问为什么我不能从pypi安装PyQt5？

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C:\Program Files (x86)\JetBrains\PyCharm 3.0.1\helpers\packaging_tool.py run on 02/05/14 16:13:23
Downloading/unpacking PyQt5

  Getting page https://pypi.python.org/simple/PyQt5/
  URLs to search for versions for PyQt5:
  * https://pypi.python.org/simple/PyQt5/
  Analyzing links from page https://pypi.python.org/simple/PyQt5/
  Could not find any downloads that satisfy the requirement PyQt5

No distributions at all found for PyQt5

Exception information:
Traceback (most recent call last):
  File "C:\Python27\lib\site-packages\pip-1.3.1-py2.7.egg\pip\basecommand.py", line 139, in main
    status = self.run(options, args)
  File "C:\Python27\lib\site-packages\pip-1.3.1-py2.7.egg\pip\commands\install.py", line 266, in run
    requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
  File "C:\Python27\lib\site-packages\pip-1.3.1-py2.7.egg\pip\req.py", line 1026, in prepare_files
    url = finder.find_requirement(req_to_install, upgrade=self.upgrade)
  File "C:\Python27\lib\site-packages\pip-1.3.1-py2.7.egg\pip\index.py", line 171, in find_requirement
    raise DistributionNotFound('No distributions at all found for %s' % req)
DistributionNotFound: No distributions at all found for PyQt5