Background Previous studies have indicated that medial meniscal subluxation (MMS) is associated with special types of medial meniscus tears (MMT) and chondral lesions. However, most of these studies lacked arthroscopic findings and did not adjust for possible confounders. The purpose of this study was to explore factors associated with MMS in patients with MMT using multivariate logistic regression analysis. Methods A retrospective analysis of 115 patients who underwent arthroscopic surgery for MMT was conducted. The medial meniscal extrusion (MME) distance was measured on a single mid-coronal magnetic resonance (MR) image, and the MMS group included patients with MME distance ≥3 mm (55 patients with 55 knees). Other patients were included as the control group (60 patients with 60 knees). Demographic and clinical data were collected as variates. A multivariate logistic regression analysis was performed to identify factors associated with MMS. Results In a univariate analysis, the Outerbridge classification (P=0.002) and the type of MMT (P<0.001) were significantly different between the MMS group and the control group. According to unadjusted and age- and body mass index (BMI)-adjusted multivariate logistic regression analysis, the type of MMT was an independent factor associated with MMS. Compared with horizontal tears, radial tears, posterior medial meniscus root tears (PMMRT) and complex tears had approximately 6-fold (adjusted OR 6.468, 95% CI 1.509–27.718, P=0.012), 10-fold (adjusted OR 10.324, 95% CI 1.719–61.989, P=0.011) and 4-fold (adjusted OR 4.458, 95% CI 1.602–12.408, P=0.004) higher associations with MMS, respectively. Conclusion The type of MMT was an independent factor associated with MMS in knees with MMT. Radial tears, PMMRT and complex tears were more likely than horizontal tears to result in MMS. The results suggest that MMT combined with MMS should be noted when managing MMT, especially radial tears, PMMRT and complex tears. Moreover, the results indicate that we must not only preserve the meniscus as much as possible but also restore its position to as close to normal as possible.

[目的]探讨前参考系统全膝关节置换术(total knee arthroplasty,TKA)前侧皮质切割发生的相关因素.[方法]回顾性分析2015年10月-2020年12月在本院因原发性膝关节骨关节炎行前参考系统TKA的86例患者(105膝)连续病例资料.根据术后膝关节侧位X线片是否有前皮质切割表现,将患者分为切割组和未切割组.采用单因素分析和多因素逻辑回归分析前皮质切割发生的相关因素.[结果]105膝中,术后影像显示共28膝发生前皮质切割,占26.7％;77例未发生前皮质切割,占73.3％.前侧皮质切割者按Tayside分级,Ⅰ级13膝(12.4％),Ⅱ级10膝(9.5％),Ⅲ级5膝(4.8％),无Ⅳ级发生.单项因素比较,两组年龄、BMI、性别、侧别、前髁厚度、LDFA、MAD、前皮质屈曲角、髁间窝形态、前髁骨赘量、开髓点位置、股骨远端截骨量、后髁截骨量、通髁线辨认情况的差异均无统计学意义(P＞0.05).但是切割组术前后髁厚度显著大于未切割组(P＜0.05);切割组股骨假体选择偏小的比率显著高于未切割组(P＜0.05).多因素逻辑回归分析显示,术前影像测量后髁厚度大(OR=1.124;P＜0.05)是前皮质切割的危险因素,术中股骨假体选择偏大(OR=0.375;P＜0.05)是前皮质切割保护因素.[结论]在前参考系统TKA中,较大术前测量后髁厚度是前皮质切割的危险因素,而术中偏大的股骨假体选择是前皮质切割保护因素.

基于我国人工智能上市企业数据,采用三阶段DEA模型对人工智能企业进行生产效率分析,并在此基础上研究企业规模和研发投入对人工智能企业生产效率的影响.实证结果表明:加大研发投入显著带动企业生产效率提升,但呈边际报酬递减趋势;企业规模扩大能够促进规模效率提升,但同时导致纯技术效率降低,最终导致实际生产效率提升幅度有限;规模效应不足是导致我国人工智能上市企业生产效率偏低的主要原因.

