英文字典中文字典


英文字典中文字典51ZiDian.com



中文字典辞典   英文字典 a   b   c   d   e   f   g   h   i   j   k   l   m   n   o   p   q   r   s   t   u   v   w   x   y   z       







请输入英文单字,中文词皆可:

helium    音标拼音: [h'iliəm]
n. 氦



helium
n 1: a very light colorless element that is one of the six inert
gasses; the most difficult gas to liquefy; occurs in
economically extractable amounts in certain natural gases
(as those found in Texas and Kansas) [synonym: {helium}, {He},
{atomic number 2}]

Noble \No"ble\, a. [Compar. {Nobler}; superl. {Noblest}.] [F.
noble, fr. L. nobilis that can be or is known, well known,
famous, highborn, noble, fr. noscere to know. See {know}.]
1. Possessing eminence, elevation, dignity, etc.; above
whatever is low, mean, degrading, or dishonorable;
magnanimous; as, a noble nature or action; a noble heart.
[1913 Webster]

Statues, with winding ivy crowned, belong
To nobler poets for a nobler song. --Dryden.
[1913 Webster]

2. Grand; stately; magnificent; splendid; as, a noble
edifice.
[1913 Webster]

3. Of exalted rank; of or pertaining to the nobility;
distinguished from the masses by birth, station, or title;
highborn; as, noble blood; a noble personage.
[1913 Webster]

Note: Noble is used in the formation of self-explaining
compounds; as, noble-born, noble-hearted, noble-minded.
[1913 Webster]

{Noble gas} (Chem.), a gaseous element belonging to group
VIII of the periodic table of elements, not combining with
other elements under normal reaction conditions;
specifically, {helium}, {neon}, {argon}, {krypton},
{xenon}, or {radon}; also called {inert gas}.

{Noble metals} (Chem.), silver, gold, and platinum; -- so
called from their resistance to oxidation by air and to
dissolution by acids. Copper, mercury, aluminium,
palladium, rhodium, iridium, and osmium are sometimes
included.
[1913 Webster]

Syn: Honorable; worthy; dignified; elevated; exalted;
superior; sublime; great; eminent; illustrious;
renowned; stately; splendid; magnificent; grand;
magnanimous; generous; liberal; free.
[1913 Webster]


Helium \He"li*um\ (h[=e]"l[i^]*[u^]m), n. [NL., fr. Gr. "h`lios
the sun.] (Chem.)
An inert, monoatomic, gaseous element occurring in the
atmosphere of the sun and stars, and in small quantities in
the earth's atmosphere, in several minerals and in certain
mineral waters. It is obtained from natural gas in industrial
quantities. Symbol, He; atomic number 2; at. wt., 4.0026
(C=12.011). Helium was first detected spectroscopically in
the sun by Lockyer in 1868; it was first prepared by Ramsay
in 1895. Helium has a density of 1.98 compared with hydrogen,
and is more difficult to liquefy than the latter. Chemically,
it is an inert noble gas, belonging to the argon group, and
cannot be made to form compounds. The helium nucleus is the
charged particle which constitutes alpha rays, and helium is
therefore formed as a decomposition product of certain
radioactive substances such as radium. The normal helium
nucleus has two protons and two neutrons, but an isotope with
only one neutron is also observed in atmospheric helium at an
abundance of 0.013 %. Liquid helium has a boiling point of
-268.9[deg] C at atmospheric pressure, and is used for
maintaining very low temperatures, both in laboratory
experimentation and in commercial applications to maintain
superconductivity in low-temperature superconducting devices.
Gaseous helium at normal temperatures is used for buoyancy in
blimps, dirigibles, and high-altitude balloons, and also for
amusement in party balloons.
[Webster 1913 Suppl. PJC]



安装中文字典英文字典查询工具!


中文字典英文字典工具:
选择颜色:
输入中英文单字

































































英文字典中文字典相关资料:


  • Install Dropbox for Windows and Mac
    Dropbox helps you create, share, and collaborate on your files, folders, and documents Learn how to download and install Dropbox for Windows and Mac
  • Download and install the Dropbox desktop app - Dropbox Help
    The Dropbox desktop app is available for Windows, macOS, and Linux operating systems Learn how to get Dropbox and install the app with ease
  • Dropbox - Free download and install on Windows | Microsoft Store
    Dropbox brings all your files together into one place so you can store, sync, and share across all your devices* and access them anytime As always, Dropbox keeps your files safe
  • Download - Dropbox
    Dropbox helps you create, share, and collaborate on your files, folders, and documents Get started today by downloading Dropbox
  • Dropbox Desktop Experience for macOS Windows
    Learn more about how the Dropbox desktop experience helps you organize your content, connect your tools and bring your team together in one place
  • Dropbox. com
    Discover Dropbox – secure, easy cloud storage for file sharing and collaboration With Dash, save time and organize all your company content in one place
  • Use Connect a Computer to install Dropbox - Dropbox Help
    Open a web browser on your computer, and navigate to dropbox com connect You should see a QR code shaped like the Dropbox logo Use the Dropbox mobile app to scan this QR code The app will tell your computer's browser to begin downloading the Dropbox installer
  • Dropbox Basic (Free account) - Dropbox
    Windows and Mac: Install our app, and everything in your account will appear in the Dropbox folder on your computer Web: Sign in to dropbox com to access everything you’ve stored on Dropbox from any browser—no software installation required
  • Installs - Dropbox Help
    Learn how to download and install Dropbox apps on your devices Get answers to common questions and tips for troubleshooting installation issues
  • What is the Dropbox desktop app? - Dropbox Help
    Once your operating system is updated, you can download and install the latest version of the Dropbox desktop app on dropbox com Learn how to download and install the Dropbox desktop app on your computer





中文字典-英文字典  2005-2009