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   26518篇
  免费   1959篇
  国内免费   48篇
耳鼻咽喉   120篇
儿科学   1046篇
妇产科学   866篇
基础医学   3117篇
口腔科学   347篇
临床医学   4210篇
内科学   4908篇
皮肤病学   445篇
神经病学   2915篇
特种医学   405篇
外科学   2142篇
综合类   368篇
一般理论   29篇
预防医学   3800篇
眼科学   370篇
药学   1635篇
中国医学   34篇
肿瘤学   1768篇
  2023年   185篇
  2022年   236篇
  2021年   422篇
  2020年   352篇
  2019年   569篇
  2018年   664篇
  2017年   529篇
  2016年   568篇
  2015年   628篇
  2014年   858篇
  2013年   1366篇
  2012年   2015篇
  2011年   1987篇
  2010年   1120篇
  2009年   1070篇
  2008年   1718篇
  2007年   1887篇
  2006年   1766篇
  2005年   1820篇
  2004年   1732篇
  2003年   1555篇
  2002年   1498篇
  2001年   265篇
  2000年   227篇
  1999年   240篇
  1998年   315篇
  1997年   229篇
  1996年   204篇
  1995年   209篇
  1994年   183篇
  1993年   159篇
  1992年   127篇
  1991年   124篇
  1990年   128篇
  1989年   114篇
  1988年   90篇
  1987年   100篇
  1986年   100篇
  1985年   114篇
  1984年   115篇
  1983年   88篇
  1982年   108篇
  1981年   87篇
  1980年   76篇
  1979年   62篇
  1978年   64篇
  1977年   49篇
  1975年   40篇
  1973年   29篇
  1972年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Children today experience many transitions within their school careers. One transition in particular, from preschool to kindergarten presents many challenges for children, families, and teachers. A model for planning and carrying out this transition is presented. The model includes developing and implementing the transition process.  相似文献   
22.
23.
24.
25.
26.
27.
1. The present study investigated the effect of prior administration of nifedipine on AVP-induced ACTH release in seven normal volunteers. Three protocols were used: 20 mg oral nifedipine; 0.14 pressor units intramuscular (i.m.) per kg bodyweight aqueous AVP; oral nifedipine plus i.m. AVP 90 min later. Plasma ACTH and cortisol were measured at intervals for 2.5 h during each test. 2. The mean peak plasma ACTH and cortisol levels and the mean peak changes from basal in these levels were significantly lower in the nifedipine/AVP test than in the AVP alone test. The integrated area under the cortisol time curve was significantly lower for the nifedipine/AVP test than that for the AVP test alone. Nifedipine alone caused no changes in ACTH or cortisol. 3. Acute administration of oral nifedipine caused an inhibition of AVP-stimulated ACTH and cortisol release in normal humans. This effect may be due to blockade of plasma membrane calcium channels normally activated during AVP stimulation of pituitary corticotrophs.  相似文献   
28.
29.
PURPOSE: A standardized, noninvasive technique to assess healing of the mandibular distraction wound is not available. Current methods include clinical examination, plain radiography, and computed tomography. These imaging techniques are expensive and obligate the patient to serial radiation exposure. In addition, anatomic overlap and metal artifacts may obscure the distraction gap. In contrast, ultrasound has been shown to be a noninvasive, efficient, and inexpensive way to evaluate bone healing. The purpose of this study was to test the feasibility of ultrasound to evaluate an experimental mandibular distraction osteogenesis wound. MATERIALS AND METHODS: Distraction devices were placed via a submandibular incision into 24 minipigs. The protocol consisted of 0-day latency and distraction rates of 1, 2, or 4 mm/d for a 12-mm gap. The wounds were assessed in vivo after 0, 8, 16, and 24 days of neutral fixation. Ex vivo radiographs were used to estimate bone fill using a semiquantitative score. A semiquantitative ultrasound score was assigned, and the beam penetration depth was measured in millimeters. RESULTS: In all groups, clinical stability of the distraction wound increased with the duration of fixation. Plain radiographs, taken during neutral fixation, showed that the desired distraction gap was achieved and maintained. The ultrasound score increased with fixation time, whereas beam penetration depth decreased as expected. Ex vivo radiographs showed increasing bone fill score with time and paralleled the ultrasound score. CONCLUSIONS: The results of this feasibility study indicate that ultrasound is potentially useful for the assessment of bone formation in distraction osteogenesis wounds.  相似文献   
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