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   64169篇
  免费   5395篇
  国内免费   2703篇
耳鼻咽喉   315篇
儿科学   1526篇
妇产科学   1419篇
基础医学   7728篇
口腔科学   999篇
临床医学   8902篇
内科学   11085篇
皮肤病学   795篇
神经病学   4681篇
特种医学   1692篇
外国民族医学   23篇
外科学   6295篇
综合类   6153篇
现状与发展   12篇
一般理论   31篇
预防医学   5999篇
眼科学   1337篇
药学   5594篇
  15篇
中国医学   1930篇
肿瘤学   5736篇
  2024年   126篇
  2023年   747篇
  2022年   1555篇
  2021年   2084篇
  2020年   1717篇
  2019年   1773篇
  2018年   1927篇
  2017年   1705篇
  2016年   1684篇
  2015年   2368篇
  2014年   2915篇
  2013年   3147篇
  2012年   4861篇
  2011年   4968篇
  2010年   2935篇
  2009年   2507篇
  2008年   3739篇
  2007年   3918篇
  2006年   3621篇
  2005年   3762篇
  2004年   3037篇
  2003年   2819篇
  2002年   2534篇
  2001年   1108篇
  2000年   1191篇
  1999年   1273篇
  1998年   935篇
  1997年   904篇
  1996年   701篇
  1995年   682篇
  1994年   611篇
  1993年   448篇
  1992年   425篇
  1991年   421篇
  1990年   398篇
  1989年   347篇
  1988年   291篇
  1987年   283篇
  1986年   254篇
  1985年   225篇
  1984年   197篇
  1983年   148篇
  1982年   124篇
  1981年   120篇
  1980年   99篇
  1979年   82篇
  1978年   80篇
  1977年   60篇
  1976年   40篇
  1975年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
Serum interleukin-2 receptor (sIL-2R) level, activities of natural killer cell (NK) and lymphokine activated killer (LAK) cells were determined in 60 patients with advanced carcinoma (AC) before and after treatment with Shenmai Injection (SMI), forty healthy persons were taken as non-carcinoma control (NC). The results showed that: Serum sIL-2R level in AC were much higher than those in NC (P<0.05) and activities of NK and LAK cells in AC were much lower than those in NC (P<0.05) before treatment. There was no significant difference among gastric, colonic and lung cancer (P>0.05). After treatment with SMI, it was found that the level of sIL-2R in all patients were obviously lowered (P<0.05) while the activities of NK and LAK cells were signifficantly higher than that prior the treatment (P<0.05). Relevancy was not found between sIL-2R and NK, LAK cells. These data suggested that the immune function was compromised in AC, and SMI has a wide effect of immuno-regulation.  相似文献   
56.
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   
57.
58.
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   
59.
为探讨醇脱氢酶(ADH)基因和醛脱氢酶(ALDH)基因多态性与酒依赖患病的相互关系,用耳血干血痕聚合酶链反应、等位基因特异性寡核苷酸探针方法,检测乙醇代谢酶ADH和ALDH基因型在我国蒙、汉民族酒依赖与非酒依赖者中分布频率。结果显示在酒依赖组(汉族52例,蒙族31例)与正常对照组(汉族48例,蒙族35例)之间:汉族的ALDH2基因型频率与等位基因频率的分布差异有非常显著性(P<0.01),而蒙族则表示为ADH2基因型频率与等位基因频率的分布差异有非常显著性(P<0.01)。这提示汉族酒依赖的发病与ALDH2基因有关,蒙族则与ADH2基因有关。  相似文献   
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