全文获取类型
收费全文 | 828篇 |
免费 | 83篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 16篇 |
妇产科学 | 7篇 |
基础医学 | 205篇 |
口腔科学 | 2篇 |
临床医学 | 133篇 |
内科学 | 181篇 |
皮肤病学 | 5篇 |
神经病学 | 41篇 |
特种医学 | 54篇 |
外科学 | 86篇 |
综合类 | 5篇 |
一般理论 | 2篇 |
预防医学 | 77篇 |
眼科学 | 4篇 |
药学 | 53篇 |
中国医学 | 4篇 |
肿瘤学 | 33篇 |
出版年
2023年 | 10篇 |
2022年 | 14篇 |
2021年 | 26篇 |
2020年 | 6篇 |
2019年 | 22篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 17篇 |
2015年 | 26篇 |
2014年 | 37篇 |
2013年 | 45篇 |
2012年 | 61篇 |
2011年 | 72篇 |
2010年 | 40篇 |
2009年 | 29篇 |
2008年 | 75篇 |
2007年 | 50篇 |
2006年 | 51篇 |
2005年 | 61篇 |
2004年 | 50篇 |
2003年 | 42篇 |
2002年 | 29篇 |
2001年 | 7篇 |
2000年 | 14篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 7篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1912年 | 1篇 |
排序方式: 共有912条查询结果,搜索用时 15 毫秒
41.
13C imaging—a new diagnostic platform 总被引:2,自引:0,他引:2
Månsson S Johansson E Magnusson P Chai CM Hansson G Petersson JS Ståhlberg F Golman K 《European radiology》2006,16(1):57-67
The evolution of magnetic resonance imaging (MRI) has been astounding since the early 1980s, and a broad range of applications has emerged. To date, clinical imaging of nuclei other than protons has been precluded for reasons of sensitivity. However, with the recent development of hyperpolarization techniques, the signal from a given number of nuclei can be increased as much as 100,000 times, sufficient to enable imaging of nonproton nuclei. Technically, imaging of hyperpolarized nuclei offers several unique properties, such as complete lack of background signal and possibility for local and permanent destruction of the signal by means of radio frequency (RF) pulses. These properties allow for improved as well as new techniques within several application areas. Diagnostically, the injected compounds can visualize information about flow, perfusion, excretory function, and metabolic status. In this review article, we explain the concept of hyperpolarization and the techniques to hyperpolarize 13C. An overview of results obtained within angiography, perfusion, and catheter tracking is given, together with a discussion of the particular advantages and limitations. Finally, possible future directions of hyperpolarized 13C MRI are pointed out. 相似文献
42.
Metabolic assessment of the brain using proton magnetic resonance spectroscopy in a growth-restricted human fetus: case report 总被引:1,自引:0,他引:1
Azpurua H Alvarado A Mayobre F Salom T Copel JA Guevara-Zuloaga F 《American journal of perinatology》2008,25(5):305-309
Proton magnetic resonance spectroscopy (MRS) is a noninvasive method to assess concentrations of different metabolites in tissues, including the brain. We evaluated a fetus with growth restriction using Doppler ultrasound and proton MRS. Doppler assessment revealed absent end diastolic flow in the umbilical artery. Diastolic flow was increased in the middle cerebral artery. Proton MRS of the fetal brain showed lactate and a low N-acetylaspartate/choline index, metabolic markers of starvation/hypoxia. Proton MRS gave us in vivo metabolic information of the brain of a fetus under starvation/hypoxic conditions. It is potentially a new tool for fetal surveillance. To our knowledge, this is the first report of cerebral lactate detection using proton MRS in a growth-restricted human fetus with no associated malformations in the English literature. Further experimental and clinical longitudinal investigations are needed to evaluate its efficacy in the clinical setting. 相似文献
43.
44.
Morten Lind Jensen Frederik Mondrup Freddy Lippert Charlotte Ringsted 《Resuscitation》2009,80(8):903-908
ContextA well-suited e-learning program might be a feasible strategy to maintain competence following a resuscitation course.AimThis study had 2 aims: (1) to examine the effect of an e-learning program as a booster of competence acquired from an Advanced Life Support (ALS) course. (2) To identify factors related to the use of the e-learning program.Materials and methodsThe study contained two parts pertaining to the two aims. The first part was a prospective single blinded randomised controlled study on junior doctors. The intervention was the monthly use of an e-learning program during one year and effect was measured as ALS-competence, a composite of a knowledge and skills test.The second part was a telephone interview of the intervention group. An interview guide was constructed based on existing knowledge of e-learning. In order to identify factors explaining the use of e-learning a univariate correlation was used to select significant variables to be included in a multiple regression analysis.ResultsOf the 134 invited to participate, 103 accepted the invitation. There were 79/103 (77%) participants, 40/51 in the intervention group and 39/52 in the control group. There was no difference between the groups with regards to ALS competence. Only ‘social interaction’ was an individually significant factor influencing the use of the e-learning program.ConclusionsThis study did not demonstrate an effect of an e-learning program as a booster of competence acquired from an ALS course. The primary factor influencing the use of e-learning was the lack of social interaction. 相似文献
45.
