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   4913047篇
  免费   397330篇
  国内免费   17844篇
耳鼻咽喉   70017篇
儿科学   158083篇
妇产科学   130256篇
基础医学   732848篇
口腔科学   137703篇
临床医学   453908篇
内科学   888694篇
皮肤病学   117379篇
神经病学   408769篇
特种医学   194768篇
外国民族医学   968篇
外科学   739240篇
综合类   150046篇
现状与发展   33篇
一般理论   2808篇
预防医学   409504篇
眼科学   115661篇
药学   354877篇
  80篇
中国医学   17093篇
肿瘤学   245486篇
  2021年   52655篇
  2019年   60102篇
  2018年   76929篇
  2017年   59260篇
  2016年   65258篇
  2015年   78481篇
  2014年   113454篇
  2013年   179755篇
  2012年   144197篇
  2011年   152167篇
  2010年   134577篇
  2009年   134203篇
  2008年   136799篇
  2007年   146190篇
  2006年   153344篇
  2005年   146920篇
  2004年   147076篇
  2003年   136298篇
  2002年   124534篇
  2001年   197216篇
  2000年   193600篇
  1999年   172069篇
  1998年   70102篇
  1997年   64781篇
  1996年   62905篇
  1995年   63797篇
  1994年   57753篇
  1993年   53535篇
  1992年   128151篇
  1991年   123298篇
  1990年   118650篇
  1989年   115174篇
  1988年   105995篇
  1987年   104136篇
  1986年   98222篇
  1985年   95663篇
  1984年   77467篇
  1983年   68036篇
  1982年   51172篇
  1981年   47257篇
  1980年   44260篇
  1979年   67322篇
  1978年   52705篇
  1977年   46166篇
  1976年   42861篇
  1975年   43741篇
  1974年   48750篇
  1973年   46734篇
  1972年   43832篇
  1971年   40501篇
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
1.
2.
3.
Modified-release opioids are often prescribed for the management of moderate to severe acute pain following total hip and knee arthroplasty, despite recommendations against their use due to increasing concerns regarding harm. The primary objective of this multicentre study was to examine the impact of modified-release opioid use on the incidence of opioid-related adverse events compared with immediate-release opioid use, among adult inpatients following total hip or knee arthroplasty. Data for total hip and knee arthroplasty inpatients receiving an opioid analgesic for postoperative analgesia during hospitalisation were collected from electronic medical records of three tertiary metropolitan hospitals in Australia. The primary outcome was the incidence of opioid-related adverse events during hospital admission. Patients who received modified with or without immediate-release opioids were matched to those receiving immediate-release opioids only (1:1) using nearest neighbour propensity score matching with patient and clinical characteristics as covariates. This included total opioid dose received. In the matched cohorts, patients given modified-release opioids (n = 347) experienced a higher incidence of opioid-related adverse events overall, compared with those given immediate-release opioids only (20.5%, 71/347 vs. 12.7%, 44/347; difference in proportions 7.8% [95%CI 2.3–13.3%]). Modified-release opioid use was associated with an increased risk of harm when used for acute pain during hospitalisation after total hip or knee arthroplasty.  相似文献   
4.

Introduction

Left ventricular (LV) dysfunction is estimated to occur in 10%–25% of the general intensive care unit (ICU) population and is frequently seen as regional wall motion abnormalities (RWMAs). Although RWMA is mostly attributed to myocardial ischemia or infarction, some studies have suggested that nonischemic RWMA might also be prevalent. We sought to establish that RWMA can be seen in critically ill patients with normal coronary arteries and to explore reasons for RWMA in this population.

Methods

In this retrospective study, data from the hospital angiography register and the ICU register were collated between 2012 and 2019. Patients were identified who underwent angiography in conjunction with their ICU stay and had RWMA on echocardiography. Patients were divided into either those with non-obstructed or those with obstructed coronary arteries. Cardiac magnetic resonance imaging (cMRI) examinations were reviewed if they had been performed on patients with non-obstructed coronaries.

Results

We identified 53 patients with RWMA and non-obstructed coronary arteries and 204 patients with RWMA and obstructed coronary arteries. Patients with non-obstructed coronary arteries were more often female, younger, and had fewer cardiovascular risk factors. They less commonly had ST elevation, but more frequently had T-wave inversion or serious arrhythmias. Troponin levels were higher in patients with obstructed coronary arteries, but NT-proBNP was similar between the groups. There were no differences in risk-adjusted 90-day mortality between patients with non-obstructed versus obstructed coronary arteries (OR 1.21, [95% CI 0.56–2.64], p = .628). In those with non-obstructed coronary arteries, follow-up echocardiography was available for 38 patients, of whom 30 showed normalization of cardiac function. Of the 14 patients with non-obstructed coronary arteries on whom cMRI was performed, 7 had a tentative diagnosis of Takotsubo syndrome or myocardial stunning; 4 had a myocardial infarction (preexisting in 3 cases); 1 patient had acute myocarditis; 1 patient had post-myocarditis; and 1 patient was diagnosed with dilated cardiomyopathy.

