全文获取类型
收费全文 | 2448篇 |
免费 | 142篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 218篇 |
妇产科学 | 36篇 |
基础医学 | 286篇 |
口腔科学 | 70篇 |
临床医学 | 190篇 |
内科学 | 484篇 |
皮肤病学 | 48篇 |
神经病学 | 185篇 |
特种医学 | 337篇 |
外科学 | 221篇 |
综合类 | 29篇 |
预防医学 | 193篇 |
眼科学 | 24篇 |
药学 | 168篇 |
1篇 | |
中国医学 | 3篇 |
肿瘤学 | 125篇 |
出版年
2021年 | 20篇 |
2020年 | 18篇 |
2019年 | 19篇 |
2018年 | 29篇 |
2017年 | 30篇 |
2016年 | 37篇 |
2015年 | 43篇 |
2014年 | 49篇 |
2013年 | 73篇 |
2012年 | 50篇 |
2011年 | 43篇 |
2010年 | 59篇 |
2009年 | 102篇 |
2008年 | 58篇 |
2007年 | 77篇 |
2006年 | 78篇 |
2005年 | 62篇 |
2004年 | 49篇 |
2003年 | 54篇 |
2002年 | 55篇 |
2001年 | 60篇 |
2000年 | 51篇 |
1999年 | 58篇 |
1998年 | 104篇 |
1997年 | 127篇 |
1996年 | 117篇 |
1995年 | 81篇 |
1994年 | 86篇 |
1993年 | 105篇 |
1992年 | 31篇 |
1991年 | 35篇 |
1990年 | 36篇 |
1989年 | 75篇 |
1988年 | 69篇 |
1987年 | 40篇 |
1986年 | 44篇 |
1985年 | 52篇 |
1984年 | 30篇 |
1983年 | 37篇 |
1982年 | 33篇 |
1981年 | 46篇 |
1980年 | 27篇 |
1979年 | 19篇 |
1978年 | 20篇 |
1977年 | 32篇 |
1976年 | 26篇 |
1974年 | 16篇 |
1973年 | 26篇 |
1972年 | 19篇 |
1971年 | 16篇 |
排序方式: 共有2620条查询结果,搜索用时 31 毫秒
981.
Cutaneous metastases from signet ring cell gastric carcinoma are uncommon. A 35-year-old male presented with a three-month history of multiple asymptomatic, indurated, pinky colored nodules of 2.5 to 4 cm in diameter, without any local and general symptoms. Nodule biopsy revealed an infiltrating signet ring cell carcinoma. Gastroscopy and biopsy confirmed the diagnosis of gastric carcinoma with signet ring cells. The present report describes an unusual clinical case of a young patient diagnosed with cutaneous metastasis before detection of his gastric carcinoma. 相似文献
982.
983.
984.
D. Major H. Bryant M. Delaney S. Fekete L. Gentile M. Harrison V. Mai E. Nicholson Y. Taylor 《Current oncology (Toronto, Ont.)》2013,20(5):252-257
Background
Early implementation of programmatic colorectal cancer (crc) screening for average-risk individuals 50–74 years of age in Canada has used fecal occult blood tests [fts (guaiac or immunochemical)] and colonoscopy for follow-up of abnormal fts. This paper presents results of an evaluation of this crc screening.Methods
Five Canadian provincial programs provided aggregated data for individuals with a first-round ft processed between January 1, 2009, and December 31, 2011.Results
The 104,750 people who successfully completed a first round of screening represented 16.1% of those who had access to the programs between January 1, 2009, and December 31, 2011 (mean age: 61.2 years; men: 61.4 years; women: 61.1 years). Of those participants, 4661 had an abnormal ft (4.4%). Uptake of colonoscopy within 180 days after an abnormal ft was 80.5%, ranging from 67.8% to 89.5% by program. The positive predictive value (ppv) for adenoma was 35.9% for guaiac ft and 50.6% for immunochemical ft. Adenoma and crc detection rates were, respectively, 16.9 and 1.8 per 1000 screened. Of invasive crcs detected, 64.6% were stage i or ii.Conclusions
Considering the variation in characteristics and stage of implementation of each provincial program, the collaboration of the provinces leading to this report on the early performance of crc screening in Canada is a major milestone. Targets are met or nearly met for significant indicators such as ppv for adenoma and cancer detection rate. Participation is expected to increase as programs are fully implemented in the provinces. Additional effort may be needed to improve timely access to follow-up colonoscopy. 相似文献985.
