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   595篇
  免费   32篇
  国内免费   11篇
耳鼻咽喉   1篇
儿科学   32篇
妇产科学   4篇
基础医学   58篇
口腔科学   2篇
临床医学   46篇
内科学   122篇
皮肤病学   7篇
神经病学   16篇
特种医学   136篇
外科学   22篇
综合类   40篇
预防医学   106篇
眼科学   2篇
药学   19篇
中国医学   3篇
肿瘤学   22篇
  2022年   1篇
  2020年   4篇
  2019年   3篇
  2018年   5篇
  2017年   1篇
  2016年   7篇
  2015年   8篇
  2014年   7篇
  2013年   25篇
  2012年   20篇
  2011年   25篇
  2010年   19篇
  2009年   22篇
  2008年   22篇
  2007年   25篇
  2006年   25篇
  2005年   17篇
  2004年   13篇
  2003年   16篇
  2002年   18篇
  2001年   14篇
  2000年   8篇
  1999年   12篇
  1998年   42篇
  1997年   35篇
  1996年   19篇
  1995年   14篇
  1994年   15篇
  1993年   15篇
  1992年   5篇
  1991年   11篇
  1990年   12篇
  1989年   11篇
  1988年   18篇
  1987年   17篇
  1986年   15篇
  1985年   18篇
  1984年   8篇
  1983年   8篇
  1982年   14篇
  1981年   9篇
  1980年   9篇
  1979年   1篇
  1978年   10篇
  1977年   8篇
  1976年   4篇
  1975年   3篇
排序方式: 共有638条查询结果,搜索用时 15 毫秒
31.
32.
Two cases of intracerebral pneumatocele following trauma are presented. One to two months after initial treatment both patients had deteriorating neurologic status. The diagnosis was made by radiography. When a pneumatocele is suspected clinically, computed tomography can play a vital role in determining the precise location of the gas collection, its relationship to the fracture site, and the amount of mass effect on the brain.  相似文献   
33.
34.
Recent reports have demonstrated that the HIV-1 transactivator protein,tat, induces apoptosis in T-lymphocyte cell lines, as well as in peripheral blood mononuclear cells, and stimulates a cascade of events resulting in up-regulation of the potent immunosuppressive cytokine, transforming growth factor-β (TGF-β). In this study we evaluated the ability of TGF-β to mediatetat induced apoptosis in T-lymphocyte cell lines. T-cells treated exogenously with either TGF-β1 or a combination of tat and pan-specific TGF-β neutralizing antibodies showed little change in the amount of apoptosis. When treated with pan-specific TGF-β neutralizing antibodies, Jurkat cells that stably expresstat protein (Jurkat-tat) showed only a modest decrease in apoptosis, while CEM-TART cells (CEM T-cells expressing both HIV-1tat andrev) demonstrated little change in the amount of apoptosis. In conclusion, we have demonstrated that TGF-β does not play a significant role in mediatingtat induced T-cell apoptosis.  相似文献   
35.
BACKGROUND: Professional societies and government organizations have promoted guidelines and best practices that encourage clinicians to routinely integrate cessation counseling into patient encounters. While research in health maintenance organizations has demonstrated that the development and maintenance of office systems do enable clinicians' smoking-cessation services, little is known about the adoption of system strategies in diverse organizations serving disadvantaged populations. METHODS: Data were collected via face-to-face interviews from November 2001 to October 2002 using a standardized systems assessment checklist at service delivery sites of 83 funded community health service agencies, which included hospitals, community health centers, and other organizations (e.g., substance abuse, mental health, and multiservice). The content of the structured assessment reflected system elements with proven effectiveness that have been included in guidelines and best practices recommendations. Detailed information was collected on the implementation strategies. RESULTS: This study found considerable attention to systems that support cessation services in diverse healthcare organizations, but much remains to be done. There is a wide diversity of implementation strategies employed, with varied degrees of sophistication. CONCLUSIONS: A major challenge is to develop systems capable of providing population-based feedback to, and between, providers, which will enable further quality improvement efforts.  相似文献   
36.
