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   2866篇
  免费   148篇
  国内免费   21篇
耳鼻咽喉   28篇
儿科学   90篇
妇产科学   45篇
基础医学   295篇
口腔科学   262篇
临床医学   251篇
内科学   583篇
皮肤病学   19篇
神经病学   188篇
特种医学   90篇
外科学   482篇
综合类   21篇
一般理论   1篇
预防医学   358篇
眼科学   14篇
药学   222篇
中国医学   1篇
肿瘤学   85篇
  2023年   8篇
  2022年   8篇
  2021年   41篇
  2020年   33篇
  2019年   46篇
  2018年   51篇
  2017年   41篇
  2016年   45篇
  2015年   41篇
  2014年   72篇
  2013年   155篇
  2012年   156篇
  2011年   174篇
  2010年   92篇
  2009年   78篇
  2008年   187篇
  2007年   200篇
  2006年   180篇
  2005年   204篇
  2004年   192篇
  2003年   201篇
  2002年   183篇
  2001年   41篇
  2000年   25篇
  1999年   57篇
  1998年   49篇
  1997年   44篇
  1996年   38篇
  1995年   22篇
  1994年   25篇
  1993年   29篇
  1992年   27篇
  1991年   28篇
  1990年   21篇
  1989年   15篇
  1988年   14篇
  1987年   13篇
  1986年   8篇
  1985年   18篇
  1984年   27篇
  1983年   14篇
  1982年   21篇
  1981年   23篇
  1980年   14篇
  1979年   11篇
  1978年   12篇
  1976年   7篇
  1975年   6篇
  1974年   6篇
  1971年   5篇
排序方式: 共有3035条查询结果,搜索用时 8 毫秒
71.
72.
Odontology - The aim was to explore the fracture-behavior, survival and marginal-microgaps within the root-canal of immature anterior teeth restored with different fiber-reinforced post-core...  相似文献   
73.
74.
Rats chronically fed ethanol developed liver injury only if they also received low doses of the alcohol dehydrogenase inhibitor, 4-methylpyrazole, suggesting that the consistency of the influence of ethanol and its metabolism, rather than the level of acetaldehyde or the degree of the metabolic effects, contributes to the pathogenesis of alcoholic liver damage.  相似文献   
75.
Glycoprotein VI is a platelet collagen receptor binding to subendothelial collagen after a rupture of an atherosclerotic plaque. The GPVI gene is polymorphic with several SNPs and the T13254C polymorphism predicting amino acid substitution (serine to proline) has been associated with the risk of MI in a preliminary study. We studied the association of the GPVI T13254C with fatal myocardial infarction (MI) and coronary artery disease among the 300 men of the Helsinki Sudden Death Study (HSDS). Genotype frequencies were 77.9% for TT, 20.7% for CT and 1.4% for CC. We found a significant association (P = 0.02) between the C-allele carriers (CT or CC) and coronary thrombosis (OR 2.5, 95% CI: 1.05-6.2). There was also a tendency (P = 0.07) for an association between the C-allele and acute myocardial infarction (AMI) (OR 2.2). The average area of complicated coronary lesions was also significantly (P = 0.01) larger in carriers compared to non-carriers of the C-allele. Our findings support previous results on the role of this GPVI polymorphism, or another linked polymorphism, as a possible predictor of the risk of coronary thrombosis.  相似文献   
76.
We study the performance of stochastic local search algorithms for random instances of the K-satisfiability (K-SAT) problem. We present a stochastic local search algorithm, ChainSAT, which moves in the energy landscape of a problem instance by never going upwards in energy. ChainSAT is a focused algorithm in the sense that it focuses on variables occurring in unsatisfied clauses. We show by extensive numerical investigations that ChainSAT and other focused algorithms solve large K-SAT instances almost surely in linear time, up to high clause-to-variable ratios alpha; for example, for K = 4 we observe linear-time performance well beyond the recently postulated clustering and condensation transitions in the solution space. The performance of ChainSAT is a surprise given that by design the algorithm gets trapped into the first local energy minimum it encounters, yet no such minima are encountered. We also study the geometry of the solution space as accessed by stochastic local search algorithms.  相似文献   
77.
78.
Accurate and reliable data on alcohol consumption and the production of alcoholic beverages are available mainly for western industrial countries. The consumption of each beverage type is highly concentrated in regions in which they are part of an established drinking culture. The rise of such a culture is based on both socio-economic and natural conditions of the production of the respective beverage type. Of the three beverage groups which are distinguished by international statistics, production and consumption of wine is most clearly concentrated in certain wine areas, whereas the prevalence of beer is independent of the production of grain. Spirits are mostly consumed in countries where also grain production is voluminous. This is interpreted so that a large part of present day beer consumption takes place in new circumstances and is not tied to old traditions and beer drinking cultures. The consumption of wine is still traditional to a much greater degree.  相似文献   
79.
80.
In the present study we aimed to investigate the incidence and predictors of spirometry based airway obstruction in a representative population-based sample. Altogether 3,863 subjects, 1,651 males and 2,212 females aged ≥30 years had normal spirometry in year 2000. Fifty-three percent of them were never and 23% current smokers. A re-spirometry was performed 11 years later. Several characteristics, such as level of education, use of alcohol, physical activity, diet using Alternate healthy eating (AHEI) index, body mass index, circumwaist, sensitive C reactive protein (CRP) and cotinine of the laboratory values and co-morbidities including asthma, allergic rhinitis, sleep apnoea and chronic bronchitis, as potential risk factors for airway obstruction were evaluated. Using forced expiratory volume in one second/ forced vital capacity below the lower limit of normal, we observed 124 new cases of airway obstruction showing a cumulative 11-year incidence of 3.2% and corresponding to an incidence rate of 5.6/1,000 per year (PY). The incidence rate was higher in men than in women (6.3/1,000 PY vs. 5.0/1,000 PY, respectively). The strongest risk factors were current smoking (Odds ratio [OR] 2.5) and previously diagnosed asthma (OR 2.1). Sensitive CRP associated with the increased risk and high AHEI index with the decreased risk of airway obstruction. Using the similar study approach our findings on the incidence of airway obstruction are in line with the previously published figures in Europe. We were able to confirm the recent findings on the protective effect of healthy diet.  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