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   2611篇
  免费   163篇
  国内免费   24篇
耳鼻咽喉   28篇
儿科学   40篇
妇产科学   83篇
基础医学   339篇
口腔科学   177篇
临床医学   198篇
内科学   625篇
皮肤病学   106篇
神经病学   165篇
特种医学   30篇
外科学   378篇
综合类   24篇
预防医学   219篇
眼科学   35篇
药学   162篇
中国医学   14篇
肿瘤学   175篇
  2023年   21篇
  2022年   17篇
  2021年   97篇
  2020年   48篇
  2019年   70篇
  2018年   86篇
  2017年   68篇
  2016年   48篇
  2015年   75篇
  2014年   126篇
  2013年   119篇
  2012年   225篇
  2011年   234篇
  2010年   135篇
  2009年   113篇
  2008年   210篇
  2007年   197篇
  2006年   165篇
  2005年   145篇
  2004年   162篇
  2003年   123篇
  2002年   126篇
  2001年   16篇
  2000年   10篇
  1999年   15篇
  1998年   14篇
  1997年   27篇
  1996年   14篇
  1995年   10篇
  1994年   6篇
  1993年   5篇
  1992年   8篇
  1991年   5篇
  1990年   3篇
  1989年   6篇
  1988年   3篇
  1987年   2篇
  1985年   2篇
  1984年   10篇
  1983年   6篇
  1982年   5篇
  1981年   3篇
  1979年   3篇
  1976年   4篇
  1974年   1篇
  1973年   1篇
  1965年   1篇
  1964年   1篇
  1944年   2篇
  1934年   1篇
排序方式: 共有2798条查询结果,搜索用时 15 毫秒
101.
102.
103.
The use of a 2-stage inlay technique in atrophic posterior mandibles with more than 10-mm thickness and less than 5-mm height above the inferior alveolar nerve is described. The first surgical procedure was a basic corticotomy of the buccal and lingual bone. One month later, a complete inlay procedure was performed. Computed tomography and conventional radiography showed a mean vertical bone gain of 11.5 mm. This 2-stage inlay technique avoids the use of chisels to complete bone osteotomy and reduces postsurgical nerve disturbances in atrophic posterior mandibles. This technique reduces intraprocedure and postoperative patient discomfort.  相似文献   
104.
105.

Introduction

The frequency of aac(6′)-Ib-cr gene in ESBL-producing strains of Klebsiella pneumoniae and Escherichia coli is unknown, in Chile.

Methodology

The aac(6′)-Ib and aac(6’)-Ib-cr genes were investigated using polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and sequencing, in strains isolated from 10 Chilean hospitals between 2008-2009.

Results

The aac(6’)-Ib-cr gene was detected in 54% of K. pneumoniae and 74% of E. coli strains. The CIM50 of CIP was higher among strains harboring aac(6’)-Ib-cr, 8 times higher in K. pneumoniae and 4 times higher in E. coli. Moreover, both aac(6’)-Ib and aac(6’)-Ib-cr were simultaneously found in 13 K. pneumoniae and 3 E. coli isolates.

Conclusion

This is the first report of aac(6’)-Ib-cr in ESBL-producing strains of K. pneumoniae and E. coli isolated from in-patients in Chilean hospitals located along an area of more than 2,800 Km.  相似文献   
106.
107.
Major depressive disorder is prevalent worldwide, and only about half of those affected will experience no further episodes or symptoms. Additionally, depressive symptoms can be challenging to identify, with many patients going undiagnosed despite a wide variety of available treatment options. Antidepressants are the cornerstone of depression treatment; however, a large number of factors must be considered in selecting the treatment best suited to the individual. To help support physicians in this process, international and national treatment guidelines have been developed. This review evaluates the current use of antidepressant treatment for major depressive disorder in six Asian countries (China, Korea, Malaysia, Philippines, Taiwan, and Thailand). No remarkable differences were noted between Asian and international treatment guidelines or among those from within Asia as these are adapted from western guidelines, although there were some local variations. Importantly, a shortage of evidence‐based information at a country level is the primary problem in developing guidelines appropriate for Asia, so most of the guidelines are consensus opinions derived from western research data utilized in western guidelines. Treatment guidelines need to evolve from being consensus based to evidence based when evidence is available, taking into consideration cost/effectiveness or cost/benefit with an evidence‐based approach that more accurately reflects clinical experience as well as the attributes of each antidepressant. In everyday practice, physicians must tailor their treatment to the patient's clinical needs while considering associated external factors; better tools are needed to help them reach the best possible prescribing decisions which are of maximum benefit to patients.  相似文献   
108.

