R语言实现PubMed格式文献文本按行结构化转换与字段提取

• 待处理数据源：存储约1000篇文献元数据的文本文件
• 原始数据格式规则：
  • 单篇文献包含PMC、PMID、AID、SO等固定字段
  • 单条字段以字段标识- 字段内容的格式存储
  • 跨多行的长字段内容，以行首缩进的形式标记为同字段续行
• 预期输出效果：
  每篇文献的全部信息整理为单行结构化数据，字段名称作为数据框列名，对应字段内容作为行值，参考效果如下：

  PMC              PMID        ........      SO
  
  PMC8882595       35237547    ........      Front ....69001
  PMC8967719       35296856    ........      Child Yo... 040
  

• 重复字段处理规则：
  单篇文献内FAU（作者全名）、AU（作者缩写）、AD（作者单位）字段会重复出现，处理优先级如下：
  • 优先从AD字段内容中提取作者所属国家名称
  • 若国家提取存在难度，直接对重复字段的内容做合并处理即可

原始数据样例 #

以下为文件内前两篇文献的原始内容，可直观参考数据格式：

PMC - PMC8882595
PMID- 35237547
IS  - 2296-2565 (Electronic)
VI  - 10
DP  - 2022
TI  - Poverty Vulnerability and Health Risk Action Path of Families of Rural Elderly
      With Chronic Diseases: Empirical Analysis of 1,852 Families in Central and
      Western China.
LID - 776901
AB  - Health poverty has become the most important cause of poverty and return to
      poverty. Understanding the health risk factors and action paths of poverty in
      families of rural elderly with chronic diseases is important to alleviate return 
      to poverty because of illness. This study selected families with at least one
      elderly member (over 60 years old) with chronic diseases (sample size was 1,852
      people and localities, the causes of poverty and returning to poverty, and the
      types of poverty vulnerabilities. The use efficiency of medical insurance should 
      be further improved, and the responsibility of medical insurance targeted poverty
      alleviation must be clarified.
FAU - Ma, Ying
AU  - Ma Y
AD  - Department of Health Management, School of Medicine and Health Management, Tongji
      Medical College, Huazhong University of Science and Technology, Wuhan, China
FAU - Xiang, Qin
AU  - Xiang Q
AD  - Department of Health Management, School of Medicine and Health Management, Tongji
      Medical College, Huazhong University of Science and Technology, Wuhan, China
FAU - Yan, Chaoyang
AU  - Yan C
AD  - Department of Health Management, School of Medicine and Health Management, Tongji
      Medical College, Huazhong University of Science and Technology, Wuhan, China
FAU - Liao, Hui
AU  - Liao H
AD  - Department of Health Management, School of Medicine and Health Management, Tongji
      Medical College, Huazhong University of Science and Technology, Wuhan, China
FAU - Wang, Jing
AU  - Wang J
AD  - Department of Health Management, School of Medicine and Health Management, Tongji
      Medical College, Huazhong University of Science and Technology, Wuhan, China
LA  - eng
PT  - Journal Article
DEP - 20220214
PHST- 2021/09/14 [received]
PHST- 2022/01/20 [accepted]
TA  - Front Public Health
JT  - Frontiers in Public Health
AID - 10.3389/fpubh.2022.776901 [doi]
SO  - Front Public Health. 2022 Feb 14;10:. doi:10.3389/fpubh.2022.776901.


    
PMC - PMC6107082
PMID- 30147212
IS  - 0190-7409 (Print)
VI  - 79
DP  - 2017 Aug
TI  - Family poverty and neighborhood poverty: Links with children’s school readiness
      before and after the Great Recession.
PG  - 368-84
AB  - This paper examines how neighborhood and family poverty predict children’s
      academic skills and classroom behavior at school entry, and whether associations 
      additional support.
FAU - Wolf, Sharon
AU  - Wolf S
AD  - Graduate School of Education, University of Pennsylvania, 3700 Walnut Street,
      Room 340, Philadelphia, PA 19104, United States
FAU - Magnuson, Katherine A.
AU  - Magnuson KA
AD  - Institute for Research on Poverty, University of Wisconsin – Madison, 1180
      Observatory Drive, Madison, WI 53706, United States
FAU - Kimbro, Rachel T.
AU  - Kimbro RT
AD  - Rice University, 6100 Main St., MS-28, Houston, TX 77005, United States
LA  - eng
PT  - Journal Article
DEP - 20170623
TA  - Child Youth Serv Rev
JT  - Children and youth services review
AID - 10.1016/j.childyouth.2017.06.040 [doi]
MID - NIHMS984695
SO  - Child Youth Serv Rev. 2017 Aug;79:368-84. Epub 2017 Jun 23
      doi:10.1016/j.childyouth.2017.06.040.

内容的提问来源于stack exchange，提问作者Nile