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   1263773篇
  免费   94841篇
  国内免费   1578篇
耳鼻咽喉   16313篇
儿科学   40999篇
妇产科学   34947篇
基础医学   189388篇
口腔科学   34731篇
临床医学   117750篇
内科学   247789篇
皮肤病学   27278篇
神经病学   101848篇
特种医学   46758篇
外国民族医学   265篇
外科学   178576篇
综合类   25749篇
现状与发展   3篇
一般理论   568篇
预防医学   104649篇
眼科学   28044篇
药学   92557篇
  7篇
中国医学   2022篇
肿瘤学   69951篇
  2018年   13530篇
  2017年   10390篇
  2016年   11323篇
  2015年   13078篇
  2014年   17999篇
  2013年   27477篇
  2012年   37572篇
  2011年   39968篇
  2010年   23053篇
  2009年   22250篇
  2008年   37752篇
  2007年   40382篇
  2006年   39962篇
  2005年   39095篇
  2004年   37542篇
  2003年   35953篇
  2002年   34864篇
  2001年   56029篇
  2000年   57042篇
  1999年   48095篇
  1998年   13396篇
  1997年   12222篇
  1996年   12643篇
  1995年   11914篇
  1994年   11107篇
  1993年   10399篇
  1992年   38198篇
  1991年   37671篇
  1990年   36445篇
  1989年   35258篇
  1988年   32690篇
  1987年   32027篇
  1986年   30524篇
  1985年   28786篇
  1984年   21941篇
  1983年   19192篇
  1982年   11364篇
  1981年   10321篇
  1979年   20944篇
  1978年   15393篇
  1977年   12790篇
  1976年   11845篇
  1975年   12810篇
  1974年   15588篇
  1973年   15362篇
  1972年   14512篇
  1971年   13552篇
  1970年   12786篇
  1969年   12065篇
  1968年   11229篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
An 80-year-old man was evaluated for an epibulbar tumor on a phthisical eye. The initial biopsy diagnosis of the epibulbar tumor was poorly differentiated neoplasm. Exenteration of the phthisical eye and orbital contents showed an extensive pleomorphic adenocarcinoma of the nonpigmented epithelium of the ciliary body with extraocular extension. There was evidence of hyaluronic acid secretion and immunohistochemical staining was strong for vimentin, focal for epithelial membrane antigen and S-100 protein, and weak for neuron-specific-enolase. Electron microscopy demonstrated desmosomes between tumor cells, areas of thick, multilaminar basement membrane production surrounding individual tumor cells, and occasional intracytoplasmic intermediate filaments.  相似文献   
972.
973.
Sodium saccharin, at high doses in the diet, has been reported to cause hyperplasia of the forestomach (squamous portion of stomach), at the limiting ridge in F344 rats, in addition to its potential to induce proliferative effects on the urinary bladder epithelium. We have characterized this hyperplasia of the squamous epithelium of the forestomach at the limiting ridge in F344 and Sprague-Dawley rats given various doses of sodium saccharin for 4 to 95 wk. With increasing doses of sodium saccharin, the limiting ridge of the forestomach showed dose-related morphological changes: basal-cell hyperplasia, early papillary hyperplasia with basal-cell hyperplasia and papillary hyperplasia. Calcium saccharin in Prolab diet caused hyperplasia of the forestomach at the limiting ridge, similar to that caused by sodium saccharin. The severity of hyperplasia was influenced by the type of diet and by the strain of rats. AIN-76A diet without added sodium saccharin caused basal-cell hyperplasia in F344 rats, whereas Prolab, Purina and NIH-07 diets without added sodium saccharin had little or no effect on the forestomach. The effect of AIN-76A diet alone persisted through 95 wk of feeding without any evidence of tumour formation. In Sprague-Dawley rats, which appeared more sensitive to effects on the forestomach than F344 rats, Prolab 3200 and Purina diets without sodium saccharin caused basal-cell hyperplasia in more than half of the treated rats. The forestomach hyperplasia associated with AIN-76A or saccharin administration appears to be mild, limited in extent to the limiting ridge, and not associated with carcinogenesis.  相似文献   
974.
We studied the spatial frequency characteristics in the upper and lower hemiretina using pattern reversal VECPs. The subjects were 56 normal volunteers ranging in age from 14 to 69 years old. The latency of the first major positive component (P100) of VECPs was measured using checker board pattern stimuli under varying conditions of spatial frequency (112', 56', 28', 14', 7'). For the upper hemiretinal stimuli, the P100 peak latency vs spatial frequencies curve reached minimum at 56' approximately 28' and increased at both lower and higher frequencies. For the lower hemiretinal stimuli, this curve shifted towards lower frequencies. The results suggested that the spatial frequency characteristics between the upper and lower hemiretina were different.  相似文献   
975.
Despite the progress achieved in the treatment of ocular diseases, removal of the eyeball still has to be resorted to rather often. The records of 12 hospitals of Moscow over a year evidence 678 enucleations and eviscerations, 248 (39 percent) of these for oncologic diseases, 189 (29.1 percent) because of injury aftereffects, 153 (24 percent) because of glaucoma, and 58 (8 percent) because of ocular inflammations. Common enucleation was carried out in 203 of +/- 400 patients (except oncologic ones) and enucleation with implantation of biological and synthetic drafts in 197 cases, i.e. in half of the patients who needed it; this is explained by the absence of the necessary implants in hospitals. A bank of grafts should be created for centralized provision of ocular hospitals.  相似文献   
976.
Immunogold localisation of laminin in normal and exfoliative iris.   总被引:1,自引:1,他引:0       下载免费PDF全文
Immunoelectron microscopic studies of exfoliative iris tissue (seven specimens) revealed the presence of laminin in the fibrillar component of exfoliation material. The immunogold label was uniformly distributed on the exfoliation fibres. Deposition of laminin labelled exfoliation material in the dilator muscle was a noteworthy feature, as was an apparent depletion of laminin in the basement membranes of ostensibly unaffected vessels. In control iris tissue (five enucleated eyes) laminin was identified in the basement membrane round vascular contractile cells, but not beneath the endothelium.  相似文献   
977.
978.
979.
In the experiment on dogs and in patients with duodenal ulcer disease, it was established that the regulation of acid production besides the vagal nerves was mediated by the intragastric gastrin transport with the blood flow. A method of preoperative diagnosis of the intensity of intragastric blood flow permitting to define more accurately the indications for the choice of a method for surgical treatment has been developed. Supplementation of the selective proximal vagotomy with circular mucosectomy at the boundary between the antrum and body of a stomach enhances the effectiveness of operation due to reduction of the antral gastrin influence on the acid-producing zones of the stomach.  相似文献   
980.
In the article is presented classification, which takes into consideration mechanisms and sequence of spinal segment destruction in case of compression-flexion violence. On the basis of experimental and clinical data are shown the stages of destruction and their roentgenologic diagnosis, prognostication of some other damages, which are not detected by common methods. Differentiated curative tactics, taking account of necessary restorative measures in correspondence with stages and resolution types, is given.  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