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   2375636篇
  免费   194646篇
  国内免费   4211篇
耳鼻咽喉   34271篇
儿科学   72789篇
妇产科学   62935篇
基础医学   334948篇
口腔科学   67597篇
临床医学   215569篇
内科学   468634篇
皮肤病学   47968篇
神经病学   200805篇
特种医学   95976篇
外国民族医学   886篇
外科学   360495篇
综合类   56218篇
现状与发展   1篇
一般理论   977篇
预防医学   190626篇
眼科学   55463篇
药学   177555篇
  4篇
中国医学   4365篇
肿瘤学   126411篇
  2018年   24216篇
  2016年   20593篇
  2015年   23288篇
  2014年   33547篇
  2013年   50851篇
  2012年   68764篇
  2011年   72307篇
  2010年   42489篇
  2009年   40880篇
  2008年   68783篇
  2007年   73118篇
  2006年   74024篇
  2005年   72055篇
  2004年   69356篇
  2003年   67040篇
  2002年   66293篇
  2001年   112463篇
  2000年   116535篇
  1999年   98348篇
  1998年   27862篇
  1997年   25529篇
  1996年   25453篇
  1995年   24617篇
  1994年   23167篇
  1993年   21557篇
  1992年   79399篇
  1991年   76397篇
  1990年   73586篇
  1989年   70849篇
  1988年   65857篇
  1987年   64804篇
  1986年   61348篇
  1985年   58411篇
  1984年   44228篇
  1983年   37659篇
  1982年   22889篇
  1981年   20337篇
  1980年   19034篇
  1979年   41303篇
  1978年   28988篇
  1977年   24354篇
  1976年   22833篇
  1975年   23966篇
  1974年   29641篇
  1973年   28046篇
  1972年   26231篇
  1971年   24152篇
  1970年   22759篇
  1969年   21093篇
  1968年   19137篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Objective: Report measured resting energy expenditure (REE) in wheelchair rugby athletes and evaluate agreement between REE and the prediction models of Chun, Cunningham, Harris-Benedict, Mifflin, Nightingale and Gorgey, and Owen.

Design: Cohort-based validation study.

Setting. Paralympic team training camp.

Participants: Fourteen internationally competitive athletes who play wheelchair rugby, 13 of whom had cervical spinal cord injuries (SCI).

Outcome Measures: A portable metabolic analyzer was used to measure REE following an overnight fast and dual-energy X-ray absorptiometry (DXA) was used to assess lean body mass for the prediction equations.

Results: REE in the current sample was 1735?±?257?kcal?×?day?1 ranging from 1324 to 2068?kcal?×?day?1 Bhambhani Y. Physiology of wheelchair racing in athletes with spinal cord injury. Sports Med 2002;32(1):2351.[Crossref], [PubMed], [Web of Science ®] [Google Scholar]. Bland–Altman analyses revealed negative mean bias but similar limits of agreement between measured REE and scores predicted by Chun, Cunningham, Mifflin, Nightingale and Gorgey, and Owen models in elite athletes who play wheelchair rugby.

Conclusion: Prediction models regressed on persons with and without SCI under-predicted REE of competitive wheelchair rugby athletes. This outcome may be explained by the higher REE/fat-free mass (FFM) ratio of current athletes compared to less active samples. Findings from the current study will help practitioners to determine nutrient intake needs on training days of varied intensity.  相似文献   
62.
63.
64.
Pulmonary hypertension of the newborn (PHN) constitutes a critical condition with severe cardiovascular and neurological consequences. One of its main causes is hypoxia during gestation, and thus, it is a public health concern in populations living above 2500 m. Although some mechanisms are recognized, the pathophysiological facts that lead to PHN are not fully understood, which explains the lack of an effective treatment. Oxidative stress is one of the proposed mechanisms inducing pulmonary vascular dysfunction and PHN. Therefore, we assessed whether melatonin, a potent antioxidant, improves pulmonary vascular function. Twelve newborn sheep were gestated, born, and raised at 3600 meters. At 3 days old, lambs were catheterized and daily cardiovascular measurements were recorded. Lambs were divided into two groups, one received daily vehicle as control and another received daily melatonin (1 mg/kg/d), for 8 days. At 11 days old, lung tissue and small pulmonary arteries (SPA) were collected. Melatonin decreased pulmonary pressure and resistance for the first 3 days of treatment. Further, melatonin significantly improved the vasodilator function of SPA, enhancing the endothelial‐ and muscular‐dependent pathways. This was associated with an enhanced nitric oxide‐dependent and nitric oxide independent vasodilator components and with increased nitric oxide bioavailability in lung tissue. Further, melatonin reduced the pulmonary oxidative stress markers and increased enzymatic and nonenzymatic antioxidant capacity. Finally, these effects were associated with an increase of lumen diameter and a mild decrease in the wall of the pulmonary arteries. These outcomes support the use of melatonin as an adjuvant in the treatment for PHN.  相似文献   
65.
66.
67.
68.
69.
Obtaining accurate assessment data from adolescents in treatment aids clinical decision making and facilitates more accurate outcome evaluations. However, findings could be biased due to underreported substance use and mental health symptoms. This article compares self-reports of youth in non-White matched client–assessor dyads and those in nonmatched dyads. There were no differences on self-reported substance use, but matched youth reported significantly fewer attention deficit/hyperactivity disorder symptoms versus the comparison group. One possible reason for these findings is the effect of in-group stereotype threat. Future studies should examine the potential effect that in-group stereotyping and perceived racism have on the therapeutic relationship.  相似文献   
70.
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