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   284246篇
  免费   21900篇
  国内免费   1165篇
耳鼻咽喉   3241篇
儿科学   7403篇
妇产科学   5310篇
基础医学   37708篇
口腔科学   5868篇
临床医学   29120篇
内科学   59969篇
皮肤病学   3749篇
神经病学   26883篇
特种医学   9531篇
外国民族医学   13篇
外科学   42806篇
综合类   4332篇
一般理论   346篇
预防医学   24890篇
眼科学   7457篇
药学   19551篇
  6篇
中国医学   388篇
肿瘤学   18740篇
  2023年   1300篇
  2022年   2134篇
  2021年   5883篇
  2020年   3542篇
  2019年   5772篇
  2018年   6490篇
  2017年   4859篇
  2016年   5362篇
  2015年   6317篇
  2014年   9299篇
  2013年   12869篇
  2012年   19432篇
  2011年   20416篇
  2010年   11393篇
  2009年   10222篇
  2008年   17969篇
  2007年   18860篇
  2006年   18611篇
  2005年   18668篇
  2004年   17438篇
  2003年   16250篇
  2002年   15261篇
  2001年   3171篇
  2000年   2739篇
  1999年   3352篇
  1998年   3423篇
  1997年   2853篇
  1996年   2517篇
  1995年   2401篇
  1994年   2056篇
  1993年   1875篇
  1992年   2103篇
  1991年   1976篇
  1990年   1854篇
  1989年   1738篇
  1988年   1690篇
  1987年   1671篇
  1986年   1631篇
  1985年   1659篇
  1984年   1735篇
  1983年   1599篇
  1982年   1660篇
  1981年   1617篇
  1980年   1422篇
  1979年   1168篇
  1978年   1117篇
  1977年   934篇
  1976年   861篇
  1974年   842篇
  1973年   758篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Magnetic resonance elastography aims to non-invasively and remotely characterize the mechanical properties of living tissues. To quantitatively and regionally map the shear viscoelastic moduli in vivo, the technique must achieve proper mechanical excitation throughout the targeted tissues. Although it is straightforward, ante manibus, in close organs such as the liver or the breast, which practitioners clinically palpate already, it is somewhat fortunately highly challenging to trick the natural protective barriers of remote organs such as the brain. So far, mechanical waves have been induced in the latter by shaking the surrounding cranial bones. Here, the skull was circumvented by guiding pressure waves inside the subject's buccal cavity so mechanical waves could propagate from within through the brainstem up to the brain. Repeatable, reproducible and robust displacement fields were recorded in phantoms and in vivo by magnetic resonance elastography with guided pressure waves such that quantitative mechanical outcomes were extracted in the human brain.  相似文献   
62.
63.
64.
65.
66.

Background

Observational studies of the relative effectiveness of influenza vaccines are essential for public health decision making. Their estimates, however, are subject to bias due to unmeasured confounders. Instrumental variable (IV) methods can control for observed and unobserved confounders.

Methods

We used linked electronic medical record databases in the Veterans Health Administration (VHA) as well as Medicare administrative files to examine the relative vaccine effectiveness (rVE) of high-dose influenza vaccine (HD) versus standard-dose influenza vaccines (SD) in preventing hospitalizations among VHA-enrolled Veterans ≥65?years of age during 5 influenza seasons (2010–2011 through 2014–2015). Using multivariable IV Poisson regression modeling to address unmeasured confounding and bias, we analyzed the data by each season and through longitudinal analysis of all five seasons.

Findings

We included 3,638,924 person–influenza seasons of observation where 158,636 (4%) were among HD vaccine recipients and 3,480,288 (96%) were among SD vaccine recipients. Of the 1,728,562 Veterans, 1,702,824 (98.5%) were male and 1,299,412 (75%) were non-Hispanic white. Based on the longitudinal analysis of all five seasons, the IV-adjusted rVE estimate of HD vs. SD was 10% (95% CI, 8–12%) against all-cause hospitalization; 18% (95% CI, 15–21%) against cardiorespiratory-associated hospitalization; and 14% (95% CI, 6–22%) against influenza/pneumonia-associated hospitalization. The findings by season were similar.

Interpretation

Our analysis of VHA clinical data collected from approximately 1.7 million Veterans 65?years and older during five seasons demonstrates that high-dose influenza vaccine is more effective than standard-dose influenza vaccines in preventing influenza- or pneumonia-associated hospitalizations, cardiorespiratory hospitalizations, and all-cause hospitalizations.  相似文献   
67.
Choledochal cysts (CDCs) and biliary atresia (BA) are rare pediatric hepatobiliary anomalies that require surgical intervention due to increased risk of malignancy and liver failure, respectively. The underlying disease and operative procedures place patients at risk for long‐term complications, which may continue to affect them into adulthood. Lack of a transitional care model in the health‐care system potentiates the challenges they will face following aging out of their pediatric providers' care. We sought to elucidate the long‐term complications and challenges patients with CDCs and BA face, review the current literature regarding transitioning care, and propose guidelines aiding adult providers in continued care and surveillance of these patients. A literature review was performed to assess short‐term and long‐term complications after surgery and the current standards for transitioning care in patients with a history of CDCs and BA. While transitional programs exist for patients with other gastrointestinal diseases, there are few that focus on CDCs or BA. Generally, authors encourage medical record transmission from pediatric to adult providers, ensuring accuracy of information and compliance with treatment plans. Patients with CDCs are at risk for developing biliary malignancies, cholangitis, and anastomotic strictures after resection. Patients with BA develop progressive liver failure, necessitating transplantation. There are no consensus guidelines regarding timing of follow up for these patients. Based on the best available evidence, we propose a schema for long‐term surveillance.  相似文献   
68.
European Journal of Clinical Microbiology & Infectious Diseases - We compared the performance of an in-house-developed flow cytometry assay for intracellular cytokine staining (FC-ICS) and a...  相似文献   
69.
70.
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