Carsten Lott Rui Araujo Mary Rose Cassar Stefano Di Bartolomeo Peter Driscoll Ivan Esposito Ernestina Gomes Peter Goode Carl Gwinnutt Michael Huepfl Freddy Lippert Giuseppe Nardi David Robinson Markus Roessler Mike Davis Karl-Christian Thies 《Resuscitation》2009,80(10):1192-1196
The European Trauma Course (ETC) was officially launched during the international conference of the European Resuscitation Council (ERC) in 2008. The ETC was developed on behalf of ESTES (European Society of Trauma and Emergency Surgery), EuSEM (European Society of Emergency Medicine), the ESA (European Society of Anaesthesiology) and the ERC. The objective of the ETC is to provide an internationally recognised and certified life support course, and to teach healthcare professionals the key principles of the initial care of severely injured patients. Its core elements, that differentiates it from other trauma courses, are a strong focus on team training and a novel modular design that is adaptable to the differing regional European requirements.This article describes the lessons learnt during the European Trauma Course development and provides an outline of the planned future development. 相似文献
46.
Since the isolation of Helicobacter pylori, many new Helicobacter species have been identified from the gastrointestinal tract in humans and animals. In humans, a spiral organism different from H. pylori and provisionally named "Helicobacter heilmannii", has been associated with gastritis, gastric ulceration and to a lesser degree, gastric cancer. In addition Helicobacter cinaedi, Helicobacter fennelliae, Helicobacter pullorum and "Flexispira rappini" have been isolated from cases of enteric disease, bacteremia and pneumonic illness. In the biliary tract, the presence of Helicobacter bilis, Helicobacter pullorum and "Flexispira rappini" has been demonstrated. Morphological, epidemiological and genotypic data suggest the involvement of animal helicobacters in these infections. In this paper, a review of the literature addressing the current knowledge about epidemiology, diagnosis, pathogenesis and therapy of these infections is given. 相似文献
47.
48.
Koch A Sørensen P Homøe P Mølbak K Pedersen FK Mortensen T Elberling H Eriksen AM Olsen OR Melbye M 《Emerging infectious diseases》2002,8(6):586-593
Acute respiratory infections (ARI) are frequent in Inuit children, in terms of incidence and severity. A cohort of 294 children <2 years of age was formed in Sisimiut, a community on the west coast of Greenland, and followed from 1996 to 1998. Data on ARI were collected during weekly visits at home and child-care centers; visits to the community health center were also recorded. The cohort had respiratory symptoms on 41.6% and fever on 4.9% of surveyed days. The incidence of upper and lower respiratory tract infections was 1.6 episodes and 0.9 episodes per 100 days at risk, respectively. Up to 65% of the episodes of ARI caused activity restriction; 40% led to contact with the health center. Compared with studies from other parts of the world, the incidence of ARI appears to be high in Inuit children. 相似文献
49.
Partanen T Johansson M Ahrens W Sala M Wesseling C Boffetta P Brenes F Font C Frentzel-Beyme R Garau I Janer G Kallas-Tarpila T Kogevinas M Loponen M Østergren L Peltomäki P Solér MD Svanström L Tempel J Neuvonen K 《Preventive medicine》2002,35(3):232-240
BACKGROUND: A simple empirically based method for assessment of the feasibility of workplace health promotion programs is described, focusing on cancer hazards (lifestyles, workplace hazards, deficient early detection). The basic components of feasibility are addressed: extent of hazards; needs of employees for hazard reduction and acceptability of WHP; and social context. METHODS: The procedure consists of six modules: guidelines on feasibility assessment; employee questionnaire; interview checklists for probing attitudes of management and partners (social context); data form; debriefing; and assessment of feasibility. Pretesting was completed in 16 workplace communities representing industry, construction, transport, telecommunications, health care, lodging and catering, teaching, and municipality jobs in five countries; a total of 1,085 subjects completed the employee questionnaire on health hazards, needs, and acceptability. RESULTS: The method demonstrated its utility in obtaining and summarizing the necessary data. Feasibility was assessed for the 16 test communities. CONCLUSION: The procedure can be customized; it has a high degree of face validity or understandability, and it is applicable in a wide variety of settings. 相似文献
50.
Serum cholesterol esterifying and cholesteryl ester hydrolyzing activities in liver diseases: relationships to cholesterol, bilirubin, and bile salt concentrations 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《The Journal of clinical investigation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Don P. Jones Freddy R. Sosa Jack Shartsis Praful T. Shah Eileen Skromak William T. Beher 《The Journal of clinical investigation》1971,50(2):259-265
Patients with acute hepatitis and chronic alcoholic liver disease had decreased net serum cholesterol esterifying activity (CEA) which correlated positively with the percentages and concentrations of cholesteryl esters in their serum. These cholesterol parameters also correlated negatively with serum bilirubin concentrations, but bilirubin added to sera in vitro failed to influence CEA. The decreased net CEA in the patients was not due to its inhibition by serum bile salts. The sera from five patients catalyzed a net hydrolysis of cholesteryl esters rather than a net esterification of free cholesterol. Since serum cholesteryl ester hydrolase activity may also have been present in the patients with decreased CEA, net CEA cannot be equated with the activity of lecithin-cholesterol acyl transferase (LCAT) in patients with liver disease. The relative contributions of LCAT and cholesteryl ester hydrolase activities to CEA in disease states remain to be evaluated by mutually independent assays. Nevertheless, the correlations found between net CEA and the concentrations and percentages of cholesteryl esters support the concepts that serum cholesterol esterifying activity is physiologically important in the formation of serum cholesteryl esters and that decreased CEA is one mechanism for the decreased level of cholesteryl esters seen in patients with liver diseases. 相似文献