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   421995篇
  免费   58075篇
  国内免费   23858篇
耳鼻咽喉   7191篇
儿科学   7806篇
妇产科学   5500篇
基础医学   36575篇
口腔科学   5933篇
临床医学   65628篇
内科学   86388篇
皮肤病学   9834篇
神经病学   29792篇
特种医学   16204篇
外国民族医学   199篇
外科学   66265篇
综合类   47121篇
现状与发展   154篇
一般理论   29篇
预防医学   24096篇
眼科学   11756篇
药学   30727篇
  320篇
中国医学   16763篇
肿瘤学   35647篇
  2024年   1682篇
  2023年   9057篇
  2022年   13082篇
  2021年   17759篇
  2020年   17095篇
  2019年   11778篇
  2018年   17237篇
  2017年   16140篇
  2016年   16665篇
  2015年   20975篇
  2014年   30866篇
  2013年   28725篇
  2012年   25191篇
  2011年   28073篇
  2010年   24142篇
  2009年   24855篇
  2008年   19774篇
  2007年   17902篇
  2006年   20574篇
  2005年   18011篇
  2004年   11508篇
  2003年   9885篇
  2002年   8696篇
  2001年   9734篇
  2000年   9592篇
  1999年   10487篇
  1998年   8448篇
  1997年   8282篇
  1996年   7067篇
  1995年   6744篇
  1994年   4859篇
  1993年   3551篇
  1992年   3600篇
  1991年   3255篇
  1990年   2621篇
  1989年   2510篇
  1988年   2147篇
  1987年   1848篇
  1986年   1634篇
  1985年   1326篇
  1984年   896篇
  1983年   734篇
  1982年   635篇
  1981年   527篇
  1980年   442篇
  1979年   396篇
  1978年   330篇
  1977年   396篇
  1975年   277篇
  1972年   302篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Patient navigation is a strategy for overcoming barriers to reduce disparities and to improve access and outcomes. The aim of this umbrella review was to identify, critically appraise, synthesize, and present the best available evidence to inform policy and planning regarding patient navigation across the cancer continuum. Systematic reviews examining navigation in cancer care were identified in the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, Cumulative Index of Nursing and Allied Health (CINAHL), Epistemonikos, and Prospective Register of Systematic Reviews (PROSPERO) databases and in the gray literature from January 1, 2012, to April 19, 2022. Data were screened, extracted, and appraised independently by two authors. The JBI Critical Appraisal Checklist for Systematic Review and Research Syntheses was used for quality appraisal. Emerging literature up to May 25, 2022, was also explored to capture primary research published beyond the coverage of included systematic reviews. Of the 2062 unique records identified, 61 systematic reviews were included. Fifty-four reviews were quantitative or mixed-methods reviews, reporting on the effectiveness of cancer patient navigation, including 12 reviews reporting costs or cost-effectiveness outcomes. Seven qualitative reviews explored navigation needs, barriers, and experiences. In addition, 53 primary studies published since 2021 were included. Patient navigation is effective in improving participation in cancer screening and reducing the time from screening to diagnosis and from diagnosis to treatment initiation. Emerging evidence suggests that patient navigation improves quality of life and patient satisfaction with care in the survivorship phase and reduces hospital readmission in the active treatment and survivorship care phases. Palliative care data were extremely limited. Economic evaluations from the United States suggest the potential cost-effectiveness of navigation in screening programs.  相似文献   
32.
33.
We propose a high order finite difference linear scheme combined with a high order bound preserving maximum-principle-preserving (MPP) flux limiter to solve the incompressible flow system. For such problem with highly oscillatory structure but not strong shocks, our approach seems to be less dissipative and much less costly than a WENO type scheme, and has high resolution due to a Hermite reconstruction. Spurious numerical oscillations can be controlled by the weak MPP flux limiter. Numerical tests are performed for the Vlasov-Poisson system, the 2D guiding-center model and the incompressible Euler system. The comparison between the linear and WENO type schemes, with and without the MPP flux limiter, will demonstrate the good performance of our proposed approach.  相似文献   
34.
35.
宫腔积液指宫腔内液体积存(积水、积血或积脓),是绝经后女性常见体征之一,常于超声检查时发现。持续宫腔积液患者,需宫腔镜检查寻找病因。本文报道1例以宫腔积液为首发症状,经宫腔镜检查确诊为胃型宫颈腺癌的患者。通过病例回顾并文献复习,以期为更多绝经后宫腔积液及宫颈病变的诊断提供参考,避免漏诊及误诊。1病例资料患者67岁,女,主因"绝经18年,不规则阴道出血2月"于2020年5月就诊于首都医科大学附属北京妇产医院妇科微创中心。  相似文献   
36.
37.
38.
Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100?nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.  相似文献   
39.
Inappropriate use of acetaminophen (APAP) can lead to morbidity and mortality secondary to hepatic necrosis. Ginsenoside Rg1 is a major active ingredient in processed Panax ginseng, which is proved to elicit biological effects. We hypothesized the beneficial effect of Rg1 on APAP-mediated hepatotoxicity was through Nrf2/ARE pathway. The study was conducted in cells and mice, comparing the actions of Rg1. Rg1 significantly improved cell survival rates and promoted the expression of antioxidant proteins. Meanwhile, Rg1 reduced the excessive ROS and the occurrence of cell apoptosis, which were related to Nrf2/ARE pathway. Expression of Nrf2 has a certain cell specificity.

  相似文献   

40.
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