Expression Search
SEARCH STRATEGY
SEARCH GUIDE
OPERATORS
| OPERATORS | DESCRIPTION | EXAMPLE | NOTES |
|---|---|---|---|
| = | Find specific query conditions | Authors=(Zhang San) | Use an equal sign (=) to connect a field and a search term |
| ? | Match any single character. | “Zhang?” can match “Zhang San” and “Zhang Fei”. | Must not appear at the beginning of the search term. To search for a literal question mark, escape it using ?. |
| * | Match zero or more characters. | Author=(Li*) matches authors whose surname starts with “Li”. | - |
| "" | Exact phrase matching: search terms are treated as a single unit. | Authors="Zhang San" matches only records where the author is exactly “Zhang San”, and will not match names such as “Zhang Sanfeng”. | Commonly used for exact matching in title, abstract, and similar fields |
| AND, && | Logical AND (all conditions must be satisfied). | Zhang San AND Li Si | - |
| OR, || | Logical OR (meets at least one condition). | Zhang San OR Li Si | - |
| () | Parentheses define a subquery and modify operator precedence. | (Tumor AND Liver) OR (Zhang San) | - |
| [] | Date range query boundary operator. | Publication Date=[2020-01-01 TO 2023-12-31] | Used together with TO |
| TO | Connection date range (start and end). | Publication Date=[2020-01-01 TO 2023-12-31] | An asterisk (*) indicates no limit, e.g., [2020-01-01 TO *]. |
SYNTAX
Differences Between Exact Matching and Fuzzy Matching Across Fields:
1. Title, Abstract, and Short Abstract
Exact Match: Enclose the search term in double quotation marks. The result must contain the complete phrase exactly as entered.
TI=("Cancer Therapy")
Fuzzy Match: Do not use double quotation marks. The system will tokenize the search term and match the individual terms.
TI=(Cancer Therapy)
2. Keywords, Authors, Author Affiliations, Funding, and Journal Title
Exact Match: Enter the search term directly without quotation marks or wildcard characters (*). The field value must match exactly.
KW=(Hypertension)
AA=(Zhang San)
Fuzzy Match: Add * after the search term to indicate that the field only needs to contain the specified term.
KW=(Hypertension*)
AF=(Peking University*)
3. DOI
Only exact matching is supported. Enter the complete DOI directly without operators or wildcard characters.
Example:
10.3760/cma.j.cn112137-2025-1222-03384
SEARCH FIELDS
1. Search Fields
ALL/ALL, Short Abstract/TKA, Title/TI, Keywords/KW, First Author/FA, Corresponding Author/CA, First/Corresponding Author/KA, All Authors/AA, Author Affiliation/AF, Journal Title/JT, Funding/FU, Abstract/AB, Publication Date/PD, DOI/DOI.
The ALL/ALL field searches the following document fields: Title, Abstract, Keywords, Indexed Keywords, Author Names, and Author Affiliations.
2. Filter Fields
Article Type: AT (available options)
Original Article, Guideline, Review Article, Meta Analysis, Case Report, News, Conference Report, Editorial, CME, Other, Letter, Abstract
Study Type: ST (available options)
Clinical Research, In Vitro Research, Secondary Research, Animal Research, Population-Based Research, Laboratory Research, Others
Study Method: SM (available options)
Systematic Review and Meta-analysis, Randomized Controlled Trial (RCT), Interventional Study, Cohort Study, Cross-sectional Study, Case-Control Study, Descriptive Study, Other
EXAMPLES
1. Filter Combination
AT=(Original Article) AND ST=((Clinical Human Research) OR (In Vitro Experiment))
2. Publication Date:
PD=[2018-01-01 TO 2019-01-01]
PD=[2018-01-01 TO *]
3. Advanced Search:
1) Search for respiratory guidelines developed by the Chinese Medical Association.
TKA=(respiratory) AND AA=(Chinese Medical Association) AND AT=(Guideline)
2) Search for guideline published after 2020 with keywords containing heart failure or diuretics.TI=((Heart Failure) OR (Diuretics)) AND AT=(Guideline) AND PD=[2020-01-01 TO *]