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   1828861篇
  免费   123400篇
  国内免费   4696篇
耳鼻咽喉   23069篇
儿科学   59965篇
妇产科学   47732篇
基础医学   276838篇
口腔科学   46576篇
临床医学   172555篇
内科学   348115篇
皮肤病学   36252篇
神经病学   146323篇
特种医学   67917篇
外国民族医学   418篇
外科学   261318篇
综合类   36109篇
现状与发展   3篇
一般理论   551篇
预防医学   152131篇
眼科学   39731篇
药学   134232篇
  7篇
中国医学   4034篇
肿瘤学   103081篇
  2019年   14523篇
  2018年   29609篇
  2017年   22806篇
  2016年   26197篇
  2015年   19537篇
  2014年   26513篇
  2013年   40457篇
  2012年   58855篇
  2011年   68535篇
  2010年   41559篇
  2009年   36887篇
  2008年   63708篇
  2007年   69684篇
  2006年   58599篇
  2005年   57814篇
  2004年   56179篇
  2003年   54871篇
  2002年   52224篇
  2001年   77474篇
  2000年   79689篇
  1999年   66435篇
  1998年   18857篇
  1997年   16872篇
  1996年   16601篇
  1995年   15808篇
  1994年   14652篇
  1993年   13907篇
  1992年   52565篇
  1991年   52790篇
  1990年   51614篇
  1989年   49386篇
  1988年   45586篇
  1987年   44764篇
  1986年   42417篇
  1985年   40526篇
  1984年   30410篇
  1983年   25904篇
  1982年   15092篇
  1979年   28004篇
  1978年   19934篇
  1977年   16186篇
  1976年   16304篇
  1975年   17467篇
  1974年   20918篇
  1973年   20249篇
  1972年   18743篇
  1971年   17677篇
  1970年   16404篇
  1969年   15000篇
  1968年   14289篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
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   
103.
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   
104.
Bowel diseases of prematurity, including necrotizing enterocolitis, are dreaded ailments of neonates. Early diagnosis is difficult, with clinical and radiographic findings often inconclusive. We present a novel use of contrast-enhanced ultrasound in detection of pediatric bowel disease. Early identification of compromised blood flow or an at-risk bowel can be quantitatively detected and monitored. This ability has implications for guidance of emerging therapies, allowing targeting of inflammation. These findings represent an advancement in detection of bowel disease in neonates.  相似文献   
105.
A 17‐year‐old boy presented with recurring severe dermatitis of the face of 5‐months duration that resembled impetigo. He had been treated with several courses of antibiotics without improvement. Biopsy showed changes consistent with allergic contact dermatitis and patch testing later revealed sensitization to benzoyl peroxide, which the patient had been using for the treatment of acne vulgaris.  相似文献   
106.
Guidelines and consensus on the management of patients with acne aim to give evidence-based, expert-group recommendations. This review compares current guidelines and consensus articles to provide a compilation of recommendations on the treatment of acne with oral isotretinoin. Ten common, relevant, clinical questions are addressed, based on published recommendations, including the indications of isotretinoin, the proposed daily dose, the cumulative isotretinoin dose and the laboratory monitoring needed. Recommendations on special considerations are also addressed, including the timing of procedures and the question of an association of depression or inflammatory bowel disease with isotretinoin. A major limitation is the use of different classification systems for acne across guidelines. The recommended daily dose ranges from 0.3 to 0.5 mg/kg in the European guidelines to up to 1 mg/kg in the US guidelines. A specific duration of treatment of at least 6 months is only recommended in the European guidelines. All guidelines report the need of strict pregnancy prevention measures. The European, French and US guidelines recommend to monitor for symptoms of depression. Important clinical questions that are inconsistently addressed in guidelines include the age indication, the recommendation for a cumulative dose, the timing of procedures, the association of isotretinoin with IBD, the recommendation for preventing acne flares and for appropriate laboratory monitoring. These topics should be clearly included in the recommendations of guidelines as they are often raised in everyday clinical practice.  相似文献   
107.
108.
109.
In 1963, Goffman argued that forming a group based on shared stigma may provide benefits. However, there is no empirical research on whether perception that a separate, unique, coherent group exists (i.e., group entitativity) influences coping, such as educating others or secrecy, for the stigmatized individual or his or her spouse. Further, little is known about how spouses influence each other in terms of promoting the education of others about a stigmatizing condition, especially when it comes to the role of believing that stigma-based groups, to which they may both belong, exist. This study provides a step toward bridging this gap in the research by applying the label management model in efforts to understand coping for couples in which one spouse is diagnosed with genetic mutations leading to alpha-1 antitrypsin deficiency (AATD). This study included 50 married couples in which one spouse is diagnosed with genetic mutations leading to alpha-1 antitrypsin deficiency (AATD). We found that group entitativity related to those with AATD counterbalanced the influence of genetic stigma on spouses’ intentions to keep the diagnosis secret or to educate others about it. Intrapersonal and interpersonal influences appeared among spouses. Attention is needed on the power of creating groups for stigmatized persons and their relatives. Indeed, people live within a dynamic world of group entities, and multiple social identities including spousal and familial. While attention has been paid to the diffusion of stigmas to loved ones, less has been paid to the uplift of group entities for them.  相似文献   
110.
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