瞪羚企业是指创业后跨过"死亡谷",以科技创新或商业模式创新为支撑进入高成长期的中小企业.瞪羚企业发展速度快、创新活力强,是推动经济发展、自主创新的主力军,同时也提供了大量就业机会.凭借其强大的发展潜力和旺盛的生命力,瞪羚企业引起社会各界的广泛关注和政府的高度重视.当前,我国瞪羚企业发展呈现出明显的区域聚集特征,以制造业等高技术行业为主,多为迈过初创阶段的小微企业,具有较高增长率.为了保障瞪羚企业长期稳步发展,进一步激发瞪羚企业促进经济增长的新动能,需要金融政策的长期支持和不断创新.本文通过系统梳理世界主要国家对瞪羚企业的支持政策,结合我国对瞪羚企业的金融支持政策,发现我国瞪羚企业在发展的不同阶段仍可能面临融资方面的问题,并结合各主体在瞪羚企业发展不同阶段的融资需求和问题,提出针对性政策建议.

Objective To evaluate the mid-term clinical efficacy of total hip replacement using a standardized 3D printed porous trabecular titanium acetabular cup. Methods Clinical data of 23 consecutive patients undergoing total hip replacement with a standardized 3D printed porous trabecular titanium acetabular cup (25 arthroplasties) between February 2016 and August 2018 were collected and retrospectively analyzed in this study. All patients were followed up for 39~69 (51.7±10.7) months. Efficacy evaluation indicators included incidence of postoperative complications and survival rate of prosthesis, as well as visual analog scale (VAS) score, Harris score, acetabular side imaging evaluation and cup survival rate at 6 months after operation and last follow-up. Results No complications were observed in all 25 hip replacements, and the survival rate of cup was 100% during the whole follow-up. The VAS scores were decreased significantly at 6 months postoperatively (1.44±0.82) and last follow-up (0.08±0.27) when compared with the scores preoperatively (7.48±0.96, P < 0.05). The Harris scores were increased significantly at 6 months postoperatively (86.88±3.52) and last follow-up (95.04±1.86) than the pre-operative scores (45.64±4.55, P < 0.05). There were no significant differences in postoperative VAS score and Harris score between the patients with and without periprosthetic radiolucent zone. Conclusion Standardized 3D printed porous trabecular titanium acetabular cup shows its favorable mid-term outcome in total hip arthroplasty, provides high acetabular survival rate, and has certain advantages in reducing aseptic loosening of the prosthesis.

[目的]探讨内侧半月板半脱位在内侧半月板撕裂中的相关因素.[方法]回顾分析2014年1月～2020年3月因内侧半月板撕裂行关节镜手术的患者资料,根据膝关节MRI上是否存在内侧半月板半脱位的表现,将患者分为半脱位组和非脱位组.收集患者的基本特征和临床数据.采用单因素分析和多因素逻辑回归分析明确内侧半月板半脱位的相关因素.[结果]共纳入110例患者,半脱位组54例,占49.09％,非脱位组56例,占50.91％.单因素分析显示,两组在年龄、性别、BMI、侧别、病程、半月板撕裂部位的差异均无统计学意义(P＞0.05),但是,半脱位组半月板撕裂复杂程度、Outerbridge分级和关节积液程度显著重于非脱位组(P＜0.05).逻辑回归显示,放射状撕裂(OR=9.444;P＜0.001)和复杂撕裂(OR---4.486;P=0.003)发生内侧半月板半脱位的风险分别是水平撕裂的9倍和4倍.[结论]内侧半月板撕裂类型是内侧半月板半脱位的独立相关因素.与水平撕裂相比,放射状撕裂和复杂撕裂更易导致内侧半月板半脱位.

大英博物馆现藏以中国媒材绘制的英女王维多利亚肖像一幅.本文从该画题跋入手,梳理了《南京条约》签订之时,作为英方代表团成员的李太郭(George Tradescant Lay)订制该幅画作赠送中国官吏的始末和原由.通过大量画作比对,作者锁定了较有可能作为该画原型的女王肖像.通过考查李氏所著出版于同一时间的《真实的中国人》一书中对于中国女性的描述和总结,作者认为该肖像在保留维多利亚外在特征的同时,也以中国品味为参照,体现出19世纪上半叶跨越国界的艺术交流与融合.同时,这一以艺术品为手段的沟通活动显然受到基督教传教活动的影响,是一次有效的艺术外交.

随着国内脱贫攻坚圆满收官,持续推动群众增收致富来巩固脱贫、防止返贫成为各级政府的工作重点,并以加强金融科技为突破口进行了战略部署.本文使用2017年我国29个省39995户家庭的微观数据,对不同地区发展金融科技、家庭信贷约束与财富积累之间的关系进行了实证研究.研究结论表明:(1)整体而言,发展金融科技可以显著提升当地家庭的财富总量,有助于家庭财富积累;(2)家庭信贷约束抑制了家庭财富积累,其中供给型信贷约束导致的抑制作用更为显著;(3)金融科技发展可以缓解家庭信贷约束对财富积累的抑制作用,特别是供给型信贷约束,从而有助于家庭财富积累;(4)发展金融科技缓解信贷约束对财富积累的抑制效应,对成员年龄偏低、属于农村住户家庭的效果更为显著.除此之外,研究还发现,地区金融科技的发展有利于避免外部负面冲击对家庭财富的侵蚀,可提升家庭财富积累的稳定性.

