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   2356307篇
  免费   173706篇
  国内免费   3845篇
耳鼻咽喉   34242篇
儿科学   80075篇
妇产科学   66810篇
基础医学   340550篇
口腔科学   65599篇
临床医学   204815篇
内科学   461805篇
皮肤病学   50102篇
神经病学   185911篇
特种医学   92984篇
外国民族医学   987篇
外科学   360224篇
综合类   49450篇
现状与发展   2篇
一般理论   707篇
预防医学   180141篇
眼科学   53255篇
药学   176238篇
  3篇
中国医学   4590篇
肿瘤学   125368篇
  2018年   23994篇
  2017年   18249篇
  2016年   20416篇
  2015年   23199篇
  2014年   32214篇
  2013年   48777篇
  2012年   67231篇
  2011年   71533篇
  2010年   42438篇
  2009年   40284篇
  2008年   68378篇
  2007年   73482篇
  2006年   74022篇
  2005年   72152篇
  2004年   69647篇
  2003年   67344篇
  2002年   65931篇
  2001年   107886篇
  2000年   111293篇
  1999年   94797篇
  1998年   27094篇
  1997年   24284篇
  1996年   24674篇
  1995年   23311篇
  1994年   22028篇
  1993年   20423篇
  1992年   75796篇
  1991年   74343篇
  1990年   72877篇
  1989年   70086篇
  1988年   65076篇
  1987年   63872篇
  1986年   60182篇
  1985年   57650篇
  1984年   43318篇
  1983年   36934篇
  1982年   21874篇
  1981年   19629篇
  1979年   39852篇
  1978年   27818篇
  1977年   23922篇
  1976年   22488篇
  1975年   24516篇
  1974年   28791篇
  1973年   27731篇
  1972年   26073篇
  1971年   24003篇
  1970年   22507篇
  1969年   21058篇
  1968年   19609篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
There is some evidence suggesting that Parkinson's disease (PD) patients exhibit lower body weight when compared to age-matched healthy subjects. Low body mass index (BMI) is correlated with low bone mineral density, both of which are major risk factors for hip fractures. Possible determinants of weight loss in PD patients include hyposmia, impaired hand-mouth coordination, difficulty chewing, dysphagia, intestinal hypomotility, depression, decreased reward processing of dopaminergic mesolimbic regions, nausea, and anorexia as the side effects of medication, and increased energy requirements due to muscular rigidity and involuntary movements. It is unclear whether PD patients in general, or only a subgroup of those affected, definitely show lower BMI in the advanced stages of the disease. We therefore recommend that the body weight of PD patients be monitored monthly as the disease progresses, and that a patient's nutrition should be supplemented with sufficient amounts of vitamin D and calcium to reduce the risk of hip fractures and strengthen bone density. Because meal times may coincide with unpredictable off periods associated with akinesia and impaired hand-mouth coordination, PD patients also need flexible food schedules that accommodate the associated symptoms of this disease.  相似文献   
42.
43.
44.
45.
46.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  相似文献   
47.
Abstract: Background: Fetal pulse oximetry improves the assessment of fetal well‐being during labor. The objective of this study was to evaluate women's satisfaction with their experience with this additional technology. Methods: We surveyed women participating in the FOREMOST trial, a randomized controlled trial comparing the addition of fetal pulse oximetry (FPO) to conventional cardiotocograph (CTG) monitoring (intervention group), versus CTG‐only (control group), in the presence of nonreassuring fetal status during labor. Our survey evaluated 3 aspects of women's experience: labor, fetal monitoring, and participation in the research. The survey was administered within a few days of giving birth and repeated 3 months later. Results: No differences were found between the intervention and control groups for women's evaluations of their labor, fetal monitoring, research, or overall experiences when surveyed on both occasions. Within each study group, a small but statistically significant decline occurred in women's scores for their experience of labor and overall experience from the initial survey close to the time of giving birth, to 3 months later. The magnitude of differences in responses over time was similar for the both groups. Women were more satisfied after a spontaneous or assisted vaginal birth than after cesarean section. Length of time the research midwife was present had a significant positive effect on women's ratings of their experience several days after giving birth (p = 0.006), but no effect at 3 months. Conclusions: The addition of fetal pulse oximetry for the assessment of fetal well‐being during labor did not affect childbearing women's perceptions of fetal monitoring or their labor. Women evaluated their experience in the research process positively overall. Small changes occurred in women's perception of their satisfaction over time. (BIRTH 33:2 June 2006)  相似文献   
48.
49.
50.
OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.  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