差异代谢物筛选
通过对代谢物进行筛选，寻找差异代谢物（biomarker）。相关差异代谢物筛选条件有：
  1. p-value ≤ 0.05 且 VIP ≥ 1[1]
  2. p-value ≤ 0.05 且 fold_change ≥ 1.5或≤0.667[2]
  3. one-way ANOVA p-value ≤ 0.05[3]
  4. two-way ANOVA p-value ≤ 0.05[4]
详细含义：
筛选值 筛选值含义 筛选阈值 备注
p-value 统计学上显著差异 p-value ≤ 0.05 无
VIP OPLS-DA第一主成分变量重要性值投影 VIP ≥ 1 无
Fold change 两两组别间倍性变化 fold_change ≥1.5或≤0.667 含量差异较大
one-way ANOVA p-value 一维方差分析 p-value ≤ 0.05 主要用于时间序列，梯度浓度处理等
two-way ANOVA p-value 两因素方差分析 p-value ≤ 0.05 一般为两因素情况，如对照-处理+时间序列样本
本实验采用条件 1 进行代谢物筛选，最终获得的差异代谢物见下表：

差异信息汇总信息
差异信息汇总表格；dam_DEG.xlsx
dam_DEG.xlsx 包含“stats”和“ALL_DEG.xlsx”两个工作簿，其中“stats”统计了各个比对组别差异代谢物的上、下调情况，“ALL_DEG”汇总了所有比对组别的差异代谢物信息。

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CAS RT VIP mean_CZ sd_CZ mean_KA sd_KA Fold Change_CZ/KA log2(FC_CZ/KA) p.value FDR
5-Hepten-2-one, 6-methyl- 110.000 738.235 1.859 0.040 0.002 0.012 0.000 3.398 1.765 0.000 0.003
2-Aminopyridine 504.000 773.260 1.856 0.057 0.004 0.012 0.000 4.880 2.287 0.000 0.003
Methane, trimethoxy- 149.000 370.065 1.849 0.158 0.017 0.012 0.000 13.485 3.753 0.000 0.009
Furan, 2-(1,2-diethoxyethyl)- 14133.000 1011.800 1.844 0.067 0.007 0.012 0.000 5.691 2.509 0.000 0.011
2-Hexenoic acid, ethyl ester 1552.000 752.590 1.843 11.441 0.238 5.455 0.754 2.098 1.069 0.000 0.011
1-Pentanol, 3-methyl- 589.000 723.575 1.826 1.146 0.666 5.756 0.494 0.199 -2.328 0.001 0.026
1-Pentanol, 4-methyl- 626.000 702.560 1.776 0.596 0.335 2.353 0.352 0.253 -1.982 0.003 0.076
3-Hexen-1-ol, acetate, (Z)- 3681.000 703.340 1.767 0.378 0.008 2.894 0.733 0.131 -2.937 0.004 0.077
Butanoic acid, 3-hydroxy-, ethyl ester 5405.000 968.605 1.765 0.283 0.010 0.501 0.064 0.565 -0.824 0.004 0.077
Octanoic acid, 3-methylbutyl ester 2035.000 1145.410 1.764 5.029 3.121 21.696 3.840 0.232 -2.109 0.004 0.077
Ethyl (E)-2-octenoate 7367.000 1018.790 1.755 0.091 0.037 0.225 0.019 0.403 -1.312 0.005 0.086
1-Butanol, 2-methyl-, acetate 624.000 437.365 1.742 1.217 0.273 0.143 0.227 8.537 3.094 0.006 0.102
1,3,5,7-Cyclooctatetraene 629.000 623.030 1.725 0.356 0.212 1.039 0.119 0.343 -1.546 0.008 0.125
Pentadecanoic acid, 3-methylbutyl ester 2306.000 1369.520 1.723 1.293 0.355 4.620 1.139 0.280 -1.837 0.008 0.125
2,6-Octadien-1-ol, 3,7-dimethyl-, (Z)- 106.000 1346.870 1.711 0.302 0.011 0.099 0.075 3.059 1.613 0.010 0.133
Acetaldehyde, butylhydrazone 20607.000 234.205 1.708 0.231 0.083 0.012 0.000 19.764 4.305 0.010 0.133
Butyrolactone 96.000 1108.740 1.671 6.572 0.682 2.007 1.833 3.275 1.711 0.016 0.180
Octanoic acid, methyl ester 111.000 808.725 1.658 3.221 1.317 7.309 1.255 0.441 -1.182 0.018 0.191
2-Heptanol, (S)- 6033.000 709.700 1.658 0.552 0.468 1.727 0.233 0.320 -1.645 0.018 0.191
3-Hexenoic acid, ethyl ester, (E)- 26553.000 696.460 1.640 0.652 0.049 0.466 0.072 1.400 0.486 0.021 0.212
Hexanoic acid, propyl ester 626.000 717.930 1.620 0.417 0.032 0.488 0.015 0.853 -0.230 0.025 0.241
Butanoic acid, 3-methyl- 503.000 1157.320 1.606 0.618 0.973 2.712 0.442 0.228 -2.133 0.027 0.257
2-Undecanone 112.000 1074.740 1.605 0.856 0.272 0.293 0.095 2.925 1.548 0.028 0.257
Propanoic acid, 2-methyl-, ethyl ester 97.000 269.125 1.577 13.305 5.790 2.695 0.291 4.936 2.303 0.034 0.305
Propanoic acid, 2-methyl- 156564.000 1038.330 1.571 5.406 1.363 1.681 1.548 3.216 1.685 0.035 0.309
CAS：CAS号；rt：保留时间(以分钟为单位)；*_VIP：VIP值；mean_*：平均值；sd_*：标准差；fold change：倍性变化；log2(FC)：倍性变化的log2值；pvalue：统计学p值；FDR：pvalue校正值
以下为差异待鉴定代谢物统计结果：
图：差异代谢物统计柱状图
代谢物上下调关系
updownstats.csv