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   2070899篇
  免费   154598篇
  国内免费   4254篇
耳鼻咽喉   28916篇
儿科学   70078篇
妇产科学   59768篇
基础医学   301814篇
口腔科学   58525篇
临床医学   182372篇
内科学   402284篇
皮肤病学   45343篇
神经病学   162814篇
特种医学   80720篇
外国民族医学   652篇
外科学   315401篇
综合类   46518篇
现状与发展   1篇
一般理论   653篇
预防医学   157678篇
眼科学   47942篇
药学   154398篇
  4篇
中国医学   4066篇
肿瘤学   109804篇
  2018年   20439篇
  2016年   17755篇
  2015年   20219篇
  2014年   27844篇
  2013年   42596篇
  2012年   57196篇
  2011年   61248篇
  2010年   36592篇
  2009年   34431篇
  2008年   58442篇
  2007年   62741篇
  2006年   63818篇
  2005年   61812篇
  2004年   59929篇
  2003年   58033篇
  2002年   56657篇
  2001年   93651篇
  2000年   95883篇
  1999年   81096篇
  1998年   23181篇
  1997年   20802篇
  1996年   20978篇
  1995年   19994篇
  1994年   18837篇
  1993年   17471篇
  1992年   65620篇
  1991年   64552篇
  1990年   63763篇
  1989年   61704篇
  1988年   56938篇
  1987年   56435篇
  1986年   53326篇
  1985年   51185篇
  1984年   38420篇
  1983年   32977篇
  1982年   19771篇
  1981年   17630篇
  1979年   36076篇
  1978年   25725篇
  1977年   22033篇
  1976年   20905篇
  1975年   22441篇
  1974年   26751篇
  1973年   25818篇
  1972年   24172篇
  1971年   22582篇
  1970年   20951篇
  1969年   19900篇
  1968年   18596篇
  1967年   16533篇
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
121.
122.
123.
We report a case of intestinal obstruction in a 73-year-old woman caused by ileocolic intussusception. The underlying cause was a giant submucosal ulcerating lipoma (6?×?3.3?×?3.8 cm) extending from the superior mucosal lip of Bauhin’s valve. Abdominal ultrasonography showed a pathognomonic target-like mass appearing as multiple concentric rings. CT scan confirmed the diagnosis. Because of apparent obstruction, a laparotomy with right hemicolectomy and ileocolic anastomosis was performed. Lipomas most frequently occur in the cecum and ascending colon where they represent the most common submucosal mesenchymal tumor. They typically occur in elderly women with an incidence that varies from 0.15 to 0.56 %. Pain, rectal bleeding, and obstruction are typical symptoms. When faced with an intussusception in children, reduction with air per rectum can be performed. In adults, however, malignant cell spreading and seeding is of big concern. Since approximately 20–50 % of all underlying causes are malignant, explorative surgery is favored in adults.  相似文献   
124.
125.
126.
Breast elastography has been available for more than 15 years but is not widely incorporated into clinical practice. Many publications report extremely high accuracy for various breast elastographic techniques. However, results in the literature are extremely variable. This variability is most likely due to variations in technique, a relatively steep learning curve, and variability in methods between vendors. This article describes our protocol for performing breast elastography using both strain elastography and shear wave elastography, which produces high sensitivity and specificity. Additionally, we will describe the most commonly known false-positive and false-negative lesions as well as how to detect them.  相似文献   
127.
128.
129.
Background: Dense deposit disease and atypical hemolytic uremic syndrome are often caused by Complement Factor H (CFH) mutations. This study describes the retinal abnormalities in dense deposit disease and, for the first time, atypical haemolytic uremic syndrome. It also reviews our understanding of drusen pathogenesis and their relevance for glomerular disease. Methods: Six individuals with dense deposit disease and one with atypical haemolytic uremic syndrome were studied from 2 to 40 years after presentation. Five had renal transplants. All four who had genetic testing had CFH mutations. Individuals underwent ophthalmological review and retinal photography, and in some cases, optical coherence tomography, and further tests of retinal function. Results: All subjects with dense deposit disease had impaired night vision and retinal drusen or whitish-yellow deposits. Retinal atrophy, pigmentation, and hemorrhage were common. In late disease, peripheral vision was restricted, central vision was distorted, and there were scotoma from sub-retinal choroidal neovascular membranes and atypical serous retinopathy. Drusen were present but less prominent in the young person with atypical uremic syndrome due to a heterozygous CFH mutation. Conclusions: Drusen are common in forms of C3 glomerulopathy caused by compound heterozygous or heterozygous CFH mutations. They are useful diagnostically but also impair vision. Drusen have an identical composition to glomerular deposits. They are also identical to the drusen of age-related macular degeneration, and may respond to the same treatments. Individuals with a C3 glomerulopathy should be assessed ophthalmologically at diagnosis, and monitored regularly for vision-threatening complications.  相似文献   
130.
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