全文获取类型
收费全文 | 18825篇 |
免费 | 1061篇 |
国内免费 | 150篇 |
专业分类
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 |
出版年
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
Johnson TR Krauss B Sedlmair M Grasruck M Bruder H Morhard D Fink C Weckbach S Lenhard M Schmidt B Flohr T Reiser MF Becker CR 《European radiology》2007,17(6):1510-1517
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.
Christoph Gassner Stefan Meyer Beat M. Frey Caren Vollmert 《Transfusion medicine reviews》2013,27(1):2-9
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.
Georg M. Schmölzer Megan O’Reilly Peter G. Davis Po-Yin Cheung Charles Christoph Roehr 《Resuscitation》2013
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.