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   384116篇
  免费   21699篇
  国内免费   2810篇
耳鼻咽喉   5218篇
儿科学   8228篇
妇产科学   10145篇
基础医学   53626篇
口腔科学   11796篇
临床医学   30340篇
内科学   78827篇
皮肤病学   8604篇
神经病学   27361篇
特种医学   14095篇
外国民族医学   82篇
外科学   60841篇
综合类   9962篇
现状与发展   1篇
一般理论   64篇
预防医学   17534篇
眼科学   9491篇
药学   31091篇
  9篇
中国医学   2210篇
肿瘤学   29100篇
  2021年   2719篇
  2019年   2870篇
  2018年   4589篇
  2017年   3548篇
  2016年   3690篇
  2015年   4102篇
  2014年   5796篇
  2013年   7497篇
  2012年   10172篇
  2011年   10353篇
  2010年   6277篇
  2009年   5914篇
  2008年   9558篇
  2007年   10387篇
  2006年   10279篇
  2005年   9367篇
  2004年   8845篇
  2003年   8579篇
  2002年   8250篇
  2001年   28261篇
  2000年   28808篇
  1999年   23644篇
  1998年   5172篇
  1997年   4264篇
  1996年   3831篇
  1995年   3483篇
  1994年   3109篇
  1993年   2845篇
  1992年   16059篇
  1991年   14816篇
  1990年   14160篇
  1989年   13966篇
  1988年   12583篇
  1987年   12066篇
  1986年   11104篇
  1985年   10321篇
  1984年   6912篇
  1983年   5599篇
  1982年   2722篇
  1979年   5480篇
  1978年   3350篇
  1977年   2973篇
  1975年   2642篇
  1974年   3064篇
  1973年   2865篇
  1972年   2828篇
  1971年   2774篇
  1970年   2510篇
  1969年   2544篇
  1968年   2250篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The expression of cytokeratin (40-52 kD), carcinoembryonic antigen (CEA), vimentin, neuron-specific enolase (NSE), S-100 protein, glial fibrillary acidic protein (GFAP) were investigated in 20 cases of pleomorphic adenoma of the salivary glands and 10 cases of normal salivary glands, in order to analyze and correlate the antigens' expressions with the probably histogenetic mechanisms of the various histopathological differentiations in pleomorphic adenoma of the salivary glands and their probably original cells in normal salivary glands. Immunohistochemistry has provided some evidence for the relationship of the tumor cells to normal salivary glands: In the normal glands, the acinic cells exhibited cytokeratin, CEA and focal, predominantly nuclear S-100 protein staining. In both normal glands and pleomorphic adenomas, the duct-lining cells were immunoreactive for cytokeratin, CEA and had both cytoplasmic and nuclear S-100 positivity; The myoepithelial cells of the normal glands as well as the periduct cells, epithelial nests/cords, squamous metaplasia and the stellate/spindle/cartilaginous cells in the myxomatous-chondroid areas of the pleomorphic adenoma contain immunoreactive vimentin, NSE, S-100 proteins and GFAP, and lesser amounts cytokeratin (40-52 kD)/CEA. The varicosities of the terminal axon may lie directly on the basal membrane, or penetrate the basal membrane and lie in direct contact with the effector cells (duct-acinar-myoepithelial cells) of the salivary glands. The peripheral neurons and axons of the autonomic nervous system were identified by vimentin, NSE, S-100 proteins and GFAP. The combination of epithelial cytokeratin and nervous system-related vimentin, NSE, S-100 and GFAP immunostaining in myoepithelium of the normal glands and in all component elements (particularly the periduct cells) of pleomorphic adenoma reflects pleomorphic adenoma of the salivary glands is an epithelial tumor, the probably original cells or the probably histogenetic mechanisms of the various histopathological differentiations is correlated not only with "duct-acinar-myoepithelial cells" but also with the neuroectoderm in the normal salivary glands."  相似文献   
42.
Effect of dental caries on pulp tissue   总被引:1,自引:0,他引:1  
  相似文献   
43.
44.
45.
A case of prepubertal periodontitis was observed and examined immunohistologically with peroxidase-antiperoxidase staining. The patient was an 11-year and 7-month-old Japanese girl, well-developed and well-nourished. Her parents were first cousins. Her chief complaint was the loosening and loss of the permanent teeth. There was a similar history of primary dentition. Her remaining permanent teeth were loosened with severe alveolar bone loss, but calculus deposit was minimal. Significantly, there was no palmar-plantar hyperkeratosis. General examination showed normal data except for the increase of the immunoglobulin concentrations. In neutrophil function tests chemotaxis was depressed, although phagocytosis, random migration and superoxide production were within normal limits. Histologically, neutrophils were seen in the gingival tissue and other findings were also similar to those of adult periodontitis. In immunohistological examination, IgG-bearing cells which mostly consisted of plasma cells predominated in the lesion. Considering the past history, the immunodeficiency and the absence of palmar-plantar hyperkeratosis, the case was diagnosed as prepubertal periodontitis.  相似文献   
46.
47.
48.
49.
Numerical determination of the teeth of two species of Japanese shrew moles, Urotrichus talpoides and Dymecodon pilirostris (Talpidae, Insectivora), was based on the position of the premaxillo-maxillary suture, comparison of the dentitions of the two species with those of their relatives and the supernumerary tooth. The premaxillo-maxillary suture is situated between the fifth and sixth tooth anterior to the M1, and the fifth tooth anterior to the M1 was determined to be C both in the two species. The supernumerary tooth which appears in the gap between the third and fourth anterior to the M1 of the lower jaw of Urotrichus talpoides was considered as a relic of pdl which seems to have been lost relatively recently in the evolution of this species. It was also shown that the first premolar of the upper jaw of the Urotrichus talpoides and the first premolars of the Dymecodon pilirostris are dihyodont. Retention of the dihyodont first premolars in these species seems to be a primitive character and is significant in determining the phylogenetical positions of these species.  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