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   1276篇
  免费   85篇
  国内免费   15篇
耳鼻咽喉   4篇
儿科学   44篇
妇产科学   11篇
基础医学   209篇
口腔科学   13篇
临床医学   71篇
内科学   261篇
皮肤病学   26篇
神经病学   73篇
特种医学   189篇
外科学   260篇
综合类   8篇
预防医学   29篇
眼科学   21篇
药学   95篇
中国医学   12篇
肿瘤学   50篇
  2023年   7篇
  2022年   13篇
  2021年   46篇
  2020年   12篇
  2019年   32篇
  2018年   40篇
  2017年   30篇
  2016年   32篇
  2015年   78篇
  2014年   77篇
  2013年   83篇
  2012年   122篇
  2011年   133篇
  2010年   75篇
  2009年   62篇
  2008年   97篇
  2007年   89篇
  2006年   61篇
  2005年   60篇
  2004年   50篇
  2003年   55篇
  2002年   31篇
  2001年   19篇
  2000年   18篇
  1999年   4篇
  1998年   13篇
  1997年   3篇
  1996年   6篇
  1995年   4篇
  1994年   4篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1989年   3篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
排序方式: 共有1376条查询结果,搜索用时 296 毫秒
81.
82.
Hepatobiliary complications, such as stone recurrence, recurrent cholangitis, liver abscess, secondary biliary cirrhosis, and cholangiocarcinoma may occur after treatment for hepatolithiasis. However, few previous studies have addressed the risk factors and long-term outcomes after initial treatment. Eighty-five patients with newly diagnosed hepatolithiasis, actively treated for hepatolithiasis, constituted the cohort of this retrospective study. Patients were treated by hepatectomy or nonoperative percutaneous transhepatic cholangioscopic lithotomy. Long-term complications, such as recurrent cholangitis, liver abscess, secondary biliary cirrhosis, and cholangiocarcinoma, and their relationships with clinical parameters were analyzed. The mean follow-up period was 57.4 months. The overall hepatobiliary complication rate after the treatment was 17.6%. Multivariate analysis of suspected risk factors showed that complications were associated with age (HR, 1.046; CI, 1.006-1.089), bile duct stricture (HR, 4.894; CI, 1.295-18.495), and residual stones (HR, 3.482; CI, 1.214-9.981). In conclusion, several long-term hepatobiliary complications occur after hepatolithiasis treatment, and regular observation is necessary in patients with concomitant biliary stricture or residual stones.  相似文献   
83.
84.
85.
Mun GH  Song YH  Bang SI 《Annals of plastic surgery》2002,49(4):337-43; discussion 344
Full exposure of the medial orbital wall for fracture repair poses difficulty with traditional approaches except coronal incision, especially in cases of wide fracture. The endoscopic-assisted approach with limited incision has been introduced. The authors used the endoscopically assisted transconjunctival approach in 21 cases: 15 isolated medial orbital wall fractures and 6 cases of concomitant floor fractures. Through the medial transconjunctival slit incision, repair of the fracture using calvarial bone graft was undertaken with the aid of an endoscope. All patients recovered without any eye symptoms including clinically notable enophthalmos, but one immediate revisional operation was needed because of a displaced bone graft. Otherwise, the desired position of the graft was confirmed via computed tomography. The endoscopically assisted transconjunctival approach to the orbital medial wall provides improved surgical exposure of the most posterior and superior aspects of the fracture site, enabling more accurate reduction of orbital soft tissue and placement of bone grafts.  相似文献   
86.
Lead and noise, via different mechanisms, may damage hearing ability, and, in some cases, cause severe and irreversible damage. To explore possible independent and synergistic effects of lead and noise on auditory function, the authors conducted a cross-sectional study in two lead-battery manufacturing factories. Lead and noise were the two most common sources of occupational exposures in the factories. Blood lead level, ambient lead concentration, noise exposure level, and hearing thresholds of 339 lead-battery workers-including clerical and managerial staffs-were measured. The authors obtained demographics and working histories via an interview-based structured questionnaire. A total of 220 lead-battery workers were exposed to high levels of lead and noise; their average blood lead concentration was 56.9 microg/dl, and their average noise exposure level was 86.0 dBALeq. Multivariate analysis, in which possible risk factors of hearing ability were considered, demonstrated a significant correlation between a high, long-term lead exposure index (defined by duration of employment and ambient lead concentration) and decreased hearing ability. In contrast, such a correlation between short-term lead exposure (defined by blood lead level) and hearing ability was not significant. Furthermore, neither noise exposure level alone nor the interaction between noise exposure level and short- or long-term lead exposure was correlated significantly with hearing ability. The present study raises an important, but typically ignored, issue: lead exposure might precipitate a more severe auditory than noise-exposure effect. The preservation of workers' hearing ability requires that preventive measures be taken against noise exposure, which is as essential as measures taken against lead exposure.  相似文献   
87.