Conclusion

RWMA can be seen to occur in critically ill patients in the absence of coronary artery obstruction. Several conditions can cause regional hypokinesia, and cMRI is useful to evaluate the underlying etiology.  相似文献   
5.
Post-induction hypotension is common and associated with postoperative complications. We hypothesised that pneumatic leg compression reduces post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy. In this double-blind randomised study, patients were allocated randomly to the pneumatic leg compression group (n = 50) or control (n = 50). In the intervention group, pneumatic leg compression was initiated before induction of anaesthesia. In the control group, pneumatic leg compression was initiated 20 min after anaesthesia induction. The primary outcome was the incidence of post-induction hypotension in these groups. Post-induction hypotension was defined as systolic blood pressure < 90 mmHg during the first 20 min after induction. Haemodynamic variables and area under the curve of post-induction systolic blood pressure over time were assessed. Complications associated with pneumatic leg compression were recorded, including: peripheral neuropathy; compartment syndrome; extensive bullae beneath the leg sleeves; and pulmonary thromboembolism. The incidence of post-induction hypotension decreased in the pneumatic leg compression group compared with that in the control group; 5 (10%) vs. 29 (58%), respectively, p < 0.001. In the pneumatic leg compression group, the lowest systolic, diastolic and mean blood pressures 20 min after induction of anaesthesia were significantly greater than the control group. Pneumatic leg compression resulted in an increased area under the curve of systolic blood pressure in the first 20 min after induction, p = 0.001. There were no pneumatic leg compression-related complications. Pneumatic leg compression reduced post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy, suggesting that it is an effective and safe intervention to prevent post-induction hypotension among elderly patients undergoing general anaesthesia.  相似文献   
6.
7.
8.
目的 探究空腹血糖与三酰甘油/ 高密度脂蛋白胆固醇(triglyceride/high density lipoprotein cholesterol, TG/HDL-C) 比值在对糖尿病患者并发新型冠状病毒肺炎(coronavirus disease 2019, COVID-19) 的预测价值。方法 连续收集2021 年12 月~ 2022 年1 月西安市第四医院收治的非糖尿病并发COVID-19 患者39 例,通过倾向性评分匹配同期西安交通大学第二附属医院健康体检者34 例( 健康对照组),比较两组间临床特征与实验室检验指标,Logistic 回归及受试者工作特征(receiver operating characteristic, ROC) 曲线分析空腹血糖与TG/HDL-C 对非糖尿病患者并发COVID-19 的预测价值。结果 COVID-19 患者均为轻型(30 例) 或普通型(9 例),整体症状较轻,中位年龄29.0 (20.0, 49.0) 岁,男性24 例(61.5%),临床预后较好。COVID-19 患者入院时空腹血糖(4.30±0.47 mmol/L) 与HDL-C[1.07(0.86, 1.30) mmol/L]较健康对照组[5.15±0.70 mmol/L, 2.24(1.77, 3.05) mmol/L] 显著降低,差异具有统计学意义(t=6.277, P < 0.001;Z =-6.026,P<0.001),而低密度脂蛋白胆固醇(low density lipoprotein cholesterol, LDL-C) [2.40(1.81, 2.91) mmol/L] 与TG/HDL-C [0.91(0.54, 1.52)] 较健康对照组[1.11 (0.99, 1.30) mmol/L, 0.54 (0.33, 0.90)] 显著升高,差异具有统计学意义(Z=-6.271, -2.801,均P < 0.005)。Logistic 回归分析显示入院时空腹血糖可能是非糖尿病患者感染COVID-19 的独立保护因素(OR :0.020,95% CI: 0.003 ~ 0.150),TG/HDL-C 升高可能是COVID-19 发病的独立危险因素(OR :4.802, 95% CI: 1.249 ~ 18.460)。ROC 曲线结果显示,空腹血糖与TG/HDL-C 能较好地预测COVID-19 发病风险,曲线下面积(area under curve, AUC) 分别为0.871 和0.708,二者联合诊断的AUC 为0.895。结论 空腹血糖降低与TG/HDL-C 升高可能是非糖尿病人群并发COVID-19 的危险因素,对COVID-19 发病具有较好的预测价值。  相似文献   
9.
In the last decade, the development of new radiopharmaceuticals for the imaging and therapy of prostate cancer has been a highly active and important area of research, especially focusing on the prostate-specific membrane antigen (PSMA), an antigen which is upregulated in prostate, as well as in other tumor cells. A large variety of PSMA ligands have been radiolabeled, to date. Among the various derivatives, PSMA-617 resulted to be one of the most interesting in terms of interaction with the antigen and clinical properties, and its lutetium-177 labeled version has recently been approved by regulatory agencies for therapeutic purposes. For this reasons, the radiolabeling with fluorine-18 of a PSMA-617 derivative might be of interest. Beside other methodologies to radiolabel macromolecules with fluorine-18, the “click-chemistry” approach resulted to be very useful, and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) is considered one of most efficient and reliable. This paper proposes the synthesis of a suitable precursor for the radiolabeling with fluorine-18 of a new PSMA-617 derivative. The whole radiosynthetic procedure has been fully automated, and the final product, which proved to be stable in plasma, has been obtained with radiochemical yield and purity suitable for subsequent preclinical studies.  相似文献   
10.
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