首页 | 官方网站   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   171975篇
  免费   9896篇
  国内免费   454篇
医药卫生   182325篇
  2023年   889篇
  2022年   1942篇
  2021年   3629篇
  2020年   2438篇
  2019年   3440篇
  2018年   4863篇
  2017年   3641篇
  2016年   3370篇
  2015年   3950篇
  2014年   5425篇
  2013年   6845篇
  2012年   10667篇
  2011年   11155篇
  2010年   5656篇
  2009年   5094篇
  2008年   8621篇
  2007年   9253篇
  2006年   8582篇
  2005年   8869篇
  2004年   8355篇
  2003年   7643篇
  2002年   5696篇
  2001年   4997篇
  2000年   4995篇
  1999年   4387篇
  1998年   1602篇
  1997年   1360篇
  1996年   1364篇
  1995年   1143篇
  1994年   1118篇
  1993年   1027篇
  1992年   2692篇
  1991年   2602篇
  1990年   2376篇
  1989年   2390篇
  1988年   2163篇
  1987年   1991篇
  1986年   1871篇
  1985年   1792篇
  1984年   1271篇
  1983年   1024篇
  1982年   584篇
  1981年   529篇
  1980年   513篇
  1979年   927篇
  1978年   615篇
  1977年   492篇
  1975年   551篇
  1974年   546篇
  1973年   544篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
6.
7.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic.  相似文献   
8.
Melatonin, the main hormone produced by the pineal gland, is secreted in a circadian manner (24‐hr period), and its oscillation influences several circadian biological rhythms, such as the regulation of clock genes expression (chronobiotic effect) and the modulation of several endocrine functions in peripheral tissues. Assuming that the circadian synchronization of clock genes can play a role in the regulation of energy metabolism and it is influenced by melatonin, our study was designed to assess possible alterations as a consequence of melatonin absence on the circadian expression of clock genes in the epididymal adipose tissue of male Wistar rats and the possible metabolic repercussions to this tissue. Our data show that pinealectomy indeed has impacts on molecular events: it abolishes the daily pattern of the expression of Clock, Per2, and Cry1 clock genes and Pparγ expression, significantly increases the amplitude of daily expression of Rev‐erbα, and affects the pattern of and impairs adipokine production, leading to a decrease in leptin levels. However, regarding some metabolic aspects of adipocyte functions, such as its ability to synthesize triacylglycerols from glucose along 24 hr, was not compromised by pinealectomy, although the daily profile of the lipogenic enzymes expression (ATP‐citrate lyase, malic enzyme, fatty acid synthase, and glucose‐6‐phosphate dehydrogenase) was abolished in pinealectomized animals.  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-23

京公网安备 11010802026262号