第2节　前言

前言（Introduction）属于论文中比较难写的一部分，好的前言可以让读者迅速把握与论文相关的研究背景以及本研究的目的，从而吸引读者阅读全文，进一步深入了解研究细节。医学基础研究论文中的前言并没有固定的格式和字数限制，但在逻辑和内容上还是有章可循。

前言的第一部分（一般是一个段落）通常会介绍所研究疾病的背景、研究该疾病的迫切性及重要性，并提出以往研究或治疗该疾病存在的不足，引出该疾病研究或治疗的新观点。如示例3-9所示。

示例3-9　前言第一部分

Osteoarthritis is the most prevalent chronic joint disease affecting knees，hands，hips，and spine；it is one of the leading musculoskeletal causes of impaired mobility（1-3）.Currently，no effective disease-modifying drug is available to treat osteoarthritis（4-6）mainly because of the limited understanding of the mechanisms that drive the pathological process at the initiation stage.【介绍所研究的疾病及其危害】Osteoarthritis is characterized by progressive degeneration of articular cartilage（AC），structural alterations of subchondral bone，osteophyte formation，and synovial inflammation（3，7，8）.AC degeneration，the primary concern in osteoarthritis that leads to joint pain and dysfunction，was initially thought to be the only factor driving osteoarthritis development（9-11）.【介绍所研究疾病的病理生理】However，treatments targeting only the signaling mechanisms responsible for AC degeneration may be insufficient to halt disease progression（7，12-14）.Recent evidence suggests that pathological alterations in subchondral bone also contribute to osteoarthritis development（15-23）.【提出目前临床治疗该疾病存在的不足，并引出该疾病研究领域的新方向】

前言第二部分（1～2个段落）通常会在上一段提出的新的研究方向或治疗方式的基础上，做进一步扩展。通过引用文献，层层递进地阐述该疾病在最新或者最热点的研究领域所取得的研究进展。紧接着，提出该疾病在上述研究领域还有哪些问题尚未得到解决，进而引出本研究的目的，说明开展本研究的必要性。如示例3-10所示。

示例3-10　前言第二部分(https://www.daowen.com)

AC and subchondral bone are integrated through the osteochondral junction，which consists of the calcified cartilage zone and subchondral plate underneath.This structure allows AC and subchondral bone to act in concert as one functional unit（8，18）.Bone provides mechanical support for the overlying AC during joint movement and undergoes constant adaptation（modeling and remodeling）in response to changes in the mechanical environment.Changes in the subchondral bone microarchitecture precede AC damage in osteoarthritis in humans（24-27）.Specifically，in early-stage osteoarthritis，the bone remodeling rate is up to20-fold faster relative to normal bone，and markers of bone remodeling，such as osteoclast activity，are increased.The rapid subchondral bone turnover observed in osteoarthritis leads to changes in the bone marrow microenvironment and simultaneous neovascularization.Increased subchondral bone angiogenesis，with blood vessel invasion into the avascular cartilage，is an early diagnostic feature of human osteoarthritis（3，28-31）.This osteochondral angiogenesis not only stimulates early osteophyte development and ossification in the cartilage but also causes innervation of AC，causing joint pain.Consistently，animal studies have shown that aberrant subchondral bone angiogenesis coupled with osteogenesis may contribute to the development of subchondral bone marrow lesions，increased subchondral bone plate thickness，and eventual AC damage（16，32-35）.【从上内容阐述了该疾病的最新研究进展】However，the key factor（s）for the development of pathological subchondral bone angiogenesis and the main source of the factor（s）during osteoarthritis development remain unclear.【提出目前的研究尚未解决的问题】

前言第三部分（一般是一个段落）介绍针对以上提出的未解决的研究问题，本研究完成了哪些研究工作，取得了哪些研究发现，并简要说明本研究的结论和意义。如示例3-11所示。

示例3-11　前言第三部分

In this study，we tested the role of preosteoclast-derived PDGF-BB in the development of the aberrant subchondral bone angiogenesis during osteoarthritis progression.Using destabilization of the medial meniscus（DMM）osteoarthritis mouse models，we found that mononuclear preosteoclasts in subchondral bone/bone marrow of osteoarthritic joints are stimulated very early in mice after DMM surgery and produce a markedly high amount of PDGF-BB，which activates PDGFR-β signaling to stimulate aberrant development of subchondral bone angiogenesis with coupled osteogenesis as well as nerve ingrowth.We further generated conditional Pdgfb deletion and transgenic mice，in which PDGF-BB is deleted and overexpressed，respectively，in Trap+preosteoclasts，【以上部分简述了本研究的主要内容，并从体内和体外实验的两个层面介绍了结果】and demonstrated that preosteoclast-derived PDGF-BB is both sufficient to cause and required for aberrant subchondral bone angiogenesis and the resultant joint structural damage and osteoarthritis pain.【简述研究的结论和意义】

综上所示，前言部分虽然没有固定的形式，但却具有很强的逻辑性。在撰写前言部分，可遵循层层递进的规律：介绍疾病背景→提出研究热点→回顾既往文献并介绍发现→提出未解决的问题→简述本研究的主要内容、结果和意义。前言部分字数并无具体要求，但通常情况该部分的字数无须过多，可控制在500～800字。