OBJECTIVE:

It is essential to identify a serological marker of injury in order to study the pathophysiology of intestinal ischemia reperfusion. In this work, we studied the evolution of several serological markers after intestinal ischemia reperfusion injury in rats. The markers of non-specific cell damage were aspartate aminotransferase, alanine aminotransaminase, and lactic dehydrogenase, the markers of inflammation were tumor necrosis factor alpha, interleukin-6, and interleukin-1 beta, and the markers of intestinal mucosal damage were intestinal fatty acid binding protein and D-lactate. We used Chiús classification to grade the histopathological damage.

METHODS:

We studied 35 Wistar rats divided into groups according to reperfusion time. The superior mesenteric artery was clamped for 30 minutes, and blood and biopsies were collected at 1, 3, 6, 12, 24, and 48 hours after reperfusion. We plotted the mean ± standard deviation and compared the baseline and maximum values for each marker using Student''s t-test.

RESULTS:

The maximum values of interleukin-1 beta and lactic dehydrogenase were present before the maximal histopathological damage. The maximum tumor necrosis factor alpha and D-lactate expressions coincided with histopathological damage. Alanine aminotransaminase and aspartate aminotransferase had a maximum expression level that increased following the histopathological damage. The maximum expressions of interluken-6 and intestinal fatty acid binding protein were not significantly different from the Sham treated group.

CONCLUSION:

For the evaluation of injury secondary to acute intestinal ischemia reperfusion with a 30 minute ischemia period, we recommend performing histopathological grading, quantification of D-lactate, which is synthesized by intestinal bacteria and is considered an indicator of mucosal injury, and quantification of tumor necrosis factor alpha as indicators of acute inflammation three hours after reperfusion.  相似文献   
109.
Purpose: The aim of this study was to investigate the relationship between surgical techniques and implant macro‐design (self‐tapping/non‐self‐tapping) for the optimization of implant stability in the low‐density bone present in the posterior maxilla using resonance frequency analysis (RFA). Materials and Methods: A total of 102 implants were studied. Fifty‐six self‐tapping BlueSkyBredent® (Bredent GmbH&Co.Kg®, Senden, Germany) and 56 non‐self‐tapping Standard Plus Straumann® (Institut Straumann AG®, Waldenburg, Switzerland) were placed in the posterior segment of the maxilla. Implants of both types were placed in sites prepared with either lateral bone‐condensing or with bone‐drilling techniques. Implant stability measurements were performed using RFA immediately after implant placement and weekly during a 12‐week follow‐up period. Results: Both types of implants placed after bone condensing achieved significantly higher stability immediately after surgery, as well as during the entire 12‐week observation period compared with those placed following bone drilling. After bone condensation, there were no significant differences in primary stability or in implant stability after the first week between both implant types. From 2 to 12 postoperative weeks, significantly higher stability was shown by self‐tapping implants. After bone drilling, self‐tapping implants achieved significantly higher stability than non‐self‐tapping implants during the entire follow‐up period. Conclusions: The outcomes of the present study indicate that bone drilling is not an effective technique for improving implant stability and, following this technique, the use of self‐tapping implants is highly recommended. Implant stability optimization in the soft bone can be achieved by lateral bone‐condensing technique, regardless of implant macro‐design.  相似文献   
110.
Purpose: The aim of this study was to evaluate the early bone response of tapered and cylindrical root form implants with two different surface treatments in fresh extraction sockets after 4 and 8 weeks. Materials and Methods: Surface treatments and implant design comprised (n = 9 each): tapered with dual acid‐etched surface; tapered with dual acid‐etched and sandblasted surface (T DAE SB); cylindrical with dual acid‐etched surface (C DAE); and cylindrical with dual acid‐etched and sandblasted surface (C DAE SB). Implants were placed in the distal sockets of mandibular premolars (2P2,3P3,4P4) of six beagle dogs, remaining in vivo for 4 and 8 weeks. After sacrifice, the implants were subjected to torque to the point of interface fracture and subsequently nondecalcified for histomorphological study. Statistical analysis was performed by a General Linear Model (GLM) analysis of variance model with a significance level of 5%. Results: Torque to interface fracture was significantly greater for the C DAE SB group than for the other groups (p < .001). Histomorphological analysis showed woven bone formation around all implant surfaces at 4 weeks and its replacement by lamellar bone at 8 weeks. Study time (4 or 8 weeks) did not affect torque measures. Conclusions: The double acid‐etched and sandblasted sample surface increased early bone biomechanical fixation of both cylindrical and tapered root form implants. The cylindrical root form implants showed higher torque to interface fracture values when compared with the tapered root form implants. The C DAE SB surface group showed the highest biomechanical fixation values (p < .001).  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