pandas在Series中的时间日期（datetime64）类型怎么取出年月日并进行判断。

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt

df = pd.read_csv('ahdy-2019-03-04-data.csv', sep=',', parse_dates=['发布时间'])
print(df.shape)
print(df.columns)
print(df.dtypes)
df = df.loc[df['发布时间'].dt.year == 2019]
print(df['发布时间'])

    str = CachedAccessor("str", StringMethods)
    dt = CachedAccessor("dt", CombinedDatetimelikeProperties)
    cat = CachedAccessor("cat", CategoricalAccessor)
    plot = CachedAccessor("plot", gfx.SeriesPlotMethods)
    sparse = CachedAccessor("sparse", SparseAccessor)