首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   225267篇
  免费   17945篇
  国内免费   9224篇
耳鼻咽喉   1528篇
儿科学   4961篇
妇产科学   2421篇
基础医学   36424篇
口腔科学   4634篇
临床医学   21587篇
内科学   31081篇
皮肤病学   2657篇
神经病学   12838篇
特种医学   4741篇
外国民族医学   53篇
外科学   17489篇
综合类   37602篇
现状与发展   33篇
一般理论   29篇
预防医学   14601篇
眼科学   5440篇
药学   22371篇
  19篇
中国医学   9770篇
肿瘤学   22157篇
  2023年   2397篇
  2022年   3863篇
  2021年   7430篇
  2020年   6503篇
  2019年   7311篇
  2018年   7106篇
  2017年   6777篇
  2016年   6999篇
  2015年   7160篇
  2014年   11155篇
  2013年   13216篇
  2012年   10991篇
  2011年   12931篇
  2010年   11009篇
  2009年   10884篇
  2008年   11182篇
  2007年   12501篇
  2006年   11587篇
  2005年   11384篇
  2004年   9999篇
  2003年   8889篇
  2002年   6983篇
  2001年   6727篇
  2000年   5565篇
  1999年   4991篇
  1998年   3793篇
  1997年   3297篇
  1996年   3091篇
  1995年   2870篇
  1994年   2432篇
  1993年   2082篇
  1992年   1771篇
  1991年   1515篇
  1990年   1272篇
  1989年   1149篇
  1988年   1047篇
  1987年   823篇
  1986年   620篇
  1985年   1211篇
  1984年   1363篇
  1983年   989篇
  1982年   1195篇
  1981年   1132篇
  1980年   907篇
  1979年   874篇
  1978年   599篇
  1977年   528篇
  1976年   599篇
  1975年   468篇
  1973年   354篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Background: Extracellular matrix molecular components, previously linked to multisystem syndromes include collagens, fibrillins and laminins. Recently, we described a novel multisystem syndrome caused by the c.9418G>A p.(V3140M) mutation in the laminin alpha-5 (LAMA5) gene, which affects connective tissues of all organs and apparatus in a three generation family. In the same family, we have also reported a myopic trait, which, however, was linked to the Prolyl 4-hydroxylase subunit alpha-2 (P4HA2) gene. Results of investigation on vitreous changes and their pathogenesis are reported in the present study.Materials and Methods: Nineteen family individuals underwent complete ophthalmic examination including best-corrected visual acuity (BCVA), fundus examination, fundus photography, intraocular pressure measurement, axial length measurement using ocular biometry, Goldmann visual field examination, standard electroretinogram, SD-OCT. Segregation analysis of LAMA5 and P4HA2 mutations was performed in enrolled members.Results: The vitreous alterations fully segregated with LAMA5 mutation in both young and adult family members. Slight reduction of retinal thickness and peripheral retinal degeneration in only two patients were reported.Conclusions: In this work we showed that PVD is a common trait of LAMA5 multisystem syndrome, therefore occurring as an age-unrelated trait. We hypothesize that the p.(V3140M) mutation results in a reduction of retinal inner limiting membrane (ILM) stability, leading to a derangement in the macromolecular structure of the vitreous gel, and PVD. Further investigations will be necessary to elucidate the role of wild type and mutated LAMA5 in the pathogenesis of PVD.  相似文献   
43.
目的分析POLG基因变异致线粒体病的临床表型及基因变异。方法回顾分析于2019年5月就诊,并经采集外周血DNA进行医学外显子、外显子-内含子交界区靶向二代测序和一代验证,1个确诊为POLG基因变异致线粒体病家系的临床资料。结果先证者,男,10岁,与其同卵双胎哥哥均有相同的体征,深感觉受损、腱反射消失、肌肉可疑萎缩。先证者3个兄姐先后于1岁多夭折。提取患儿及其父母的外周血,先证者及同卵双胎哥哥POLG基因均存在G.2558A(p.R853Q)、c.2890T(p.R964C)复合杂合变异,分别来源于患儿父母亲。结论 POLG基因复合杂合变异线粒体病家系成员有不同的表型;POLG相关疾病,即使同种基因变异,其临床异质性也较大。  相似文献   
44.
