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   21463篇
  免费   1255篇
  国内免费   205篇
耳鼻咽喉   137篇
儿科学   1217篇
妇产科学   312篇
基础医学   2540篇
口腔科学   367篇
临床医学   1368篇
内科学   3829篇
皮肤病学   624篇
神经病学   1337篇
特种医学   795篇
外国民族医学   5篇
外科学   2870篇
综合类   808篇
一般理论   1篇
预防医学   1548篇
眼科学   1072篇
药学   2077篇
  5篇
中国医学   307篇
肿瘤学   1704篇
  2022年   269篇
  2021年   412篇
  2020年   279篇
  2019年   304篇
  2018年   373篇
  2017年   306篇
  2016年   393篇
  2015年   445篇
  2014年   623篇
  2013年   837篇
  2012年   1122篇
  2011年   1147篇
  2010年   699篇
  2009年   591篇
  2008年   946篇
  2007年   961篇
  2006年   904篇
  2005年   851篇
  2004年   766篇
  2003年   769篇
  2002年   720篇
  2001年   626篇
  2000年   656篇
  1999年   607篇
  1998年   310篇
  1997年   276篇
  1996年   253篇
  1995年   232篇
  1994年   200篇
  1993年   191篇
  1992年   418篇
  1991年   402篇
  1990年   389篇
  1989年   432篇
  1988年   348篇
  1987年   341篇
  1986年   272篇
  1985年   281篇
  1984年   266篇
  1983年   223篇
  1982年   148篇
  1981年   137篇
  1980年   123篇
  1979年   189篇
  1978年   134篇
  1975年   142篇
  1974年   145篇
  1973年   145篇
  1972年   130篇
  1971年   151篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Unilateral and bilateral variation in the course and elongation of the cervical (extracranial) part of the internal carotid artery (ICA) leading to its tortuosity, kinking and coiling or looping is not a rare condition, which could be caused by both embryological and acquired factors. Patients with such variations may be asymptomatic in some cases; in others, they can develop cerebrovascular symptoms due to carotid stenosis affecting cerebral circulation. The risk of transient ischemic attacks in patients with carotid stenosis is high and its surgical correction is indicated for the prevention of ischemic stroke. Detection of developmental variations of the ICA and evaluation of its stenotic areas is very important for surgical interventions and involves specific diagnostic imaging techniques for vascular lesions including contrast arteriography, duplex ultrasonography and magnetic resonance angiography. Examination of obtained images in cases of unusual and complicated variations of vascular pattern of the ICA may lead to confusion in interpretation of data. Awareness about details and topographic anatomy of variations of the ICA may serve as a useful guide for both radiologists and vascular surgeons. It may help to prevent diagnostic errors, influence surgical tactics and interventional procedures and avoid complications during the head and neck surgery. Our present study was conducted with a purpose of updating data about developmental variations of the ICA. Dissections of the main neurovascular bundle of the head and neck were performed on a total 14 human adult cadavers (10 – Africans: 7 males & 3 females and 4 – East Indians: all males). Two cases of unilateral congenital elongation of the cervical part of the ICA with kinking and looping and carotid stenoses were found only in African males. Here we present their detailed case reports with review of the literature.  相似文献   
22.
Coexistent primary hyperparathyroidism and monoclonal gammopathy, although rare, has been reported previously by a number of investigators. We report four patients with such an occurrence who were seen between 1976 and 1988. Another patient with primary hyperparathyroidism also had multiple myeloma and was in remission for 12 years. These patients represent approximately 1% of the 386 patients with primary hyperparathyroidism seen during the same 12-year period. Although several mechanisms have been proposed to explain this concurrence, we believe it is the result of a chance occurrence. A review of the literature, an estimate of the chance occurrence of coincidental monoclonal gammopathy, benign or malignant, in patients with primary hyperparathyroidism, and some practical implications of this interesting coexistence are presented.  相似文献   
23.

Background  

Almost 400,000 deaths are registered each year in Thailand. Their value for public health policy and planning is greatly diminished by incomplete registration of deaths and by concerns about the quality of cause-of-death information. This arises from misclassification of specified causes of death, particularly in hospitals, as well as from extensive use of ill-defined and vague codes to attribute the underlying cause of death. Detailed investigations of a sample of deaths in and out of hospital were carried out to identify misclassification of causes and thus derive a best estimate of national mortality patterns by age, sex, and cause of death.  相似文献   
24.
BACKGROUND: Perfusion functional magnetic resonance imaging (fMRI) was used to investigate the effect of genetic variation of the human serotonin transporter (5-HTT) gene (5-HTTLPR, SLC6A4) on resting brain function of healthy individuals. METHODS: Twenty-six healthy subjects, half homozygous for the 5-HTTLPR short allele (s/s group) and half homozygous for the long allele (l/l group), underwent perfusion functional and structural magnetic resonance imaging during a resting state. The two genotype groups had no psychiatric illness and were similar in age, gender, and personality scores. RESULTS: Compared with the l/l group, the s/s group showed significantly increased resting cerebral blood flow (CBF) in the amygdala and decreased CBF in the ventromedial prefrontal cortex. The effect of functional modulation in these regions by 5-HTTLPR genotype cannot be accounted for by variations in brain anatomy, personality, or self-reported mood. CONCLUSIONS: The 5-HTTLPR genotype alters resting brain function in emotion-related regions in healthy individuals, including the amygdala and ventromedial prefrontal cortex. Such alterations suggest a broad role of the 5-HTT gene in brain function that may be associated with the genetic susceptibility for mood disorders such as depression.  相似文献   
25.
26.
27.
    
We present our comments on the above article.  相似文献   
28.
29.
30.
为阐明IL-1对粒系细胞和红系细胞的作用,我们通过对小鼠骨髓及外周血的研究探讨了IL-1对粒系和红系造血细胞的调节作用.结果表明:IL-1单剂量腹腔注射后第7天红系造血细胞明显减少,外周血网织红细胞在第8天显著下降.在5~10万U/kg剂量范围内IL-1明显促进粒系细胞的增殖.应用流式细胞仪对DNA分析显示IL-1并不引起全骨髓细胞DNA的变化,但大体积细胞在注射IL-1后第3天S期细胞明显增多.我们的结果表明IL-1抑制红系造血细胞的分化增殖,在适当的剂量范围内促进粒系细胞的增殖和分化成熟.其作用的分子基础是诱导造血细胞的细胞周期变化.  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