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   2328872篇
  免费   170796篇
  国内免费   14184篇
耳鼻咽喉   32972篇
儿科学   74453篇
妇产科学   60310篇
基础医学   322059篇
口腔科学   62129篇
临床医学   210805篇
内科学   442561篇
皮肤病学   50524篇
神经病学   173918篇
特种医学   92589篇
外国民族医学   927篇
外科学   347825篇
综合类   80387篇
现状与发展   51篇
一般理论   626篇
预防医学   172368篇
眼科学   52541篇
药学   183767篇
  198篇
中国医学   17272篇
肿瘤学   135570篇
  2021年   21989篇
  2019年   20002篇
  2018年   27365篇
  2017年   22292篇
  2016年   23860篇
  2015年   29087篇
  2014年   38916篇
  2013年   54265篇
  2012年   75008篇
  2011年   79643篇
  2010年   49945篇
  2009年   45880篇
  2008年   71585篇
  2007年   75440篇
  2006年   75669篇
  2005年   72020篇
  2004年   67687篇
  2003年   65309篇
  2002年   62809篇
  2001年   114833篇
  2000年   118013篇
  1999年   99133篇
  1998年   26407篇
  1997年   23705篇
  1996年   23842篇
  1995年   22431篇
  1994年   20751篇
  1993年   19226篇
  1992年   75650篇
  1991年   73179篇
  1990年   71678篇
  1989年   68561篇
  1988年   62618篇
  1987年   61257篇
  1986年   57273篇
  1985年   54514篇
  1984年   40143篇
  1983年   33771篇
  1982年   19047篇
  1979年   35800篇
  1978年   24454篇
  1977年   21252篇
  1976年   19190篇
  1975年   21263篇
  1974年   24766篇
  1973年   23849篇
  1972年   22353篇
  1971年   20593篇
  1970年   19268篇
  1969年   18051篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Reactive lymphoid infiltrates of the skin composed predominantly of gamma‐delta (γδ) T cells are not well described in the literature. Herein we report a case of an otherwise healthy 4‐year‐old male who presented with a waxing and waning papular rash characterized by small, discrete crusted papules spread across his trunk, face and extremities. Clinical evaluation revealed no evidence of systemic disease. Microscopic examination revealed a dermal, perivascular infiltrate of highly atypical lymphocytes with a γδ T cell phenotype, worrisome for primary cutaneous γδ T cell lymphoma. The clinical course, however, was that of a reactive condition and prompted consideration of a diagnosis of pityriasis lichenoides et varioliformis acuta (PLEVA) and lymphomatoid papulosis (LyP). In many ways, this case defies current classification schemes and seems to expand the spectrum of reactive γδ T cell infiltrates of the skin.  相似文献   
82.
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   
83.
Evidence continues to grow on potential environmental health hazards associated with engineered nanomaterials (ENMs). While the geno- and cytotoxic effects of ENMs have been investigated, their potential to target the epigenome remains largely unknown. The aim of this study is two-fold: 1) determining whether or not industry relevant ENMs can affect the epigenome in vivo and 2) validating a recently developed in vitro epigenetic screening platform for inhaled ENMs. Laser printer-emitted engineered nanoparticles (PEPs) released from nano-enabled toners during consumer use and copper oxide (CuO) were chosen since these particles induced significant epigenetic changes in a recent in vitro companion study. In this study, the epigenetic alterations in lung tissue, alveolar macrophages and peripheral blood from intratracheally instilled mice were evaluated. The methylation of global DNA and transposable elements (TEs), the expression of the DNA methylation machinery and TEs, in addition to general toxicological effects in the lung were assessed. CuO exhibited higher cell-damaging potential to the lung, while PEPs showed a greater ability to target the epigenome. Alterations in the methylation status of global DNA and TEs, and expression of TEs and DNA machinery in mouse lung were observed after exposure to CuO and PEPs. Additionally, epigenetic changes were detected in the peripheral blood after PEPs exposure. Altogether, CuO and PEPs can induce epigenetic alterations in a mouse experimental model, which in turn confirms that the recently developed in vitro epigenetic platform using macrophage and epithelial cell lines can be successfully utilized in the epigenetic screening of ENMs.  相似文献   
84.
85.
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   
86.
87.
肝门部胆管癌(hilar cholangiocarcinoma,HC)分型和分期系统较为庞杂,包括改良Bismuth-Corlette分型,Gazzaniga T分期,Blumgart T分期,美国纪念Sloan-Kattering癌症中心(Memorial Sloan Katering Cancer Center,MSKCC)T分期,Mayo分期系统,美国癌症联合委员会(American Joint Committee on Cancer,AJCC)和国际抗癌联盟(International Union Against Cancer,UICC)联合发布的TNM分期,欧洲肝胆胰协会分期(Consensus classification from the European Hepato-Pancreato-Biliary Association,EHPBA),以及日本肝胆胰外科学会(Japanese Society of Hepato-Biliary-Pancreatic Surgery,JSHBPS)分期,各分期系统所包含的内容差异较大,各具特色和优缺点,本文就HC常见的分型和分期系统及其在临床中的应用价值做一综述。  相似文献   
88.
89.
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