Fekete PZ Brzuszkiewicz E Blum-Oehler G Olasz F Szabó M Gottschalk G Hacker J Nagy B 《International journal of medical microbiology : IJMM》2012,302(1):4-9
In this study the plasmid pTC, a 90 kb self-conjugative virulence plasmid of the porcine enterotoxigenic Escherichia coli (ETEC) strain EC2173 encoding the STa and STb heat-stable enterotoxins and tetracycline resistance, has been sequenced in two steps. As a result we identified five main distinct regions of pTC: (i) the maintenance region responsible for the extreme stability of the plasmid, (ii) the TSL (toxin-specific locus comprising the estA and estB genes) which is unique and characteristic for pTC, (iii) a Tn10 transposon, encoding tetracycline resistance, (iv) the tra (plasmid transfer) region, and (v) the colE1-like origin of replication. It is concluded that pTC is a self-transmissible composite plasmid harbouring antibiotic resistance and virulence genes. pTC belongs to a group of large conjugative E. coli plasmids represented by NR1 with a widespread tra backbone which might have evolved from a common ancestor. This is the first report of a completely sequenced animal ETEC virulence plasmid containing an antimicrobial resistance locus, thereby representing a selection advantage for spread of pathogenicity in the presence of antimicrobials leading to increased disease potential. 相似文献
986.
987.
988.
MJ Heradien PA Brink MJ Heradien J Augustyn A Saaiman 《Cardiovascular journal of Africa》2016,27(1):53-55
Renal denervation is a minimally invasive procedure that aims to reduce brain–kidney sympathetic cross-talk. Despite the negative results of the recent SYMPLICITY HTN-3 trial, the procedure is considered safe and has been associated with many beneficial effects, including the reversal of hypertensive heart disease substrate and the prevention of cardiac arrhythmia. The first-generation radiofrequency catheter system featured a monopolar catheter that required sequential singlepoint energy application, followed by rotation, partial withdrawal of the catheter and re-application of energy. The latest generation device features four electrodes configured in a helical arrangement that can simultaneously ablate in four quadrants of the vessel circumference. Renal denervation via brachial or radial arterial access with the second-generation system has not been described before. 相似文献
989.
Nadia Barakat Pallav Shah Scott H Faro John P Gaughan Devon Middleton MJ Mulcahey Feroze B Mohamed 《World journal of radiology》2015,7(9):279-285
AIM: To assess inter- and intra-rater reliability (agreement) between two region of interest (ROI) methods in pediatric spinal cord diffusion tensor imaging (DTI).METHODS: Inner-Field-of-View DTI data previously acquired from ten pediatric healthy subjects (mean age = 12.10 years) was used to assess for reliability. ROIs were drawn by two neuroradiologists on each subject data twice within a 3-mo interval. ROIs were placed on axial B0 maps along the cervical spine using free-hand and fixed-size ROIs. Agreement analyses for fractional anisotropy (FA), axial diffusivity, radial diffusivity and mean diffusivity were performed using intra-class-correlation (ICC) and Cronbach’s alpha statistical methods.RESULTS: Inter- and intra-rater agreement between the two ROI methods showed moderate (ICC = 0.5) to strong (ICC = 0.84). There were significant differences between raters in the number of pixels selected using free-hand ROIs (P < 0.05). However, no significant differences were observed in DTI parameter values. FA showed highest variability in ICC values (0.10-0.87). Cronbach’s alpha showed moderate-high values for raters and ROI methods.CONCLUSION: The study showed that high reproducibility in spinal cord DTI can be achieved, and demonstrated the importance of setting detailed methodology for post-processing DTI data, specifically the placement of ROIs. 相似文献
990.