ATX主板系列包括四种尺寸规范，其中尺寸最小的是( )。

A．ATX

B．Mini-ATX

C．Micro-AXT

D．Flex-ATX

Elizabeth Hazen and Rachel Brown copatented one of the most widely acclaimed wonder drugs of the post-Second World War years. Hazen and Brown's work was stimulated by the wartime need to find a cure for the fungus(真菌类) infections that afflicted many military personnel. Scientists had been feverishly searching for an antibiotic toxic enough to kill the fungi but safe enough for human use, since, unfortunately, the new "wonder drugs" such as penicillin and streptomycin(链霉素) killed the very bacteria in the body that controlled the fungi. It was to discover a fungicide without that double effect that Brown, of New York State's Department of Health Laboratories at Albany, and Hazen, senior microbiologist at the Department of Health in New York, began their long-distance collaboration. Based upon Hazen's previous research at Columbia University, where she had built an impressive collection of fungus cultures, both were convinced that an antifungal organism already existed in certain soils.

They divided the work. Hazen methodically screened and cultured scores of soil samples, which she then sent to her partner, who prepared extracts, isolated and purified active agents, and shipped them back to New York, where Hazen could study their biological properties. On a 1948 vacation, Hazen accidentally collected a clump of soil from the edge of W.B. Nourse's cow pasture in Fauquier County, Virginia, that, when tested, revealed the presence of the microorganisms. In farm owner Nourse's honor, Hazen named it Streptomyces noursci , and within a year the two scientists knew that the properties of their substance distinguished it from previously described antibiotics. After further research they eventually reduced their substance to a fine, yellow powder, which they first named "fungiciden", then renamed "nystatin"(to honor the New York State laboratory) when they learned the previous name was already in use. Of their major discovery, Brown said lightly that it simply illustrated "how unpredictable consequences can come from rather modest beginnings."

What is the main topic of the passage?

A．The lives of Hazen and Brown.

B．The development of a safe fungicide.

C．The New York State Department of Health.

D．The development of penicillin.

听力原文： Trees have a spectacular survival record. Over a period of more than 400 million years, they have evolved as the tallest, most massive and longest-lived organisms ever to inhabit the Earth. Yet trees lack a means of defense that almost every animal has: threes cannot move away from destructive forces. Because they cannot move, all types of living and nonliving enemies—fire, storm, micro-organisms, insects, other animals and later, humans—have wounded them throughout their history. Trees have survived because their evolution has made them into a highly compartmented organism; that is, they wall off injured and infected wood.

In that respect trees are radically different from animals. Fundamentally, animals heal: they preserve their life by making billions of repairs, installing new cells in the positions of old one. Trees cannot heal: they make no repairs, instead, they defend themselves from the consequences of injury and infection by walling off the damage. At the same time they put new cells in new positions; in effect they grow a new tree over the old one every year. The most obvious results of the process are growth rings, which are visible on the cross section of a trunk, a root, or a branch.

(30)

A．Tall.

B．Green.

C．Massive.

D．Long-lived.

Watching Microcurrents Flow

We can now watch electricity as it flows through even the tiniest circuits. By scanning the magnetic field generated as electric currents flow through objects, physicists have managed(46). The technology will allow manufacturers to scan microchips for faults, as well as revealing microscopic defects in anything from aircraft to banknotes.

Gang Xiao and Ben Schrag at Brown University in Providence, Rhode Island, visualize the current by measuring subtle changes in the magnetic field of an object and(47)

Their sensor is adapted from an existing piece of technology that is used to measure large magnetic fields in computer hard drives. "We redesigned the magnetic sensor to make it capable of measuring very weak changes in magnetic fields," says Xiao.

The resulting device is capable of detecting a current as weak as 10 microamperes, even when the wire is buried deep within a chip, and it shows up features as small as 40 nanometers across.

At present, engineers looking for defects in a chip have to peel off the layers and examine the circuits visually; this is one of the obstacles(48). But the new magnetic microscope is sensitive enough to look inside chips and reveal faults such as short circuits, nicks in the wires or electro migration -- where a dense area of current picks up surrounding atoms and moves them along. "It is like watching a river flow," explains Xiao.

As well as scanning tiny circuits, the microscope can be used to reveal the internal structure of any object capable of conducting electricity. For example, it could look directly at microscopic cracks in an aeroplane's fuselage,(49). The technique cannot yet pick up electrical activity in the human brain because the current there is too small, but Xiao doesn't rule it out in the future. "I can never say never," he says.

Although the researchers have only just made the technical details of the microscope public, it is already on sale, from electronics company Micro Magnetics in Fall River, Massachusetts. It is currently the size of a refrigerator and takes several minutes to scan a circuit, but Xiao and Schrag are working(50).

A. to shrink it to the size of a desktop computer and cut the scanning time to 30 seconds

B. to making chips any smaller

C. to take tiny chips we require

D. to picture the progress of the currents

E. converting the information into a color picture showing the density of current at each point

F. faults in the metal strip of a forged banknote or bacteria in a water sample

At the turn of the 20th century, Dutch physician Christiaan Eijkman showed that disease can be caused not only by microorganisms but by a dietary efficiency of certain substances【M1】______ now called vitamins. In 1909 German bacteriologist Paul Ehrlich introduced the worlds first bactericide, a chemical designed to kill specific kinds of bacteria with killing the patients cells as well.【M2】______ Following the discovery of penicillin in 1928 by British bacteriologist Sir Alexander Fleming, antibiotics joined medicines chemical armory, making the fight against bacterial infection almost a routine matter. Antibiotics cannot act as viruses, but【M3】______ vaccines have been used to greatly effect to prevent some of the【M4】______ deadliest viral diseases. Smallpox, once a worldwide killer, was completely eradicated by the late 1970s, and in the United States a【M5】______ number of polio cases dropped from 38,000 in the 1950s to less than 10 a year by the 21st century. By the middle of the 20th century scientists believed they were well on the way to treating, preventing, or eradicating many of the most deadly infectious diseases that plagued humankind for【M6】______ centuries. And by the 1980s the medical communitys confidence【M7】______ in its ability to control the infectious diseases had been shaken by【M8】______ the emergency of new types of disease-causing microorganisms.【M9】______ New cases of tuberculosis developed, caused by bacteria strains that were resistant to antibiotics. New, deadly infections on which【M10】______ there was no known cure also appeared, including the viruses that cause hemorrhagic fever and the human immunodeficiency virus (HTV), the cause of acquired immunodeficiency syndrome.

【M1】