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   3204292篇
  免费   279400篇
  国内免费   13849篇
耳鼻咽喉   44364篇
儿科学   102463篇
妇产科学   81955篇
基础医学   515048篇
口腔科学   86962篇
临床医学   284841篇
内科学   567435篇
皮肤病学   89171篇
神经病学   278339篇
特种医学   126319篇
外国民族医学   368篇
外科学   504791篇
综合类   96839篇
现状与发展   23篇
一般理论   2182篇
预防医学   266254篇
眼科学   72117篇
药学   217927篇
  22篇
中国医学   10024篇
肿瘤学   150097篇
  2021年   55605篇
  2020年   37691篇
  2019年   63649篇
  2018年   74975篇
  2017年   58786篇
  2016年   64625篇
  2015年   78873篇
  2014年   112857篇
  2013年   178204篇
  2012年   86515篇
  2011年   85530篇
  2010年   118535篇
  2009年   122136篇
  2008年   72411篇
  2007年   73895篇
  2006年   84871篇
  2005年   80681篇
  2004年   82598篇
  2003年   73851篇
  2002年   63955篇
  2001年   89764篇
  2000年   82330篇
  1999年   85173篇
  1998年   63461篇
  1997年   61806篇
  1996年   59505篇
  1995年   54938篇
  1994年   49136篇
  1993年   45921篇
  1992年   58555篇
  1991年   55231篇
  1990年   52403篇
  1989年   51799篇
  1988年   48346篇
  1987年   47256篇
  1986年   45301篇
  1985年   45502篇
  1984年   43136篇
  1983年   39953篇
  1982年   39862篇
  1981年   37600篇
  1980年   35563篇
  1979年   35116篇
  1978年   32181篇
  1977年   29717篇
  1976年   27297篇
  1975年   25812篇
  1974年   26286篇
  1973年   25133篇
  1972年   23660篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
86.
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   
87.
Children who expect they can bring about good outcomes and avoid bad outcomes tend to experience more personal successes. Little is known about factors that contribute to these ‘control expectancies’. The purpose of the present study was to determine whether children's internal control expectancies occur in the context of parents’ internal control expectancies, low family strain, and high family cohesiveness and whether these factors are more strongly related to daughters’ than sons’ control expectancies. A community sample of 85 children aged 9–11 years and their parents (85 mothers; 63 fathers) completed rating scales. Fathers’ more internal control expectancies and mothers’ reports of fewer family strains were associated with daughters’ but not sons’ greater internal control expectancies, and greater family cohesiveness was related to both daughters’ and sons’ internal control orientations. These findings suggest that family factors may contribute to children's, particularly daughters’, development of internal control expectancies.  相似文献   
88.
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   
89.
Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.  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