88.
A kanamycin producer,Streptomyces kanamyceticus IFO 13414 is highly resistant to kanamycin. Cloning of the kanamycin resistance genes inS. lividans 1326 with pIJ702 gave several kanamycin resistant transformants. Two transformants,S. lividans SNUS 90041 andS. lividans SNUS 91051 showed similar resistance patterns to various aminoglycoside antibiotics. Gene mapping experiments revealed that plasmids pSJ5030 and pSJ2131 isolated from the transformants have common resistant gene fragments. Subcloning of pSJ5030 gave a 1.8 Kb gene fragment which showed resistance to kanamycin. Cell free extracts ofS. lividans SNUS 90041,S. lividans SNUS 91051 and subclone aS. lividans SNUS 91064 showed kanamycin acetyltransferase activity. The detailed gene map is included.  相似文献   
89.
The cross-section of the mainstem bronchi is not completely round. For preoperative selection of a double-lumen endobronchial tube size, it may be necessary to measure the mediolateral and the anteroposterior bronchial diameters, which can be measured respectively on chest radiograph and computed tomography. With Internal Review Board approval and patients' informed consent, 105 elective thoracic surgical patients who needed left-sided double-lumen tubes were enrolled. Double-lumen tube size was selected depending on the arithmetic mean of the mediolateral and anteroposterior bronchial diameters. Moreover, the outer diameters of the bronchial tube should be smaller than both mediolateral and anteroposterior diameters. The recommended bronchial diameter for each double-lumen tube size was chosen so that the mean of the two bronchial diameters was 0 to 2.0 mm larger than the upper limit of 95% confidence interval of the averaged outer diameter of the bronchial tube of the selected double-lumen tube. In no case was the predicted double-lumen tube size inappropriate. Generally, anteroposterior bronchial diameters appeared to be different from mediolateral diameters (P=0.001). The double-lumen tube size to be selected based on only one bronchial diameter was different from the one selected based on two perpendicularly measured bronchial diameters in 54.3% of patients (57/105). Preoperative selection of the double-lumen tube size based on the anteroposterior, mediolateral and mean bronchial diameters seems to be useful in that this may obviate the need to change an inappropriately sized double-lumen tube and may be helpful in reducing the related complications.  相似文献   
90.
To reduce the possibility of cardiac tamponade, a rare but lethal complication of central venous catheters, the tip of the central venous catheter should be located above the cephalic limit of the pericardial reflection, not only above the superior vena cava-right atrium junction. This study was performed to measure the superior vena cava lengths above and below the pericardial reflection in cardiac surgical patients. Cardiac surgical patients (n = 61; 27 male), whose age [mean +/- SD (range)] was 47 +/- 15 (15-75) years, were studied. The intrapericardial and extrapericardial lengths, and the length of the medial duplicated part were measured separately. The whole vertical lengths of the superior vena cava on either side were calculated respectively by adding the intra-and extrapericardial and medial duplication lengths. The lateral extrapericardial was 29.1 +/- 6.5 (Mean +/- SD) (9-49) mm (range), and lateral extrapericardial length was 32.6 +/- 6.9 (20-53) mm. The medial extrapericardial length was 23.3 +/- 5.0 (11-39) mm, medical duplicated length was 7.2 +/- 3.3 (4-20) mm, and medial intrapericardial was 28.3 +/- 7.0 (20-52) mm. The averaged superior vena cava length of both sides was 60.3 +/- 9.0 (44.5-90) mm. Almost half of the superior vena cava was found to be within the pericardium and half out. This information may be helpful in deciding how far a central venous catheter should be withdrawn beyond the superior vena cava-right atrial junction during right atrial electrocardiographic guided insertion, and in the prediction of optimal central venous catheter insertion depth.  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