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   24203篇
  免费   1542篇
  国内免费   108篇
耳鼻咽喉   347篇
儿科学   562篇
妇产科学   508篇
基础医学   2953篇
口腔科学   693篇
临床医学   1912篇
内科学   6202篇
皮肤病学   503篇
神经病学   2088篇
特种医学   580篇
外科学   4010篇
综合类   149篇
一般理论   9篇
预防医学   1510篇
眼科学   666篇
药学   1384篇
  2篇
中国医学   54篇
肿瘤学   1721篇
  2024年   53篇
  2023年   185篇
  2022年   360篇
  2021年   809篇
  2020年   429篇
  2019年   685篇
  2018年   859篇
  2017年   486篇
  2016年   581篇
  2015年   700篇
  2014年   934篇
  2013年   1166篇
  2012年   1908篇
  2011年   2001篇
  2010年   1045篇
  2009年   973篇
  2008年   1575篇
  2007年   1638篇
  2006年   1515篇
  2005年   1367篇
  2004年   1200篇
  2003年   1042篇
  2002年   972篇
  2001年   256篇
  2000年   262篇
  1999年   259篇
  1998年   216篇
  1997年   156篇
  1996年   150篇
  1995年   171篇
  1994年   134篇
  1993年   129篇
  1992年   159篇
  1991年   102篇
  1990年   105篇
  1989年   103篇
  1988年   89篇
  1987年   97篇
  1986年   104篇
  1985年   73篇
  1984年   88篇
  1983年   66篇
  1982年   78篇
  1981年   77篇
  1980年   47篇
  1979年   53篇
  1978年   49篇
  1977年   39篇
  1976年   32篇
  1973年   35篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
Laryngotracheoesophageal cleft is an uncommon disease that is difficult to diagnose and treat. Repair of the cleft depends on length and localization of the defect as well as the associated anomalies. A successful repair of a type II cleft is reported in this paper. An anterior split of the larynx and trachea was used and provided excellent exposure and safe repair without injury to the neurovascular structures. This is the best approach and should be used to correct all type II defects.  相似文献   
54.
The radiologic findings on conventional examinations (plain films and cholangiograms) in a large group of patients with proven hepatobiliary tuberculosis are reviewed. The plain film findings of large chalky and confluent hepatic calcifications or nodal-type calcifications along the course of the common bile duct are suggestive of hepatobiliary tuberculosis. Small, discrete, scattered calcifications may be mimicked by histoplasmosis but can be differentiated from hepatobiliary tuberculosis. Obstructing defects seen on cholangiography are indicative of tuberculosis when adjacent calcifications are present. The patterns of liver calcifications could provide a clue to the diagnosis of hepatobiliary tuberculosis and its differentiation from liver calcifications of various other etiologies.  相似文献   
55.
Mucosal hemodynamics (by reflectance spectrophotometry) and mucosal damage (by histologic examination) following acute colonic ischemia were evaluated in different anatomic locations in the colon of anesthetized rats. The reflectance spectrophotometer provides an index of mucosal hemoglobin concentration (IHB) and an index of oxygen saturation of hemoglobin (ISO2). The patterns of ischemia without congestion (IHB, ISO2) during superior mesenteric artery occlusion, and ischemia with congestion (IHB, ISO2) during portal vein occlusion, previously demonstrated in the stomach and duodenum, are also applicable to the colon. The significant linear correlations between changes (as percent of baseline) in IHB, ISO2, and hydrogen gas clearance suggest that changes in these indices are adequate indicators of changes in colonic mucosal perfusion. Superior mesenteric artery ligation produced significant reductions in both indices, and an increase in damage in the mucosa of the cecum, transverse colon, splenic flexure, and left colon, but not the rectum. Inferior mesenteric artery ligation produced only slight reduction in these indices and minimal damage only in the mucosa of the splenic flexure. These results support the hypothesis that the superior mesenteric artery is more important than the inferior mesenteric artery in maintaining colonic perfusion and colonic mucosal integrity in the rat.Supported by the American Society for Gastrointestinal Endoscopy Career Development Award (H850208, H870212), Veterans Administration Medical Research Funds; and in part by research grants (0162-01, 0162-02; 0291-01) from the Smokeless Tobacco Research Council, Inc.; and by funds provided by the Cigarette and Tobacco Surtax Fund of the State of California through the Tobacco Related Disease Research Program of the University of California.  相似文献   
56.
Several reports suggest that the glutathione-S-transferase (GST) family of enzymes is involved in a variety of cancers, due to their carcinogen-detoxification properties. A polymorphism in codon 105 of the pi variant (GSTP1 I105V), which affects the enzymatic activity of the enzyme, has been linked to the incidence of cancers from different organs. However, the published data in prostate cancer (PCa) is controversial. Some studies report an association with the GSTP1 I105V polymorphism and sporadic PCa, whereas other studies report no association. Recently, one study showed a positive correlation between the GSTP1 I105V polymorphism and familial PCa in a Japanese population. In the present study, we assessed the correlation of the GSTP1 I105V polymorphism with familial and sporadic PCa in an American population. We analyzed DNA samples from 438 patients with familial PCa, 499 patients with sporadic PCa, and 510 controls. We found no significant association between the GSTP1 I105V polymorphism and familial or sporadic PCa when compared to the control group [odds ratio (OR) =1.0 (0.74-1.37); P=0.58]. Moreover, no association was found after stratification for age of diagnosis, Gleason grade, or lymph node involvement [OR =0.84 (0.65-1.09), P=0.37]. These data indicate that there is no associated risk for sporadic or familial PCa in American families containing the GSTP1 I105V polymorphism.  相似文献   
57.
The expression and cellular localization of angiotensin II (Ang II) and AT(1) receptor proteins were examined in the normal human prostate and benign prostatic hyperplasia (BPH) by immunohistochemistry. In the normal prostate, Ang II immunoreactivity was localized to the basal layer of the epithelium and AT(1) receptor immunostaining was found predominantly on stromal smooth muscle and also on vascular smooth muscle of prostatic blood vessels. Ang II immunoreactivity was markedly increased in hyperplastic acini in BPH compared with acini in the normal prostate (normal: 7.4+/-0.2%, n=5 vs. BPH: 22.7+/-1.9%, n=5, p<0.001). However, AT(1) receptor immunoreactivity was significantly decreased in BPH compared with the normal prostate [normal: 16.4+/-2.2%, n=4 vs. BPH: 9.4+/-1.3%, n=5, p<0.05 (p=0.025)]. The present study demonstrates the presence of Ang II peptide in the basal layer of the epithelium and AT(1) receptors on stromal smooth muscle, suggesting that Ang II may mediate paracrine functions on cellular growth and smooth muscle tone in the human prostate. Furthermore, AT(1) receptor down-regulation in BPH may be due to receptor hyperstimulation by increased local levels of Ang II in BPH. These data extend previous findings in support of the novel concept that overactivity of the renin-angiotensin system (RAS) may be involved in the pathophysiology of BPH.  相似文献   
58.
Four recent cases of Yersinia enterocolitica infections from Florida are discussed. Two of the cases presented as acute mesenteric lymphadenitis, and the other two presented as septicemia. Three of the isolates were an uncommon serotype, O:2,3, and the fourth was serotype O:5. The increasing occurrence of Y. enterocolitica in semitropical areas of the United States is emphasized.  相似文献   
59.
60.
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