在安装cuda 9，cudnn 7，tensorflow和keras之后，keras无法找到后端。在Ubuntu上运行。 知道该怎么办吗？
谢谢！
以下输出可能有助于发现问题：
1）
$ python3
Python 3.6.5 |Anaconda custom (64-bit)| (default, Apr 29 2018,16:14:56） Linux上的[GCC 7.2.0] 输入“帮助”，“版权”，“信用”或“许可证”以获取更多信息。
import keras from keras import backend as K Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: cannot import name 'backend'
2）
〜/ .keras $更多keras.json
{
"epsilon": 1e-07, "floatx": "float32", "image_data_format": "channels_last", "backend": "tensorflow" }
3）
pip list
Package Version
---------------------------------- ---------
absl-py 0.2.2
alabaster 0.7.10
anaconda-client 1.6.14
anaconda-navigator 1.7.0
anaconda-project 0.8.2
asn1crypto 0.24.0
astor 0.6.2
astroid 1.6.3
astropy 3.0.2
attrs 18.1.0
Babel 2.5.3
backcall 0.1.0
backports.shutil-get-terminal-size 1.0.0
beautifulsoup4 4.6.0
bitarray 0.8.1
bkcharts 0.2
blaze 0.11.3
bleach 1.5.0
bokeh 0.12.16
boto 2.48.0
Bottleneck 1.2.1
certifi 2018.4.16
cffi 1.11.5
chardet 3.0.4
click 6.7
cloudpickle 0.5.3
clyent 1.2.2
colorama 0.3.9
conda 4.5.5
conda-build 3.4.1
conda-verify 2.0.0
contextlib2 0.5.5
cryptography 2.2.2
cycler 0.10.0
Cython 0.28.2
cytoolz 0.9.0.1
dask 0.18.1
datashape 0.5.4
decorator 4.3.0
distributed 1.21.8
docutils 0.14
entrypoints 0.2.3
et-xmlfile 1.0.1
fastcache 1.0.2
filelock 3.0.4
Flask 1.0.2
Flask-Cors 3.0.4
gast 0.2.0
gevent 1.3.0
gitdb2 2.0.3
GitPython 2.1.9
glob2 0.6
gmpy2 2.0.8
greenlet 0.4.13
grpcio 1.12.1
h5py 2.7.1
heapdict 1.0.0
html5lib 0.9999999
idna 2.6
imageio 2.3.0
imagesize 1.0.0
ipykernel 4.8.2
ipython 6.4.0
ipython-genutils 0.2.0
ipywidgets 7.2.1
isort 4.3.4
itsdangerous 0.24
jdcal 1.4
jedi 0.12.0
Jinja2 2.10
jsonschema 2.6.0
jupyter 1.0.0
jupyter-client 5.2.3
jupyter-console 5.2.0
jupyter-core 4.4.0
jupyterlab 0.32.1
jupyterlab-launcher 0.10.5
Keras 2.2.0
Keras-Applications 1.0.2
Keras-Preprocessing 1.0.1
kiwisolver 1.0.1
lazy-object-proxy 1.3.1
llvmlite 0.23.1
locket 0.2.0
lxml 4.2.1
Markdown 2.6.11
MarkupSafe 1.0
matplotlib 2.2.2
mccabe 0.6.1
missinglink-kernel 0.5028
missinglink-sdk 0.5028
mistune 0.8.3
mkl-fft 1.0.0
mkl-random 1.0.1
more-itertools 4.1.0
mpmath 1.0.0
msgpack 0.5.6
msgpack-python 0.5.6
multipledispatch 0.5.0
navigator-updater 0.1.0
nbconvert 5.3.1
nbformat 4.4.0
networkx 2.1
nltk 3.3
nose 1.3.7
notebook 5.5.0
numba 0.38.0
numexpr 2.6.5
numpy 1.14.3
numpydoc 0.8.0
odo 0.5.1
olefile 0.45.1
opencv-python 3.4.1.15
openpyxl 2.5.3
packaging 17.1
pandas 0.23.3
pandocfilters 1.4.2
parso 0.2.0
partd 0.3.8
path.py 11.0.1
pathlib2 2.3.2
patsy 0.5.0
pep8 1.7.1
pexpect 4.5.0
pickleshare 0.7.4
Pillow 5.1.0
pip 10.0.1
pkginfo 1.4.2
pluggy 0.6.0
ply 3.11
prompt-toolkit 1.0.15
protobuf 3.5.2
psutil 5.4.5
ptyprocess 0.5.2
py 1.5.3
pycodestyle 2.4.0
pycosat 0.6.3
pycparser 2.18
pycrypto 2.6.1
pycurl 7.43.0.1
pyflakes 1.6.0
Pygments 2.2.0
pylint 1.8.4
pyodbc 4.0.23
pyOpenSSL 18.0.0
pyparsing 2.2.0
PySocks 1.6.8
pytest 3.5.1
pytest-arraydiff 0.2
pytest-astropy 0.3.0
pytest-doctestplus 0.1.3
pytest-openfiles 0.3.0
pytest-remotedata 0.2.1
python-dateutil 2.7.3
pytz 2018.4
PyWavelets 0.5.2
PyYAML 3.12
pyzmq 17.0.0
QtAwesome 0.4.4
qtconsole 4.3.1
QtPy 1.4.1
requests 2.18.4
retrying 1.3.3
rope 0.10.7
ruamel-yaml 0.15.35
scikit-image 0.13.1
scikit-learn 0.19.1
scipy 1.1.0
seaborn 0.8.1
Send2Trash 1.5.0
setuptools 39.1.0
simplegeneric 0.8.1
singledispatch 3.4.0.3
six 1.11.0
smmap2 2.0.3
snowballstemmer 1.2.1
sortedcollections 0.6.1
sortedcontainers 1.5.10
Sphinx 1.7.4
sphinxcontrib-websupport 1.0.1
spyder 3.2.8
SQLAlchemy 1.2.7
statsmodels 0.9.0
style 1.1.0
sympy 1.1.1
tables 3.4.3
tblib 1.3.2
tensorboard 1.8.0
tensorflow 1.8.0
tensorflow-gpu 1.8.0
termcolor 1.1.0
terminado 0.8.1
testpath 0.3.1
toolz 0.9.0
tornado 5.0.2
traitlets 4.3.2
typing 3.6.4
unicodecsv 0.14.1
update 0.0.1
urllib3 1.22
wcwidth 0.1.7
webencodings 0.5.1
Werkzeug 0.14.1
wheel 0.31.1
widgetsnbextension 3.2.1
wrapt 1.10.11
xlrd 1.1.0
XlsxWriter 1.0.4
xlwt 1.3.0
zict 0.1.3