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   2379585篇
  免费   198694篇
  国内免费   4241篇
耳鼻咽喉   34369篇
儿科学   72974篇
妇产科学   63114篇
基础医学   335896篇
口腔科学   68008篇
临床医学   216171篇
内科学   470459篇
皮肤病学   48135篇
神经病学   201385篇
特种医学   96089篇
外国民族医学   886篇
外科学   361469篇
综合类   56253篇
现状与发展   2篇
一般理论   983篇
预防医学   191537篇
眼科学   55574篇
药学   178048篇
  4篇
中国医学   4404篇
肿瘤学   126760篇
  2018年   24522篇
  2016年   20822篇
  2015年   23551篇
  2014年   33869篇
  2013年   51228篇
  2012年   69322篇
  2011年   72913篇
  2010年   42829篇
  2009年   41160篇
  2008年   69215篇
  2007年   73594篇
  2006年   74456篇
  2005年   72399篇
  2004年   69703篇
  2003年   67326篇
  2002年   66560篇
  2001年   112556篇
  2000年   116681篇
  1999年   98446篇
  1998年   27911篇
  1997年   25551篇
  1996年   25462篇
  1995年   24632篇
  1994年   23196篇
  1993年   21576篇
  1992年   79427篇
  1991年   76443篇
  1990年   73622篇
  1989年   70887篇
  1988年   65879篇
  1987年   64839篇
  1986年   61364篇
  1985年   58439篇
  1984年   44242篇
  1983年   37669篇
  1982年   22900篇
  1981年   20350篇
  1980年   19048篇
  1979年   41319篇
  1978年   29009篇
  1977年   24355篇
  1976年   22844篇
  1975年   23983篇
  1974年   29665篇
  1973年   28062篇
  1972年   26246篇
  1971年   24162篇
  1970年   22770篇
  1969年   21090篇
  1968年   19149篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
96.
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   
97.
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   
98.
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   
99.
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   
100.
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