问题 问答题 简答题

简述有机微量元素添加剂有哪些类型?

答案

参考答案:

(1)金属氨基酸络合物——一种可溶性的金属盐与一种或几种氨基酸的络合物。

(2)金属氨基酸螯合物——可溶性金属盐中的金属离子与氨基酸按摩尔比(1:1-3,理想的为1:2)反应形成的配位共价键。

(3)金属多糖络合物——可溶性金属盐与多糖溶液进行络合反应所形成的产物。

(4)金属蛋白盐——可溶性金属盐与氨基酸或部分水解蛋白质进行螯合作用形成的产物。

选择题
阅读理解

阅读理解。

     Lawmakers in the United States have expanded an investigation into the use of location-tracking

systems on mobile devices. The action follows recent reports about the storing of information on the

Apple iPhone. Some people consider location tracking to be a threat to personal privacy and security.

     Allan Friedman, the research director, says,"All wireless companies do some location tracking as

part of their networks. This information is usually stored by the companies, not the devices, and there

are laws to protect it. Law enforcement (执法) agencies, for example, have to have a fairly high standard

before it can access that data. And the phone company is also prohibited from selling that information.

     Now, two researchers report that location tracking information is being stored directly on Apple

devices. They said Apple's newest operating systems gather global positioning system and timestamp

information. The information is stored on the device in a file that is also uploaded (上传) to any computer

that the device is connected to. The researchers say the information is available to anyone who has access

to the device or computer.

     Allan Friedman says,"This raises additional concerns. There's the idea that because it's on my phone

and on my computer, rogue applications (恶意程序) that I pay for or that I'm tricked into downloading

may be able to access this data and somehow misuse it."

     Apple says it is "not tracking the location of your iPhone". It is simply keeping a database of Wi-Fi

hotspots and cellphone towers near the user's location. This information is meant to help the iPhone

quickly find its location when needed.

     Letters have been sent to some of the leading mobile device developers, including Apple and Google.

The letters asked for more information about their location tracking systems. Allan Friedman calls this

an important start to strengthening privacy laws. He says,"There aren't strong controls over things like

location information, what they are doing with it, how long they are keeping it. And perhaps the most

important question is, is my location data with other facts about me?"

1. Why did American lawmakers investigate the use of location-tracking systems on cell-phones?

A. Because the systems can store users' information

B. Because many users have suffered loss after using them.

C. Because it is thought to threaten users' privacy.

D. Because many reporters have shown the problem of the systems.

2. Allan Friedman believes that _______.

A. wireless companies focus on personal privacy.

B. people are forbidden to get access to private data at will

C. phone companies may sell private information secretly

D. customers may ask wireless companies to locate their tracking

3. What do we know from Paragraph 3?

A. Location tracking information is stored online.

B. Apple's newest operating systems collect all kinds of information.

C. Location tracking information may be uploaded to any iPhone.

D. Apple's newest operating systems may reveal the private information of users.

4. Which of the following statements is TRUE according to the passage?

A. Apple denies that it tracks the location of users.

B. The researchers may misunderstand the Apple's systems.

C. The global positioning system is to blame for rogue applications.

D. The iPhone can quickly find its location by using its user's information.