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   171626篇
  免费   3637篇
  国内免费   1887篇
耳鼻咽喉   1720篇
儿科学   6359篇
妇产科学   2799篇
基础医学   20536篇
口腔科学   5397篇
临床医学   11432篇
内科学   32676篇
皮肤病学   3076篇
神经病学   10440篇
特种医学   3481篇
外国民族医学   4篇
外科学   26280篇
综合类   10428篇
现状与发展   2篇
一般理论   4篇
预防医学   9157篇
眼科学   3303篇
药学   18447篇
  10篇
中国医学   6339篇
肿瘤学   5260篇
  2022年   1017篇
  2021年   2453篇
  2020年   1240篇
  2019年   12772篇
  2018年   12471篇
  2017年   5601篇
  2016年   1200篇
  2015年   1256篇
  2014年   2903篇
  2013年   4752篇
  2012年   3071篇
  2011年   3228篇
  2010年   2735篇
  2009年   2677篇
  2008年   3132篇
  2007年   4207篇
  2006年   4439篇
  2005年   4299篇
  2004年   3380篇
  2003年   3479篇
  2002年   3344篇
  2001年   3300篇
  2000年   3500篇
  1999年   3161篇
  1998年   3203篇
  1997年   2538篇
  1996年   2368篇
  1995年   2698篇
  1994年   2514篇
  1993年   1943篇
  1992年   1548篇
  1991年   1552篇
  1990年   1302篇
  1989年   1024篇
  1988年   1045篇
  1987年   1030篇
  1986年   855篇
  1985年   5432篇
  1984年   7319篇
  1983年   5840篇
  1982年   6276篇
  1981年   5731篇
  1980年   4918篇
  1979年   4980篇
  1978年   4073篇
  1977年   3053篇
  1976年   3535篇
  1975年   2735篇
  1974年   2526篇
  1973年   2228篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.

Background

Purulent bacterial pericarditis is a rare and potentially fatal disease. The course may be fulminant, and the presentation may pose a diagnostic challenge.

Case report

An otherwise healthy 75-year-old male was brought to the emergency department in a state of general deterioration, confusion, and shock. Bedside ultrasound showed a significant pericardial effusion. His condition quickly deteriorated and the resuscitation included emergent bedside pericardiocentesis. The drainage was purulent and later cultures grew out Streptococcus pneumoniae.

Why should an emergency physician be aware of this?

Purulent pericarditis is extremely rare but should be considered in the patient with a fulminant infectious process (particularly pneumonia) and signs of pericardial effusion. Treatment should include appropriate antibiotics and early drainage.  相似文献   
22.
Owing to the frequent incidence of blast-induced traumatic brain injury (bTBI) in recent military conflicts, there is an urgent need to develop effective therapies for bTBI-related pathologies. Blood-brain barrier (BBB) breakdown has been reported to occur after primary blast exposure, making restoration of BBB function and integrity a promising therapeutic target. We tested the hypothesis that treatment with dexamethasone (DEX) after primary blast injury potentiates recovery of an in vitro BBB model consisting of mouse brain endothelial cells (bEnd.3). DEX treatment resulted in complete recovery of transendothelial electrical resistance and hydraulic conductivity 1 day after injury, compared with 3 days for vehicle-treated injured cultures. Administration of RU486 (mifepristone) inhibited effects of DEX, confirming that barrier restoration was mediated by glucocorticoid receptor signaling. Potentiated recovery with DEX treatment was accompanied by stronger zonula occludens (ZO)-1 tight junction immunostaining and expression, suggesting that increased ZO-1 expression was a structural correlate to BBB recovery after blast. Interestingly, augmented ZO-1 protein expression was associated with specific upregulation of the α+ isoform but not the α isoform. This is the first study to provide a mechanistic basis for potentiated functional recovery of an in vitro BBB model because of glucocorticoid treatment after primary blast injury.  相似文献   
23.
24.
In this paper, we introduce a new type of troubled-cell indicator to improve hybrid weighted essentially non-oscillatory (WENO) schemes for solving the hyperbolic conservation laws. The hybrid WENO schemes selectively adopt the high-order linear upwind scheme or the WENO scheme to avoid the local characteristic decompositions and calculations of the nonlinear weights in smooth regions. Therefore, they can reduce computational cost while maintaining non-oscillatory properties in non-smooth regions. Reliable troubled-cell indicators are essential for efficient hybrid WENO methods. Most of troubled-cell indicators require proper parameters to detect discontinuities precisely, but it is very difficult to determine the parameters automatically. We develop a new troubled-cell indicator derived from the mean value theorem that does not require any variable parameters. Additionally, we investigate the characteristics of indicator variable; one of the conserved properties or the entropy is considered as indicator variable. Detailed numerical tests for 1D and 2D Euler equations are conducted to demonstrate the performance of the proposed indicator. The results with the proposed troubled-cell indicator are in good agreement with pure WENO schemes. Also the new indicator has advantages in the computational cost compared with the other indicators.  相似文献   
25.
The Poisson-Nernst-Planck (PNP) system is a widely accepted model for simulation of ionic channels. In this paper, we design, analyze, and numerically validate a second order unconditional positivity-preserving scheme for solving a reduced PNP system, which can well approximate the three dimensional ion channel problem. Positivity of numerical solutions is proven to hold true independent of the size of time steps and the choice of the Poisson solver. The scheme is easy to implement without resorting to any iteration method. Several numerical examples further confirm the positivity-preserving property, and demonstrate the accuracy, efficiency, and robustness of the proposed scheme, as well as the fast approach to steady states.  相似文献   
26.
目的:探讨D6S1043、D12S391基因座的基因多态性对主动攻击行为的影响。方法:应用聚合酶链反应技术结合毛细管电泳法对114例男性主动攻击行为者(研究组)及120名健康男性(对照组)进行D6S1043、D12S391基因座的基因型及等位基因检测,分析D6S1043、D12S391基因座多态性与主动攻击行为的相关性。结果:研究组D6S1043基因座中12~19基因型频率(13.16%)明显高于对照组(1.67%)(P0.05);两组等位基因频率差异无统计学意义;两组D12S391基因座的基因型及等位基因频率差异无统计学意义。结论:D6S1043基因座中12~19基因型可能主动攻击行为有关。  相似文献   
27.
28.
This is the first Japanese autopsy case of Leucine-rich repeat kinase 2 (LRRK2) G2019S mutation with atypical TDP43 proteinopathy. Our case is important that presented clinically dysphagia and pathologically TDP-43 proteinopathy. TDP43 may play an important role of clinical presentation with LRRK2 G2019S mutation carriers.  相似文献   
29.
30.
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