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   148417篇
  免费   13667篇
  国内免费   3627篇
耳鼻咽喉   1150篇
儿科学   2025篇
妇产科学   1502篇
基础医学   13953篇
口腔科学   4436篇
临床医学   16273篇
内科学   14391篇
皮肤病学   1856篇
神经病学   8738篇
特种医学   3984篇
外国民族医学   11篇
外科学   10180篇
综合类   25910篇
现状与发展   8篇
一般理论   5篇
预防医学   20881篇
眼科学   1466篇
药学   21779篇
  257篇
中国医学   10337篇
肿瘤学   6569篇
  2024年   213篇
  2023年   2580篇
  2022年   4344篇
  2021年   6811篇
  2020年   6881篇
  2019年   5922篇
  2018年   5429篇
  2017年   5920篇
  2016年   6255篇
  2015年   6127篇
  2014年   12719篇
  2013年   12422篇
  2012年   11290篇
  2011年   11233篇
  2010年   8336篇
  2009年   7139篇
  2008年   6673篇
  2007年   6469篇
  2006年   5418篇
  2005年   4533篇
  2004年   3712篇
  2003年   3299篇
  2002年   2583篇
  2001年   2395篇
  2000年   1936篇
  1999年   1582篇
  1998年   1382篇
  1997年   1206篇
  1996年   1029篇
  1995年   1045篇
  1994年   1012篇
  1993年   784篇
  1992年   705篇
  1991年   609篇
  1990年   529篇
  1989年   549篇
  1988年   463篇
  1987年   418篇
  1986年   340篇
  1985年   524篇
  1984年   514篇
  1983年   366篇
  1982年   404篇
  1981年   334篇
  1980年   301篇
  1979年   260篇
  1978年   175篇
  1977年   116篇
  1976年   145篇
  1975年   95篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
ObjectiveTo develop a trail running injury screening instrument (TRISI) for utilisation as clinical decision aid in determining if a trail runner is at an increased risk for injury.DesignMultiple methods approach.MethodsThe study utilised five phases 1) identification of injury risk factors 2) determining the relevance of each identified risk factor in a trail running context, 3) creating the content of the Likert scale points from 0 to 4, 4) rescaling the Likert scale points to determine numerical values for the content of each Likert scale point, and 5) determining a weighted score for each injury risk factor that contributes to the overall combined composite score.ResultsOf the 77 identified injury risk factors, 26 were deemed relevant in trail running. The weighted score for each injury risk factor ranged from 2.21 to 5.53 with the highest calculated score being 5.53. The final TRISI includes risk categories of training, running equipment, demographics, previous injury, behavioural, psychological, nutrition, chronic disease, physiological, and biomechanical factors.ConclusionThe developed TRISI aims to assist the clinician during pre-race injury screening or during a training season to identify meaningful areas to target in designing injury risk management strategies and/or continuous health education.  相似文献   
102.
目的探讨不同修复方法修复口腔颌面部肿瘤术后缺损的效果。方法选取口腔颌面部肿瘤根治术后缺损患者89例,根据最终选取的修复方案分为A组(n=49)和B组(n=40),A组给予股前外侧嵌合皮瓣修复,B组给予串联皮瓣修复。观察2组手术情况,采用华盛顿大学头颈肿瘤生活质量量表(UW-QOL)对患者术后生活质量进行评价,检测唾液中唾液酸(SA)及癌胚抗原(CEA)水平。结果A组手术时间、胃管拔除时间和经口进食时间分别为(6.30±1.19)h、(19.77±2.81)d和(20.32±2.19)d,明显少于B组(P<0.05);但A组皮瓣制作时间为(1.20±0.28)h,明显多于B组(P<0.05)。A组术后6个月UW-QOL量表中外观、吞咽、咀嚼、言语、肩功能、情绪评分分别为(63.29±4.54)分、(54.93±5.03)分、(47.12±6.02)分、(64.49±4.33)分、(82.20±5.43)分和(75.50±7.20)分,明显高于B组(P<0.05)。A组和B组术后6个月UW-QOL量表中疼痛、活动、娱乐、味觉、唾液及焦虑评分比较差异无统计学意义(P>0.05)。A组修复后1个月唾液中SA和CEA分别为(7.29±1.33)ng/dl和(50.04±16.62)ng/ml,明显低于B组(P<0.05)。A组血管危险发生率为2.04%,明显低于B组(P<0.05)。A组和B组感染、皮瓣坏死发生率差异比较无统计学意义(P>0.05)。结论相比较串联皮瓣修复,股前外侧嵌合皮瓣修复口腔颌面部肿瘤根治术后缺损有较好的效果,可以改善患者生活质量。  相似文献   
103.
