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   18825篇
  免费   1061篇
  国内免费   150篇
耳鼻咽喉   153篇
儿科学   373篇
妇产科学   277篇
基础医学   2345篇
口腔科学   564篇
临床医学   1927篇
内科学   4054篇
皮肤病学   383篇
神经病学   2389篇
特种医学   1276篇
外科学   2861篇
综合类   96篇
一般理论   7篇
预防医学   618篇
眼科学   406篇
药学   1000篇
中国医学   13篇
肿瘤学   1294篇
  2024年   14篇
  2023年   156篇
  2022年   318篇
  2021年   539篇
  2020年   348篇
  2019年   409篇
  2018年   498篇
  2017年   440篇
  2016年   568篇
  2015年   636篇
  2014年   794篇
  2013年   914篇
  2012年   1447篇
  2011年   1444篇
  2010年   949篇
  2009年   867篇
  2008年   1296篇
  2007年   1409篇
  2006年   1182篇
  2005年   1200篇
  2004年   1138篇
  2003年   1051篇
  2002年   940篇
  2001年   166篇
  2000年   136篇
  1999年   175篇
  1998年   167篇
  1997年   128篇
  1996年   104篇
  1995年   73篇
  1994年   66篇
  1993年   65篇
  1992年   51篇
  1991年   40篇
  1990年   24篇
  1989年   33篇
  1988年   36篇
  1987年   20篇
  1986年   21篇
  1985年   19篇
  1984年   16篇
  1983年   18篇
  1982年   14篇
  1981年   8篇
  1980年   11篇
  1979年   10篇
  1978年   16篇
  1977年   13篇
  1974年   7篇
  1972年   7篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
92.
Material differentiation by dual energy CT: initial experience   总被引:9,自引:0,他引:9  
The aim of this study was to assess the feasibility of a differentiation of iodine from other materials and of different body tissues using dual energy CT. Ten patients were scanned on a SOMATOM Definition Dual Source CT (DSCT; Siemens, Forchheim, Germany) system in dual energy mode at tube voltages of 140 and 80 kVp and a ratio of 1:3 between tube currents. Weighted CT Dose Index ranged between 7 and 8 mGy, remaining markedly below reference dose values for the respective body regions. Image post-processing with three-material decomposition was applied to differentiate iodine or collagen from other tissue. The results showed that a differentiation and depiction of contrast material distribution is possible in the brain, the lung, the liver and the kidneys with or without the underlying tissue of the organ. In angiographies, bone structures can be removed from the dataset to ease the evaluation of the vessels. The differentiation of collagen makes it possible to depict tendons and ligaments. Dual energy CT offers a more specific tissue characterization in CT and can improve the assessment of vascular disease. Further studies are required to draw conclusions on the diagnostic value of the individual applications.  相似文献   
93.
94.
95.
96.
97.
Guidelines provided by the Director of Public Prosecutions suggest that anyone assisting another to commit suicide in England and Wales, or elsewhere, will not be prosecuted provided there are no self-seeking motives and no active encouragement. This reflects the position in Switzerland. There, however, no difference is made between assistance and inducement. In addition, the Swiss approach makes it possible to establish organisations to assist the suicides of both their citizens and foreign visitors. It should not be assumed that this approach is without controversy in Switzerland. Proposals for reform continue to be debated there, not least because of the concern about some of the actual practices of certain end-of-life organisations. It is likely that a few English citizens will continue to avail themselves of these services in Switzerland if they cannot find the help they require here. This paper explores the legitimacy of the current restrictive position adopted towards assisted suicide in England. It argues that the provisions within the guidelines prohibiting organisations that assist suicides, leaves some without the help they need. While legislative decriminalisation of assisted suicide and the establishment of state-sponsored suicide centres would represent the most permissive regime, this paper proposes that this would be a step too far. The preference here is for decriminalisation but adopting a ‘middle way’ between the two extremes: the more permissive approach provided by the ‘Swiss model’ is one that could be employed here, albeit within a more robust regulatory regime.  相似文献   
98.
Although matrix-assisted laser desorption/ionisation, time-of-flight mass spectrometry (MALDI-TOF MS) has previously been reported for high throughput blood group genotyping, those reports are limited to only a few blood group systems. This review describes the development of a large cooperative Swiss-German project, aiming to employ MALDI-TOF MS for the molecular detection of the blood groups Rh, Kell, Kidd, Duffy, MNSs, a comprehensive collection of low incidence antigens, as well as the platelet and granulocyte antigens HPA and HNA, representing a total of 101 blood group antigens, encoded by 170 alleles, respectively. Recent reports describe MALDI-TOF MS as a technology with short time-to-resolution, ability for high throughput, and cost-efficiency when used in genetic analysis, including forensics, pharmacogenetics, oncology and hematology. Furthermore, Kell and RhD genotyping have been performed on fetal DNA from maternal plasma with excellent results. In summary, this article introduces a new technological approach for high throughput blood group genotyping by means of MALDI-TOF MS. Although all data presented are preliminary, the observed success rates, data quality and concordance with known blood group types are highly impressive, underlining the accuracy and reliability of this cost-efficient high throughput method.  相似文献   
99.
Tracheal intubation remains a common procedure during neonatal intensive care. Rapid confirmation of correct tube placement is important because tube malposition is associated with serious adverse outcomes. The current gold standard test to confirm tube position is a chest radiograph, however this is often delayed until after ventilation has commenced. Hence, point of care methods to confirm correct tube placement have been developed. The aim of this article is to review the available literature on tube placement in newborn infants. We reviewed books, resuscitation manuals and articles from 1830 to the present with the search terms “Infant, Newborn”, “Endotracheal intubation”, “Resuscitation”, “Clinical signs”, “Radiography”, “Respiratory Function Tests”, “Laryngoscopy”, “Ultrasonography”, and “Bronchoscopy”. Various techniques have been studied to help clinicians assess tube placement. However, despite 85 years of clinical practice, the search for higher success rates and quicker intubation continues. Currently, chest radiography remains the gold standard test to confirm tube position. However, rigorous evaluation of new techniques is required to ensure the safety of newborn infants.  相似文献   
100.
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