全文获取类型
收费全文 | 781篇 |
免费 | 51篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 20篇 |
妇产科学 | 10篇 |
基础医学 | 113篇 |
口腔科学 | 3篇 |
临床医学 | 99篇 |
内科学 | 226篇 |
皮肤病学 | 5篇 |
神经病学 | 37篇 |
特种医学 | 44篇 |
外科学 | 110篇 |
综合类 | 19篇 |
预防医学 | 62篇 |
眼科学 | 3篇 |
药学 | 54篇 |
肿瘤学 | 43篇 |
出版年
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 15篇 |
2019年 | 15篇 |
2018年 | 20篇 |
2017年 | 11篇 |
2016年 | 18篇 |
2015年 | 18篇 |
2014年 | 19篇 |
2013年 | 32篇 |
2012年 | 34篇 |
2011年 | 38篇 |
2010年 | 16篇 |
2009年 | 22篇 |
2008年 | 37篇 |
2007年 | 53篇 |
2006年 | 38篇 |
2005年 | 34篇 |
2004年 | 34篇 |
2003年 | 30篇 |
2002年 | 38篇 |
2001年 | 21篇 |
2000年 | 21篇 |
1999年 | 19篇 |
1998年 | 22篇 |
1997年 | 20篇 |
1996年 | 22篇 |
1995年 | 13篇 |
1994年 | 20篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 16篇 |
1989年 | 19篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 12篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1938年 | 1篇 |
1935年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有850条查询结果,搜索用时 0 毫秒
31.
C. Cooper R. Fielding M. Visser L. J. van Loon Y. Rolland E. Orwoll K. Reid S. Boonen W. Dere S. Epstein B. Mitlak Y. Tsouderos A. A. Sayer R. Rizzoli J. Y. Reginster J. A. Kanis 《Calcified tissue international》2013,93(3):201-210
This review provides a framework for the development of an operational definition of sarcopenia and of the potential end points that might be adopted in clinical trials among older adults. While the clinical relevance of sarcopenia is widely recognized, there is currently no universally accepted definition of the disorder. The development of interventions to alter the natural history of sarcopenia also requires consensus on the most appropriate end points for determining outcomes of clinical importance which might be utilized in intervention studies. We review current approaches to the definition of sarcopenia and the methods used for the assessment of various aspects of physical function in older people. The potential end points of muscle mass, muscle strength, muscle power, and muscle fatigue, as well as the relationships between them, are explored with reference to the availability and practicality of the available methods for measuring these end points in clinical trials. Based on current evidence, none of the four potential outcomes in question is sufficiently comprehensive to recommend as a uniform single outcome in randomized clinical trials. We propose that sarcopenia may be optimally defined (for the purposes of clinical trial inclusion criteria as well as epidemiological studies) using a combination of measures of muscle mass and physical performance. The choice of outcome measures for clinical trials in sarcopenia is more difficult; co-primary outcomes, tailored to the specific intervention in question, may be the best way forward in this difficult but clinically important area. 相似文献
32.
33.
牛津膝置换是使用最广泛的膝关节单髁置换(UKR)。牛津膝在37年前开始应用,拥有一个全匹配的活动衬垫,因而磨损率非常低。牛津膝最主要的使用指征是膝关节前内侧骨关节炎,这种病人至少占所有需要行膝关节置换术患者的50%。由于这一系统的设计特点,传统UKR的反指征,如年龄、活动量、肥胖、髌股关节损害和软骨钙质沉着症等对于牛津膝均不是反指征。与全膝关节置换(TKR)相比,牛津膝提供更快的康复、更好的功能、更大的活动度和更好的术后满意度,发生并发症更少、程度更轻,病残率和死亡率更低。一个持续超过30年的研究显示在90%的病例中,牛津膝为患者终生提供了优或良的临床结果,且不需要翻修。在最近15年,牛津膝通过微创手术入路植入,涉及6000多例使用该入路牛津膝置换的9个研究报道显示,10年生存率约95%。在许多这样的研究中,医生们在拟行膝关节置换的患者中约50%使用了牛津单髁膝置换。 相似文献
34.
