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   1372955篇
  免费   115474篇
  国内免费   6400篇
耳鼻咽喉   17119篇
儿科学   44017篇
妇产科学   37364篇
基础医学   188266篇
口腔科学   37130篇
临床医学   124820篇
内科学   284878篇
皮肤病学   32418篇
神经病学   114071篇
特种医学   56846篇
外国民族医学   276篇
外科学   214771篇
综合类   32116篇
现状与发展   2篇
一般理论   448篇
预防医学   110161篇
眼科学   28982篇
药学   95988篇
  7篇
中国医学   2273篇
肿瘤学   72876篇
  2018年   13890篇
  2017年   11095篇
  2016年   13238篇
  2015年   14819篇
  2014年   20651篇
  2013年   30896篇
  2012年   37794篇
  2011年   40600篇
  2010年   25319篇
  2009年   24723篇
  2008年   37846篇
  2007年   40470篇
  2006年   41500篇
  2005年   40014篇
  2004年   38203篇
  2003年   37222篇
  2002年   35248篇
  2001年   66953篇
  2000年   68856篇
  1999年   57376篇
  1998年   17138篇
  1997年   15368篇
  1996年   16361篇
  1995年   16547篇
  1994年   15381篇
  1993年   14412篇
  1992年   47785篇
  1991年   46454篇
  1990年   44633篇
  1989年   42513篇
  1988年   39324篇
  1987年   38728篇
  1986年   36456篇
  1985年   35251篇
  1984年   26849篇
  1983年   22514篇
  1982年   14146篇
  1981年   12713篇
  1980年   12005篇
  1979年   24017篇
  1978年   17450篇
  1977年   14701篇
  1976年   13516篇
  1975年   14014篇
  1974年   16468篇
  1973年   15717篇
  1972年   14451篇
  1971年   13311篇
  1970年   12111篇
  1969年   11328篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Malignant tumors of the bones   总被引:2,自引:0,他引:2  
  相似文献   
92.
93.
94.
The Dundee Memory Clinic was established in 1991. This paper reviews the diagnosis of the first 150 attenders and compares the findings with those of other memory clinics.  相似文献   
95.
96.
Choristomas, masses of normal tissues in aberrant locations, contain smooth muscle fibers and fibrous tissues. We describe the MR imaging features of two choristomas located in the internal auditory canals and arising from the facial and vestibulocochlear nerves. Both lesions enhanced with contrast material. In one case, enhancement was seen in the geniculate ganglion and greater superficial petrosal nerve. In the other, a medial component enhanced less than the lateral component did.  相似文献   
97.
The ability of three Porphyromonas spp., seven Prevotella spp., seven Fusobacterium spp. and two related Bacteroides spp. (B. levii and B. macacae) to degrade an extensive range of synthetic endo-, amino- and diamino peptidase substrates linked to the fluorescent leaving group 7-amido-4-methylcoumarin (NHMec) was investigated. Many more species than was previously recognized exhibited peptidase activities, albeit at lower levels than those already described for Porphyromonas gingivalis. Detection of chymotrypsin-like activity was dependent on which of three NHMec-linked substrates was used, but all species exhibited degradative activity with at least one of these substrates. Elastase-like activity was detected in all species though not all species reacted with each of the elastase substrates. Glycylprolyl peptidase activity was detected in all of the species tested with the exception of F. mortiferum, F. gonidiaformans, F. naviforme and F. necrophorum. While the detection of peptidase activities does not appear to be useful for the differentiation of species within the genera Bacteroides and Prevotella, its ability to differentiate species of the genus Porphyromonas or Fosobacterium further investigation.  相似文献   
98.
The value of ultrasound in the diagnosis of a large rapidly growing thyroid mass was assessed in a study of 42 patients with a large (> 3 cm) rapidly growing (< two months) solitary mass. Haemorrhage into a thyroid nodule was present in 31 patients and thyroid malignancy in 11. Ultrasound of haemorrhage into a thyroid nodule revealed a large cystic mass in all 31 patients containing internal debris (22), septations (three), or a combination of both (six). The malignant causes of a large rapidly growing mass were lymphoma (two), anaplastic carcinoma (four) and metastasis (five). Ultrasound of these thyroid malignancies revealed a mass with a smooth, well-defined margin and strikingly low homogeneous echogenicity in all cases. Patients with thyroid metastases had evidence of widespread metastatic disease elsewhere. Lymphoma was differentiated from anaplastic carcinoma on fine-needle aspiration cytology or surgical biopsy. Ultrasound was of value in differentiating between a benign haemorrhagic nodule and a malignant tumour. The various malignant tumours had similar appearances, however, and could not be distinguished on ultrasound.  相似文献   
99.
100.
Summary GM1- and GM2-gangliosides were isolated from brain and radio-labelled. The labelled moieties were localized by hydrolysis with lysosomal enzymes, followed by thin-layer chromatography of the products. High-resolution loading tests with labelled gangliosides were developed and found to differentiate infantile and juvenile forms of GM1- and GM2-gangliosidoses as well as the identification of B, O and AB types of GM2-gangliosidosis.  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