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   3460106篇
  免费   276626篇
  国内免费   13853篇
耳鼻咽喉   47793篇
儿科学   104437篇
妇产科学   87166篇
基础医学   548145篇
口腔科学   94800篇
临床医学   308312篇
内科学   610293篇
皮肤病学   91223篇
神经病学   293182篇
特种医学   135748篇
外国民族医学   146篇
外科学   546745篇
综合类   101308篇
现状与发展   23篇
一般理论   2424篇
预防医学   281090篇
眼科学   79352篇
药学   239692篇
  24篇
中国医学   10114篇
肿瘤学   168568篇
  2021年   55925篇
  2020年   35566篇
  2019年   58742篇
  2018年   72317篇
  2017年   55023篇
  2016年   60667篇
  2015年   74743篇
  2014年   109236篇
  2013年   174599篇
  2012年   93961篇
  2011年   93860篇
  2010年   117884篇
  2009年   121852篇
  2008年   80957篇
  2007年   83479篇
  2006年   94043篇
  2005年   89380篇
  2004年   90924篇
  2003年   81557篇
  2002年   71199篇
  2001年   111964篇
  2000年   105139篇
  1999年   103332篇
  1998年   65555篇
  1997年   63153篇
  1996年   60923篇
  1995年   56361篇
  1994年   50326篇
  1993年   46995篇
  1992年   71941篇
  1991年   68549篇
  1990年   65077篇
  1989年   64323篇
  1988年   59359篇
  1987年   57921篇
  1986年   54689篇
  1985年   54811篇
  1984年   49042篇
  1983年   44924篇
  1982年   41576篇
  1981年   39119篇
  1980年   36794篇
  1979年   40089篇
  1978年   35111篇
  1977年   32498篇
  1976年   29213篇
  1975年   28182篇
  1974年   28985篇
  1973年   27708篇
  1972年   26123篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
113.
114.
115.
116.
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   
117.
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   
118.
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   
119.
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   
120.
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