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   2050818篇
  免费   154405篇
  国内免费   18318篇
耳鼻咽喉   27904篇
儿科学   64578篇
妇产科学   52033篇
基础医学   294356篇
口腔科学   53937篇
临床医学   193076篇
内科学   392832篇
皮肤病学   43016篇
神经病学   151292篇
特种医学   79433篇
外国民族医学   856篇
外科学   299479篇
综合类   74137篇
现状与发展   58篇
一般理论   532篇
预防医学   150233篇
眼科学   47988篇
药学   159780篇
  199篇
中国医学   16648篇
肿瘤学   121174篇
  2021年   23650篇
  2020年   16276篇
  2019年   20833篇
  2018年   27093篇
  2017年   21613篇
  2016年   22668篇
  2015年   28166篇
  2014年   37504篇
  2013年   48852篇
  2012年   67607篇
  2011年   72502篇
  2010年   43084篇
  2009年   39047篇
  2008年   62943篇
  2007年   66622篇
  2006年   67359篇
  2005年   65392篇
  2004年   59857篇
  2003年   57591篇
  2002年   55423篇
  2001年   95752篇
  2000年   99142篇
  1999年   84730篇
  1998年   24660篇
  1997年   22279篇
  1996年   22183篇
  1995年   20970篇
  1994年   19454篇
  1993年   17376篇
  1992年   64015篇
  1991年   62725篇
  1990年   60827篇
  1989年   58518篇
  1988年   53711篇
  1987年   52459篇
  1986年   49033篇
  1985年   46551篇
  1984年   34633篇
  1983年   29122篇
  1982年   16623篇
  1979年   30882篇
  1978年   21489篇
  1977年   18195篇
  1976年   17153篇
  1975年   18655篇
  1974年   21787篇
  1973年   20895篇
  1972年   19403篇
  1971年   17795篇
  1970年   16925篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
162.
Traditionally, major complications and unanticipated admission/readmission rates were used to assess outcome after day surgery. However, in view of the relative absence of major complications the quality of recovery (QOR) should be considered one of the principal endpoints after day surgery. In our study, the level of QOR is defined by a combination of the Global Surgical Recovery (GSR) Index and the Quality of Life (QOL).The aim of this study was to analyze prevalence and predictors of QOR after day surgery on the fourth postoperative day.Elective patients scheduled for day surgery from November 2008 to April 2010 were enrolled in a prospective cohort study. Outcome parameters were measured by using questionnaire packages at 2 time points: 1 week preoperatively and 4 days postoperatively. Primary outcome parameter is the QOR and is defined as good if the GSR index >80% as well as the postoperative QOL is unchanged or improved as compared with baseline. QOR is defined as poor if both the GSR index ≤80% and if the postoperative QOL is decreased as compared with baseline. QOR is defined as intermediate in all other cases. Three logistic regression analyses were performed to determine predictors for poor QOR after day surgery.A total of 1118 patients were included. A good QOR was noted in 17.3% of patients, an intermediate QOR in 34.8%, and a poor QOR in 47.8% 4 days after day surgery. The best predictor for poor QOR after day surgery was type of surgery. Other predictors were younger age, work status, and longer duration of surgery. A history of previous surgery, expected pain (by the patient) and high long-term surgical fear were significant predictors of poor QOR in only 1 of 3 prediction models.The QOR at home 4 days after day surgery was poor in the majority of patients and showed a significant procedure-specific variation. Patients at risk for poor QOR can be identified during the preoperative period based on type of surgery, age, work status, and the duration of the surgery.  相似文献   
163.
164.
Electrocardiogram (ECG) signal gives a lot of information on the physiology of heart. In reality, noise from various sources interfere with the ECG signal. To get the correct information on physiology of the heart, noise cancellation of the ECG signal is required. In this paper, the effectiveness of extended Kalman smoother (EKS) with the differential evolution (DE) technique for noise cancellation of the ECG signal is investigated. DE is used as an automatic parameter selection method for the selection of ten optimized components of the ECG signal, and those are used to create the ECG signal according to the real ECG signal. These parameters are used by the EKS for the development of the state equation and also for initialization of the parameters of EKS. EKS framework is used for denoising the ECG signal from the single channel. The effectiveness of proposed noise cancellation technique has been evaluated by adding white, colored Gaussian noise and real muscle artifact noise at different SNR to some visually clean ECG signals from the MIT-BIH arrhythmia database. The proposed noise cancellation technique of ECG signal shows better signal to noise ratio (SNR) improvement, lesser mean square error (MSE) and percent of distortion (PRD) compared to other well-known methods.  相似文献   
165.
166.
167.
168.
169.
170.

Aims

Variations of the anatomy of donor hepatic arteries increase the number of arterial anastomoses during liver transplantation and, possibly, the incidence of hepatic artery thrombosis (HAT). In this study, we describe the arterial anatomic variations in liver grafts procured and transplanted by a single center in Greece, the techniques of arterial anastomosis, and their effect on the incidence of early HAT.

Materials and Methods

From January 2013 to December 2017, the arterial anatomy of 116 grafts procured for liver transplantation were recorded, as well as the technique of arterial anastomosis and the incidence of early hepatic artery thrombosis (HAT <30 days).

Results

A single hepatic artery was recorded in 72.41% of the procured grafts, an aberrant left hepatic artery (accessory or replaced) in 18 grafts (15.52%), and an aberrant right hepatic artery (accessory or replaced) in 17 grafts (14.66%), while other variations were observed in less than 1% of the procured livers. Of the 116 primary liver transplantations, 6 patients (5.17%) developed early HAT <30 days. Two of these patients (1.72%) had 1 anastomosis of the hepatic artery and 4 (3.45%) had 2 anastomoses due to anatomic variations.

Conclusions

Anatomic variations of the hepatic artery in liver grafts is a common finding and increase the incidence of early HAT but not to a degree to make these grafts unusable.  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