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   1339238篇
  免费   112579篇
  国内免费   6372篇
耳鼻咽喉   16714篇
儿科学   43044篇
妇产科学   36568篇
基础医学   183683篇
口腔科学   36282篇
临床医学   120817篇
内科学   278727篇
皮肤病学   31892篇
神经病学   110578篇
特种医学   55561篇
外国民族医学   274篇
外科学   210454篇
综合类   31542篇
现状与发展   2篇
一般理论   414篇
预防医学   106690篇
眼科学   28092篇
药学   93757篇
  5篇
中国医学   2227篇
肿瘤学   70866篇
  2018年   13377篇
  2017年   10648篇
  2016年   12814篇
  2015年   14311篇
  2014年   19963篇
  2013年   29768篇
  2012年   36287篇
  2011年   38920篇
  2010年   24387篇
  2009年   23928篇
  2008年   36401篇
  2007年   38816篇
  2006年   39935篇
  2005年   38518篇
  2004年   36774篇
  2003年   35861篇
  2002年   33862篇
  2001年   66076篇
  2000年   67944篇
  1999年   56609篇
  1998年   16737篇
  1997年   15028篇
  1996年   16023篇
  1995年   16238篇
  1994年   15102篇
  1993年   14157篇
  1992年   47106篇
  1991年   45758篇
  1990年   43982篇
  1989年   41829篇
  1988年   38763篇
  1987年   38092篇
  1986年   35869篇
  1985年   34645篇
  1984年   26362篇
  1983年   22112篇
  1982年   13851篇
  1981年   12452篇
  1980年   11725篇
  1979年   23550篇
  1978年   17076篇
  1977年   14387篇
  1976年   13183篇
  1975年   13728篇
  1974年   16102篇
  1973年   15404篇
  1972年   14177篇
  1971年   13039篇
  1970年   11890篇
  1969年   11102篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
952.
953.
Inflammatory abnormalities may be involved in the inadequate basal oxidant/antioxidant balance and local exercise-induced oxidative stress in chronic obstructive pulmonary disease (COPD) patients. The time course of oxidative stress and inflammation was investigated in 10 COPD patients and seven healthy subjects before and after local dynamic quadriceps endurance exercise at 40% of maximal strength. Venous samples were collected before, immediately after and up to 48 h after exercise. At rest, levels of an oxidant released by stimulated phagocytes, the superoxide anion, were significantly higher in patients, as were plasma levels of C-reactive protein, tumour necrosis factor-alpha and interleukin-6, inflammatory markers. An inverse relationship was found between baseline C-reactive protein levels and endurance time in patients. Six hours after exercise, superoxide anion release and levels of protein oxidation products, an index of oxidative stress, increased similarly in both groups, whereas thiobarbituric acid reactive substance levels, another index of oxidative stress, increased significantly only in patients. Plasma nonenzymatic antioxidant and inflammatory cytokine levels were unchanged by the exercise protocol. The increased baseline systemic inflammation in chronic obstructive pulmonary disease patients could be related to disturbed oxidant/antioxidant balance, and, together, these may have triggered the exercise-induced oxidative stress. The absence, however, of local exercise-induced systemic inflammation suggests that additional mechanisms explain local exercise-induced oxidative stress.  相似文献   
954.
955.
956.
957.
958.
Osteochondromatosis   总被引:5,自引:0,他引:5  
  相似文献   
959.
Objective   This study evaluated the Impact on Sibling scale, a six-item measure of parents' perception of the effects of a child's illness on healthy siblings.
Methods   Participants were 122 parents of a child with chronic illness, developmental disability, or autism spectrum disorder, and a well sibling aged 4–13 years. Parents completed the Impact on Sibling scale and the Child Behavior Checklist about the sibling, and completed the revised Impact on Family scale and the Brief Symptom Inventory about themselves.
Results   The Impact on Sibling score was correlated with measures of sibling, parent and family functioning. The internal consistency of the Impact on Sibling scale was higher for families with children with chronic illness compared with the other two diagnostic groups.
Conclusion   The Impact on Sibling scale is a brief set of items that can help identify siblings who are negatively affected by a brother/sister's illness. Findings support further research on the Impact on Sibling scale, particularly with families of children with chronic illnesses.  相似文献   
960.
This study aimed to assess the ability of global and local systolic parameters measured with gated blood-pool SPECT (GBPS) to diagnose and characterize the severity of diffuse or localized arrhythmogenic right ventricular dysplasia (ARVD). METHODS: Fifty-nine subjects with symptomatic ventricular arrhythmias were prospectively included in the study. With the International Society and Federation of Cardiology criteria for ARVD as a gold standard, these subjects were classified as subjects without ARVD (21 control subjects) and patients with localized ARVD (16 patients) or diffuse ARVD (22 patients). Right ventricular volumes, right ventricular ejection fractions (EF), the SD of local EF (sigma-EF), and the SD of the local times of end systole (sigma-TES) were computed from GBPS data and compared among the groups in the study population. RESULTS: sigma-EF did not differ between control subjects and patients with diffuse or localized ARVD. Right ventricular EF and volumes differed between patients with diffuse ARVD and control subjects, with similar areas under the receiver-operating-characteristic curves, but right ventricular EF and volumes failed to differentiate patients with localized ARVD. In contrast, sigma-TES differed between patients with diffuse or localized ARVD and control subjects. Regression analysis showed that the systolic parameter most strongly associated with the diagnosis of ARVD was sigma-TES. The probabilities of a randomly chosen patient in the diffuse ARVD group and of a randomly chosen patient in the localized ARVD group having sigma-TES values greater than that of a randomly chosen control subject were 98.5% and 96.7%, respectively. For the diagnosis of localized ARVD, a threshold of 80 ms for sigma-TES corresponded to sensitivity, specificity, and positive and negative predictive values of 100%, 81%, 80%, and 100%, respectively. CONCLUSION: With GBPS, both diffuse ARVD and localized ARVD can be accurately diagnosed by computing sigma-TES for all of the pixels on the surface of the right ventricle.  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