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   4021545篇
  免费   285021篇
  国内免费   9079篇
耳鼻咽喉   55889篇
儿科学   131734篇
妇产科学   110666篇
基础医学   573723篇
口腔科学   112113篇
临床医学   370279篇
内科学   776081篇
皮肤病学   92950篇
神经病学   325960篇
特种医学   152129篇
外国民族医学   1141篇
外科学   600763篇
综合类   83653篇
现状与发展   15篇
一般理论   1602篇
预防医学   314797篇
眼科学   93686篇
药学   296274篇
  16篇
中国医学   7866篇
肿瘤学   214308篇
  2019年   32342篇
  2018年   44708篇
  2017年   33873篇
  2016年   38953篇
  2015年   43853篇
  2014年   61258篇
  2013年   92758篇
  2012年   124976篇
  2011年   132709篇
  2010年   79824篇
  2009年   75925篇
  2008年   124222篇
  2007年   132056篇
  2006年   133991篇
  2005年   129279篇
  2004年   124380篇
  2003年   119885篇
  2002年   115951篇
  2001年   183136篇
  2000年   187985篇
  1999年   158949篇
  1998年   47202篇
  1997年   41482篇
  1996年   41638篇
  1995年   40019篇
  1994年   36759篇
  1993年   34582篇
  1992年   124642篇
  1991年   120824篇
  1990年   117524篇
  1989年   113902篇
  1988年   104822篇
  1987年   102725篇
  1986年   96722篇
  1985年   92704篇
  1984年   69300篇
  1983年   59002篇
  1982年   35179篇
  1981年   31677篇
  1979年   62896篇
  1978年   44725篇
  1977年   37761篇
  1976年   35546篇
  1975年   37969篇
  1974年   45288篇
  1973年   43147篇
  1972年   40607篇
  1971年   38143篇
  1970年   35120篇
  1969年   33799篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
A 65-year-old man with spontaneous rupture of the esophagus survived with a direct suture of the esophagus 15 hours after the onset of symptoms. Endoscopic examination of the esophagus was especially of great help in determining the surgical procedure in this patient, and we want to stress the importance of prompt diagnosis and immediate surgery for this disease.  相似文献   
993.
A two-week elective to introduce first- and second-year medical students to primary care internal medicine was developed and evaluated. Course time is divided between conference sessions (25 percent) provided by full-time clinical faculty members and office experience (75 percent) provided by volunteer clinical faculty members (general internists in private practice and in prepaid health plans). Evaluations by the students (n = 58) who took the elective consisted of a questionnaire assessment of the conference session topics, the student's ability to carry out course objectives, and the preceptor's teaching activities. The conference topics were highly rated, with a mean score of 4.1 on a rating scale ranging from 1 (unfavorable) to 5 (favorable). The course objectives and teaching activities were also well rated, with a mean score of 4.1 and 3.9, respectively, on a rating scale ranging from 1 (none) to 5 (outstanding).  相似文献   
994.
995.
996.
997.
Effects of dexamethasone on central and peripheral ACTH systems in the rat   总被引:1,自引:0,他引:1  
To investigate the simultaneous effects of dexamethasone on peripheral and central adrenocorticotropic hormone (ACTH) systems, rats were treated with dexamethasone or saline for 4 days. Pituitary, plasma, hypothalamus and cerebrospinal fluid (CSF) were then collected and analyzed for ACTH immunoreactivity. Additionally, hypothalamic tissue extracts were analyzed for corticotropin-releasing hormone (CRH) immunoreactivity. Dexamethasone significantly lowered peripheral levels of ACTH as measured in pituitary and plasma. Hypothalamic ACTH content significantly increased while CSF ACTH significantly decreased with dexamethasone treatment. Hypothalamic CRH concentrations showed a small but statistically insignificant decrease. These results suggest that prolonged exposure to dexamethasone affects central as well as peripheral ACTH activity, corroborate our previous findings in rhesus monkeys of decreased CSF ACTH in response to prolonged dexamethasone treatment, suggest that dexamethasone may inhibit the release of ACTH from hypothalamic neurons into the CSF, and provide evidence that the effect of dexamethasone on pituitary ACTH content is of greater magnitude than its effect on hypothalamic CRH.  相似文献   
998.
It is possible to determine the management and prognosis of mushroom poisoning from the history and initial symptoms with a high degree of confidence. The most important intoxications are those involving Amanita phalloides or other potentially fatal amatoxin-containing mushrooms, which have a latent period of ten to 12 hours before the patient becomes symptomatic. Because aggressive gastroenteric decontamination can reduce the extent of hepatic damage, it is important to attempt to determine during this asymptomatic period whether amatoxin exposure has occurred. Various laboratory methods that might be useful are reviewed.  相似文献   
999.
The cellular mechanisms by which pepsinogen (PNG) secretion is controlled are not understood. The aim of this study was to explore whether modulation of PNG secretion is mediated by cAMP or calcium-calmodulin (C-C). PNG secretion in isolated rabbit gastric fundic glands (IGG) was tested, using agents believed to act via cAMP or C-C. IGG were stimulated for 30 minutes with histamine (H) 10(-5) M, isoproterenol (I) 10(-5) M, carbachol (C) 10(-5) M, cholecystokinin-octapeptide (CCK-8) 10(-7) M, forskolin (F) 10(-5) M, 8 bromo-cAMP (8B) 10(-3) M, and A23187 (A) 10(-6) M. PNG levels were determined by spectrophotometric assay of hemoglobin digestion products. PNG amounts secreted were (mean per cent above basal levels of total IGG PNG units +/- SEM): H, -0.02 +/- 0.30%; I, 3.5 +/- 0.9%; C, 5.1 +/- 2.2%; CCK-8, 5.3 +/- 1.5%; F, 10.6 +/- 3.8%; 8B, 13.8 +/- 4.5%; A, 2.1 +/- 1.1%. All secretagogues except H stimulated PNG release significantly above basal levels (p less than 0.05). A primary histaminergic mechanism for pepsinogen secretion is unlikely. Since two other adenylate cyclase activators, isoproterenol and forskolin and the 3':5'-cyclic adenosine monophosphate analog 8-bromo cAMP stimulated pepsinogen secretion, cAMP-dependence is probable. Since carbachol, CCK-8, and A23187, which are believed to act via calcium-calmodulin, also stimulated pepsinogen secretion, this system, too, presumably plays a substantial role. Thus the data support a dual 3':5'-cyclic adenosine monophosphate/calcium-calmodulin modulation of pepsinogen secretion.  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