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   170854篇
  免费   9729篇
  国内免费   425篇
耳鼻咽喉   2231篇
儿科学   5529篇
妇产科学   3605篇
基础医学   23170篇
口腔科学   7561篇
临床医学   12462篇
内科学   38288篇
皮肤病学   4349篇
神经病学   14211篇
特种医学   5282篇
外国民族医学   26篇
外科学   21039篇
综合类   1388篇
现状与发展   1篇
一般理论   60篇
预防医学   17824篇
眼科学   3155篇
药学   10346篇
中国医学   691篇
肿瘤学   9790篇
  2023年   889篇
  2022年   1943篇
  2021年   3628篇
  2020年   2429篇
  2019年   3429篇
  2018年   4834篇
  2017年   3631篇
  2016年   3371篇
  2015年   3945篇
  2014年   5413篇
  2013年   6832篇
  2012年   10647篇
  2011年   11149篇
  2010年   5612篇
  2009年   5051篇
  2008年   8614篇
  2007年   9238篇
  2006年   8556篇
  2005年   8840篇
  2004年   8313篇
  2003年   7600篇
  2002年   5653篇
  2001年   4963篇
  2000年   4949篇
  1999年   4352篇
  1998年   1541篇
  1997年   1290篇
  1996年   1275篇
  1995年   1083篇
  1994年   1078篇
  1993年   984篇
  1992年   2664篇
  1991年   2576篇
  1990年   2352篇
  1989年   2345篇
  1988年   2118篇
  1987年   1960篇
  1986年   1832篇
  1985年   1755篇
  1984年   1257篇
  1983年   1010篇
  1982年   566篇
  1981年   513篇
  1980年   494篇
  1979年   924篇
  1978年   605篇
  1977年   475篇
  1975年   547篇
  1974年   540篇
  1973年   543篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO.  相似文献   
5.
6.
7.
8.
9.
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   
10.
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   
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