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   2734977篇
  免费   240034篇
  国内免费   14634篇
耳鼻咽喉   38330篇
儿科学   83610篇
妇产科学   70374篇
基础医学   452219篇
口腔科学   74350篇
临床医学   237709篇
内科学   461355篇
皮肤病学   79803篇
神经病学   236918篇
特种医学   108966篇
外国民族医学   108篇
外科学   439526篇
综合类   90320篇
一般理论   2048篇
预防医学   220559篇
眼科学   63379篇
药学   191022篇
  18篇
中国医学   9379篇
肿瘤学   129652篇
  2021年   42542篇
  2020年   33512篇
  2019年   56477篇
  2018年   67703篇
  2017年   51439篇
  2016年   56649篇
  2015年   71645篇
  2014年   106013篇
  2013年   171068篇
  2012年   72681篇
  2011年   69109篇
  2010年   110305篇
  2009年   116657篇
  2008年   56600篇
  2007年   57257篇
  2006年   69007篇
  2005年   64224篇
  2004年   66475篇
  2003年   57909篇
  2002年   47746篇
  2001年   78145篇
  2000年   69324篇
  1999年   73204篇
  1998年   56822篇
  1997年   55190篇
  1996年   52212篇
  1995年   53038篇
  1994年   47240篇
  1993年   44250篇
  1992年   48848篇
  1991年   45692篇
  1990年   42437篇
  1989年   42877篇
  1988年   39549篇
  1987年   38496篇
  1986年   36306篇
  1985年   37075篇
  1984年   36606篇
  1983年   34236篇
  1982年   37097篇
  1981年   35211篇
  1980年   33196篇
  1979年   27671篇
  1978年   27033篇
  1977年   25692篇
  1976年   22775篇
  1975年   20874篇
  1974年   19900篇
  1973年   18989篇
  1972年   17936篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
ObjectiveTo determine prognostic factors and survival patterns for different treatment modalities for nasal cavity (NC) and paranasal sinus (PS) mucosal melanoma (MM).MethodsPatients from 1973 to 2013 were analyzed using the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier method and multivariable cox proportional hazard modeling were used for survival analyses.ResultsOf 928 cases of mucosal melanoma (NC = 632, PS = 302), increasing age (Hazard Ratio [HR]:1.05/year, p < 0.001), T4 tumors (HR: 1.81, p = 0.02), N1 status (HR: 6.61, p < 0.001), and PS disease (HR: 1.50, p < 0.001) were associated with worse survival. Median survival length was lower for PS versus NC (16 versus 26 months, p < 0.001). Surgery and surgery + radiation therapy (RT) improved survival over non-treatment or RT alone (p < 0.001). Adding RT to surgery did not yield a survival difference compared with surgery alone (p = 0.43). Five-year survival rates for surgery and surgery + RT were similar, at 27.7% and 25.1% (p = 0.43).ConclusionSurgery increased survival significantly over RT alone. RT following surgical resection did not improve survival.  相似文献   
2.
3.
4.
5.
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   
6.

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   
7.
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   
8.
AIDS and Behavior - Transactional sex increases HIV risk among adolescent girls and young women (AGYW). Understanding the individual and dyadic nature of transactional sex may provide evidence for...  相似文献   
9.
Journal of Thrombosis and Thrombolysis - The decision by pulmonary embolism response teams (PERTs) to utilize anticoagulation (AC) with or without systemic thrombolysis (ST) or catheter-directed...  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