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   299636篇
  免费   42957篇
  国内免费   1712篇
耳鼻咽喉   4554篇
儿科学   7803篇
妇产科学   6466篇
基础医学   28895篇
口腔科学   9249篇
临床医学   44746篇
内科学   67291篇
皮肤病学   5900篇
神经病学   31641篇
特种医学   10221篇
外国民族医学   13篇
外科学   49296篇
综合类   3505篇
现状与发展   42篇
一般理论   291篇
预防医学   31549篇
眼科学   6348篇
药学   15181篇
  12篇
中国医学   381篇
肿瘤学   20921篇
  2024年   998篇
  2023年   5933篇
  2022年   2576篇
  2021年   5998篇
  2020年   7213篇
  2019年   5188篇
  2018年   10405篇
  2017年   10172篇
  2016年   10861篇
  2015年   11612篇
  2014年   15861篇
  2013年   20142篇
  2012年   16312篇
  2011年   17255篇
  2010年   14350篇
  2009年   15783篇
  2008年   16579篇
  2007年   16399篇
  2006年   17029篇
  2005年   16124篇
  2004年   14962篇
  2003年   13774篇
  2002年   13238篇
  2001年   3550篇
  2000年   2508篇
  1999年   3594篇
  1998年   4741篇
  1997年   4196篇
  1996年   4021篇
  1995年   3499篇
  1994年   2753篇
  1993年   2506篇
  1992年   1895篇
  1991年   1725篇
  1990年   1521篇
  1989年   1426篇
  1988年   1470篇
  1987年   1361篇
  1986年   1309篇
  1985年   1345篇
  1984年   1710篇
  1983年   1736篇
  1982年   2011篇
  1981年   1817篇
  1980年   1666篇
  1979年   870篇
  1978年   1069篇
  1977年   1039篇
  1976年   909篇
  1975年   735篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
B.  Greg  Brown  John  Growley  宋善俊 《美国医学会杂志》2006,25(2):124-126
过去15年来,有关动脉粥样硬化的流行病学、基础生物学和实验研究均支持下述假设:抗氧化剂可通过抑制动脉壁低密度脂蛋白的氧化而抑制动脉粥样硬化的发生。这种作用机制可抑制胆固醇酯通过巨噬细胞清除受体在动脉斑块内发生病理性沉积。胆固醇酯病理沉积是一种可引起斑块破裂及心血管事件的过程。同样,生物机制亦已确定,癌基因可被抗氧化剂阻断。  相似文献   
13.
CONTEXT: Although the nonmedical use of stimulant drugs such as cocaine and methamphetamine is increasingly common in many rural areas of the United States, little is known about the health beliefs of people who use these drugs. PURPOSE: This research describes illicit stimulant drug users' views on health and health-related concepts that may affect their utilization of health care services. METHODS: A respondent-driven sampling plan was used to recruit 249 not-in-treatment, nonmedical stimulant drug users who were residing in 3 rural counties in west central Ohio. A structured questionnaire administered by trained interviewers was used to collect information on a range of topics, including current drug use, self-reported health status, perceived need for substance abuse treatment, and beliefs about health and health services. FINDINGS: Participants reported using a wide variety of drugs nonmedically, some by injection. Alcohol and marijuana were the most commonly used drugs in the 30 days prior to the interview. Powder cocaine was used by 72.3% of the sample, crack by 68.3%, and methamphetamine by 29.7%. Fair or poor health status was reported by 41.3% of the participants. Only 20.9% of the sample felt they needed drug abuse treatment. Less than one third of the sample reported that they would feel comfortable talking to a physician about their drug use, and 65.1% said they preferred taking care of their problems without getting professional help. CONCLUSIONS: Stimulant drug users in rural Ohio are involved with a range of substances and hold health beliefs that may impede health services utilization.  相似文献   
14.
15.