Karem. H. Alzoubi Omar. F. Khabour Noor H. Tashtoush Sayer I. Al‐azzam Nizar M. Mhaidat 《Hippocampus》2013,23(9):812-819
In this study, we examined the ability of Pentoxifylline (PTX) to prevent sleep deprivation induced memory impairment probably through decreasing oxidative stress. Sleep deprivation was chronically induced 8 h/day for 6 weeks in rats using modified multiple platform model. Concurrently, PTX (100 mg/kg) was administered to animals on daily basis. After 6 weeks of treatment, behavioral studies were conducted to test the spatial learning and memory using the Radial Arm Water Maze. Additionally, the hippocampus was dissected; and levels/activities of antioxidant defense biomarkers glutathione reduced (GSH), glutathione oxidized (GSSG), GSH/GSSG ratio, glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD), were assessed. The results show that chronic sleep deprivation impaired short‐ and long‐term memories, which was prevented by chronic treatment with PTX. Additionally, PTX normalized sleep deprivation‐induced reduction in the hippocampus GSH/GSSG ratio (P < 0.05), and activities of GPx, catalase, and SOD (P < 0.05). In conclusion, chronic sleep deprivation induces memory impairment, and treatment with PTX prevented this impairment probably through normalizing antioxidant mechanisms in the hippocampus. © 2013 Wiley Periodicals, Inc. 相似文献
35.
36.
Background
The assessment of physical activity levels of hospitalised older people requires accurate and reliable measures. Physical activities that older people in hospital commonly engage in include exercises and walking. Measurement of physical activity levels of older inpatients is essential to evaluate the impact of interventions to improve physical activity levels and to determine associations between physical activity in hospital and other health-related outcome measures.Objective
To determine which measures are used to measure physical activity of older people in hospital, and to describe their properties and applications.Method
A systematic review of four databases: Medline, Embase, CINAHL and AMED was conducted for papers published from 1996 to 2016. Inclusion criteria were participants aged ≥ 65 years and studies which included measures of physical activity in the acute medical inpatient setting. Studies which specifically assessed the activity levels of surgical patients or patients with neurological conditions such as stroke or brain injury were excluded. All study designs were included in the review.Results
18 studies were included from 127 articles selected for full review. 15 studies used objective measures to measure the physical activity of older inpatients: 11 studies used accelerometers and four used direct systematic observations. Seven accelerometers were identified including the StepWatch Activity Monitor, activPAL, GENEActiv, Kenz Lifecorder EX, Actiwatch-L, Tractivity and AugmenTech Inc. Pittsburgh accelerometer. Three studies used a subjective measure (interviews with nurses and patients) to classify patients into low, intermediate and high mobility groups. The StepWatch Activity Monitor was reported to be most accurate at step-counting in patients with slow gait speed or altered gait. The activPAL was reported to be highly accurate at classifying postures.Conclusion
Physical activity levels of older inpatients can be measured using accelerometers. The accuracy of the accelerometers varies between devices and population-specific validation studies are needed to determine their suitability in measuring physical activity levels of hospitalised older people. Subjective measures are less accurate but can be a practical way of measuring physical activity in a larger group of patients.37.
OBJECTIVES: To determine why there has been a decrease in the amount of applicants to Florida-based obstetrics and gynecology (OB/GYN) residency programs, and how this has been affected by the current medical liability climate. METHODS: Fourth year Florida medical students were surveyed about their concerns of a career in OB/GYN. The students were then grouped into three categories: students never interested in OB/GYN, students at one point interested in OB/GYN, and students pursuing a career in OB/GYN. The groups were analyzed for differences in their concerns about OB/GYN and the impact it had on their final career decisions. Finally, we addressed the question of whether or not medical liability played a significant role in their career choice. RESULTS: From September to November of 2005, 198 total students were surveyed. Of those surveyed, 10.8% were applying for OB/GYN, 47.7% had considered OB/GYN but chose another field, and 41.5% never considered OB/GYN as a specialty. The primary and secondary reasons for not choosing OB/GYN were the same in the two groups pursuing different specialties; "more interested in a different specialty" and "desire a specialty with more predictable work hours/lifestyle," respectively. Approximately 27% of those who considered OB/GYN but did not choose it ranked "fear of being sued" first or second, compared with 6.7% of those who never considered it (P < 0.01). Of the 21 students who will pursue careers in OB/GYN, 85.7% stated they are considering leaving Florida because of high malpractice/litigation. CONCLUSIONS: There is a subgroup of students in Florida who were initially interested in OB/GYN but may have been deterred by current medical liability issues. Florida is a state known as being in a professional liability crisis and this survey demonstrates evidence that this has adversely affected students' decisions to pursue OB/GYN. 相似文献
38.
