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   781篇
  免费   54篇
儿科学   44篇
妇产科学   7篇
基础医学   84篇
口腔科学   14篇
临床医学   90篇
内科学   189篇
皮肤病学   60篇
神经病学   14篇
特种医学   140篇
外科学   67篇
综合类   16篇
预防医学   34篇
眼科学   12篇
药学   30篇
肿瘤学   34篇
  2022年   14篇
  2021年   23篇
  2019年   9篇
  2018年   18篇
  2017年   10篇
  2016年   13篇
  2015年   19篇
  2014年   17篇
  2013年   43篇
  2012年   19篇
  2011年   22篇
  2010年   32篇
  2009年   30篇
  2008年   14篇
  2007年   12篇
  2006年   19篇
  2005年   14篇
  2004年   14篇
  2003年   11篇
  2002年   12篇
  2001年   18篇
  2000年   11篇
  1999年   15篇
  1998年   32篇
  1997年   30篇
  1996年   32篇
  1995年   27篇
  1994年   28篇
  1993年   23篇
  1992年   14篇
  1991年   13篇
  1990年   5篇
  1989年   23篇
  1988年   17篇
  1987年   20篇
  1986年   13篇
  1985年   12篇
  1984年   9篇
  1983年   9篇
  1982年   10篇
  1981年   12篇
  1979年   6篇
  1978年   8篇
  1977年   13篇
  1976年   9篇
  1975年   11篇
  1973年   7篇
  1972年   5篇
  1971年   9篇
  1968年   5篇
排序方式: 共有835条查询结果,搜索用时 15 毫秒
61.
Background Perceived age is important to women and is a primary driver for topical product use and facial cosmetic surgery. Changes in facial features and biophysical skin parameters with chronological age and their associations with perceived age have not been described in Asian populations. Objective To investigate the relationship between biophysical properties of the skin, visual features of skin ageing and perceived facial age in Chinese women. Methods Facial photographs were collected of 250 Chinese women, aged 25–70 years in Shanghai, China. The perceived facial age was determined and related to the chronological age for each participant and to a range of visual assessments of skin appearance and objective biophysical measurements of the skin. The profile of changes in these parameters with age was investigated together with the differences in those parameters for women judged to look younger than their chronological age and those judged to look older than their chronological age. Results Large discrepancies in perceived age (up to 29 years) were found in women of the same chronological age. Each objective skin measure and visual assessment parameter had a stronger correlation with perceived age than with chronological age. The strongest relationships to perceived age were for wrinkles and hyperpigmentation. Skin colour, hydration and trans‐epidermal water loss (TEWL) had weaker associations with perceived age. Women judged to look older than their chronological age had significantly higher scores than those judged to look younger for coarse wrinkles and hyperpigmentation across all age groups. The appearance differences between these groups were evident in composite facial images of the same average chronological age. Conclusions We have identified the skin attributes which differ with perceived age in Chinese women. Perceived age is a better measure of the biological age of facial skin than is chronological age in this population.  相似文献   
62.
63.
64.
BACKGROUND: Antegrade femoral access is fraught by technical challenges and steeper learning curve, in comparison with retrograde contralateral femoral access. We appraised learning curve, complications, and technical aspects inherent in the adoption of antegrade approach. METHODS: Consecutive cases in which antegrade access was attempted by a cardiologist experienced in retrograde access, but inexperienced in antegrade, under supervision of an operator with anterograde expertise, were collected. The primary end-point was the occurrence of antegrade access failure or local complications. Major complications were defined as those life-threatening, requiring transfusion, percutaneous, or surgical repair. RESULTS: Anterograde access was attempted in 120 patients. The primary end-point occurred in 14 (11.6%) cases, but according to the learning curve, in 12 (20%) for first 60 cases vs 2 (3.3%) for the last 60 cases (P = 0.008). Access failure in the hands of the in-training operator was similarly found in all cases but one during the first 60 cases. No major complications occurred, while minor complications were found in 9 (7.5%) patients, again with all but two of them occurring in the first 60 cases. These included peri-adventitial extravasation in 8 patients (6.7%), and perforation of a small branch in one (0.8%); all these complications were conservatively and successfully managed. Obesity was the only significant predictor of access failure/complication (P = 0.004). CONCLUSIONS: This work, the first to report on the learning curve of the antegrade approach, supports the feasibility and safety of this access site even for an in-training operator, if supervised. A minimum caseload of 60 procedures is likely needed to master this technique.  相似文献   
65.
