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   3212701篇
  免费   245624篇
  国内免费   8152篇
耳鼻咽喉   43696篇
儿科学   104458篇
妇产科学   87205篇
基础医学   462058篇
口腔科学   89432篇
临床医学   292703篇
内科学   629707篇
皮肤病学   73385篇
神经病学   257544篇
特种医学   124064篇
外国民族医学   743篇
外科学   488318篇
综合类   70612篇
现状与发展   14篇
一般理论   1168篇
预防医学   257193篇
眼科学   73460篇
药学   235400篇
  15篇
中国医学   5970篇
肿瘤学   169332篇
  2018年   35055篇
  2017年   26740篇
  2016年   30743篇
  2015年   34572篇
  2014年   48667篇
  2013年   73528篇
  2012年   97249篇
  2011年   103934篇
  2010年   62877篇
  2009年   60047篇
  2008年   97276篇
  2007年   103793篇
  2006年   105164篇
  2005年   102010篇
  2004年   97332篇
  2003年   94195篇
  2002年   90882篇
  2001年   146413篇
  2000年   150265篇
  1999年   126692篇
  1998年   38035篇
  1997年   33517篇
  1996年   34244篇
  1995年   33250篇
  1994年   30743篇
  1993年   28937篇
  1992年   100965篇
  1991年   98528篇
  1990年   95842篇
  1989年   92025篇
  1988年   84925篇
  1987年   83380篇
  1986年   78509篇
  1985年   75500篇
  1984年   56889篇
  1983年   48326篇
  1982年   29343篇
  1981年   26424篇
  1979年   52196篇
  1978年   37565篇
  1977年   31354篇
  1976年   29697篇
  1975年   31623篇
  1974年   37748篇
  1973年   35909篇
  1972年   33767篇
  1971年   31650篇
  1970年   29012篇
  1969年   27626篇
  1968年   25455篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
153.
154.
Porocarcinoma is an unusual, locally aggressive and potentially fatal neoplasm. Several cutaneous malignancies have been described in association with porocarcinoma, including squamous cell carcinoma, basal cell carcinoma and tricholemmal carcinoma. Previous reports have indicated that the occurrence of malignant tumours in combination with porocarcinoma is extremely rare, in particular with regard to Bowen disease (BD). We report an uncommon case of porocarcinoma occurring synchronously in a single BD lesion in a 63‐year‐old woman with multiple BD lesions. The clinical and histological findings confirmed this diagnosis.  相似文献   
155.
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   
156.
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   
157.
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   
158.
159.
160.
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