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   1265093篇
  免费   96789篇
  国内免费   1585篇
耳鼻咽喉   16353篇
儿科学   41114篇
妇产科学   35074篇
基础医学   189818篇
口腔科学   34788篇
临床医学   117909篇
内科学   248281篇
皮肤病学   27357篇
神经病学   102156篇
特种医学   46834篇
外国民族医学   265篇
外科学   179382篇
综合类   25772篇
现状与发展   3篇
一般理论   570篇
预防医学   104819篇
眼科学   28113篇
药学   92753篇
  7篇
中国医学   2044篇
肿瘤学   70055篇
  2018年   13641篇
  2017年   10489篇
  2016年   11425篇
  2015年   13174篇
  2014年   18111篇
  2013年   27623篇
  2012年   37786篇
  2011年   40220篇
  2010年   23200篇
  2009年   22370篇
  2008年   37953篇
  2007年   40610篇
  2006年   40150篇
  2005年   39292篇
  2004年   37703篇
  2003年   36120篇
  2002年   35023篇
  2001年   56135篇
  2000年   57183篇
  1999年   48195篇
  1998年   13429篇
  1997年   12253篇
  1996年   12664篇
  1995年   11947篇
  1994年   11129篇
  1993年   10414篇
  1992年   38268篇
  1991年   37732篇
  1990年   36487篇
  1989年   35307篇
  1988年   32721篇
  1987年   32068篇
  1986年   30561篇
  1985年   28813篇
  1984年   21971篇
  1983年   19214篇
  1982年   11381篇
  1981年   10340篇
  1979年   20957篇
  1978年   15403篇
  1977年   12801篇
  1976年   11853篇
  1975年   12825篇
  1974年   15597篇
  1973年   15385篇
  1972年   14526篇
  1971年   13565篇
  1970年   12793篇
  1969年   12070篇
  1968年   11233篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
The human prostatic urethra has been investigated by means of scanning electron microscopy. On the posterior wall of the urethra, the seminal colliculus with the orifices of the ejaculatory ducts is clearly detectable. The upper portion of the prostatic urethra shows a typical transitional epithelium with large superficial cells of a ruffled appearance. In the lower portion of the organ (underneath the openings of the ejaculatory ducts), the apical pattern of the cells varies considerably. Four main aspects are recognizable: apices provided with microvilli, dome-shaped apices with an almost smooth surface, large apices with labyrinthic microplicae and ciliated apices. Also, apices showing intermediate characteristics can be noted. The functional significance of the morphological patterns as well as the possibility of a transition among the various types of surface structures are discussed.  相似文献   
993.
We isolated hybridoma cells, which secreted monoclonal antibody (MAb) 121 SLE, an IgM showing the following reactivities: (1) by immunodiffusion, MAb 121 SLE and MAb NS 19-9 (a monoclonal antibody directed against a sialylated Lewis(a) antigen called CA 19-9) showed an identical precipitin line with mucin preparation containing this CA 19-9; (2) by immunoradiometric assay, MAb 121 SLE totally inhibited fixation of radiolabelled MAb NS 19-9; (3) by immunoperoxidase, MAb 121 SLE stained the normal gastrointestinal mucosa of Le-positive individuals exclusively, and this staining disappeared after neuraminidase treatment, as observed using MAb NS 19-9. However, the pattern of the staining obtained with MAb 121 SLE differed slightly from that given by MAb 19-9 on the different positive areas of the gastrointestinal mucosae. These differences principally concerned the number of positive epithelial cells and the intensity of their staining; (4) moreover, antibodies against idiotype determinant of NS 19-9 antibody did not react with the antibody 121 SLE. We concluded that MAb 121 SLE is different from the MAb NS 19-9. However, both these antibodies were associated with the same molecular sialylated Lewis(a) structure.  相似文献   
994.
995.
996.
A human factors engineering analysis of a chemical containment laboratory was performed to develop appropriate standards for future laboratory design. In order to perform this evaluation, a state-of-the-art facility was studied in depth. Measurements and observations were made of key operating areas. In addition, technicians were observed and interviewed as they performed various tasks. Compiled data were compared to existing ergonomic standards. The occupational implications of instituting ergonomically developed laboratory design standards are as follows: increased worker health, safety and productivity, improved work quality and reduced stress.  相似文献   
997.
The ganglioside composition of human melanoma was analyzed in five sets of tumor specimens obtained directly from surgery, from the autologous tissue culture cell lines, and from the autologous cell lines grown in athymic nude mice. Total gangliosides of these 15 melanoma specimens were isolated and purified, and the amount of each component ganglioside was analyzed by thin-layer chromatography and a thin-layer chromatography scanner. The ganglioside composition of the five surgical melanoma specimens clearly exhibited different patterns from each other. Moreover, none of the autologous cultured melanomas possessed the same ganglioside composition as their original biopsied tumors. However, when these melanoma cell lines were transplanted into nude mice, the ganglioside composition was converted back to the same ganglioside pattern as in the original surgical specimens. The results support the view that changes in the ganglioside composition of melanoma during in vitro growth are caused by the culture environment rather than by selection of melanoma cells with a particular genotype. Reestablishment of the original ganglioside patterns after passage in nude mice provides clear evidence that in vivo expression of gangliosides is a conserved and stable function specified by the human melanoma cells.  相似文献   
998.
999.
Summary The authors report 165 cases of thoraco-lumbar lesions with neurological dysfunction. All the patient were operated. They analyze the neurological and mechanical results and indicate the use of different osteosynthesis apparatus according to the type and level of lesions.Harrington's rods seem to give more precise repositioning while Roy Camille's plates give more stability. When the posterior wall of the spinal canal is intact, Kempf's compression rods can be used.Thoraxic spine injuries seem to be an indication for Harrington's rods, while lumbar injuries seem to call for Camille's plates.  相似文献   
1000.
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