问题 单项选择题

男,69岁,上腹不适1年余,近一个月腹痛加重,呕吐,体重减轻。结合图像,最可能的诊断为()

A.十二指肠良性溃疡

B.胰头癌

C.胆管癌

D.十二指肠癌

E.十二指肠憩室

答案

参考答案:D

解析:十二指肠恶性肿瘤可以是原发的,也可以是继发于邻近脏器如胃、胆管、胰腺等恶性肿瘤对十二指肠的直接侵蚀。十二指肠癌发病率相对较低,常被忽视。本例于十二指肠降段可见一巨大不规则龛影,黏膜皱襞破坏中断。病理证实为十二指肠腺癌。

单项选择题
单项选择题

The sudden, dramatic explosion in value of online social media sites like Facebook and Twitter is reminiscent of the rise, about 15 years ago, of the online businesses that created the "dotcom bubble. " The Internet was far less widely used than it is today. Still, visionaries saw the potential for the Internet we have today, so virtual companies sprung up and grew like weeds as investors threw money their way. Some, like Google and Amazon, developed an enduring online presence and lasting financial value. But far too many quickly lost value when it became apparent that their rapid growth wasn’t yielding revenue.

So, how much is Facebook’s network of users really worth The potential is clear—when so many people are gathered in one virtual place, offering so much personal information about themselves, they create an unprecedented platform for targeted advertising. Or they would, if they were on the network to shop. When eBay and Amazon suggest products to their customers, they’re talking to people who’ve already proven that they’re interested in buying similar products. People go on Facebook for a variety of reasons-to catch up with old friends, share pictures, make new acquaintances, and talk, sometimes endlessly, about themselves. Whether they’ll appreciate having their virtual conversations interrupted by advertising, targeted or not, remains unclear.

It’s also unclear whether Facebook will actually be able to share information about its users’ browsing habits with advertisers. Complaints about the ineffectiveness of Facebook’s privacy policies have arisen in multiple countries, part of a larger social concern about how private information gets used on line. In December, the Federal Trade Commission issued a proposed framework that, among other things, would permit Facebook users to block advertisers from accessing information about their online interests. If that framework is implemented and widely used by Facebook subscribers, it could seriously impair the site’s value as a potential platform for targeted marketing.

What is clear is that Goldman Sachs has a significant interest in Facebook’s financial value, at least for the short term. Goldman Sachs’ decision to invest heavily in Facebook has had some interesting impacts. For one thing, the investment has allowed Facebook an opportunity to postpone issuing an IPO. That means that, at least for the moment, Facebook doesn’t yet have to disclose its finances or publicly address investor complaints.

Goldman Sachs’ investment also puts the firm in an ideal position to handle Facebook’s IPO when it eventually is issued, perhaps sometime next year. That, of course, has the potential to generate substantial revenues for Goldman Sachs’ clients. Google’s 2004 IPO raised an initial $1.2 billion for the company. After all the propaganda, Facebook’s IPO can hardly be expected to raise less. However, there remains a significant question as to whether Facebook’s potential for generating income is more virtual than real. If it turns out that Facebook can’t live up to its potential for generating advertising revenue, venture capitalists who invest for the long term may get burned.

One dilemma faced by social media like Facebook is that()

A. its customers often exchange private information on it

B. advertisers often interrupt its customers’ conversations

C. the FTC threatens to limit its service with new regulations

D.the users’ private information is misused by advertisers