《Vaccine》2020,38(3):570-577
IntroductionPediatric pneumococcal pneumonia complicated by parapneumonic pleural effusion/empyema (PPE/PE) remains a major concern despite general immunization with pneumococcal conjugate vaccines (PCVs).MethodsIn a nationwide pediatric hospital surveillance study in Germany we identified 584 children <18 years of age with bacteriologically confirmed PPE/PE from October 2010 to June 2018. Streptococcus pneumoniae was identified by culture and/or PCR of blood samples and/or pleural fluid and serotyped.ResultsS. pneumoniae was identified in 256 of 584 (43.8%) children by culture (n = 122) and/or PCR (n = 207). The following pneumococcal serotypes were detected in 114 children: serotype 3 (42.1%), 1 (25.4%), 7F (12.3%), 19A (7.9%), other PCV13 serotypes (4.4%) and non-PCV13 serotypes (7.9%). Between October 2010 and June 2014 serotype 1 (38.1%) and serotype 3 (25.4%) were most prevalent, whereas between July 2014 and June 2018 serotype 3 (62.7%) and non-PCV13 serotypes (15.7%) were dominant. Compared to children with other pneumococcal serotypes, children with serotype 3 associated PPE/PE were younger (median 3.2 years [IQR 2.1–4.3 years] vs. median 5.6 years [IQR 3.8–8.2 years]; p < 0.001) and more frequently admitted to intensive care (43 [89.6%] vs. 48 [73.8%]; p = 0.04). Seventy-six of 114 (66.7%) children with pneumococcal PPE/PE had been vaccinated with pneumococcal vaccines. Thirty-nine of 76 (51.3%) had received a vaccine covering the serotype detected. Thirty of these 39 breakthrough cases were age-appropriately vaccinated with PCV13 and considered vaccine failures, including 26 children with serotype 3, three children with serotype 19A and one child with serotype 1.ConclusionFollowing the introduction of PCV13 in general childhood vaccination we observed a strong emergence of serotype 3 associated PPE/PE in the German pediatric population, including a considerable number of younger children with serotype 3 vaccine breakthrough cases and failures. Future PCVs should not only cover newly emerging serotypes, but also include a more effective component against serotype 3.  相似文献   
45.
46.
Lifetime red cell concentrate (RCC) transfusions still account for significant iron overload‐related morbidity and mortality despite chelation therapy in thalassaemia. The cumulative risk of transfusion‐transmitted infections is substantial for thalassaemia patients. Pathogen reduction technologies for RCC may imply a proactive approach against new/re‐emerging pathogens and may be an ultimate safeguard for transfusion safety in the developing countries. Red cell alloimmunization may become a significant clinical challenge in thalassaemia. The availability of high‐throughput molecular blood group antigen typing in the donors may allow perfect match transfusion, beyond ABO‐D and CEK antigen‐matched transfusions. Allogeneic stem cell transplantation (A‐SCT) is the only available curative therapy in thalassaemia, but carries a substantial risk of serious adverse events and mortality. Gene addition therapy for correction of the α‐globin chain imbalance overcomes the problems of donor availability and immunological complications of A‐SCT. Gene editing by either gene disruption or correction emerged as a potential alternative to gene addition therapy in beta‐thalassaemia. A new era of novel therapeutics targeting α/β imbalance, ineffective erythropoiesis or iron dysregulation is unfolding in thalassaemia management, and a number of those now have agents in preclinical and clinical development. Hydroxyurea (HU) may improve globin chain imbalance and be beneficial for reducing or omitting transfusion requirement. Ruxolitinib has allowed steady decrease in spleen volume that may serve for avoiding splenectomy in beta‐thalassaemia. Luspatercept may restore normal erythroid differentiation and improve anaemia. Hepcidin mimetics or TMPRSS6 inhibitors may modulate ineffective erythropoiesis by iron restriction and improve anaemia and organ iron loading.  相似文献   
47.
48.
49.
目的:探讨D6S1043、D12S391基因座的基因多态性对主动攻击行为的影响。方法:应用聚合酶链反应技术结合毛细管电泳法对114例男性主动攻击行为者(研究组)及120名健康男性(对照组)进行D6S1043、D12S391基因座的基因型及等位基因检测,分析D6S1043、D12S391基因座多态性与主动攻击行为的相关性。结果:研究组D6S1043基因座中12~19基因型频率(13.16%)明显高于对照组(1.67%)(P0.05);两组等位基因频率差异无统计学意义;两组D12S391基因座的基因型及等位基因频率差异无统计学意义。结论:D6S1043基因座中12~19基因型可能主动攻击行为有关。  相似文献   
50.
Interstitial cystitis/bladder pain syndrome (IC/BPS) and vulvodynia are chronic pain syndromes that appear to be intertwined from the perspectives of embryology, pathology and epidemiology. These associations may account for similar responses to various therapies.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号