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   28577篇
  免费   1473篇
  国内免费   436篇
耳鼻咽喉   12篇
儿科学   724篇
妇产科学   193篇
基础医学   3113篇
口腔科学   39篇
临床医学   3450篇
内科学   10560篇
皮肤病学   38篇
神经病学   790篇
特种医学   956篇
外科学   2859篇
综合类   3682篇
预防医学   1017篇
眼科学   15篇
药学   2062篇
  13篇
中国医学   831篇
肿瘤学   132篇
  2023年   361篇
  2022年   608篇
  2021年   851篇
  2020年   803篇
  2019年   1003篇
  2018年   1050篇
  2017年   719篇
  2016年   743篇
  2015年   859篇
  2014年   1993篇
  2013年   1760篇
  2012年   1475篇
  2011年   1866篇
  2010年   1520篇
  2009年   1526篇
  2008年   1615篇
  2007年   1357篇
  2006年   1361篇
  2005年   1211篇
  2004年   926篇
  2003年   784篇
  2002年   597篇
  2001年   573篇
  2000年   529篇
  1999年   391篇
  1998年   294篇
  1997年   304篇
  1996年   243篇
  1995年   264篇
  1994年   215篇
  1993年   179篇
  1992年   199篇
  1991年   158篇
  1990年   117篇
  1989年   127篇
  1988年   135篇
  1987年   109篇
  1986年   87篇
  1985年   123篇
  1984年   132篇
  1983年   106篇
  1982年   117篇
  1981年   118篇
  1980年   138篇
  1979年   108篇
  1978年   100篇
  1977年   94篇
  1976年   86篇
  1975年   98篇
  1973年   86篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
PurposeTo evaluate the safety and efficacy of balloon pulmonary angioplasty (BPA) for nonoperable chronic thromboembolic pulmonary hypertension (CTEPH) patients during the initial experience of a single center.MethodsA total of 18 CTEPH patients (5 with residual pulmonary hypertension after pulmonary endarterectomy) were treated with BPA during the period 2014–2018 and were retrospectively reviewed. Mean age was 61 ± 19 years; 55% were female; mean pulmonary artery pressure was 44 ± 12 mmHg; cardiac output was 4.3 ± 1.0 l/min; and pulmonary vascular resistance was 8.4 ± 3.6 WU. Patients were evaluated by New York Heart Association functional class, 6-minute walk distance, N-terminal pro b-type natriuretic peptide, echocardiography, right heart catheterization, and before and after completions of BPA.ResultsA total of 91 procedures were performed, with a median number of 4 BPA sessions per patient (range, 2–8). There were no deaths or major complications requiring extracorporeal support or (non)invasive ventilation. The most common complication was self-limiting hemoptysis (3%). According to Society of Interventional Radiology classification, 4 mild, 4 moderate, and 1 severe adverse events were noted. Invasive hemodynamics significantly improved, with a cardiac index increase of 15% (P = .0333), decrease of mean pulmonary artery pressure of 30% (P = .0013), and decrease of pulmonary vascular resistance of 45% (P = .0048). Stroke volume index (P = .0171) and pulmonary arterial compliance (P = .0004) were also significantly enhanced.ConclusionsBPA significantly improves cardiopulmonary hemodynamics with an acceptable safety profile. Further studies assessing the long-term efficacy of BPA are required.  相似文献   
52.
53.
54.
55.
56.
BackgroundOur previous work with 123iodine meta-iodobenzylguanidine (123I-mIBG) radionuclide imaging among patients with cardiomyopathy reported limitations associated with the prognostic power of global parameters derived from planar imaging [1]. Employing multivariate analysis, we further showed the regional washout associated with territories adjacent to infarcted myocardium obtained from single-photon emission computed tomography imaging (SPECT) yielded superior prognostic power over the other planar and SPECT indices in predicting future cardiac events [1]. The aim of this study was to apply an artificial neural network (Neural Analyser version 2.9.5) to the original data from the same patient cohort to evaluate the most potent prognostic index for future cardiac events among patient with cardiomyopathy.MethodsThe original data were reevaluated using an artificial neural network (Neural Analyser version 2.9.5). There were 84 input variables in the original 22 patients from clinical data, electrocardiogram (rest, stress, and continuous ambulatory electrocardiogram recording), transthoracic echocardiography, coronary angiogram, sestamibi myocardial perfusion SPECT, planar and SPECT 123I-mIBG, and genetic and biomarkers, detailed in the previous work. A single binary output was a cardiac event or no cardiac event in the follow-up period.ResultsFollowing training and validation phases, the optimal number of inputs was determined to be two with a training loss of 0.025 and selection loss <0.001. The final architecture had inputs of a change in left ventricular ejection fraction (Δ > −10%) and 123I-mIBG planar global washout (>30%), two hidden layers of 6 and 1 node, respectively, and a binary output. Using receiver operator characteristics analysis demonstrated an area under the curve of 0.75 correlating to a sensitivity of 100% and specificity of 50%.ConclusionThe premise that regional washout of 123I-mIBG SPECT from noninfarcted tissue is the best predictor of cardiac events was built on has a sound and logical foundation. By artificial neural network analysis; however, 123I-mIBG planar global washout of >30% was shown to be the best indicator for risk of cardiac event when accompanied by a decline in left ventricular ejection fraction of >10%. Further investigation should be undertaken assessing assimilation into big data and the potential for automated feature extraction from raw image datasets with convolutional neural networks.  相似文献   
57.
目的:探究瓜蒌薤白桂枝汤对老年冠心病患者血脂及NT-proBNP、hs-CRP、Fib水平影响。方法:选取2014年4月至2018年4月西藏民族大学附属医院收治的老年冠心病患者78例作为研究对象,根据就诊顺序编号,按照随机数字表法随机分为对照组和观察组,每组39例。对照组常规西医治疗,观察组在对照组基础上加用瓜蒌薤白桂枝汤治疗,同时治疗4周。观察2组治疗前、完成治疗后血脂、NT-pro BNP、hs-CRP、Fib、WBC、HCY、血流流变学、心脏功能水平变化并比较;完成治疗后进行疗效评价。结果:观察组患者治疗后TC、TG、HDL-C、NT-proBNP、hs-CRP、Fib、WBC、HCY、全血高切黏度、全血低切黏度、血浆黏度、红细胞聚集指数下降较对照组患者幅度更低,LDL-C、EDD、NEDD、LVEF、LVPFR上升幅度及治疗后临床总有效率较对照组更高(P<0.05)。结论:瓜蒌薤白桂枝汤能降低老年冠心病患者血脂水平,抑制炎性反应,改善冠状动脉血循环,从而提高疗效,改善心功能。  相似文献   
58.
59.
60.
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