全文获取类型
收费全文 | 1299292篇 |
免费 | 74678篇 |
国内免费 | 1459篇 |
专业分类
耳鼻咽喉 | 16719篇 |
儿科学 | 42460篇 |
妇产科学 | 32706篇 |
基础医学 | 178281篇 |
口腔科学 | 31535篇 |
临床医学 | 113704篇 |
内科学 | 242905篇 |
皮肤病学 | 25549篇 |
神经病学 | 102124篇 |
特种医学 | 52957篇 |
外国民族医学 | 202篇 |
外科学 | 198483篇 |
综合类 | 24674篇 |
现状与发展 | 1篇 |
一般理论 | 309篇 |
预防医学 | 98044篇 |
眼科学 | 27632篇 |
药学 | 98444篇 |
7篇 | |
中国医学 | 3470篇 |
肿瘤学 | 85223篇 |
出版年
2021年 | 8285篇 |
2019年 | 8593篇 |
2018年 | 34816篇 |
2017年 | 27663篇 |
2016年 | 31896篇 |
2015年 | 13075篇 |
2014年 | 17215篇 |
2013年 | 24806篇 |
2012年 | 40008篇 |
2011年 | 56515篇 |
2010年 | 39295篇 |
2009年 | 31178篇 |
2008年 | 53378篇 |
2007年 | 58916篇 |
2006年 | 35677篇 |
2005年 | 36266篇 |
2004年 | 36262篇 |
2003年 | 36466篇 |
2002年 | 33092篇 |
2001年 | 60664篇 |
2000年 | 62362篇 |
1999年 | 51429篇 |
1998年 | 13105篇 |
1997年 | 11625篇 |
1996年 | 11426篇 |
1995年 | 10690篇 |
1994年 | 9731篇 |
1993年 | 9202篇 |
1992年 | 38033篇 |
1991年 | 36550篇 |
1990年 | 35999篇 |
1989年 | 34514篇 |
1988年 | 31069篇 |
1987年 | 30188篇 |
1986年 | 28393篇 |
1985年 | 26633篇 |
1984年 | 19348篇 |
1983年 | 16262篇 |
1982年 | 9003篇 |
1979年 | 17159篇 |
1978年 | 11499篇 |
1977年 | 10277篇 |
1976年 | 8926篇 |
1975年 | 10096篇 |
1974年 | 11707篇 |
1973年 | 11287篇 |
1972年 | 10768篇 |
1971年 | 10099篇 |
1970年 | 9292篇 |
1969年 | 8986篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Contraceptive use is an important strategy for the prevention of unwanted pregnancy and avoidance of induced abortion. Of all the contraception methods, emergency contraceptive (EC) offers the last chance to achieve this. However, few studies have documented the use of EC among young people in Ghana. This study explored knowledge and usage of EC as well as the factors associated with it among University of Cape Coast students. Data were obtained on the knowledge and usage of ECs among University of Cape Coast students in 2013. Logistic regression analysis was used to investigate the association between students’ socio-demographic characteristics and EC knowledge and use. More male students (72 %) than females (59 %) were sexually active. Fifty-seven percent of the respondents had ever heard of EC and 36 % had ever used EC. Although males were more likely to be sexually active, females were more likely to have knowledge of EC use compared to males. The study underscores the need to increase awareness regarding EC among University students in order to offer them the opportunity that EC provides if other forms of contraceptives are missed. 相似文献
73.
D. Panigrahy P. K. Sahu 《Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine》2016,39(3):783-795
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
74.
75.
76.
77.
Gastroesophageal reflux is the most common benign disorder of the esophagus and laparoscopic Nissen fundoplication has become the standard surgical treatment for its treatment. In our area, where the use of bougie calibration is debatable, postoperative dysphagia is encountered often after this surgery although it is usually not permanent. The aim of this study was to investigate the effect of using a soft silicone tube 39 F in diameter for esophageal calibration during laparoscopic Nissen fundoplication on the incidence of postoperative dysphagia. We divided cases scheduled to undergo laparoscopic Nissen fundoplication between January 2009 and November 2010 into two groups, each consisting 25 patients. Esophageal calibration with a 39 F silicone orogastric tube was used for the first group while there was no operative calibration in the second group. The surgical duration was recorded; the presence and severity of the postoperative dysphagia was calculated by using a dysphagia severity scoring system during the 1-year postoperative follow-up. The dysphagia severity scores were significantly lower in group 1 than group 2 on the postoperative second day and at the end of the first week and first month. We did not find a significant difference at the end of the 6-month and first year. There was also no significant difference regarding surgery duration. The use of a soft orogastric tube 39 F in diameter for esophagus calibration during laparoscopic Nissen fundoplication has significantly decreased the incidence of postoperative transient dysphagia without affecting the duration of surgery. Although dysphagia gradually resolves in the majority of patients, a safe and easy calibration method for its prevention is worth developing, and we believe that the use of our method in larger series could be beneficial. 相似文献
78.
I. Fouzas C. Papanikolaou G. Katsanos N. Antoniadis N. Salveridis K. Karakasi S. Vasileiadou A. Fouza E. Mouloudi G. Imvrios V. Papanikolaou 《Transplantation proceedings》2019,51(2):416-420
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79.
80.