Over 100 mutations in the presenilin‐1 gene (PSEN1) have been shown to result in familial early onset Alzheimer disease (EOAD), but only a relatively few give rise to plaques with an appearance like cotton wool (CWP) and/or spastic paraparesis (SP). A family with EOAD, seizures and CWP was investigated by neuropathological study and DNA sequencing of the PSEN1 gene. Aβ was identified in leptomeningeal vessels and in cerebral plaques. A single point mutation, p.L420R (g.1508T > G) that gives rise to a missense mutation in the eighth transmembrane (TM8) domain of PS1 was identified in two affected members of the family. p.L420R (g.1508T > G) is the mutation responsible for EOAD, seizures and CWP without SP in this family.  相似文献   
16.
Clinical decisions are often made with incomplete information, yet patient care decisions are made every day. Patients vary clinically, uncertainty exists in diagnostic and prognostic information, and many preventive and treatment alternatives have not been formally assessed for their effectiveness. Because scientific information will never answer all clinical questions, clinical decisions are partially based on probabilistic information.
This paper describes how to apply clinical decision making to diagnosing and managing dental caries and periodontal diseases. By using explicit information to quantify probabilities and outcomes, clinical decision making analyzes decisions made under uncertain conditions and the uncertain impact of clinical information.
Clinical decision making incorporates concepts for preventing, diagnosing and treating dental caries and periodontal diseases: risk assessment, evidence-based dentistry, and multiple oral health outcomes. This information can serve as a tool for clinicians to augment clinical judgment and expertise.  相似文献   
17.
High levels of tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, are present in the wound fluid of chronic nonhealing wounds. This leads to increased inflammation, cytokine expression, and ultimately results in impaired wound healing and tissue destruction. Etanercept is a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1. It is an effective inhibitor of TNF-alpha and has been shown to provide rapid and sustained improvement in rheumatoid arthritis by acting as a soluble receptor binding TNF-alpha and preventing its proinflammatory activities. Therefore, the aim of this study was to determine whether Etanercept could inhibit TNF-alpha activity in chronic wound fluid. Wound fluid was collected from the venous leg ulcers of 16 different patients. The effect of Etanercept on TNF-alpha activity was evaluated using both a TNF-alpha bioassay and an enzyme-linked immunoassay. Etanercept was found to reduce the cytotoxic effect of chronic wound fluid on L929 fibroblasts by approximately 30% and neutralized TNF-alpha binding in the enzyme-linked immunoassay by up to 80%. Direct application of Etanercept to chronic wounds may therefore reduce the inflammatory activity of TNF-alpha, which could reduce the chronicity of venous leg ulcers and thus aid in the healing of these wounds.  相似文献   
18.
19.
CONTEXT: The physician assistant profession has been moving toward requiring master's degrees for new practitioners, but some argue this could change the face of the discipline. PURPOSE: To see if there is an association between physician assistants' academic degrees and practice in primary care, in rural areas, and with the medically underserved. METHODS: Surveys were sent to 880 graduates of the first 32 University of Washington physician assistant classes through 2000. Respondents noted their academic degree at program entry and the highest degree attained at any time up to the time of survey. Relationships between practice characteristics and academic degree levels were tested by unadjusted odds ratios and logistic regression after controlling for year of graduation and sex. RESULTS: Of the 478 respondents, 54% worked in primary care, about 30% practiced in nonmetropolitan communities, and 42% reported providing care for the medically underserved. Respondents with no degree (33% of total at entry, 24% at survey) were significantly more likely than degree holders to work in primary care and nonmetropolitan areas. Respondents with no degree at program entry were significantly more likely, and those with no degree at the time of the survey were marginally more likely, to self-report work with the medically underserved. CONCLUSION: Respondents with no academic degree are significantly more likely to demonstrate a commitment to primary, rural, and underserved health care. These findings may inform the national debate about the impact of required advanced degrees on the practice patterns of nonphysician providers.  相似文献   
20.
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