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   4442篇
  免费   344篇
  国内免费   9篇
耳鼻咽喉   32篇
儿科学   107篇
妇产科学   51篇
基础医学   878篇
口腔科学   57篇
临床医学   490篇
内科学   623篇
皮肤病学   85篇
神经病学   454篇
特种医学   124篇
外科学   816篇
综合类   133篇
一般理论   6篇
预防医学   313篇
眼科学   49篇
药学   380篇
中国医学   2篇
肿瘤学   195篇
  2023年   27篇
  2022年   60篇
  2021年   127篇
  2020年   71篇
  2019年   138篇
  2018年   163篇
  2017年   147篇
  2016年   138篇
  2015年   111篇
  2014年   167篇
  2013年   249篇
  2012年   374篇
  2011年   401篇
  2010年   203篇
  2009年   184篇
  2008年   318篇
  2007年   307篇
  2006年   287篇
  2005年   225篇
  2004年   180篇
  2003年   158篇
  2002年   158篇
  2001年   43篇
  2000年   41篇
  1999年   41篇
  1998年   28篇
  1997年   20篇
  1996年   24篇
  1995年   29篇
  1994年   21篇
  1992年   31篇
  1991年   20篇
  1990年   20篇
  1989年   16篇
  1988年   10篇
  1987年   17篇
  1986年   19篇
  1985年   16篇
  1983年   9篇
  1981年   9篇
  1980年   10篇
  1978年   12篇
  1975年   13篇
  1974年   10篇
  1973年   11篇
  1972年   13篇
  1971年   11篇
  1969年   9篇
  1966年   8篇
  1960年   8篇
排序方式: 共有4795条查询结果,搜索用时 15 毫秒
11.
12.
A 48-year-old Caucasian man was found to have a rare neoplastic process of vascular endothelial origin. The clinical presentation was that of plum-colored cutaneous plaques of the lower extremities. The histopathology, natural history, and treatment of this case are discussed and compared with previously reported cases. It is suggested that this disease entity represents a malignant state with systemic involvement and a poor prognosis.  相似文献   
13.
Insertion mutations were isolated in cya and crp of Yersinia enterocolitica, which encode adenylate cyclase and the cyclic AMP (cAMP) receptor protein (CRP). The cya and crp mutants were affected for the production of proteins exported by the Ysc, Ysa, and flagellar type III secretion systems (TTSS). Protein production by each TTSS was restored when the respective mutation was complemented by a plasmid-encoded copy of the wild-type gene. Both cya and crp mutants exhibited reduced virulence for orally infected BALB/c mice in a 50% lethal dose analysis. Examination of bacterial survival in host tissues showed that cya and crp mutants colonized Peyer's patches and, to a lesser extent, mesenteric lymph nodes. However, the mutants did not appear to disseminate to the liver and spleen of infected mice. An initial examination of the effectiveness of Y. enterocolitica cya and crp mutants to stimulate protective immunity against subsequent challenge with virulent bacteria in mice was promising. The results indicate that the cAMP-CRP regulatory system is required for Y. enterocolitica virulence.  相似文献   
14.
Injuries to the Achilles tendon are a challenge to the foot and ankle surgeon. In recent years, research has led to a relative change in the way that many surgeons view acute Achilles tendon rupture. In an effort to fully evaluate these trends, as well as to evaluate all aspects of care for acute Achilles tendon rupture, the American College of Foot and Ankle Surgeons convened a panel of experts to create a clinical consensus statement to address selected aspects of care of the acute Achilles tendon injury.  相似文献   
15.
