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   2982267篇
  免费   219005篇
  国内免费   4734篇
耳鼻咽喉   42301篇
儿科学   94692篇
妇产科学   82595篇
基础医学   424451篇
口腔科学   89408篇
临床医学   266186篇
内科学   568507篇
皮肤病学   64869篇
神经病学   234978篇
特种医学   117162篇
外国民族医学   730篇
外科学   456037篇
综合类   68426篇
现状与发展   4篇
一般理论   965篇
预防医学   222663篇
眼科学   70328篇
药学   230394篇
  13篇
中国医学   6482篇
肿瘤学   164815篇
  2018年   28946篇
  2016年   25477篇
  2015年   28979篇
  2014年   39946篇
  2013年   60021篇
  2012年   81556篇
  2011年   86128篇
  2010年   50995篇
  2009年   48381篇
  2008年   81974篇
  2007年   86710篇
  2006年   88119篇
  2005年   85143篇
  2004年   82987篇
  2003年   79446篇
  2002年   77461篇
  2001年   146465篇
  2000年   151326篇
  1999年   127529篇
  1998年   33945篇
  1997年   30169篇
  1996年   30020篇
  1995年   28743篇
  1994年   26628篇
  1993年   25072篇
  1992年   101377篇
  1991年   98314篇
  1990年   96161篇
  1989年   93026篇
  1988年   85820篇
  1987年   84170篇
  1986年   79766篇
  1985年   76837篇
  1984年   56474篇
  1983年   48359篇
  1982年   27506篇
  1981年   24316篇
  1979年   52923篇
  1978年   36431篇
  1977年   31338篇
  1976年   28609篇
  1975年   31200篇
  1974年   37557篇
  1973年   36181篇
  1972年   34026篇
  1971年   32036篇
  1970年   29759篇
  1969年   28104篇
  1968年   25613篇
  1967年   23103篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
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   
56.
ABSTRACT: Background: Although increases in perinatal mortality risk associated with fetal macrosomia are well documented, the optimal route of delivery for fetuses with suspected macrosomia remains controversial. The objective of this investigation was to assess the risk of neonatal death among macrosomic infants delivered vaginally compared with those delivered by cesarean section. Methods: Data were derived from the U.S. 1995–1999 Linked Live Birth‐Infant Death Cohort files and term (37–44 wk), single live births to United States resident mothers selected. A proportional hazards model was used to analyze the risk of neonatal death associated with cesarean delivery among 3 categories of macrosomic infants (infants weighing 4,000–4,499 g; 4,500–4,999 g; and 5,000+ g). Results: After controlling for maternal characteristics and complications, the adjusted hazard ratio for neonatal death associated with cesarean delivery among the 3 categories of macrosomic infants was 1.40, 1.30, and 0.85. Conclusions: Although cesarean delivery may reduce the risk of death for the heaviest infants (5,000+ g), the relative benefit of this intervention for macrosomic infants weighing 4,000–4,999 g remains debatable. Thus, policies in support of prophylactic cesarean delivery for suspected fetal macrosomia may need to be reevaluated. (BIRTH 33:4 December 2006)  相似文献   
57.
58.
59.
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   
60.
We report the case of a 38-year-old woman who presented with chronic lower abdominal pain. Her past medical history included a splenectomy due to abdominal trauma. Ultrasound examination revealed four pelvic tumors which, upon laparotomy, were found to be the result of splenosis. Approximately 100 cases of splenosis have been reported but only a minority of them have been published in the gynecological literature. Our case indicates that those involved in pelvic scanning (even of asymptomatic women) and/or treating those complaining of lower abdominal pain or presenting with pelvic tumors should be aware of splenosis as a possible diagnosis.  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