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   2910篇
  免费   173篇
  国内免费   3篇
儿科学   124篇
妇产科学   44篇
基础医学   314篇
口腔科学   38篇
临床医学   450篇
内科学   669篇
皮肤病学   77篇
神经病学   255篇
特种医学   334篇
外科学   188篇
综合类   26篇
预防医学   233篇
眼科学   88篇
药学   103篇
中国医学   2篇
肿瘤学   141篇
  2021年   17篇
  2019年   31篇
  2018年   48篇
  2017年   25篇
  2016年   31篇
  2015年   33篇
  2014年   48篇
  2013年   72篇
  2012年   84篇
  2011年   75篇
  2010年   100篇
  2009年   84篇
  2008年   113篇
  2007年   126篇
  2006年   118篇
  2005年   96篇
  2004年   90篇
  2003年   113篇
  2002年   73篇
  2001年   68篇
  2000年   53篇
  1999年   62篇
  1998年   64篇
  1997年   84篇
  1996年   74篇
  1995年   58篇
  1994年   66篇
  1993年   59篇
  1992年   65篇
  1991年   47篇
  1990年   48篇
  1989年   85篇
  1988年   81篇
  1987年   74篇
  1986年   68篇
  1985年   63篇
  1984年   35篇
  1983年   44篇
  1982年   30篇
  1981年   41篇
  1980年   33篇
  1979年   28篇
  1978年   36篇
  1977年   20篇
  1976年   24篇
  1975年   27篇
  1974年   17篇
  1973年   25篇
  1972年   31篇
  1968年   20篇
排序方式: 共有3086条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Conventional risk factors have very low predictive power in identifying haemodialysis patients at high risk of vascular accidents. A role for apolipoprotein E isotypes was looked for in a small, but rigorously defined, cohort of longterm haemodialysis patients. In individuals with high vascular risk, as identified by higher common carotid intima/media thickness, we found an excess of apolipoprotein E4 alleles. This preliminary result requires confirmation in large patient cohorts.   相似文献   
5.
6.
OBJECTIVES: To determine electrocardiogram (ECG) predictors of positive cardiac markers and short-term adverse cardiac events in an undifferentiated chest pain population presenting to emergency departments (EDs). The authors hypothesized that specific ECG findings, other than those previously identified in higher-risk populations, would be predictive of cardiac outcomes and positive cardiac markers. METHODS: This study used data from a prospectively collected, retrospectively analyzed Internet-based data registry of undifferentiated chest pain patients (i*trACS). Logistic regression modeling was performed to determine the ECG findings that were predictive of 1) positive cardiac markers and 2) short-term adverse cardiac events. RESULTS: ST-segment elevation (STE), ST-segment depression (STD), pathological Q-waves (PQW), and T-wave inversion were associated with increased odds of percutaneous coronary intervention or catheterization, myocardial infarction, or coronary artery bypass grafting. The odds of creatine kinase-MB (CK-MB) measuring positive were increased if STE, STD, or PQW were present [odds ratio (OR) 2.495, 2.582, and 1.295, respectively]. A right bundle branch block tended to decrease the odds of CK-MB measuring positive (OR 0.658). A similar pattern of results was observed for troponin I (OR 3.608 for STE, 3.72 for STD, 1.538 for PQW). Troponin T showed an increased odds of measuring positive if any of STE, STD, left bundle branch block, or T-wave inversion were evident (OR 2.313, 2.816, 1.80, and 1.449, respectively). CONCLUSIONS: Initial ECG criteria can be used to predict short-term cardiac outcomes and positive cardiac markers. These findings can be important aids in the risk-stratification and aggressive treatment regimens of chest pain patients presenting to EDs.  相似文献   
7.
Effect of aging and caloric restriction on intestinal permeability.   总被引:2,自引:0,他引:2  
Intestinal permeability is increased in several disorders such as Crohn's disease or rheumatoid arthritis. Since aging leads to alteration of many biological functions, the effect of aging on intestinal permeability was studied by measuring the intestinal permeability in aging rats gavaged with different size permeability probes--mannitol, polyethylene glycol (PEG) 400, and inulin. In rats fed with control diet, there was a significant increase in intestinal permeability to medium size probes PEG 400 (14.8 +/- 0.4 and 21.0 +/- 1.1% at 3 and 28 months respectively, p less than .01) and mannitol (3.41 +/- 0.4 and 5.3 +/- 0.5% at 3 and 28 months, respectively, p less than .01). Intestinal permeability of the large macromolecule inulin did not change (0.42 +/- 0.03 and 0.38 +/- 0.02% at 3 and 28 months, respectively) with aging. There was no correlation between weight of the rats and their intestinal permeability. Because dietary caloric restriction has been found to prolong the life span, retard deterioration of several biological functions, and affect intestinal absorptive functions, we examined the effect of lifelong calorie restriction on intestinal permeability changes. Lifelong calorie-restricted diet did not affect age-related change in intestinal permeability. We conclude that intestinal permeability of medium size probes increases with aging and that lifelong caloric restriction does not prevent this change. We speculate that age-associated deterioration in intestinal barrier functions could permit increased systemic absorption of lumenal antigens and could perhaps contribute to the genesis of antigen-related age-associated diseases.  相似文献   
8.
9.
10.
To investigate the effect of fluoxetine on serotonergic sensitivity in obsessive-compulsive disorder (OCD), the partial serotonin agonist metachlorophenylpiperazine (mCPP) was compared to placebo under double-blind conditions in six patients with OCD before and during treatment with fluoxetine. Readministration of oral mCPP (0.5 mg/kg) after at least 12 weeks of fluoxetine treatment did not increase obsessive-compulsive (OC) symptoms, in contrast to exacerbation of OC symptoms produced by mCPP before treatment. Chronic fluoxetine treatment resulted in a significant increase in prolactin and cortisol response to mCPP. This may be accounted for, however, by substantially increased plasma mCPP levels during fluoxetine treatment. Chronic fluoxetine treatment diminished the behavioral sensitivity to mCPP and did not diminish, but may have partially normalized, the neuroendocrine response to mCPP in patients with OCD. These adaptive homeostatic effects may reflect fluoxetine's antiobsessional mechanism.  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