Yojiro Koda Hiroto Kitahara Sara Kalantari Bow Chung Bryan Smith Jayant Raikhelkar Gene Kim Nitasha Sarswat Gabriel Sayer David Onsager Tae Song Nir Uriel Valluvan Jeevanandam Takeyoshi Ota 《Artificial organs》2020,44(4):367-374
The purpose of this study is to compare clinical outcomes of left ventricular assist device (LVAD) patients with device thrombosis who underwent device exchange (DE) or medical therapy (MT) alone. Consecutive patients undergoing LVAD implant between July 2008 and December 2017 were included. Device thrombosis was diagnosed with comprehensive assessments including ramp test, laboratory data, device parameters, and clinical presentations. First, MT was initiated in all patients. After MT, DE was considered if device thrombosis was refractory to initial MT, and it caused end-organ impairment and/or hemodynamic instability. Among 319 consecutive LVAD patients, 43 patients (13.5%) were diagnosed with device thrombosis. DE was performed in 28 patients (DE group); device explant was performed in 1 patient. MT was continued in 14 patients (MT group). In-hospital mortality was significantly lower in the DE group than the MT group (3.6% [1/28] vs. 28.6% [4/14], P = .0184). One-year survival was significantly better in the DE group (74.0% vs. 30.1%; log-rank = .001), and freedom from cerebrovascular accident (CVA) at 1 year was greater in the DE group (87.1% vs. 47.7%; log-rank = .004). DE was associated with improved 1-year survival and fewer CVAs. Surgical intervention, if feasible, is recommended for LVAD device thrombosis. 相似文献
39.
Teruhiko Imamura Nikhil Narang Daisuke Nitta Takeo Fujino Ann Nguyen Gene Kim Jayant Raikhelkar Daniel Rodgers Takeyoshi Ota Valluvan Jeevanandam Gabriel Sayer Nir Uriel 《Artificial organs》2020,44(12):e509-e519
Cannula position in HeartMate II and HeartWare left ventricular assist devices (LVADs) is associated with clinical outcome. This study aimed to investigate the clinical implication of the device positioning in HeartMate 3 LVAD cohort. Consecutive patients who underwent HeartMate 3 LVAD implantation were followed for one year from index discharge. At index discharge, chest X-ray parameters were measured: (a) cannula coronal angle, (b) height of pump bottom, (c) cannula sagittal angle, and (d) cannula lumen area. The association of each measurement of cannula position with one-year clinical outcomes was investigated. Sixty-four HeartMate 3 LVAD patients (58 years old, 64% male) were enrolled. In the multivariable Cox regression model, the cannula coronal angle was a significant predictor of death or heart failure readmission (hazard ratio 1.27 [1.01-1.60], P = .045). Patients with a cannula coronal angle ≤28° had lower central venous pressure (P = .030), lower pulmonary capillary wedge pressure (P = .027), and smaller left ventricular size (P = .019) compared to those with the angle >28°. Right ventricular size and parameters of right ventricular function were also better in the narrow angle group, as was one-year cumulative incidence of death or heart failure readmission (10% vs. 50%, P = .008). Narrow cannula coronal angle in patients with HeartMate 3 LVADs was associated with improved cardiac unloading and lower incidence of death or heart failure readmission. Larger studies to confirm the implication of optimal device positioning are warranted. 相似文献
40.
Karem. H Alzoubi Omar. F Khabour Sayer I Al-azzam Murad H Tashtoush Nizar M Mhaidat 《Current Neuropharmacology》2014,12(2):186-192
Chronic administration of L-methionine leads to memory impairment, which is attributed to increase in the level of oxidative stress in the brain. On the other hand, metformin is a commonly used antidiabetic drug with strong antioxidant properties. In the current study, we tested if chronic metformin administration prevents memory impairment induced by administration of L-methionine. In addition, a number of molecules related to the action of metformin on cognitive functions were examined. Both metformin and L-methionine were administered to animals by oral gavage. Testing of spatial learning and memory was carried out using radial arm water maze (RAWM). Additionally, hippocampal levels or activities of catalase, thiobarbituric acid reactive substances (TBARs), glutathione peroxidase (GPx), glutathione (GSH), oxidized glutathione (GSSG) and GSH/GSSG ratio were determined. Results showed that chronic L-methionine administration resulted in both short- and long- term memory impairment, whereas metformin treatment prevented such effect. Additionally, L-methionine treatment induced significant elevation in GSSG and TBARs, along with reduction in GSH/GSSG ratio and activities of catalase, and GPx. These effects were shown to be restored by metformin treatment. In conclusion, L-methionine induced memory impairment, and treatment with metformin prevented this impairment probably by normalizing oxidative stress in the hippocampus. 相似文献