BackgroundThe growing enthusiasm for the use of reverse shoulder arthroplasty (RSA) in the treatment of primary glenohumeral osteoarthritis (GHOA) with an intact rotator cuff is based on data derived from single-center studies with limited generalizability and follow-up. This study compared patient-reported outcomes (PROs) between RSA and total shoulder arthroplasty (TSA) for the treatment of primary GHOA with up to 5-year follow-up and examined temporal trends in the treatment of GHOA between 2012 and 2021.MethodsA retrospective review was performed on patients with primary GHOA undergoing primary arthroplasty surgery from the Surgical Outcomes System global registry between 2012 and 2021. PROs including the American Shoulder and Elbow Surgeons (ASES) score, Single Assessment Numeric Evaluation (SANE) score, and visual analog scale (VAS) for pain were compared between RSA and TSA at 1, 2, and 5 years postoperatively.ResultsA total of 4451 patients were included, with 2693 (60.5%) undergoing TSA and 1758 (39.5%) undergoing RSA. Both RSA and TSA provided clinically excellent outcomes at 1 year postoperatively (ASES: 80.8 ± 17.9 vs. 85.9 ± 15.2, respectively; SANE: 74.8 ± 24.7 vs. 79.5 ± 22.9; VAS pain: 1.3 ± 2.0 vs. 1.1 ± 1.7; all P < .05) that were maintained at 2 years (ASES: 81.3 ± 19.3 vs. 87.3 ± 14.9; SANE: 74.8 ± 26.2 vs. 79.7 ± 24.7; VAS pain: 1.3 ± 2.1 vs. 1.0 ± 1.6; all P < .05) and 5 years (ASES: 81.7 ± 16.5 vs. 86.9 ± 15.3; SANE: 71.6 ± 28.5 vs. 78.2 ± 25.9; VAS pain: 1.0 ± 1.7 vs. 1.0 ± 1.7; all P < .05), with statistical significance favoring TSA. After controlling for age and sex, there was an adjusted difference of 4.5 units in the ASES score favoring TSA (P = .005) at 5 years postoperatively but no differences in adjusted SANE (P = .745) and VAS pain (P = .332) scores. The use of RSA for GHOA grew considerably over time, from representing only 17% of all replacements performed for GHOA in 2012 to nearly half (47%) in 2021 (P < .001).ConclusionRSA as a treatment for GHOA with an intact rotator cuff seems to yield PROs that are largely clinically equivalent to TSA extending to 5 years postoperatively. The observed statistical significance favoring TSA appears to be of marginal clinical benefit based on established minimal clinically important differences and may be a result of the large sample size. Further research using more granular clinical data and examining differences in range of motion and complications is warranted as it may change the value analysis.  相似文献   
104.
目的 Dof(DNA binding with one finger)家族是高等植物中特有的一类转录因子家族,参与植物中光、激素、非生物胁迫等多种胁迫响应调控。本研究基于全基因组数据对黄花蒿Dof(AaDof)转录因子家族进行鉴定及表达模式分析,探究Dof家族基因在青蒿素合成调控中的作用。方法 经PFAM数据库鉴定获得AaDof序列,通过生物信息学软件分析其理化性质、亚细胞定位、基因结构、蛋白保守结构以及启动子序列结合元件等,并基于赤霉素(Gibberellic acid, GA)、紫外线B(UV-B)及二者协同胁迫下黄花蒿转录组数据对其表达模式进行分析。结果 本研究从全基因组水平共鉴定出51个AaDof基因,均含有保守的C2-C2单锌指结构,依据系统发育分析分为8个亚族,同一亚族内基因结构与蛋白保守结构域相对保守。亚细胞定位预测显示12个AaDof蛋白定位在细胞外,其余均定位在细胞核。启动子元件分析发现AaDof家族基因启动子区富含光、激素等多种响应元件。对AaDof在GA、UV-B和GA+UV-B处理下的表达模式分析发现,AaDof基因对GA胁迫处理响应较弱,仅有少量基因敏感,其表达主要受到UV-B胁迫影响。C1及C2.1亚族大部分基因在UV-B胁迫下上调表达,而A亚族大部分基因在UV-B胁迫下下调表达。qRT-PCR验证表明AaDof1AaDof17AaDof44在GA和UV-B处理下表达量显著上调,推测其可能通过参与GA和UV-B调控网络,正向调控青蒿素生物合成。结论 本研究系统鉴定了黄花蒿AaDof家族基因并筛选了3个可能正向调控青蒿素生物合成的候选AaDof基因,为黄花蒿Dof家族基因功能研究及其在青蒿素生物合成中的调控机制解析奠定基础。  相似文献   
105.
