全文获取类型
收费全文 | 17722篇 |
免费 | 1062篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 209篇 |
儿科学 | 361篇 |
妇产科学 | 459篇 |
基础医学 | 2915篇 |
口腔科学 | 432篇 |
临床医学 | 1815篇 |
内科学 | 3223篇 |
皮肤病学 | 343篇 |
神经病学 | 1694篇 |
特种医学 | 909篇 |
外科学 | 2656篇 |
综合类 | 115篇 |
一般理论 | 2篇 |
预防医学 | 948篇 |
眼科学 | 580篇 |
药学 | 1209篇 |
中国医学 | 56篇 |
肿瘤学 | 907篇 |
出版年
2023年 | 72篇 |
2022年 | 118篇 |
2021年 | 279篇 |
2020年 | 161篇 |
2019年 | 301篇 |
2018年 | 346篇 |
2017年 | 285篇 |
2016年 | 351篇 |
2015年 | 373篇 |
2014年 | 503篇 |
2013年 | 725篇 |
2012年 | 994篇 |
2011年 | 989篇 |
2010年 | 670篇 |
2009年 | 628篇 |
2008年 | 973篇 |
2007年 | 1056篇 |
2006年 | 1066篇 |
2005年 | 1084篇 |
2004年 | 895篇 |
2003年 | 879篇 |
2002年 | 861篇 |
2001年 | 174篇 |
2000年 | 138篇 |
1999年 | 178篇 |
1998年 | 193篇 |
1997年 | 151篇 |
1996年 | 144篇 |
1995年 | 146篇 |
1994年 | 118篇 |
1993年 | 119篇 |
1992年 | 95篇 |
1991年 | 81篇 |
1990年 | 72篇 |
1988年 | 68篇 |
1985年 | 67篇 |
1984年 | 83篇 |
1983年 | 64篇 |
1982年 | 90篇 |
1981年 | 80篇 |
1933年 | 97篇 |
1932年 | 93篇 |
1931年 | 81篇 |
1930年 | 83篇 |
1929年 | 76篇 |
1928年 | 78篇 |
1927年 | 69篇 |
1926年 | 80篇 |
1924年 | 77篇 |
1923年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Louis E. Samuels M.D. Sameer Sharma B.A. Rohinton J. Morris M.D. M.L. Ray Kuretu M.D. Karl E. Grunewald M.D. Michael D. Strong III M.D. Stanley K. Brockman M.D. 《Journal of cardiac surgery》1996,11(2):121-127
A bstract Objectives and Background : The purpose of this study was to document our initial experience with patients 90 years of age and older and to determine whether cardiac surgery is justified in this age group. Cardiac surgery in octogenarians has proven to be a successful and worthwhile procedure. A small group of nonagenarians with severe coronary artery disease (CAD) and aortic valve disease refractory to medical therapy have been considered for surgery. Methods : Fourteen patients aged 90 or more underwent cardiac surgery for symptomatic CAD or aortic valvular disease refractory to medical therapy. Eight patients underwent isolated coronary artery bypass grafting (CABG) and six patients underwent aortic valve replacement (AVR). All patients were in NYHA Class IV preoperatively. Results : Hospital mortality occurred in one patient (7%). Hospital morbidity occurred in 10 patients (71%) and included 7 cardiac, 5 neurological, 1 gastrointestinal, 1 infectious, and 1 pulmonary event. All survivors left the hospital symptomatically improved. The mean length of stay was 26 days. Four CABG patients went on to die at a mean of 2 years and 2 months, and 3 remain alive at a mean of 2 years and 4 months. Three AVR patients expired at a mean of 3 years and 4 months, and 3 remain alive at 4 years and 1 month. Conclusions : Cardiac surgery in carefully selected nonagenarians is justified and can be performed with acceptable results. 相似文献
22.
