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   2108篇
  免费   230篇
  国内免费   25篇
耳鼻咽喉   21篇
儿科学   83篇
妇产科学   19篇
基础医学   217篇
口腔科学   44篇
临床医学   282篇
内科学   540篇
皮肤病学   34篇
神经病学   112篇
特种医学   152篇
外科学   434篇
综合类   60篇
现状与发展   20篇
预防医学   101篇
眼科学   38篇
药学   83篇
中国医学   2篇
肿瘤学   121篇
  2023年   47篇
  2021年   31篇
  2020年   38篇
  2019年   20篇
  2018年   70篇
  2017年   58篇
  2016年   53篇
  2015年   60篇
  2014年   62篇
  2013年   100篇
  2012年   62篇
  2011年   76篇
  2010年   73篇
  2009年   92篇
  2008年   78篇
  2007年   73篇
  2006年   101篇
  2005年   90篇
  2004年   74篇
  2003年   79篇
  2002年   88篇
  2001年   80篇
  2000年   78篇
  1999年   63篇
  1998年   60篇
  1997年   55篇
  1996年   61篇
  1995年   38篇
  1994年   25篇
  1993年   31篇
  1992年   30篇
  1991年   27篇
  1990年   25篇
  1989年   23篇
  1988年   23篇
  1987年   27篇
  1986年   20篇
  1985年   23篇
  1984年   13篇
  1983年   12篇
  1982年   12篇
  1981年   9篇
  1979年   16篇
  1978年   20篇
  1977年   14篇
  1976年   12篇
  1975年   11篇
  1974年   11篇
  1969年   12篇
  1968年   11篇
排序方式: 共有2363条查询结果,搜索用时 15 毫秒
51.
BACKGROUND: Video-assisted thoracoscopic surgery (VATS) for pulmonary nodules close to the visceral pleura is an established procedure. Different methods have been developed to mark these nodules when resecting small nodules distant to the pleural surface. The possibility of tumor cell spread due to nodule penetration is a major drawback. Furthermore, guide wire-based marking systems have revealed the problem of accidental wire dislocation prior to resection. METHODS: In this study, a new marker system for computed tomography-guided extranodular spiral fixed wire marking (ESFWM) was evaluated in an attempt to maintain tumor integrity while reducing the risk of wire dislocation. RESULTS: Our study included 42 patients with 44 marked nodules. 40 nodules were resected by VATS in 38 of these patients. The remaining 4 patients required conversion to thoracotomy due to adhesions and a non-deflated lung. Wire dislocation and nodule penetration occurred only once. CONCLUSION: The new lung marker system revealed a very low risk of wire dislocation. Peritumoral marking allows the safe resection of subpleural nodules without a risk of tumor cell spread.  相似文献   
52.
Laboratory evolution experiments have led to important findings relating organism adaptation and genomic evolution. However, continuous monitoring of long-term evolution has been lacking for natural systems, limiting our understanding of these processes in situ. Here we characterize the evolutionary dynamics of a lineage of a clinically important opportunistic bacterial pathogen, Pseudomonas aeruginosa, as it adapts to the airways of several individual cystic fibrosis patients over 200,000 bacterial generations, and provide estimates of mutation rates of bacteria in a natural environment. In contrast to predictions based on in vitro evolution experiments, we document limited diversification of the evolving lineage despite a highly structured and complex host environment. Notably, the lineage went through an initial period of rapid adaptation caused by a small number of mutations with pleiotropic effects, followed by a period of genetic drift with limited phenotypic change and a genomic signature of negative selection, suggesting that the evolving lineage has reached a major adaptive peak in the fitness landscape. This contrasts with previous findings of continued positive selection from long-term in vitro evolution experiments. The evolved phenotype of the infecting bacteria further suggests that the opportunistic pathogen has transitioned to become a primary pathogen for cystic fibrosis patients.  相似文献   
53.
After publication of this work [Beenackers et al: Int J Behav Nutr Phys Act 2011, 8:76] it was realized that formula 3 and formula 4 in the Statistical Analysis section of the Methods were incorrectly listed. Since the formulas were correctly used in the analysis, this correction does not affect the results or conclusions of the paper.  相似文献   
54.
55.
56.
57.
58.
59.
To study the relationship between nocturnal blood pressure (BP) variation and spontaneous intracerebral hemorrhage (ICH) among Chinese hypertensive patients and its clinical significance, the authors retrospectively screened 371 patients with primary hypertension (189 patients with ICH, 182 patients without ICH) in Shanghai and analyzed their demographics, clinical information, nocturnal blood pressure variability and medication. Compared with the control group, the levels of blood glucose, triglycerides, and creatinine were significantly increased in the ICH group, along with a marked reduction in nocturnal BP drop (P<.05). Multivariate logistic regression indicated that blood glucose, creatinine, and nocturnal mean arterial pressure were risk factors for ICH, and the magnitude of nocturnal BP drop was negatively related to the risk for ICH. There was no significant difference in the prevalence of reverse dippers between the large hematoma volume group and the small hematoma volume group (χ2=2.529, P=.112), nor among the patients taking angiotensin‐converting enzyme inhibitors, angiotensin receptor blockers, or calcium channel blockers (χ2=1.981, P=.371). Reverse dipping is associated with the risk for ICH, suggesting that appropriate antihypertensive drug and chronotherapy might be effective to normalize the rhythm of abnormal circadian variation in hypertensive patients.  相似文献   
60.
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