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   214369篇
  免费   9757篇
  国内免费   615篇
耳鼻咽喉   3262篇
儿科学   5897篇
妇产科学   4845篇
基础医学   29267篇
口腔科学   7679篇
临床医学   14518篇
内科学   51514篇
皮肤病学   6310篇
神经病学   17902篇
特种医学   5099篇
外国民族医学   2篇
外科学   26343篇
综合类   1253篇
一般理论   70篇
预防医学   20400篇
眼科学   4454篇
药学   15155篇
中国医学   1074篇
肿瘤学   9697篇
  2023年   1314篇
  2022年   1863篇
  2021年   4848篇
  2020年   2574篇
  2019年   4697篇
  2018年   7091篇
  2017年   4327篇
  2016年   4325篇
  2015年   5181篇
  2014年   6411篇
  2013年   9253篇
  2012年   15802篇
  2011年   16816篇
  2010年   8405篇
  2009年   6447篇
  2008年   13370篇
  2007年   14068篇
  2006年   13406篇
  2005年   13169篇
  2004年   11947篇
  2003年   11063篇
  2002年   10321篇
  2001年   5904篇
  2000年   6931篇
  1999年   4882篇
  1998年   1073篇
  1997年   816篇
  1996年   712篇
  1995年   636篇
  1994年   512篇
  1993年   438篇
  1992年   1647篇
  1991年   1385篇
  1990年   1213篇
  1989年   1031篇
  1988年   886篇
  1987年   811篇
  1986年   831篇
  1985年   731篇
  1984年   570篇
  1983年   462篇
  1982年   336篇
  1979年   488篇
  1978年   341篇
  1974年   429篇
  1973年   418篇
  1972年   342篇
  1971年   380篇
  1970年   341篇
  1969年   366篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Mentally retarded adolescents and MA-matched nonretarded children participated in three experiments designed to examine differences in language-processing efficiency. A compressed speech technique was used in Experiments 1 and 2. Experiment 3 relied on a sentence-picture verification procedure. Our results suggest that retarded and nonretarded individuals differ in the speed with which they are able to execute the semantic-analytic processes but not necessarily the phonological encoding processes that are involved in auditory language comprehension. In addition, the data suggest a possible group difference in the quality of the semantic representation encoded during sentence processing.  相似文献   
43.
Gallibacterium anatis (previously named Pasteurella haemolytica-like) is considered a normal inhabitant of genital and upper respiratory tracts of healthy chickens, but it is also associated with different pathological conditions. Secreted metalloproteases from field and reference G. anatis cultures were obtained by methanol precipitation and were characterized. Proteins of molecular mass higher than 100 kDa showing proteolytic activity were observed in 10% polyacrylamide gels copolymerized with 1% bovine casein. They were active at alkaline pH, and inhibited by ethylenediamine tetraacetic acid. Their activity was stable at 50 degrees C, but partially inhibited at 60 degrees C, and totally inhibited at higher temperatures. Secreted proteins were able to degrade chicken IgG after 24 h of incubation, and cross-reacted with a polyclonal antibody against purified protease from Actinobacillus pleuropneumoniae. Secreted metalloproteases could play a role in infections caused by G. anatis.  相似文献   
44.
Glomeruloid haemangioma is considered a specific marker of POEMS ( p olyneuropathy, o rganomegaly, e ndocrinopathy, M -protein and s kin changes) syndrome and it is usually but not always associated with multicentric Castleman's disease. We report a 78-year-old man who presented with a single, red-violet soft nodule with superficial telangiectases on the scalp. Histopathologically, the lesion consisted of lobules of coiled aggregated capillaries that involved the lumina of dilated vascular structures, mimicking renal glomeruli. A collagenous stroma separated the capillary lobules, and eosinophilic, periodic-acid–Schiff positive globules of varying sizes and shapes were seen within the cytoplasm of endothelial cells. Immunohistochemical studies with antibodies against IgA and IgG, and against the kappa and lambda light chains of immunoglobulins showed immunoreactivity within the eosinophilic globules. Results of complete blood count, liver, renal and thyroid function tests, fasting blood sugar measurement, serum levels of oestradiol, testosterone, prolactin and cortisol, serum protein electrophoresis, immunoelectrophoresis and immunofixation yielded normal or negative results. No Bence–Jones proteinuria was found in a sample from a 24-h urine collection. To our knowledge, only two cases of glomeruloid haemangioma have been previously reported in patients without POEMS syndrome. We describe the third case of glomeruloid haemangioma in a patient without features of POEMS syndrome.  相似文献   
45.
46.
47.
48.
49.
L1 disease is the most common genetic cause of congenital hydrocephalus. Mutations in the L1CAM gene are associated with an overlapping clinical spectrum of four X-linked neurological conditions, characterized by hydrocephalus, mental retardation, lower limb spasticity and adducted thumbs. Brain anomalies are frequently present in L1 disease. We describe these anomalies by reporting a case of a male newborn presenting with congenital hydrocephalus along with corpus callosum agenesis and enlargement of the massa intermedia. These findings, in association with the presence of clasped thumbs, raised the suspicion of L1 disease, which was confirmed by the detection of a mutation in the L1CAM gene. In cases of congenital hydrocephalus, recognition of the brain anomalies associated with L1 disease may contribute to pursuing the genetic analysis needed for the diagnosis and genetic counseling.  相似文献   
50.
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