“婕妤挡熊”这个故事,讲述的是汉元帝刘奭(前74-前33)之妃冯媛(?-前6,挡熊时为婕妤,后升为昭仪)在一次上林苑观斗兽的意外中勇敢站到皇帝面前挡住破笼而出即将伤人性命的黑熊的英勇事迹.一股认为该故事最早出自汉代刘向(约前77-前6)的《列女传》.但是,查据便知其实它只是在相传班昭(约45-117)所增补的《续列女传》20人中以“汉冯昭仪”为题出现.

Department of minimally invasive gastrointestinal surgery in Peking University Cancer Hospital (also named as Department of Gastrointestinal Surgery IV) was established on April 7, 2009. Up to now, ten years have passed since its foundation. As the first department built in specialized cancer hospital, which mainly focuses on laparoscopic surgery, its foundation and development has a very important historical and practical significance in the development of surgical oncology in China. Reviewing the rapid growth of the Department of Minimally Invasive Gastrointestinal Surgery over the past decade, on the one hand, it has benefited from the opportunities of the times and the support of leaders in Peking University Cancer Hospital at that time. More importantly, the progress owes to the pioneering Professor Su Xiangqian, who is brave and innovative, with indomitable spirit and advanced management philosophy. With rigorous training, the ability of the team has been steadily enhanced, the competitiveness has been gradually improved, and the development direction which focuses on laparoscopic gastric cancer surgery and laparoscopic colorectal cancer surgery has been established. Now, the Department of Minimally Invasive Gastrointestinal Surgery has become a well-known domestic gastrointestinal tumor center. In the past ten years, under the leadership of Professor Su Xiangqian, the growth of this team is innovative and comprehensive: (1) Introduce the internationally advanced Baldrige medical service management framework, and propose the "management by principle" concept to improve the core competitiveness of the department; (2) Establish an academic brand by laparoscopic standardized surgery training courses for gastrointestinal tumors, promote cooperation and exchange at home and abroad, and participate in international multi-center clinical research projects; (3) Adhere to the "formation of a research-oriented department, conducting clinical and basic research simultaneously" as the development direction; (4) Stick to the core development concept of team building and cultivate professional talents. Looking forward to the future, our team will not forget the beginning of the heart, and move forward! In the next ten years, we will break through ourselves and continue to pursue the higher level!

妊娠相关子宫颈神经内分泌癌是发生于孕期或产后的子宫颈神经内分泌恶性肿瘤.由于其病理类型特殊,发病率极低,早期易发生转移,预后极差.目前报道病例数量少,缺乏诊治经验,对其治疗方案尚无统一定论.本文就妊娠相关子宫颈神经内分泌癌的诊疗进展进行探讨,以期为临床决策提供依据.

欧洲是“一带一路”倡议的重点覆盖地域,是亚欧大陆经济走廊的重要组成,维护其地区安全稳定,排除干扰中欧两大市场合作互联的潜在安全隐患,对于“一带一路”倡议的稳固推进十分必要.基于地理学视角,考虑难民安置政策因素,采用灰色关联分析、层次分析、多目标规划等方法对2015-2017年欧洲难民危机时空演变过程及迁移格局优化进行分析.①时空演化分析显示难民集中于2015年登陆欧洲,欧洲各国登陆难民、接收难民数量极化突出,双重失衡;②灰色关联分析显示难民迁移决策具有福利优先、收入优先的导向,各国难民政策调整为迁移决策带来不确定性,既有迁移格局难以长期维持;③层次分析显示北欧西欧国家难民宜居性较高,东欧南欧国家宜居性相对较差,部分避难国承担安置难民数量与其宜居性不符;④多目标规划的优化格局显示,由于欧洲各国忽视全球化背景致使难民政策指向错误,迁移网络更加混乱失衡,优化后来自土耳其、乌克兰的难民迁移趋势向西欧集中,来自希腊、匈牙利的难民迁移趋势在空间上更加平均分散,来自意大利的难民迁移趋势向西欧南欧呈扇形分散.优化后迁移格局有助于缓解地区安全局势、为“一带一路”建设创造良好的政治、经济环境,平衡劳动力资源配置,为建设投资提供潜在市场.最后在研究结果的基础上提出若干协同合作调整难民迁移格局的危机缓解措施.