目的 开发并评估一种用于预测子宫内膜病变患者内膜病理类型的临床模型;方法 选取2019年11月至2021年11月因妇科B超发现子宫内膜病变并于山东中医药大学附属医院行宫腔镜下内膜活检的患者,结合其病史与最小绝对收缩和选择算子法(Least absolute shrinkage and selection operator,LASSO)筛选影响内膜病变的独立危险因素,列线图(nomogram)函数建立列线图模型,采用ROC曲线下方的面积大小(Area Under Curve, AUC)、C指数(C-index)、拟合优度(Hosmer-Lemeshow)检验、自举法(bootstrap)评估及验证模型,依据列线图对纳入患者进行风险赋分,绘制ROC曲线获取风险评分的截断值,从而划分高低风险的人群;结果 阴道流血、绝经、无流产史、并发高血压、B超内膜厚度增厚、内膜回声不正常,中医证型为虚实夹杂证是发生子宫内膜癌及癌前病变的独立危险因素,评估模型所得AUC值与C-index均>0.9,Hosmer-Lemeshow检验显示P>0.05,bootstrap内部验证法所得C-index亦高于0.9,均说明模型准确度、区分度及可信度良好,当患者的风险评分总和≥177分时,属于高风险人群;结论 本模型可以预测B超提示子宫内膜病变患者的内膜病理类型为癌前或恶变型的概率并识别高风险人群。  相似文献   
106.
ObjectiveTo evaluate the performance of a deep learning (DL)-based radiomics strategy on contrast-enhanced computed tomography (CT) to predict microvascular invasion (MVI) status and clinical outcomes, recurrence-free survival (RFS) and overall survival (OS) in patients with early stage hepatocellular carcinoma (HCC) receiving surgical resection.MethodsAll 283 eligible patients were included retrospectively between January 2008 and December 2015, and assigned into the training cohort (n = 198) and the testing cohort (n = 85). We extracted radiomics features via handcrafted radiomics analysis manually and DL analysis of pretrained convolutional neural networks via transfer learning automatically. Support vector machine was adopted as the classifier. A clinical-radiological model for MVI status integrated significant clinical features and the radiological signature generated from the radiological model with the optimal area under the receiver operating characteristics curve (AUC) in the testing cohort. Otherwise, DL-based prognostic models were constructed in prediction of recurrence and mortality via Cox proportional hazard analysis.ResultsThe clinical-radiological model for MVI represented an AUC of 0.909, accuracy of 96.47%, sensitivity of 90.91%, specificity of 97.30%, positive predictive value of 83.33%, and negative predictive value of 98.63% in the testing cohort. The clinical-radiological models for identification of RFS and OS outperformed prediction performance of the clinical model or the DL signature alone. The DL-based integrated model for prognostication showed great predictive value with significant classification and discrimination abilities after validation.ConclusionsThe integrated DL-based radiomics models achieved accurate preoperative prediction of MVI status, and might facilitate predicting tumor recurrence and mortality in order to optimize clinical decisions for patients with early stage HCC.  相似文献   
107.
