运算符 | 功能示例 | 适用场景 |
"精确短语" | "soil microbial diversity" | 排除同义词干扰 |
* 通配符 | agricultur* → agriculture, agricultural | 跨词性扩展 |
AND NOT | CRISPR AND NOT "Cas9" | 排除干扰概念 |
NEAR/5 | "gene editing" NEAR/5 ethics | 限定关键词共现距离 |
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