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   735篇
  免费   39篇
  国内免费   12篇
耳鼻咽喉   2篇
儿科学   23篇
妇产科学   22篇
基础医学   80篇
口腔科学   17篇
临床医学   72篇
内科学   215篇
皮肤病学   12篇
神经病学   22篇
特种医学   102篇
外科学   77篇
综合类   31篇
一般理论   2篇
预防医学   33篇
眼科学   11篇
药学   27篇
肿瘤学   38篇
  2021年   12篇
  2020年   4篇
  2019年   9篇
  2018年   10篇
  2017年   9篇
  2016年   8篇
  2015年   19篇
  2014年   23篇
  2013年   25篇
  2012年   35篇
  2011年   36篇
  2010年   33篇
  2009年   28篇
  2008年   23篇
  2007年   33篇
  2006年   28篇
  2005年   21篇
  2004年   25篇
  2003年   13篇
  2002年   10篇
  2001年   15篇
  2000年   12篇
  1999年   13篇
  1998年   28篇
  1997年   25篇
  1996年   36篇
  1995年   19篇
  1994年   17篇
  1993年   19篇
  1992年   7篇
  1991年   9篇
  1990年   12篇
  1989年   14篇
  1988年   18篇
  1987年   15篇
  1986年   16篇
  1985年   12篇
  1984年   10篇
  1983年   14篇
  1982年   8篇
  1981年   13篇
  1980年   7篇
  1979年   2篇
  1978年   5篇
  1977年   7篇
  1976年   8篇
  1975年   4篇
  1973年   3篇
  1972年   3篇
  1971年   2篇
排序方式: 共有786条查询结果,搜索用时 15 毫秒
731.
PURPOSE: To determine if multilayer amniotic membrane transplantation (AMT) is useful in the treatment of corneal perforations, and in particular to assess to what extent efficacy is affected by perforation size. METHODS: Fifteen patients (15 eyes) with corneal perforations of different sizes were divided into 3 groups: group A (microperforation, 6 eyes), group B (0.5-1.5 mm, 4 eyes), and group C (>1.5 mm, 5 eyes). The corneal perforation was caused by autoimmunity-related ulcer (3 eyes), neurotrophic ulcer (9 eyes), infectious keratitis (1 eye), or postkeratoplasty ulcer (2 eyes). Two layers of AM (for microperforations) or 3-4 layers (for the other groups) were trimmed to the size of the ulcer and sutured in place with interrupted 10-0 nylon sutures. In all cases, a bandage contact lens was then applied. RESULTS: Mean epithelialization time was 3.7 weeks (range 2-6). Mean time to recovery of corneal stroma thickness was 10.1 weeks (range 7-15). In all cases, ocular inflammation subsided within 2-5 weeks. The treatment was judged successful in 73% (11/15) of eyes. Three of the 4 unsuccessful treatments were of perforations 3 mm or more in diameter; of the 5 eyes with perforations of more than 1.5 mm in diameter, only 2 were treated successfully. CONCLUSIONS: These results suggest that multilayer AMT is effective for treating corneal perforations with diameter less than 1.5 mm. The technique may be a good alternative to penetrating keratoplasty, especially in acute cases in which graft rejection risk is high.  相似文献   
732.
733.
734.
735.
P53 protein plays an important role in regulation of the cell cycle. Recently, a role in tumour genesis has also been suggested. The protein is induced after various forms of DNA damage. Immunohistochemical detection of p53 protein showed positive cells in human skin after UV- irradiation, in mouse skin after benzo[a]pyrene treatment and in mouse spleen, thymus and bone after gamma-irradiation. However, no staining was found in mouse and rat liver with traditional immunohistochemical staining methods due to the low amount of p53 present. This seriously hampered studies on the role of p53 in hepatocarcinogenesis. We have developed a more sensitive immunohistochemical method for staining of p53 in paraffin-embedded sections of rat liver using microwave irradiation for antigen retrieval, avidin-biotin complexing and tyramide amplification. A strong, specific fluorescence signal for p53 was found in hepatocytes of rats that had received the hepatocarcinogen N-hydroxy-2-acetylaminofluorene; in control liver no such p53 staining was observed. The fluorescence was located in the nucleus of hepatocytes in zone 1 of the liver. This agrees with the fact that N- hydroxy-2-acetylaminofluorene causes cytotoxicity in this zone.   相似文献   
736.
737.
738.