Context  Despite decades of use and considerable research, the role of estrogen alone in preventing chronic diseases in postmenopausal women remains uncertain. Objective  To assess the effects on major disease incidence rates of the most commonly used postmenopausal hormone therapy in the United States. Design, Setting, and Participants  A randomized, double-blind, placebo-controlled disease prevention trial (the estrogen-alone component of the Women's Health Initiative [WHI]) conducted in 40 US clinical centers beginning in 1993. Enrolled were 10 739 postmenopausal women, aged 50-79 years, with prior hysterectomy, including 23% of minority race/ethnicity. Intervention  Women were randomly assigned to receive either 0.625 mg/d of conjugated equine estrogen (CEE) or placebo. Main Outcome Measures  The primary outcome was coronary heart disease (CHD) incidence (nonfatal myocardial infarction or CHD death). Invasive breast cancer incidence was the primary safety outcome. A global index of risks and benefits, including these primary outcomes plus stroke, pulmonary embolism (PE), colorectal cancer, hip fracture, and deaths from other causes, was used for summarizing overall effects. Results  In February 2004, after reviewing data through November 30, 2003, the National Institutes of Health (NIH) decided to end the intervention phase of the trial early. Estimated hazard ratios (HRs) (95% confidence intervals [CIs]) for CEE vs placebo for the major clinical outcomes available through February 29, 2004 (average follow-up 6.8 years), were: CHD, 0.91 (0.75-1.12) with 376 cases; breast cancer, 0.77 (0.59-1.01) with 218 cases; stroke, 1.39 (1.10-1.77) with 276 cases; PE, 1.34 (0.87-2.06) with 85 cases; colorectal cancer, 1.08 (0.75-1.55) with 119 cases; and hip fracture, 0.61 (0.41-0.91) with 102 cases. Corresponding results for composite outcomes were: total cardiovascular disease, 1.12 (1.01-1.24); total cancer, 0.93 (0.81-1.07); total fractures, 0.70 (0.63-0.79); total mortality, 1.04 (0.88-1.22), and the global index, 1.01 (0.91-1.12). For the outcomes significantly affected by CEE, there was an absolute excess risk of 12 additional strokes per 10 000 person-years and an absolute risk reduction of 6 fewer hip fractures per 10 000 person-years. The estimated excess risk for all monitored events in the global index was a nonsignificant 2 events per 10 000 person-years. Conclusions  The use of CEE increases the risk of stroke, decreases the risk of hip fracture, and does not affect CHD incidence in postmenopausal women with prior hysterectomy over an average of 6.8 years. A possible reduction in breast cancer risk requires further investigation. The burden of incident disease events was equivalent in the CEE and placebo groups, indicating no overall benefit. Thus, CEE should not be recommended for chronic disease prevention in postmenopausal women.   相似文献   
37.
The Revised Children's Manifest Anxiety Scale (RCMAS) and the Hooked on Nicotine Checklist (HONC) were used to measure trait anxiety and tobacco dependence in a population of 581 adolescents. Smokers demonstrated higher mean RCMAS scores (9.3, S.D.=6.5) than nonsmokers did (7.4, S.D.=6.2, t=-3.7, P<.001). Participants with symptoms of tobacco dependence had higher RCMAS scores (mean=11.6, S.D.=6.0, n=115) than did the participants without symptoms (mean=7.8, S.D.=6.0, n=177, t=-5.3, P<.001). Scores on the RCMAS and the HONC correlated positively (n=292, r=.32, P<.001). Participants who had felt relaxed in response to their first exposure to nicotine were also more likely to develop dependence and to report that stress caused cravings or a need to smoke. Trait anxiety and relaxation in response to the first dose of nicotine were unrelated and appear to be independent risk factors for the development of nicotine dependence and a reliance on tobacco to cope with stress.  相似文献   
38.
OBJECTIVE: To develop and test items for the Health Plan Employee Data and Information Set (HEDIS) that assess delivery of the full range of provider-delivered tobacco interventions. MATERIALS AND METHODS: The authors identified potential items via literature review; items were reviewed by national experts. Face validity of candidate items was tested in focus groups. The final survey was sent to a random sample of 1711 adult primary care patients; the re-test survey was sent to self-identified smokers. RESULTS: The process identified reliable items to capture provider assessment of motivation and provision of assistance and follow-up. CONCLUSIONS: One can reliably assess patient self-report of provider delivery of the full range of brief tobacco interventions. Such assessment and feedback to health plans and providers may increase use of evidence-based brief interventions.  相似文献   
39.
40.
The authors examined sources of variance in self-reported physical activity in a cohort of healthy adults (n = 580) from Worcester, Massachusetts (the Seasonal Variation of Blood Cholesterol Study, 1994-1998). Fifteen 24-hour physical activity recalls of total, occupational, and nonoccupational activity (metabolic equivalent-hours/day) were obtained over 12 months. Random effects models were employed to estimate variance components for subject, season, day of the week, and residual error, from which the number of days of assessment required to achieve 80% reliability was estimated. The largest proportional source of variance in total and nonoccupational activity was within-subject variance (50-60% of the total). Differences between subjects accounted for 20-30% of the overall variance in total activity, and seasonal and day-of-the-week effects accounted for 6% and 15%, respectively. For total activity, 7-10 days of assessment in men and 14-21 days of assessment in women were required to achieve 80% reliability. For nonoccupational activity, 21-28 days of assessment were required. This study is among the first to have examined the sources of variance in daily physical activity levels in a large population of adults using 24-hour physical activity recall. These findings provide insight for understanding the strengths and limitations of short term and long term physical activity assessments employed in epidemiologic studies.  相似文献   
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