《Genetics in medicine》2022,24(10):2014-2027
PurposeMethodological challenges have limited economic evaluations of genome sequencing (GS) and exome sequencing (ES). Our objective was to develop conceptual frameworks for model-based cost-effectiveness analyses (CEAs) of diagnostic GS/ES.MethodsWe conducted a scoping review of economic analyses to develop and iterate with experts a set of conceptual CEA frameworks for GS/ES for prenatal testing, early diagnosis in pediatrics, diagnosis of delayed-onset disorders in pediatrics, genetic testing in cancer, screening of newborns, and general population screening.ResultsReflecting on 57 studies meeting inclusion criteria, we recommend the following considerations for each clinical scenario. For prenatal testing, performing comparative analyses of costs of ES strategies and postpartum care, as well as genetic diagnoses and pregnancy outcomes. For early diagnosis in pediatrics, modeling quality-adjusted life years (QALYs) and costs over ≥20 years for rapid turnaround GS/ES. For hereditary cancer syndrome testing, modeling cumulative costs and QALYs for the individual tested and first/second/third-degree relatives. For tumor profiling, not restricting to treatment uptake or response and including QALYs and costs of downstream outcomes. For screening, modeling lifetime costs and QALYs and considering consequences of low penetrance and GS/ES reanalysis.ConclusionOur frameworks can guide the design of model-based CEAs and ultimately foster robust evidence for the economic value of GS/ES.  相似文献   
108.
109.
In patients treated by orbital wall decompression for endocrine orbitopathy (EO) there is limited evidence on the effect of orbital wall resections. Thus, the aim of this study was to evaluate the effect of one, two, and three-wall resections on orbital parameters to determine if any such correlations exist. Preoperative and postoperative data from all patients at a tertiary care centre who underwent decompression surgery from 2010 - 2020 were digitally analysed. The effect of the number and area of resected walls on orbital area, orbital volume, and Hertel value, and the effect of lateral rim advancement (LARA) were determined. A total of 131 orbital areas showed an increase from a mean (SD) preoperative area of 42.0 (4.6) cm2 to 47.3 (6.1) cm2 postoperatively (p<0.001). In total, the mean (SD) area of osseous wall removed in all patients was 6.2 (1.7) cm2 at the lateral orbit (n = 129), 6.7 (2.3) cm2 at the orbital floor (n = 123), and 5.8 (1.8) cm2 at the medial orbital wall (n =30). The mean (SD) orbital volume increased by 6.0 (3.0) cm3 after decompression. There was also a significant reduction in exophthalmos of 7.3 (3.2) mm (from 25.2 (3.9) to 17.9 (3.5), p<0.001). LARA was performed in 50 patients. Changes in volume and area, and reduction in exophthalmos were not significantly different with or without LARA. The postoperative effects of orbital wall resection are predictable and exhibit a relation with six units of change. Two-wall resection is the most common intervention.  相似文献   
110.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has triggered a widespread outbreak since December 2019. The SARS-CoV-2 infection-related illness has been dubbed the coronavirus disease 2019 (COVID-19) by the World Health Organization. Asymptomatic and subclinical infections, a severe hyper-inflammatory state, and mortality are all examples of clinical signs. After attaching to the angiotensin converting enzyme 2 (ACE2) receptor, the SARS-CoV-2 virus can enter cells through membrane fusion and endocytosis. In addition to enabling viruses to cling to target cells, the connection between the spike protein (S-protein) of SARS-CoV-2 and ACE2 may potentially impair the functionality of ACE2. Blood pressure is controlled by ACE2, which catalyzes the hydrolysis of the active vasoconstrictor octapeptide angiotensin (Ang) II to the heptapeptide Ang-(1-7) and free L-Phe. Additionally, Ang I can be broken down by ACE2 into Ang-(1-9) and metabolized into Ang-(1-7). Numerous studies have demonstrated that circulating ACE2 (cACE2) and Ang-(1-7) have the ability to restore myocardial damage in a variety of cardiovascular diseases and have anti-inflammatory, antioxidant, anti-apoptotic, and anti-cardiomyocyte fibrosis actions. There have been some suggestions for raising ACE2 expression in COVID-19 patients, which might be used as a target for the creation of novel treatment therapies. With regard to this, SARS-CoV-2 is neutralized by soluble recombinant human ACE2 (hrsACE2), which binds the viral S-protein and reduces damage to a variety of organs, including the heart, kidneys, and lungs, by lowering Ang II concentrations and enhancing conversion to Ang-(1-7). This review aims to investigate how the presence of SARS-CoV-2 and cACE2 are related. Additionally, there will be discussion of a number of potential therapeutic approaches to tip the ACE/ACE-2 balance in favor of the ACE-2/Ang-(1-7) axis.  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