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   23035篇
  免费   1340篇
  国内免费   209篇
耳鼻咽喉   178篇
儿科学   1317篇
妇产科学   353篇
基础医学   2731篇
口腔科学   471篇
临床医学   1463篇
内科学   4125篇
皮肤病学   458篇
神经病学   1517篇
特种医学   841篇
外国民族医学   5篇
外科学   3167篇
综合类   903篇
一般理论   1篇
预防医学   1532篇
眼科学   1136篇
药学   2227篇
  5篇
中国医学   319篇
肿瘤学   1835篇
  2022年   213篇
  2021年   479篇
  2020年   322篇
  2019年   356篇
  2018年   448篇
  2017年   382篇
  2016年   434篇
  2015年   491篇
  2014年   704篇
  2013年   958篇
  2012年   1308篇
  2011年   1331篇
  2010年   804篇
  2009年   656篇
  2008年   1099篇
  2007年   1130篇
  2006年   1016篇
  2005年   965篇
  2004年   862篇
  2003年   856篇
  2002年   796篇
  2001年   644篇
  2000年   649篇
  1999年   590篇
  1998年   308篇
  1997年   277篇
  1996年   244篇
  1995年   218篇
  1994年   184篇
  1993年   196篇
  1992年   372篇
  1991年   402篇
  1990年   378篇
  1989年   427篇
  1988年   319篇
  1987年   334篇
  1986年   263篇
  1985年   277篇
  1984年   245篇
  1983年   220篇
  1982年   142篇
  1981年   132篇
  1980年   123篇
  1979年   192篇
  1978年   127篇
  1975年   141篇
  1974年   146篇
  1973年   141篇
  1972年   128篇
  1971年   144篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
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   
22.

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   
23.
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   
24.
25.
26.
    
We present our comments on the above article.  相似文献   
27.
28.
29.
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   
30.
Changes in carbohydrate metabolism were studied in midgut gland, muscle, and gill tissues of marine prawn Penaeus indicus exposed to a sublethal concentration (0.3 ppm) of phosphamidon. A significant decrease in glycogen and pyruvate and an increase in lactate content were observed in all phosphamidon-exposed prawn tissues after 96 hr. An increase in phosphorylase a and aldolase activity levels suggested the increased formation of triose sugars during phosphamidon toxicity. LDH activity was considerably decreased and an increment in lactate content was observed which indicates reduced mobilization of pyruvate into the citric acid cycle. Glucose-6-phosphate dehydrogenase activity was considerably increased, suggesting the enhanced oxidation of glucose in the hexose monophosphate shunt pathway. Krebs cycle enzymes such as NAD-isocitrate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase were found to be decreased, suggesting the impairment in mitochondrial oxidative metabolism due to the acute toxic impact of phosphamidon. Cytochrome-c oxidase and Mg2+ ATPase activity levels were also decreased considerably, suggesting impaired energy synthesis and breakdown during phosphamidon toxicity, as a result of reduced oxidation of glucose aerobically. The increase in acid and alkaline phosphatase activities indicates the enhanced breakdown of phosphate to release energy in view of inhibiton or impairment in the ATPase system during phosphamidon-induced stress. These results suggest that phosphamidon has a profound effect on the oxidative metabolism of prawn which results in the triggering of compensatory metabolic pathways for survivability.  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