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   1342169篇
  免费   112843篇
  国内免费   6376篇
耳鼻咽喉   16733篇
儿科学   43128篇
妇产科学   36632篇
基础医学   184091篇
口腔科学   36324篇
临床医学   121176篇
内科学   279152篇
皮肤病学   31930篇
神经病学   110872篇
特种医学   55700篇
外国民族医学   274篇
外科学   210824篇
综合类   31612篇
现状与发展   2篇
一般理论   417篇
预防医学   107107篇
眼科学   28150篇
药学   93971篇
  5篇
中国医学   2231篇
肿瘤学   71057篇
  2018年   13425篇
  2017年   10694篇
  2016年   12839篇
  2015年   14366篇
  2014年   20048篇
  2013年   29877篇
  2012年   36412篇
  2011年   39069篇
  2010年   24501篇
  2009年   24001篇
  2008年   36523篇
  2007年   38961篇
  2006年   40035篇
  2005年   38632篇
  2004年   36895篇
  2003年   35978篇
  2002年   34006篇
  2001年   66172篇
  2000年   68049篇
  1999年   56670篇
  1998年   16761篇
  1997年   15052篇
  1996年   16044篇
  1995年   16272篇
  1994年   15128篇
  1993年   14193篇
  1992年   47168篇
  1991年   45821篇
  1990年   44046篇
  1989年   41890篇
  1988年   38824篇
  1987年   38147篇
  1986年   35929篇
  1985年   34694篇
  1984年   26403篇
  1983年   22154篇
  1982年   13878篇
  1981年   12469篇
  1980年   11741篇
  1979年   23580篇
  1978年   17108篇
  1977年   14401篇
  1976年   13201篇
  1975年   13753篇
  1974年   16115篇
  1973年   15421篇
  1972年   14204篇
  1971年   13059篇
  1970年   11904篇
  1969年   11119篇
排序方式: 共有10000条查询结果,搜索用时 15 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