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   4720806篇
  免费   381651篇
  国内免费   17285篇
耳鼻咽喉   67017篇
儿科学   144593篇
妇产科学   125722篇
基础医学   709755篇
口腔科学   135335篇
临床医学   426954篇
内科学   857119篇
皮肤病学   114394篇
神经病学   395092篇
特种医学   189895篇
外国民族医学   789篇
外科学   721323篇
综合类   141447篇
现状与发展   30篇
一般理论   2700篇
预防医学   388660篇
眼科学   111381篇
药学   339289篇
  25篇
中国医学   13838篇
肿瘤学   234384篇
  2021年   59321篇
  2019年   60884篇
  2018年   76708篇
  2017年   58615篇
  2016年   65741篇
  2015年   79920篇
  2014年   115017篇
  2013年   181180篇
  2012年   133127篇
  2011年   137672篇
  2010年   130133篇
  2009年   131134篇
  2008年   121961篇
  2007年   130809篇
  2006年   138241篇
  2005年   132922篇
  2004年   133709篇
  2003年   123526篇
  2002年   111988篇
  2001年   171398篇
  2000年   167787篇
  1999年   153171篇
  1998年   73291篇
  1997年   68903篇
  1996年   66751篇
  1995年   62314篇
  1994年   56487篇
  1993年   52511篇
  1992年   115082篇
  1991年   110910篇
  1990年   106909篇
  1989年   104201篇
  1988年   97127篇
  1987年   95158篇
  1986年   90602篇
  1985年   88638篇
  1984年   73586篇
  1983年   64747篇
  1982年   50690篇
  1981年   46889篇
  1980年   44251篇
  1979年   66373篇
  1978年   52506篇
  1977年   46458篇
  1976年   42685篇
  1975年   43577篇
  1974年   49420篇
  1973年   47507篇
  1972年   45023篇
  1971年   41487篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.

The exercise pressor reflex is a feedback mechanism engaged upon stimulation of mechano- and metabosensitive skeletal muscle afferents. Activation of these afferents elicits a reflex increase in heart rate, blood pressure, and ventilation in an intensity-dependent manner. Consequently, the exercise pressor reflex has been postulated to be one of the principal mediators of the cardiorespiratory responses to exercise. In this updated review, we will discuss classical and recent advancements in our understating of the exercise pressor reflex function in both human and animal models. Particular attention will be paid to the afferent mechanisms and pathways involved during its activation, its effects on different target organs, its potential role in the abnormal cardiovascular response to exercise in diseased states, and the impact of age and biological sex on these responses. Finally, we will highlight some unanswered questions in the literature that may inspire future investigations in the field.

  相似文献   
22.
23.
Journal of Behavioral Medicine - Evidence supports the use of graphic warnings to educate the public about the health harms of smoking and suggests warnings eliciting negative emotional responses...  相似文献   
24.
Noninvasive imaging of cardiac fibrosis is important for early diagnosis and intervention in chronic heart diseases. Here, we investigated whether noninvasive, contrast agent-free MRI T2-mapping can quantify myocardial fibrosis in preclinical models of aging and pressure overload. Myocardial fibrosis and remodeling were analyzed in two animal models: (i) aging (15-month-old male CF-1 mice vs. young 6- to 8-week-old mice), and (ii) pressure overload (PO; by transverse aortic constriction in 4- to 5-month-old male C57BL/6 mice vs. sham-operated for 14 days). In vivo T2-mapping was performed by acquiring data during the isovolumic and early diastolic phases, with a modified respiratory and ECG-triggered multiecho TurboRARE sequence on a 7-T MRI. Cine MRI provided cardiac morphology and function. A quantitative segmentation method was developed to analyze the in vivo T2-maps of hearts at midventricle, apex, and basal regions. The cardiac fibrosis area was analyzed ex vivo by picro sirius red (PSR) staining. Both aged and pressure-overloaded hearts developed significant myocardial contractile dysfunction, cardiac hypertrophy, and interstitial fibrosis. The aged mice had two phenotypes, fibrotic and mild-fibrotic. Notably, the aged fibrotic subgroup and the PO mice showed a marked decrease in T2 relaxation times (25.3 ± 0.6 in aged vs. 29.9 ± 0.7 ms in young mice, p = 0.002; and 24.3 ± 1.7 in PO vs. 28.7 ± 0.7 ms in shams, p = 0.05). However, no significant difference in T2 was detected between the aged mild-fibrotic subgroup and the young mice. Accordingly, an inverse correlation between myocardial fibrosis percentage (FP) and T2 relaxation time was derived (R2 = 0.98): T2 (ms) = 30.45 – 1.05 × FP. Thus, these results demonstrate a statistical agreement between T2-map–quantified fibrosis and PSR staining in two different clinically relevant animal models. In conclusion, T2-mapping MRI is a promising noninvasive contrast agent-free quantitative technique to characterize myocardial fibrosis.  相似文献   
25.
26.
Collagens are the most abundant proteins in the extracellular matrix. They provide a framework to build organs and tissues and give structural support to make them resistant to mechanical load and forces. Several intra‐ and extracellular modifications are needed to make functional collagen molecules, intracellular post‐translational modifications of proline and lysine residues having key roles in this. In this article, we provide a review on the enzymes responsible for the proline and lysine modifications, that is collagen prolyl 4‐hydroxylases, 3‐hydroxylases and lysyl hydroxylases, and discuss their biological functions and involvement in diseases.  相似文献   
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