Selection of Streptococcus pneumoniae Mutants Having Reduced Susceptibility to Moxifloxacin and Levofloxacin 下载免费PDF全文
With Streptococcus pneumoniae, moxifloxacin was 4- and 10-fold more effective than levofloxacin at restricting selection of resistant mutants and at killing resistant mutants, respectively. The selection frequency for first-step topoisomerase mutants was 1,000 times lower for moxifloxacin than for levofloxacin; this difference was lost when second-step mutants were selected. 相似文献
23.
24.
Thomas Verse Alexander Baisch Joachim T Maurer Boris A Stuck Karl H?rmann 《Otolaryngology--head and neck surgery》2006,134(4):571-577
OBJECTIVE: To determine the efficacy of a new multilevel surgical protocol for obstructive sleep apnea (OSA). STUDY DESIGN AND SETTING: Sixty patients with moderate to severe OSA because of multilevel pharyngeal obstruction were enrolled into this prospective, controlled clinical trial after clinical examination, endoscopy, and polysomnography. Surgery included uvulaflap, tonsillectomy, hyoid suspension, and radiofrequency treatment of the tongue base (group A). A second group did not receive hyoid suspension (group B). In both groups, nasal surgery was performed if necessary. Polysomnography and Epworth Sleepines Scale (ESS) were recorded at baseline and 2 to 15 months after surgery. RESULTS: In group A, the mean apnea-hypopnea index (AHI) decreased significantly after surgery (38.9 +/- 20.0 vs 20.7 +/- 20.6, P < 0.0001), whereas in group B the AHI did not. All secondary variables (minimal oxygen saturation, mean oxygen saturation, arousal index), and the ESS significantly improved in group A with only changes in arousal index and ESS reaching levels of significance in group B. CONCLUSION: The presented protocol including the hyoid suspension proved to be effective in the treatment of OSA, whereas surgery without hyoid suspension was less successful. EBM rating: B-2b. 相似文献
25.
26.
Radionuclide scanning is a valuable diagnostic tool based on metabolic and anatomic imaging. When used in the appropriate clinical setting, radionuclide imaging is a sensitive, minimally invasive imaging modality that detects and differentiates skeletal from nonskeletal pathology in the painful foot. Isotopic scanning is of particular value in the evaluation of the diabetic foot and in the subsequent follow-up of response to therapy. 相似文献
27.
Because of rapid advances in the treatment of chronic heart failure, four important guidelines, including those from the European Society of Cardiology, have recently been updated. This review compares and contrasts the levels of evidence and classes of recommendation given to each of the key pharmacological and device therapies advocated by these guidelines. Possible explanations for discrepancies between the guidelines are discussed. Future approaches that might clarify the grade of evidence allocated and class of recommendation made are also described. 相似文献
28.
Karl Hittmair Gregor Gomiscek Karl Langenberger Michael Recht Herwig Imhof Josef Kramer 《Magnetic resonance in medicine》1994,31(5):567-571
In previous papers relative signal intensity increase was used as a quantitative assessment parameter for contrast uptake in contrastenhanced MRI. However, relative signal intensity increase does not only reflect contrast uptake but depends also on tissue parameters (native T1 relaxation time) and sequence parameters (repetition time and flip angle); thus, the contrast uptake cannot be assessed accurately using relative signal intensity increase. Based on an analysis of the contrast behavior of spoiled gradient echo sequences, a method is described in this paper that overcomes the limitations of relative signal intensity increase measurement. A parameter, called “enhancement factor” (EF) is introduced that approximates differential T1 relaxation rate. The enhancement factor scales linearly with contrast uptake and is independent of tissue and sequence parameters. The additional measurement time involved in determining the enhancement factor is less than 1 min and computation is straightforward. The practicality of the new method was confirmed by phantom measurements using T1-weighted and proton density-weighted spoiled gradient echo sequences (FLASH-2D). Enhancing tissues were simulated by water phantoms doped with increasing concentrations of Gd-DTPA. 相似文献
29.
30.
Extracellular matrix remodeling in hypertensive heart disease. 总被引:2,自引:0,他引:2