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   153547篇
  免费   45402篇
  国内免费   1956篇
耳鼻咽喉   2436篇
儿科学   5847篇
妇产科学   3145篇
基础医学   25191篇
口腔科学   6199篇
临床医学   19928篇
内科学   36812篇
皮肤病学   8762篇
神经病学   17915篇
特种医学   5197篇
外国民族医学   7篇
外科学   23721篇
综合类   4656篇
现状与发展   7篇
一般理论   55篇
预防医学   10327篇
眼科学   3045篇
药学   11500篇
  23篇
中国医学   2755篇
肿瘤学   13377篇
  2023年   716篇
  2022年   1689篇
  2021年   3924篇
  2020年   6415篇
  2019年   12412篇
  2018年   12233篇
  2017年   12879篇
  2016年   13586篇
  2015年   14212篇
  2014年   14870篇
  2013年   16024篇
  2012年   10028篇
  2011年   9846篇
  2010年   12282篇
  2009年   8253篇
  2008年   6431篇
  2007年   5402篇
  2006年   5200篇
  2005年   4585篇
  2004年   4246篇
  2003年   4082篇
  2002年   3709篇
  2001年   2912篇
  2000年   2551篇
  1999年   1814篇
  1998年   670篇
  1997年   568篇
  1996年   500篇
  1995年   454篇
  1994年   426篇
  1993年   292篇
  1992年   870篇
  1991年   725篇
  1990年   690篇
  1989年   660篇
  1988年   563篇
  1987年   563篇
  1986年   471篇
  1985年   397篇
  1984年   303篇
  1983年   249篇
  1982年   138篇
  1981年   153篇
  1980年   125篇
  1979年   251篇
  1978年   182篇
  1977年   122篇
  1976年   127篇
  1975年   131篇
  1974年   120篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
Ganoderma sinensis has been used widely in Oriental countries for the prevention and treatment of various diseases including cancer. Previous studies have shown that the lipid extract from Ganoderma exhibits direct cytotoxicity against tumor cells. Here, it is reported that the lipid extract from germinating G. sinensis spores, at lower concentrations that have no direct tumoricidal activity, induce potent antitumor immune responses in human monocytes/macrophages. Upon stimulation with the lipid extract, monocytes/macrophages exhibited markedly increased production of proinflammatory cytokines and surface expression of costimulatory molecules. Conditioned medium from stimulated cells effectively suppressed the growth of tumor cells. Apparently, the lipid extract triggered macrophage activation via a mechanism different from that associated with LPS. Moreover, it was observed that the lipid extract could partially re‐establish the antitumor activity of the immunosuppressive tumor‐associated macrophages. These results indicated that in addition to its direct tumoricidal activity, the lipid extract from G. sinensis spores could exert antitumor activity by stimulating the activation of human monocytes/macrophages. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
46.
47.
48.
The influence of age on the regional arterial and venous effects of serotonin (5-HT) was investigated in 13 young (aged 22-31 years) and seven older (aged 50-69 years) healthy volunteers. Single-dose infusions of 5-HT (1, 10, and 80 ng/kg/min) and of the 5-HT2 receptor antagonist ritanserin (50, 150, and 500 ng/kg/min) were administered into the brachial artery. Subsequently, the relative arterial and venous effects of the highest dose of 5-HT were investigated. Forearm blood flow (FBF) and maximum venous outflow (MVO) were measured by venous occlusion plethysmography. Heart rate (HR) and intraarterial (i.a.) blood pressure were recorded semicontinuously. In both age groups, 5-HT induced an initial transient arterial dilation, followed by a persistent increase in FBF for the doses of 1 and 10 ng/kg/min and a relative small decrease in FBF for the highest dose. In both age groups, the highest dose of 5-HT induced a similar large reduction in MVO (p less than 0.05 for both). The reduction in MVO was attenuated by ritanserin (500 ng/kg/min, p less than 0.05 for both groups). In the younger subjects, this dose of ritanserin also unmasked an arterial dilator effect of the highest dose of 5-HT (p less than 0.05). The single infusions of ritanserin did not influence FBF significantly in either study group. No significant differences were observed between the age groups. These results show that in the forearm of healthy subjects arterial and venous vascular responses to 5-HT were not age-related. In the arterial vascular bed, 5-HT acted predominantly as a vasodilator; at high doses, mainly venous vasoconstriction was observed.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
49.
The first‐order kernel analysis in multifocal electroretinogram (mfERG) using low contrast stimulation is suggested as a way to detect the inner retinal responses in animal studies. In this case report, this protocol is applied to human patients with glaucoma to demonstrate the possibility of using mfERG as a tool to detect glaucomatous damage. Two patients with glaucoma were recruited and had mfERG measurements with the 103‐scaled hexagonal stimulus pattern at low (50 per cent) contrast. Their responses were analysed and compared with those from normal subjects with the mfERG measured under the same condition. In the normal subjects, there were obvious oscillatory components on the ascending and descending limbs of the first‐order kernel response to 50 per cent contrast. In the glaucomatous patients, the oscillatory component on the descending limb was obviously diminished. In addition, this component was significantly diminished in the quadrant with a glaucomatous visual field defect. This suggests that the low‐contrast stimulation condition in mERG measurement may provide a good way to detect glaucomatous damage and this may help in clinical diagnosis of glaucoma.  相似文献   
50.
BACKGROUND AND PURPOSE: This study investigated the characteristics of intussusception in Taiwanese children of different age groups, including the incidence, length of hospitalization and hospital costs. METHODS: Children with a diagnosis of intussusception who were hospitalized from 1999 through 2001 were identified from a nationwide health insurance claims database. The incidence of intussusception was calculated by age, gender, and season. Length of hospitalization and hospital costs were also analyzed. RESULTS: A total of 6988 cases of intussusception were identified in Taiwan from 1999 to 2001. Among them, 4859 cases occurred in children below 15 years of age. The average incidence among children below age 15 years was 34.5 per 100,000, with a peak incidence of 118.8 per 100,000 observed among children younger than 24 months old. The highest incidence of intussusception in Taiwanese children occurred between 12 and 24 months of age. According to the data for patients below 15 years of age hospitalized for intussusception in year 2000, males were more likely to be affected than females (61.3% vs 38.7%). Intussusception-related hospitalizations were rare in infants in the first few months of life, increased in those 6 to 12 months old, and peaked among children 1 to 3 years old. Among the 952 patients with intussusception admitted to hospitals in 2000, 297 (31.2%) received surgery, incurring higher median medical costs (New Taiwan Dollars [NT dollars] 42,265 or US dollars 1234) and longer median hospital stay (6.2 days) than the 655 patients who did not require surgery (NT dollars 6290 or US dollars 185 for hospitalization of 2.4 days). CONCLUSIONS: The study found that the incidence of intussusception peaked in the second year of life in Taiwanese children. There was also a male predominance and lack of seasonal variation in incidence.  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