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   3022320篇
  免费   241049篇
  国内免费   6140篇
耳鼻咽喉   43152篇
儿科学   96255篇
妇产科学   82084篇
基础医学   428278篇
口腔科学   87245篇
临床医学   277418篇
内科学   585521篇
皮肤病学   63945篇
神经病学   251255篇
特种医学   119724篇
外国民族医学   1131篇
外科学   454868篇
综合类   72750篇
现状与发展   1篇
一般理论   1323篇
预防医学   245844篇
眼科学   71321篇
药学   224146篇
  9篇
中国医学   5737篇
肿瘤学   157502篇
  2018年   31363篇
  2016年   26944篇
  2015年   30280篇
  2014年   43316篇
  2013年   66337篇
  2012年   88668篇
  2011年   93759篇
  2010年   55602篇
  2009年   52841篇
  2008年   88637篇
  2007年   94359篇
  2006年   95411篇
  2005年   92608篇
  2004年   89620篇
  2003年   86291篇
  2002年   84612篇
  2001年   138133篇
  2000年   142950篇
  1999年   120608篇
  1998年   35171篇
  1997年   31903篇
  1996年   31518篇
  1995年   30535篇
  1994年   28677篇
  1993年   26638篇
  1992年   97496篇
  1991年   94537篇
  1990年   91605篇
  1989年   88298篇
  1988年   81613篇
  1987年   80769篇
  1986年   76327篇
  1985年   73180篇
  1984年   55490篇
  1983年   47398篇
  1982年   28915篇
  1981年   25801篇
  1980年   24157篇
  1979年   52188篇
  1978年   36875篇
  1977年   31187篇
  1976年   29407篇
  1975年   30871篇
  1974年   38016篇
  1973年   36175篇
  1972年   33763篇
  1971年   31348篇
  1970年   29301篇
  1969年   27308篇
  1968年   24953篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Cancer Causes & Control - Congenital malformations are strong risk factors for childhood cancer. Our objective was to determine whether cancer survival differs by birth defect status among...  相似文献   
22.
Post-induction hypotension is common and associated with postoperative complications. We hypothesised that pneumatic leg compression reduces post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy. In this double-blind randomised study, patients were allocated randomly to the pneumatic leg compression group (n = 50) or control (n = 50). In the intervention group, pneumatic leg compression was initiated before induction of anaesthesia. In the control group, pneumatic leg compression was initiated 20 min after anaesthesia induction. The primary outcome was the incidence of post-induction hypotension in these groups. Post-induction hypotension was defined as systolic blood pressure < 90 mmHg during the first 20 min after induction. Haemodynamic variables and area under the curve of post-induction systolic blood pressure over time were assessed. Complications associated with pneumatic leg compression were recorded, including: peripheral neuropathy; compartment syndrome; extensive bullae beneath the leg sleeves; and pulmonary thromboembolism. The incidence of post-induction hypotension decreased in the pneumatic leg compression group compared with that in the control group; 5 (10%) vs. 29 (58%), respectively, p < 0.001. In the pneumatic leg compression group, the lowest systolic, diastolic and mean blood pressures 20 min after induction of anaesthesia were significantly greater than the control group. Pneumatic leg compression resulted in an increased area under the curve of systolic blood pressure in the first 20 min after induction, p = 0.001. There were no pneumatic leg compression-related complications. Pneumatic leg compression reduced post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy, suggesting that it is an effective and safe intervention to prevent post-induction hypotension among elderly patients undergoing general anaesthesia.  相似文献   
23.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
24.
25.
Troppmair  Teresa  Egger  J.  Krösbacher  A.  Zanvettor  A.  Schinnerl  A.  Neumayr  A.  Baubin  M. 《Der Anaesthesist》2022,71(4):272-280
Die Anaesthesiologie - Die Qualität eines Rettungssystems zeichnet sich auch durch den effizienten Einsatz seiner personellen und Fahrzeugressourcen aus. So können im berechtigten Fall...  相似文献   
26.
27.
28.
29.
30.
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