Yoga interventions can reduce stress, but the mechanisms underlying that stress reduction remain largely unidentified. Understanding how yoga works is essential to optimizing interventions. The present study tested five potential psychosocial mechanisms (increased mindfulness, interoceptive awareness, spiritual well-being, self-compassion and self-control) that have been proposed to explain yoga's impact on stress. Forty-two participants (62% female; 64% White) in a yoga program for stress reduction completed surveys at baseline (T1), mid-intervention (T2) and post-intervention (12 weeks; T3). We measured two aspects of stress, perceived stress and stress reactivity. Changes were assessed with paired t-tests; associations between changes in mechanisms were tested in residual change models. Only stress reactivity decreased, on average, from T1 to T3. Except for self-compassion, all psychosocial mechanisms increased from T1 to T3, with minimal changes from T2 to T3. Except for self-control, increases in each mechanism were strongly associated with decreases in both measures of stress between T1 and T2 and decreases in perceived stress from T1 to T3 (all p's < 0.05). Increased psychosocial resources are associated with stress reduction. Yoga interventions targeting these resources may show stronger stress reduction effects. Future research should test these linkages more rigorously using active comparison groups and larger samples.  相似文献   
16.

Of the many changes in daily life brought about by the COVID-19 pandemic, social distancing efforts and governmentally mandated lockdowns were among the most drastic. Coinciding with these changes, popular pornography websites made some previously premium content available for free, spurring dramatic increases in traffic to these websites. This increase in time spent at home and reported increases in traffic to specific pornographic websites led to some speculation that pornography use might generally increase over the course of the pandemic and that problematic use might also increase. To test these speculations and quantify the effects of the pandemic and its associated restrictions on social behaviors on pornography use, we analyzed data from a longitudinal sample of American adults. Baseline, nationally representative data were collected in August 2019 via YouGov (N?=?2518). Subsequent data were collected in February 2020 (n?=?1677), May 2020 (n?=?1533), August 2020 (n?=?1470), and October 2020 (n?=?1269). Results indicated that, in May 2020, immediately following the height of the first wave of pandemic-related lockdowns, more people reported past-month pornography use than at other follow-up time points, but less did so than at baseline. Among those who reported use in May 2020, only 14% reported increases in use since the start of the pandemic, and their use returned to levels similar to all other users by August 2020. In general, pornography use trended downward over the pandemic, for both men and women. Problematic pornography use trended downward for men and remained low and unchanged in women. Collectively, these results suggest that many fears about pornography use during pandemic-related lockdowns were largely not supported by available data.

  相似文献   
17.
18.
Benzodiazepine use among injecting drug users (IDUs) presents a major clinical and public health problem that may increase in importance. The current paper examines the research on the extent of benzodiazepine use among IDUs and the harmful consequences associated with such use. Numerous studies have found benzodiazepine use to be widespread among IDUs, and to be associated with greater levels of risk-taking and polydrug use, and poorer psychosocial functioning than other IDUs. The injection of benzodiazepines has also been reported, and presents problems in itself. The implications of existing research for both clinical practice and research are discussed.  相似文献   
19.
The current demands for cost reduction, increased efficiency, and quality care placed upon hospital pharmacy departments underscores the need for an effective information system. In this article, we describe the stepwise approach we used to evaluate and select a new pharmacy information system. The importance of involving staff in the evaluation process is discussed, along with the mechanisms we used to learn as much as we could about the vendors before making our selection.  相似文献   
20.
PURPOSE: To determine the nature and relative frequency of operator-dependent data analysis errors in dual x-ray absorptiometry. MATERIALS AND METHODS: Over 40 months, 2,528 dual x-ray absorptiometric examinations of the forearm, femoral neck, and lumbar spine were performed by 11 technologists by using standard techniques and software. Each analysis was reviewed by a radiologist; errors were recorded and corrected. RESULTS: There were no forearm analysis errors. There were 24 (0.9%) femoral neck analysis errors, of which 23 resulted from misplacement of the analysis region. There were 33 (1.3%) spinal analysis errors, of which 24 resulted from misplacement of intervertebral disk space markers. Analysis errors of the femur and spine resulted in six misdiagnoses (0.2%). CONCLUSION: Misdiagnosis due to analysis errors is rare. Femoral neck analysis errors were easily detectable, but accurate spinal analyses depended on accurate identification of vertebral end plates and posterior elements. Nonetheless, these potentially serious errors can be detected and corrected if the analyses are reviewed and interpreted by a supervising physician who is familiar with the relevant anatomy, proper analysis techniques, and factors--such as artifacts--that adversely affect the accuracy of the analysis.  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