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   171253篇
  免费   6783篇
  国内免费   341篇
耳鼻咽喉   3034篇
儿科学   6440篇
妇产科学   4349篇
基础医学   24122篇
口腔科学   4776篇
临床医学   12764篇
内科学   31236篇
皮肤病学   4668篇
神经病学   15714篇
特种医学   8904篇
外国民族医学   24篇
外科学   28363篇
综合类   1118篇
一般理论   37篇
预防医学   8062篇
眼科学   4601篇
药学   11865篇
中国医学   345篇
肿瘤学   7955篇
  2021年   1219篇
  2020年   1106篇
  2019年   1295篇
  2018年   2841篇
  2017年   2347篇
  2016年   3272篇
  2015年   3639篇
  2014年   3831篇
  2013年   5382篇
  2012年   8310篇
  2011年   7739篇
  2010年   4618篇
  2009年   3707篇
  2008年   7686篇
  2007年   8547篇
  2006年   8594篇
  2005年   8970篇
  2004年   8549篇
  2003年   8484篇
  2002年   8336篇
  2001年   6246篇
  2000年   6283篇
  1999年   5441篇
  1998年   1624篇
  1997年   1326篇
  1996年   1026篇
  1995年   830篇
  1994年   774篇
  1992年   2408篇
  1991年   2343篇
  1990年   2309篇
  1989年   2139篇
  1988年   1878篇
  1987年   1880篇
  1986年   1736篇
  1985年   1663篇
  1984年   1314篇
  1983年   1051篇
  1979年   1406篇
  1978年   1033篇
  1977年   877篇
  1976年   755篇
  1975年   1095篇
  1974年   1135篇
  1973年   1036篇
  1972年   1030篇
  1971年   1006篇
  1970年   890篇
  1969年   835篇
  1968年   806篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
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   
34.
35.

Background Context

The concept of dynamic stabilization (DS) of the lumbar spine for treatment of degenerative instability has been introduced almost two decades ago. Dynamic stabilization follows the principle of controlling movement in the coronal plane by providing load transfer of the spinal segment without fusion and, at the same time, reducing side effects such as adjacent segment disease (ASD). So far, only little is known about revision rates after DS due to ASD and screw loosening (SL).

Purpose

The present study aimed to evaluate the longitudinal revision rates following dynamic pedicle screw stabilization in the lumbar spine and to determine specific risk factors predictive for ASD, SL, and overall reoperation in a large cohort with considerable follow-up.

Design

We carried out a post hoc analysis of a prospectively collected database in a level I spine center.

Patients Example

The patient sample comprised 283 (151 female/132 male) consecutive patients suffering from painful degenerative lumbar segmental instability with or without spinal stenosis who underwent DS of the lumbar spine (Ulrich Cosmic, Ulrich Medical, Ulm, Germany) between January 2008 and December 2011.

Outcome Measures

Longitudinal reoperation rate and risk factors predictive for revision surgery were evaluated.

Methods

We analyzed the longitudinal reoperation rate due to ASD and SL and overall reoperation. Risk factors such as age, gender, body mass index, lumbar lordosis (LL), number of segments, and number of previous surgeries were taken into account. Regular and mixed model logistic regressions were performed to determine risk factors for revision surgery on a patient and on a screw level.

Results

The mean age was 65.7±10.2 years (range 31–88). One hundred thirty-two patients were stabilized in 1 segment, 134 in 2 segments, 15 in 3 segments, and 2 patients in 4 segments. Reoperation rate for ASD and SL after 1 year was 7.4 %, after 2 years was 15.0%, and after a mean follow-up of 51.4±15 months was 22.6%. Reasons for revision were SL in 19 cases (6.6%), ASD in 39 cases (13.7%), SL and ASD in 6 cases, hematoma in 2 cases (0.7%), cerebrospinal fluid fistulae in 3 cases (1.1%), infection in 6 cases (2.1%), and implant failure in 1 case (0.4%). The patients' age, the number of stabilized segments, and the number of previous surgeries and postoperative LL had a significant influence on the probability for revision surgery.

Conclusions

Reoperation rates after DS of the lumbar spine are comparable with rigid fixations. The younger the patient and the more segments are involved, the lower the LL and the more previous surgeries were found, the higher was the risk of revision. Risk of revision was almost twice as high in men compared with women. We therefore conclude that for clear clinical indication and careful evaluation of preoperative imaging data, DS using the Cosmic system seems to be a possible option. The presented data will help to further tailor indication and patient selection.  相似文献   
36.
37.
38.
39.
40.
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