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   752篇
  免费   67篇
  国内免费   22篇
耳鼻咽喉   2篇
儿科学   49篇
妇产科学   6篇
基础医学   77篇
口腔科学   42篇
临床医学   69篇
内科学   144篇
皮肤病学   28篇
神经病学   16篇
特种医学   219篇
外科学   50篇
综合类   36篇
预防医学   35篇
眼科学   4篇
药学   23篇
肿瘤学   41篇
  2020年   4篇
  2018年   6篇
  2017年   7篇
  2016年   10篇
  2015年   8篇
  2014年   14篇
  2013年   10篇
  2012年   6篇
  2011年   8篇
  2010年   23篇
  2009年   21篇
  2008年   18篇
  2007年   16篇
  2006年   15篇
  2005年   11篇
  2004年   10篇
  2003年   9篇
  2002年   4篇
  2001年   11篇
  2000年   8篇
  1999年   13篇
  1998年   39篇
  1997年   44篇
  1996年   42篇
  1995年   37篇
  1994年   26篇
  1993年   31篇
  1992年   19篇
  1991年   20篇
  1990年   16篇
  1989年   24篇
  1988年   28篇
  1987年   45篇
  1986年   29篇
  1985年   17篇
  1984年   11篇
  1983年   13篇
  1982年   15篇
  1981年   20篇
  1980年   17篇
  1979年   11篇
  1978年   6篇
  1977年   9篇
  1976年   22篇
  1975年   10篇
  1934年   4篇
  1933年   3篇
  1930年   3篇
  1927年   4篇
  1926年   4篇
排序方式: 共有841条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
A hospital-based case-control study was carried out to clarify the characteristics of mucoid presentation of acute enterocolitis in children. One hundred sixty-eight cases of acute mucoid enterocolitis (study population) were compared with 200 cases of watery diarrhoea and 118 cases of blood dysentery (control groups) on the basis of clinical characteristics and findings on stool examination. Study and control groups were comparable with respect to age, body weight and nutritional status. There was no significant difference in clinical characteristics (duration of diarrhoea, stool frequency, presence of vomiting, fever and dehydration) between patients suffering from mucoid enterocolitis and blood dysentery. However, watery diarrhoea patients had significantly high frequencies of vomiting (p = 0.00001) and dehydration (p  相似文献   
96.
Intestinal permeability can be assessed non-invasively using the lactulose-rhamnose (L-R) test, which is a reliable measure of small intestinal integrity. AIMS: To determine risk factors for abnormal intestinal permeability in kwashiorkor, and to measure changes in L-R ratios with inpatient rehabilitation. DESIGN: A case-control study of 149 kwashiorkor cases and 45 hospital controls. The L-R test was adapted to study kwashiorkor in Malawi, with testing at weekly intervals during nutritional rehabilitation. Urine sugars were measured by thin layer chromatography in London. RESULTS: The initial geometric mean L-R ratios (x100) (with 95% confidence interval) in kwashiorkor were 17.3 (15.0 to 19.8) compared with 7.0 (5.6 to 8.7) for controls. Normal ratios are < 5, so the high ratios in controls indicate tropical enteropathy syndrome. Abnormal permeability in kwashiorkor was associated with death, oliguria, sepsis, diarrhoea, wasting and young age. Diarrhoea and death were associated with both decreased L-rhamnose absorption (diminished absorptive surface area) and increased lactulose permeation (impaired barrier function) whereas nutritional wasting affected only L-rhamnose absorption. Despite, clinical recovery, mean L-R ratios improved little on treatment, with mean weekly ratios of 16.3 (14.0 to 19.0), 13.3 (11.1 to 15.9) and 14.4 (11.0 to 18.8). CONCLUSION: Abnormal intestinal permeability in kwashiorkor correlates with disease severity, and improves only slowly with nutritional rehabilitation.  相似文献   
97.
98.
Tone recognition is partially subserved by neural activity in the right frontal and primary auditory cortices. First we determined the brain areas associated with tone perception and recognition. This study then examined how regional cerebral blood flow (rCBF) in these and other brain regions correlates with the behavioral characteristics of a difficult tone recognition task. rCBF changes were assessed using H2(15)O positron emission tomography. Subtraction procedures were used to localize significant change regions and correlational analyses were applied to determine how response times (RT) predicted rCBF patterns. Twelve trained normal volunteers were studied in three conditions: REST, sensory motor control (SMC) and decision (DEC). The SMC-REST contrast revealed bilateral activation of primary auditory cortices, cerebellum and bilateral inferior frontal gyri. DEC-SMC produced significant clusters in the right middle and inferior frontal gyri, insula and claustrum; the anterior cingulate gyrus and supplementary motor area; the left insula/claustrum; and the left cerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed a positive correlation in right inferior and middle frontal cortex; rCBF in bilateral auditory cortices and cerebellum exhibited significant negative correlations with RT These changes suggest that neural activity in the right frontal, superior temporal and cerebellar regions shifts back and forth in magnitude depending on whether tone recognition RT is relatively fast or slow, during a difficult, accurate assessment.   相似文献   
99.
100.
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