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   7383篇
  免费   456篇
  国内免费   39篇
耳鼻咽喉   107篇
儿科学   177篇
妇产科学   195篇
基础医学   1031篇
口腔科学   603篇
临床医学   614篇
内科学   1623篇
皮肤病学   168篇
神经病学   753篇
特种医学   109篇
外科学   636篇
综合类   30篇
一般理论   2篇
预防医学   701篇
眼科学   177篇
药学   504篇
中国医学   63篇
肿瘤学   385篇
  2023年   76篇
  2022年   83篇
  2021年   336篇
  2020年   214篇
  2019年   329篇
  2018年   370篇
  2017年   197篇
  2016年   230篇
  2015年   286篇
  2014年   381篇
  2013年   432篇
  2012年   692篇
  2011年   752篇
  2010年   354篇
  2009年   331篇
  2008年   522篇
  2007年   493篇
  2006年   407篇
  2005年   338篇
  2004年   304篇
  2003年   252篇
  2002年   207篇
  2001年   36篇
  2000年   39篇
  1999年   39篇
  1998年   18篇
  1997年   12篇
  1996年   9篇
  1995年   18篇
  1994年   8篇
  1993年   9篇
  1992年   10篇
  1991年   4篇
  1990年   9篇
  1989年   3篇
  1988年   4篇
  1983年   3篇
  1982年   3篇
  1979年   3篇
  1978年   3篇
  1977年   6篇
  1975年   3篇
  1974年   9篇
  1973年   4篇
  1972年   4篇
  1971年   5篇
  1970年   6篇
  1969年   3篇
  1968年   8篇
  1965年   2篇
排序方式: 共有7878条查询结果,搜索用时 15 毫秒
1.
2.
Journal of Digital Imaging - Vertebral Compression Fracture (VCF) occurs when the vertebral body partially collapses under the action of compressive forces. Non-traumatic VCFs can be secondary to...  相似文献   
3.
Objective:The present study evaluates a training program for fitting different hearing protection devices (HPDs) based on personal attenuation rating (PAR) before, immediately after, and six months after training.Methods:A total of 67 workers from a public university in the city of São Paulo, Brazil, were invited to participate in the measurement of PARs for foam and silicone protectors through the 3M™ E-A-Rfit Validation System. Two evaluations were performed for each protector at each sampling date: one after reading printed material (the package instructions) and another after being trained by an audiologist. The same procedures were repeated after six months. The final sample consisted of 30 individuals. ANOVA was used for statistical analysis.Results:Larger PAR values were observed after training by the audiologist, and smaller values were observed after six months. Then, after re-training, the values increased again. There were no statistically significant differences in PAR among the HPDs tested. Even after the two training sessions, 23 to 27% of the subjects did not obtain adequate PAR values.Conclusion:These findings emphasize the need for continual worker training in the correct fit of earplug HPDs and the importance of longitudinal PAR monitoring. In addition, some workers, despite the training provided, did not adapt to the HPDs used. Therefore, it is essential that other protection methods and/or other HPD types are made available to these individuals.Key words: Hearing, noise-induced hearing loss, occupational health, personal protective equipment, hearing protection devices  相似文献   
4.
5.
6.
ABSTRACT

Prior studies on substance use in Brazil have not focused on opioid misuse, previously thought to be nearly non-existent. This paper presents new findings on heroin and non-medical use of opioid analgesics. Data come from the 2015 Brazilian Household Survey on Substance Use (BHSU-3), a nationally representative survey estimating epidemiological parameters related to substance use by residents across Brazil. BHSU-3 used stratified multi-stage probability sampling across multiple geographic domains of interest, resulting in 16,273 interviews with household residents. Lifetime heroin use among Brazilians was 0.3 (95% C.I:0.2–0.4). Lifetime, past-year, and past-month non-medical use of opioid analgesics were respectively 2.9 (95%C.I.:2.3–3.4), 1.4 (95%C.I.:1.1–1.7) and 0.6 (95%C.I.:0.4–0.8). Past-year prevalence of non-medical opioid analgesics use was lower among males [Prevalence Ratio (PR): 0.54 (95% C.I.:0.36–0.78)], those aged 12–24 [0.56 (95% C.I.:0.34–0.92)], persons with monthly family incomes between R$1,501–3,000 [0.59 (95% C.I.:0.38–0.92)] or greater than R$3,000 [0.64 (95% C.I.:0.42–0.98)], and persons who were unemployed [0.65 (95% C.I.:0.46–0.92)]. Non-medical use of opioids in Brazil may be more prevalent than previously recognised. Proper measurement and evaluation of opioid misuse across Brazil and other Latin American countries is critical to understand and prevent opioid-related harms.  相似文献   
7.
8.
In 2015, an outbreak of presumed waterborne toxoplasmosis occurred in Gouveia, Brazil. We conducted a 3-year prospective study on a cohort of 52 patients from this outbreak, collected clinical and multimodal imaging findings, and determined risk factors for ocular involvement. At baseline examination, 12 (23%) patients had retinochoroiditis; 4 patients had bilateral and 2 had macular lesions. Multimodal imaging revealed 2 distinct retinochoroiditis patterns: necrotizing focal retinochoroiditis and punctate retinochoroiditis. Older age, worse visual acuity, self-reported recent reduction of visual acuity, and presence of floaters were associated with retinochoroiditis. Among patients, persons >40 years of age had 5 times the risk for ocular involvement. Five patients had recurrences during follow-up, a rate of 22% per person-year. Recurrences were associated with binocular involvement. Two patients had late ocular involvement that occurred >34 months after initial diagnosis. Patients with acquired toxoplasmosis should have long-term ophthalmic follow-up, regardless of initial ocular involvement.  相似文献   
9.
The current coronavirus disease (COVID‐19) outbreak, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has raised the possibility of potential neurotropic properties of this virus. Indeed, neurological sequelae of SARS‐CoV‐2 infection have already been reported and highlight the relevance of considering the neurological impact of coronavirus (CoV) from a translational perspective. Animal models of SARS and Middle East respiratory syndrome, caused by structurally similar CoVs during the 2002 and 2012 epidemics, have provided valuable data on nervous system involvement by CoVs and the potential for central nervous system spread of SARS‐CoV‐2. One key finding that may unify these pathogens is that all require angiotensin‐converting enzyme 2 as a cell entry receptor. The CoV spike glycoprotein, by which SARS‐CoV‐2 binds to cell membranes, binds angiotensin‐converting enzyme 2 with a higher affinity compared with SARS‐CoV. The expression of this receptor in neurons and endothelial cells hints that SARS‐CoV‐2 may have higher neuroinvasive potential compared with previous CoVs. However, it remains to be determined how such invasiveness might contribute to respiratory failure or cause direct neurological damage. Both direct and indirect mechanisms may be of relevance. Clinical heterogeneity potentially driven by differential host immune‐mediated responses will require extensive investigation. Development of disease models to anticipate emerging neurological complications and to explore mechanisms of direct or immune‐mediated pathogenicity in the short and medium term is therefore of great importance. In this brief review, we describe the current knowledge from models of previous CoV infections and discuss their potential relevance to COVID‐19.  相似文献   
10.
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