OBJECTIVES: To investigate medical students' self-assessments of their communication skills through medical school related to background factors, curriculum design and perceived medical school stress. METHODS: Medical students at all year levels attending Norwegian universities in the spring of 2003 were mailed the Oslo Inventory of Self-reported Communication Skills (OSISCS) developed by the authors. Of the total number of students (N=3055), 60% responded. One school had a traditional curriculum, the other three ran integrated models. RESULTS: Students assessed their instrumental communication skills to increase linearly year by year, while the relational skills showed a curve-linear trajectory reaching the optimum level half-way into the curriculum. Students attending the traditional school reported lower levels of instrumental skills compared to the students from the integrated schools. In relational skills, a similar difference was maintained half-way into the curriculum, but disappeared towards the end. Perceived medical school stress correlated to the self-reported end point levels of the two types of communication skills. DISCUSSION: The trajectories of self-reported instrumental and relational skills indicate significant variations in facilitating mechanisms between curricula, cognitive processing and perceived medical school stress. CONCLUSIONS: Self-reported instrumental and relational communication skills develop differently in medical students over the years according to the type of curriculum. PRACTICE IMPLICATIONS: Curricula should be evaluated for improvement implementations.  相似文献   
739.
The aim of this study was to characterize the expression of the novel glucose transporter GLUT12 in the fetal membranes of the human placenta. RT-PCR and Western blotting of extracts of amnion and choriodecidua from four normal term placentas identified GLUT12 mRNA and protein expression. In all four samples the signals for GLUT12 were markedly stronger in the choriodecidua than in the amnion, whereas the signals for GLUT1, a glucose transporter know to be expressed in fetal membranes, were similar for the two tissues. In further studies, paraffin sections of fetal membranes were analyzed by immunohistochemistry with GLUT12 and GLUT1-specific polyclonal antibodies. GLUT12 immunoreactivity was localized predominantly to the trophoblast cells in the chorion and to a lesser extent to decidual cells and to epithelial and fibroblast cells of the amnion. GLUT1 was localized to chorionic trophoblast cells and amniotic epithelial and fibroblast cells. GLUT12 expression was predominantly cytoplasmic, whereas GLUT1 was associated with the membrane of the cells. These results show that GLUT12 is expressed in cells of human fetal membranes and suggest that GLUT12 may play a role in the facilitation of glucose transport into these cells.  相似文献   
740.
Long-Term Follow-Up of Iliac Wallstents   总被引:3,自引:0,他引:3  
We evaluated the long-term results of the iliac artery stent placement for the treatment of patients with intermittent claudication. From November 1988 to December 1998, 303 legs were treated with metal stents in 259 patients with iliac occlusive arterial disease in a follow-up study approved by the institutional review board. Stenoses (n = 162) were treated after failed angioplasty and occlusions (n = 141) were treated with primary stent placement. According to Fontaines clinical classification of chronic ischemia, 266 (88%) legs presented stage IIB, 14 (5%) stage III, and 23 (7%) stage IV. In all legs, self-expandable stents (Wallstent) were implanted. The patients were followed up with clinical examination, ankle brachial- index examination measurement and intravenous angiography. The data were analyzed using the univariate analysis (Kaplan-Meier method) and multivariate analysis (Cox proportional model). The primary endpoint of the study was the identification of restenosis or reoclusion of the stenting arterial segment and a secondary endpoint that was an identification of the risk factors of restenosis and reoclusion. The mean ± SD ankle-brachial index pre-, post-procedure, and in the last control was 0.58 ± 0.18, 0.90 ± 0.23, and 0.86 ± 0.24, respectively. Primary cumulative patency rates were 70% ± 4 after 5 years, and 65% ± 5 after 7 years, and secondary patency rates were 92% ± 2 after 5 years, and 87% ± 4 after 9 years. Immediate complications in the first 24 hours appeared in 12 (4%) legs, thrombosis in 5 legs, 3 legs presented with distal embolism, 2 thrombi at the access site and pseudo aneurysm and artery rupture in 1 leg. A patient died in the first 24 hours. Within 30 days after the procedure seven complications, 3 thromboses and 4 stenosis appeared. During follow-up, 42 (16%) patients died of other causes. The main causes of death were cardiac disease (39%), cerebrovascular disease (15%), cancer (7%), respiratory diseases (4%), and death due to accidents (2%), and other causes (9%). In 24% of the cases there was insufficient information to assign a principal cause of death. Thirty-six patients (13%) were lost to follow-up. Complications arose in 54 (18%) legs due to occlusion of the treated segment (29%), and stenosis due to intimal hyperplasia (27%). Thirteen patients required surgical treatment. Primary and secondary patency mean time was 80 ± 3.7 and 102 ± 2.4 months, respectively. We found no significant relation between patency and the quality of run-off, but a small vessel diameter and the female gender were negative predictive factors for failure (proportional hazards model). The use of stents for treatment of iliac artery occlusive disease may be considered an effective method with a low complication rate and acceptable long-term follow-up results.  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