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   686471篇
  免费   35741篇
  国内免费   882篇
耳鼻咽喉   8953篇
儿科学   21962篇
妇产科学   16563篇
基础医学   114503篇
口腔科学   17253篇
临床医学   60945篇
内科学   129393篇
皮肤病学   16741篇
神经病学   48583篇
特种医学   24748篇
外国民族医学   83篇
外科学   99084篇
综合类   8344篇
现状与发展   2篇
一般理论   159篇
预防医学   51277篇
眼科学   14757篇
药学   51752篇
  1篇
中国医学   1547篇
肿瘤学   36444篇
  2021年   7050篇
  2019年   6958篇
  2018年   9752篇
  2017年   7001篇
  2016年   8140篇
  2015年   8452篇
  2014年   11459篇
  2013年   17043篇
  2012年   24631篇
  2011年   27092篇
  2010年   15373篇
  2009年   13459篇
  2008年   24191篇
  2007年   26272篇
  2006年   25463篇
  2005年   24810篇
  2004年   23872篇
  2003年   23008篇
  2002年   22219篇
  2001年   27678篇
  2000年   28886篇
  1999年   23175篇
  1998年   6731篇
  1997年   5563篇
  1996年   5377篇
  1995年   4972篇
  1992年   15994篇
  1991年   17330篇
  1990年   17286篇
  1989年   16884篇
  1988年   15432篇
  1987年   15264篇
  1986年   14184篇
  1985年   13713篇
  1984年   10249篇
  1983年   8738篇
  1982年   4768篇
  1979年   9629篇
  1978年   6887篇
  1977年   5626篇
  1976年   5943篇
  1975年   7094篇
  1974年   7916篇
  1973年   7712篇
  1972年   7033篇
  1971年   6712篇
  1970年   6287篇
  1969年   5870篇
  1968年   5529篇
  1967年   4958篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Abstract

This study was undertaken to compare the concentrations of pro- and anti-angiogenic growth factors, nitric oxide (NO) stable metabolites in maternal serum and embryonic left ventricular (LV) isovolumic relaxation time (IRT, ms) during the first trimester in two groups of women: with pregnancy conceived by assisted reproductive technologies (ART, n?=?39) and normally conceived (control group, n?=?68) pregnancy. The concentration of vasoconstrictor endothelin 1 was 45.5 times more in ART than in control group. On the contrary, the concentrations of NO stable metabolites in ART were 1.9 times less than in control women. The assessment of angiogenic suppressors in ART women demonstrates the decrease in s-endoglin concentration was 1.6 times and in soluble receptor to vascular endothelial growth factor concentration was 2.0 times in comparison with control group. There was a significant increase in LV IRT in ART embryos in comparison to control ones. These data suggest significant changes in pro- anti-angiogenic factors balance and increase in vascular impedance in ART-conceived embryos.  相似文献   
5.
6.
We report the case of a littoral‐cell angioma of the spleen, a recently described benign vascular tumour, whose imaging and pathological characteristics have been discussed only by a few authors. The diagnosis was made after elective splenectomy. The CT images, scintigraphy and histological specimens are presented, and differential diagnoses discussed.  相似文献   
7.
8.
Allergoid immunotherapy is a new form of allergen immunotherapy allowing safe administration of high allergen doses. There is limited information on the effects of allergoid immunotherapy in children with allergic rhinitis. To investigate the immunological and clinical effects of allergoid immunotherapy in children with allergic rhinitis due to grass pollen allergy. Children with allergic rhinitis were assigned to allergoid immunotherapy (n = 27) or control (n = 26, no immunotherapy) groups. Children in the immunotherapy group received seven injections of grass pollen allergoid immunotherapy before grass pollen season and continued to receive maintenance immunotherapy for 27 months. All patients were offered a pharmacotherapy regimen to be used on demand during the pollen seasons. Clinical and laboratory parameters were compared between the immunotherapy and control groups. The rhinoconjunctivitis symptom-medication score and asthma symptom score were lower in the immunotherapy group after 1 yr of maintenance immunotherapy (p < 0.01 for both). Skin test reactivity and nasal reactivity as determined by nasal provocation testing for grass pollen were significantly decreased after 1 yr of immunotherapy (p < 0.001 for both). The seasonal increase in bronchial reactivity and nasal lavage eosinophil cationic protein levels were prevented after the first year of immunotherapy (p < 0.05 for both). The seasonal increase in immunoglobulin (Ig)E decreased (p < 0.05) and grass-specific IgG, IgG(1) and IgG(4) increased significantly already at the end of the seven-injection build-up therapy (p < 0.001, for all). Interleukin (IL)-4 levels in the culture supernatants showed a steady decline from baseline at first and second year of immunotherapy (p < 0.001) but remained unchanged in the control group. Allergoid immunotherapy is an effective method in the treatment of grass pollen-induced allergic rhinitis in children and prevents the seasonal increase in bronchial hyper-reactivity. Changes in specific IgE and IgG levels and decreased IL-4 production in peripheral blood mononuclear cell culture supernatants may account for the observed clinical effects.  相似文献   
9.
10.
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