摘要（Abstract 或 Summary) 是一篇論文的縮影，是對全文內容的高度提煉和概括。
摘要能讓讀者在最短的時間裡掌握論文最重要的信息，促使讀者進一步閱讀和引用，進而擴大論文的影響和價值。
然而，當前很多學者對如何寫好 SCI 論文中摘要並不十分明晰，本文以 LANCET 上在線發表的文章為例，淺談下 SCI 論文摘要的寫作套路。
在介紹摘要寫作之前，概括下常用的 Abstract 類型，包括描述性，信息型，結構化和非結構化。
對於 Lancet，NEJM 和 JAMA 這些頂刊的摘要，文章的摘要各有風格：
- NEJM 摘要包括 Background，Methods，Results 和 Conclusions 四個部分。
- Lancet 摘要包括 Background，Methods， Findings 和 Interpretations 四個部分。
- JAMA摘要包括 Objective，Design，Setting and Participants，Interventions，Main outcomes and Measures，Results 和 Conclusion 部分。
其中，我們最常見的是結構化摘要，本文以 2019 年 8 月在 Lancet 發表的題為《Prevalence, risk factors, and management of asthma in China: a national cross- sectional study》文章為例，和大家分享下 SCI 摘要寫作的套路。
BACKGROUND：
Asthma is a common chronic airway disease worldwide. Despite its large population size, China has had no comprehensive study of the national prevalence, risk factors, and management of asthma.
背景介紹，用 1-2 句話，引入本研究的問題。
We therefore aimed to estimate the national prevalence of asthma in a representative sample of the Chinese population.
直截了當地介紹研究目的，注意 Lancet 雜誌沒有 Objectives 項，研究目的在背景中闡明。
注意：表示研究目的常用語：動詞不定式 + 動詞原型，如：
- To investigate
- To explore
- We aimed to assess...
- To examine...
- To determine whether..
- To study...
METHODS：
A representative sample of 57 779 adults aged 20 years or older was recruited for the national cross-sectional China Pulmonary Health (CPH) study using a multi-stage stratified sampling method with parameters derived from the 2010 census.
概括研究設計類型，研究對象，研究年份及資料來源。
Ten Chinese provinces, representative of all socioeconomic settings, from six geographical regions were selected, and all assessments were done in local health centres. Exclusion criteria were temporary residence, inability to take a spirometry test, hospital treatment of cardiovascular conditions or tuberculosis, and pregnancy and breastfeeding.
研究中明確的排除標準。
Asthma was determined on the basis of a self-reported history of diagnosis by a physician or by wheezing symptoms in the preceding 12 months. All participants were assessed with a standard asthma questionnaire and were classed as having or not having airflow limitation through pulmonary function tests before and after the use of a bronchodilator (400 μg of salbutamol).
對研究待分析的主要健康結局進行定義，介紹疾病結局的診斷標準，常見的有臨床金標準診斷，生化指標分析或問卷調查結果。
Risk factors for asthma were examined by multivariable-adjusted analyses done in all participants for whom data on the variables of interest were available.
說明採用的統計分析方法。
Disease management was assessed by the self-reported history of physician diagnosis, treatments, and hospital visits in people with asthma.
Abstract 中方法部分的寫作，主要說明研究課題的設計思路，使用何種材料和方法，如何對照分組，以及採用何種數據處理方法。
FINDINGS：
Between June 22, 2012, and May 25, 2015, 57 779 participants were recruited into the CPH study. 50 991 (21 446 men and 29 545 women) completed the questionnaire survey and had reliable post-bronchodilator pulmonary function test results and were thus included in the final analysis.
寫結果時，首先從研究對象資料入手，如果是生物或臨床方面的文章，應先提及研究的生物體，病人群組結果等。
The overall prevalence of asthma in our sample was 4.2% (95% CI 3.1-5.6), representing 45.7 million Chinese adults. The prevalence of asthma with airflow limitation was 1.1% (0.9-1.4), representing 13.1 million adults. Cigarette smoking (odds ratio [OR] 1.89, 95% CI 1.26-2.84; p=0.004), allergic rhinitis (3.06, 2.26-4.15; p<0.0001), childhood pneumonia or bronchitis (2.43, 1.44-4·10; p=0.002), parental history of respiratory disease (1.44, 1.02-2.04; p=0.040), and low education attainment (p=0.045) were associated with prevalent asthma. In 2032 people with asthma, only 28·8% (95% CI 19.7-40.0) reported ever being diagnosed by a physician, 23·4% (13.9-36.6) had a previous pulmonary function test, and 5.6% (3.1-9.9) had been treated with inhaled corticosteroids.
結果部分很詳細，提供了 OR 和 95% CI，以及差異統計學意義的 P 值結果。
Furthermore, 15.5% (11.4-20.8) people with asthma reported at least one emergency room visit and 7.2% (4.9-10.5) at least one hospital admission due to exacerbation of respiratory symptoms within the preceding year.
結果部分是摘要的最重要的部分，讀者在閱讀一篇 SCI 摘要時，主要目的就是為了瞭解研究的主要發現，以及對自己的研究是否有幫助，故而，建議在寫 Abstract 中儘量提供結果的細節內容。
INTERPRETATION：
Asthma is prevalent but largely undiagnosed and undertreated in China. It is crucial to increase the awareness of asthma and disseminate standardised treatment in clinical settings to reduce the disease burden.
簡要對文章的分析結果進行總結，給出符合科學規律的結論，或對未來研究進行展望。
接下來，分享一下 Abstract 寫作的注意事項
1. 字數要求
不同的 SCI 雜誌對摘要的字數有不同的要求，大多數為 150-350 個詞 ，建議作者在閱讀「Guideline/information for authors」的要求後，對稿件的摘要進行撰寫。
2. 寫作語態要求
摘要寫作中的語態多為一般現在時和一般過去時，當然，有時讀者也會在摘要中看到現在完成時或過去完成時，而它們的功能也很明確。
一般現在時，常用於說明研究目的，敘述研究內容，描述結論或建議等。而概述實驗程序，方法和主要結果時，通常用過去時。
3. 內容要求
摘要寫作圍繞背景，目的，方法結果和結論幾個方面內容，注意應排除本學科領域已成為常識的內容，切忌把應在引言中出現的內容寫入摘要，一般也不要對論文內容進行詮釋或評論。
總結一下，本文以
Lancet 發表的文章為例，向大家分享了 SCI 論文中摘要的寫作，建議作者在平時多寫多練，不斷提升科研寫作能力！原文鏈接：
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)31147-X/fulltext
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