AIMS: The role of aspirin in patients with coronary artery disease (CAD) is well established, yet patients happen to discontinue aspirin according to physician's advice or unsupervised. We thus undertook a systematic review to appraise the hazards inherent to aspirin withdrawal or non-compliance in subjects at risk for or with CAD. METHODS AND RESULTS: Electronic databases were systematically searched (updated January 2006). Study designs, patient characteristics, and outcomes were abstracted. Pooled estimates for odds ratios (OR) were computed according to random-effect methods. From the 612 screened studies, six were selected (50,279 patients). One study (31,750 patients) focused on adherence to aspirin therapy in the secondary prevention of CAD, two studies (2594) on aspirin discontinuation in acute CAD, two studies (13,706) on adherence to aspirin therapy before or shortly after coronary artery bypass grafting, and another (2229) on aspirin discontinuation among patients undergoing drug-eluting stenting. Overall, aspirin non-adherence/withdrawal was associated with three-fold higher risk of major adverse cardiac events (OR=3.14 [1.75-5.61], P=0.0001). This risk was magnified in patients with intracoronary stents, as discontinuation of antiplatelet treatment was associated with an even higher risk of adverse events (OR=89.78 [29.90-269.60]). CONCLUSION: Non-compliance or withdrawal of aspirin treatment has ominous prognostic implication in subjects with or at moderate-to-high risk for CAD. Aspirin discontinuation in such patients should be advocated only when bleeding risk clearly overwhelms that of atherothrombotic events.  相似文献   
66.
The instability of atherosclerotic plaque is partly determined by local factors, but systemic factors such as infection, inflammation, autoimmunity or genes might also be important. We aimed to analyze whether patients with acute myocardial infarction (AMI) might have a higher proportion of unstable plaques in the carotid arteries compared with patients who had had no acute coronary events. METHODS: Sixty-nine consecutive patients with AMI (Group 1) and 95 patients without acute coronary events (Group 2) had carotid artery duplex ultrasounds. Carotid atherosclerosis was quantified by number of plaques in the two carotid arteries, intimal media thickening and degree of maximal stenosis. According to their morphology, plaques were divided into stable (fibrocalcific) and unstable (soft and/or not homogeneous). RESULTS: The two groups did not differ as regards age (66+/-8 vs. 68+/-19; p=0.3), female sex (13% vs. 21%; p=0.3), mean number of carotid plaques (2.8+/-1 vs. 2.5+/-2; p=0.2), degree of stenosis (59+/-2% vs. 36+/-1%; p=0.2) or intimal media thickening (1.04+/-0.2 vs. 1.06+/-0.2; p=0.8). However, Group 1 pts more frequently had unstable carotid plaques compared with Group 2 (43% vs. 15%; p=0.004), and had a greater number of unstable carotid plaques (0.51+/-0.6 vs. 0.16+/-0.4: p<0.0001) and a higher ratio of unstable to stable plaque (19% vs. 8%; p=0.005). In the overall population, logistic regression analysis showed that after adjustment for degree of maximal stenosis, the presence of coronary artery event (AMI pts) predicted the presence of unstable carotid plaque (OR: 4.3 95% CI: 2.0-9.2; p=0.0002). CONCLUSION: Patients with unstable coronary artery disease expressed clinically as AMI, frequently had unstable atherosclerotic plaques in other arterial sites such as carotid arteries. This finding supports the hypothesis that plaque instability might reflect a systemic process.  相似文献   
67.
68.
69.
70.
Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor superfamily of proteins. Although initial data illustrated the key role that OPG plays in bone turnover, numerous recent reports indicate that OPG is also an important factor in inflammatory pathways and tumor cell survival. OPG contributes directly to inflammatory processes and has been evaluated as a novel non‐invasive biomarker of gut inflammation. Furthermore, OPG affects cell turn‐over, differentiation, death, and survival via extracellular pathways, correlating with worse prognosis in inflammatory bowel diseases and several gastrointestinal carcinomas. It is now clear that OPG has multiple functions and characteristics. This review gives an overview of OPG, highlights its roles in different extracellular pathways, and outlines how OPG could be used as a novel non‐invasive biological marker in inflammatory bowel diseases and gastrointestinal carcinomas.  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