在有机物中,在同一平面上碳原子最多有几个,在同一直线上的碳原子最多有几个( )

题型:选择题

问题:

在有机物中,在同一平面上碳原子最多有几个,在同一直线上的碳原子最多有几个(  )

A.11、4

B.10、3

C.12、3

D.13、4

考点:结构式
题型:选择题

我国是世界上生物种类最丰富的国家之一,高等植物和野生动物物种均占世界10%左右,然而,环境污染和生态破坏导致了动植物生存环境的破坏,物种数量急剧减少,有的物种已经灭绝。据统计,近50年约有200种高等植物灭绝,平均每年灭绝4种;野生动物中约有400种处于濒危或受威胁的状态。 这段文字意在说明( )。

A.动植物灭绝速度逐年加速

B.环境恶化导致动植物灭绝或濒危

C.我国动植物种比较丰富

D.高等植物比野生动物更需要保护

题型:选择题

井下接地网上任一保护接地点测得的接地电阻值不应超过().

A.1

B.2

C.3

题型:选择题

男性两侧输精管被结扎后,生理上表现为 [ ]

A.不产生精子,第二性征不变

B.产生精子,第二性征 改变

C.不产生精子,第二性征不变

D.产生精子,第二性征不变

题型:选择题

专线电路

题型:选择题

If phone calls and web pages can be beamed through the air to portable devices, then why not electrical power, too It is a question many consumers and device manufacturers have been asking themselves for some time. But to seasoned observers of the electronics industry, the promise of wireless recharging sounds depressingly familiar. In 2004 Splashpower, a British technology firm, was citing “very p” interest from consumer-electronics firms for its wireless charging pad. Based on the principle of electromagnetic induction (EMI) that Faraday had discovered in the 19th century, the company’s “Splashpad” contained a coil that generated a magnetic field when a current flowed through it. When a mobile device containing a corresponding coil was brought near the pad, the process was reversed as the magnetic field generated a current in the second coil, charging the device’ s battery without the use of wires. Unfortunately, although Faraday’s principles of electromagnetic induction have stood the test of time, Splashpower has not — it was declared bankrupt last year without having launched a single product.

Thanks to its simplicity .and measurability, electromagnetic induction is still the technology of choice among many of the remaining companies in the wireless-charging arena. But, as Splashpower found, turning the theory into profitable practice is not straightforward. But lately there have been some promising developments.

The first is the formation in December 2008 of the Wireless Power Consortium, a body dedicated to establishing a common standard for inductive wireless charging, and thus promoting its adoption. The new consortium’s members include big consumer-electronics firms, such as Philips and Sanyo, as well as Texas Instruments, a chipmaker.

Fierce competition between manufacturers of mobile devices is also accelerating the introduction of wireless charging. The star of this year’s Consumer Electronics Show held in Las Vegas was the Pre, a smart-phone from Palm. The Pre has an optional charging pad, called the Touchstone, which uses electromagnetic induction to charge the device wirelessly.

As wireless-charging equipment based on electromagnetic induction heads towards the market, a number of alternative technologies are also being developed. PowerBeam, a start-up based in Silicon Valley, uses lasers to beam power from one place to another.

It now seems to be a matter of when, rather than if, wireless charging enters the mainstream. And if those in the field do find themselves languishing in the disillusionment, they could take some encouragement from Faraday himself. He observed that “nothing is too wonderful to be true if it be consistent with the laws of nature.” Not even a wirelessly rechargeable iPhone.

What’s the final goal of the Wireless Power Consortium()

A.To turn the Faraday’s theory into profitable practice

B.To find ways for the consumer-electronics industry

C. To integrate consumer-electronics firms and chipmakers

D. To promote a common standard for inductive wireless charging

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