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   1416843篇
  免费   108109篇
  国内免费   2495篇
耳鼻咽喉   20391篇
儿科学   48695篇
妇产科学   37989篇
基础医学   201544篇
口腔科学   40268篇
临床医学   121697篇
内科学   287814篇
皮肤病学   31615篇
神经病学   112267篇
特种医学   55815篇
外国民族医学   682篇
外科学   213581篇
综合类   28243篇
现状与发展   3篇
一般理论   427篇
预防医学   110129篇
眼科学   30768篇
药学   103786篇
  2篇
中国医学   3163篇
肿瘤学   78568篇
  2021年   11362篇
  2019年   12215篇
  2018年   17412篇
  2017年   13172篇
  2016年   14054篇
  2015年   16175篇
  2014年   22319篇
  2013年   32548篇
  2012年   45800篇
  2011年   48340篇
  2010年   28195篇
  2009年   26470篇
  2008年   44224篇
  2007年   47394篇
  2006年   46916篇
  2005年   46163篇
  2004年   44835篇
  2003年   42927篇
  2002年   40526篇
  2001年   67289篇
  2000年   69651篇
  1999年   59249篇
  1998年   16347篇
  1997年   14737篇
  1996年   15137篇
  1995年   14251篇
  1994年   13556篇
  1993年   12532篇
  1992年   46229篇
  1991年   45135篇
  1990年   43725篇
  1989年   41603篇
  1988年   38280篇
  1987年   37513篇
  1986年   34882篇
  1985年   33508篇
  1984年   24997篇
  1983年   20924篇
  1982年   12107篇
  1981年   11039篇
  1979年   21993篇
  1978年   15233篇
  1977年   12836篇
  1976年   11967篇
  1975年   13014篇
  1974年   15063篇
  1973年   14504篇
  1972年   13290篇
  1971年   12033篇
  1970年   11397篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
Advancement in microelectromechanical system has facilitated the microfabrication of polymeric substrates and the development of the novel class of controlled drug delivery devices. These vehicles have specifically tailored three dimensional physical and chemical features which together, provide the capacity to target cell, stimulate unidirectional controlled release of therapeutics and augment permeation across the barriers. Apart from drug delivery devices microfabrication technology’s offer exciting prospects to generate biomimetic gastrointestinal tract models. BioMEMS are capable of analysing biochemical liquid sample like solution of metabolites, macromolecules, proteins, nucleic acid, cells and viruses. This review summarized multidisciplinary application of biomedical microelectromechanical systems in drug delivery and its potential in analytical procedures.  相似文献   
85.
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   
86.
87.
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   
88.
89.
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   
90.
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