双关是自元杂剧、明清小说流行以来汉语中较常用的一种修辞手法,双关图像也在明清以降大量出现.溯及其源,学者往往以“古已有之”不加分别地对一些视觉材料作出双关图像的解读.本文首先界定了包括谐音双关和语意双关两种主要类型在内的双关图像的含义;继而考察其较为明确和广泛出现的时间脉络.在确定双关图像出现的时间下限(明代中期)的基础之上,将关注点放在双关图像可能出现的宋代.一方面,通过梳理《宣和画谱》中“三元(猿)”、“马上封侯(猴)”等今日极为常见的“双关图像”个案,剥去今人习以为常的定性,只参考同时代人的命名和议论,讨论其在当时是否已普遍出现;另一方面,基于双关图像往往表现吉祥寓意这一特性,指出这一时期以图像表现吉祥寓意的主要方式并非利用双关.因此,作者认为双关图像较为明确和广泛的出现当在宋元间.

建设国际一流的肿瘤治疗中心,除了先进的治疗理念、精密的检测仪器、技艺精湛的医疗团队,还需要什么?季加孚院长这样说—— "坚持正确导向,打造积极、先进、开放的医院文化,以先进的医院文化引领医院发展,为医院发展保驾护航."

子宫内膜癌术后复发主要与局部治疗不彻底或首次治疗时已发生治疗范围外的亚临床转移癌,具有肿瘤复发的高危因素如病理分级高、肌层浸润深度深、盆腔及腹主动脉旁淋巴结转移和腹腔冲洗液中有癌细胞等有关[1].复发部位以局部复发最为常见,其中62% ~73%局限在阴道[2].阴道顶端复发与宫颈受累关系较为密切.

表现书面或口头文学故事作品的绘画,在中国美术史上数量庞大,受众广博.例如表现东汉末年才女蔡文姬被掳匈奴十二载、后被其父蔡邕旧友曹操遣使赎回汉地的《文姬归汉图》,或表现后成为春秋五霸之一的晋文公重耳(前671或前697年-前628年)逃亡各国忍辱负重、最后在秦国支持下回到晋国继位的《晋文公复国图》等.这些画作虽多,但由于在明代董其昌(1555-1636年)等人所倡导的以文人画为主要标准的中国美术史价值体系中地位较低,长期以来并未受到美术史学界的重视.虽然零星地出现在不少学者的研究中,却鲜少被作为一个整体来看待和讨论.1

图绘叙事,简言之,指以图绘的方式视觉呈现(visualize)文本或口头故事.在本文的讨论中,主要涉及叙事绘画和有与绘画相似视觉效果的叙事浮雕.(1)这些作品表现的故事,除开极少量只涉及动物的寓言之外,都与人物相关联.(2)所以在绘画中,按照惯常的中国画分科方法,这些作品大多应归入人物画的大类别中.(3)在不少著述中,它们常被宽泛地称为“人物故事画”或“历史故事画”.例如发行量较大的中央美术学院版的《中国美术简史》中,就把宋代的《文姬归汉》《采薇图》等几幅叙事画作为“历史故事画”进行讲述.(4)

Utilizing the binary RRAM devices, a hardware implemented network based on the modified k-nearest neighbor (KNN) algorithm is proposed for pattern recognition. Regarding to the recognition of the handwritten digits, the hardware network shows brilliant performance with simple training scheme, high tolerance of input noise (up to 40%) and variation (up to 60%), and high recognition accuracy rate (more than 90%). The simulations show that the stable binary rather than multilevel resistance characteristics of RRAM enable the better coupling of device and algorithm for the proposed learning network.

以视觉艺术品为研究对象的艺术史专业是目前世界一流综合性大学的重要学科组成部分.北京大学艺术学院的艺术史论专业,在吸纳西方较成熟的艺术史研究之上,传承我国悠久的跨门类艺术理论传统,背靠北大坚实的艺术学理论基础,形成了具有我国自身特色的史论结合、打通各艺术门类的艺术史论专业.凭借百年北大深厚的人文底蕴和跨学科的综合氛围,依靠本专业优质的师资力量和良好的硬软件设施,形成了个性化和多元化的培养模式,为培养具备宽厚艺术史论素养、传承北大人文学科传统、兼具中国思想和国际视野、引领未来的艺术学人不断探索和努力.