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   1414165篇
  免费   107594篇
  国内免费   2394篇
耳鼻咽喉   20270篇
儿科学   48654篇
妇产科学   37901篇
基础医学   200831篇
口腔科学   40283篇
临床医学   121545篇
内科学   287939篇
皮肤病学   31412篇
神经病学   111921篇
特种医学   55322篇
外国民族医学   682篇
外科学   212990篇
综合类   28221篇
现状与发展   2篇
一般理论   425篇
预防医学   110732篇
眼科学   30672篇
药学   103190篇
  2篇
中国医学   3017篇
肿瘤学   78142篇
  2021年   11151篇
  2019年   12018篇
  2018年   17220篇
  2017年   12986篇
  2016年   13747篇
  2015年   15715篇
  2014年   21774篇
  2013年   32004篇
  2012年   45016篇
  2011年   47544篇
  2010年   27665篇
  2009年   26076篇
  2008年   43798篇
  2007年   47003篇
  2006年   46548篇
  2005年   45868篇
  2004年   44601篇
  2003年   42769篇
  2002年   40362篇
  2001年   67282篇
  2000年   69633篇
  1999年   59252篇
  1998年   16314篇
  1997年   14718篇
  1996年   15134篇
  1995年   14249篇
  1994年   13551篇
  1993年   12524篇
  1992年   46236篇
  1991年   45150篇
  1990年   43747篇
  1989年   41617篇
  1988年   38330篇
  1987年   37540篇
  1986年   34911篇
  1985年   33531篇
  1984年   25021篇
  1983年   20986篇
  1982年   12157篇
  1981年   11093篇
  1979年   22043篇
  1978年   15275篇
  1977年   12890篇
  1976年   12001篇
  1975年   13044篇
  1974年   15102篇
  1973年   14554篇
  1972年   13318篇
  1971年   12076篇
  1970年   11429篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
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   
72.
73.
In the 6th Basic Plan for Long-Term Electricity Supply and Demand (6th BPE) for Korea, for the first time, the environmental costs of air pollution caused by oxides of sulfur (SOx), oxides of nitrogen (NOx), and particulate matters (PM) from power plants were estimated and included. However, several deficiencies in evaluating the environmental costs were found. In this study, (1) the validity of the environmental costs used in the 6th BPE was assessed, (2) a systematic approach was suggested and used to improve the environmental costs estimation, and (3) the sensitivity of the cost of generating electricity to the environmental costs by fuel type with the proposed approach was discussed. We found that the applied environmental costs used in the 6th BPE did not fully include the demographic characteristics of Korea. By applying more realistic parameter values, it was found that the newly estimated environmental cost was about 23 times higher than the cost estimated in the original 6th BPE for coal-fired power plants and about 1.5 times higher for liquefied natural gas (LNG)-fired power plants, suggesting that LNG-fired power plants are more economical if using more realistic environmental costs. Thus, it is critical to check the validity of parameter values when calculating environmental costs.  相似文献   
74.
75.
Plasma provided by COVID-19 convalescent patients may provide therapeutic relief as the number of COVID-19 cases escalates steeply worldwide. Prior findings in various viral respiratory diseases including SARS-CoV-related pneumonia suggest that convalescent plasma can reduce mortality, although formal proof of efficacy is still lacking. By reducing viral spread early on, such an approach may possibly downplay subsequent immunopathology. Identifying, collecting, qualifying and preparing plasma from convalescent patients with adequate SARS-CoV-2-neutralizing Ab titres in an acute crisis setting may be challenging, although well within the remit of most blood establishments. Careful clinical evaluation should allow to quickly establish whether such passive immunotherapy, administered at early phases of the disease in patients at high risk of deleterious evolution, may reduce the frequency of patient deterioration, and thereby COVID-19 mortality.  相似文献   
76.
77.
78.
79.
80.
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