收费全文 | 17561篇 |
免费 | 1632篇 |
国内免费 | 33篇 |
耳鼻咽喉 | 315篇 |
儿科学 | 533篇 |
妇产科学 | 569篇 |
基础医学 | 2412篇 |
口腔科学 | 272篇 |
临床医学 | 2319篇 |
内科学 | 3094篇 |
皮肤病学 | 238篇 |
神经病学 | 1795篇 |
特种医学 | 483篇 |
外国民族医学 | 1篇 |
外科学 | 2110篇 |
综合类 | 335篇 |
一般理论 | 23篇 |
预防医学 | 1949篇 |
眼科学 | 382篇 |
药学 | 1191篇 |
中国医学 | 18篇 |
肿瘤学 | 1187篇 |
2022年 | 140篇 |
2021年 | 347篇 |
2020年 | 272篇 |
2019年 | 355篇 |
2018年 | 446篇 |
2017年 | 330篇 |
2016年 | 364篇 |
2015年 | 388篇 |
2014年 | 567篇 |
2013年 | 786篇 |
2012年 | 1110篇 |
2011年 | 1037篇 |
2010年 | 546篇 |
2009年 | 502篇 |
2008年 | 855篇 |
2007年 | 859篇 |
2006年 | 879篇 |
2005年 | 877篇 |
2004年 | 762篇 |
2003年 | 715篇 |
2002年 | 651篇 |
2001年 | 391篇 |
2000年 | 372篇 |
1999年 | 363篇 |
1998年 | 173篇 |
1997年 | 140篇 |
1996年 | 120篇 |
1995年 | 124篇 |
1994年 | 119篇 |
1993年 | 98篇 |
1992年 | 270篇 |
1991年 | 268篇 |
1990年 | 254篇 |
1989年 | 221篇 |
1988年 | 242篇 |
1987年 | 238篇 |
1986年 | 238篇 |
1985年 | 208篇 |
1984年 | 180篇 |
1983年 | 179篇 |
1982年 | 136篇 |
1981年 | 134篇 |
1980年 | 116篇 |
1979年 | 190篇 |
1978年 | 139篇 |
1977年 | 107篇 |
1976年 | 129篇 |
1975年 | 122篇 |
1974年 | 131篇 |
1973年 | 107篇 |
Introduction
Little is known about dementia incidence in diverse populations of oldest-old, the age group with highest dementia incidence.Methods
Incident dementia diagnoses from 1/1/2010 to 9/30/2015 were abstracted from medical records for 2350 members of an integrated health care system in California (n = 1702 whites, n = 375 blacks, n = 105 Latinos, n = 168 Asians) aged ≥90 in 2010. We estimated race/ethnicity-specific age-adjusted dementia incidence rates and implemented Cox proportional hazards models and Fine and Gray competing risk of death models adjusted for demographics and comorbidities in midlife and late-life.Results
Dementia incidence rates (n = 771 cases) were lowest among Asians (89.9/1000 person-years), followed by whites (96.9/1000 person-years), Latinos (105.8/1000 person-years), and blacks (121.5/1000 person-years). Cox regression and competing risk models estimated 28% and 36% higher dementia risk for blacks versus whites adjusting for demographics and comorbidities.Discussion
Patterns of racial/ethnic disparities in dementia seen in younger older adults continue after the age of 90 years, though smaller in magnitude. 相似文献Objective: To quantify spatiotemporal and kinematic BW characteristics in post-stroke community ambulators and compare their performance to controls.
Methods: Individuals post-stroke (n = 15, 60.1 ± 12.9 years, forward speed: 1.13 ± 0.23 m/s) and healthy adults (n = 12, 61.2 ± 16.2 years, forward speed: 1.40 ± 0.13 m/s) performed forward walking (FW) and BW during a single session. Step characteristics and peak lower extremity joint angles were extracted using 3D motion analysis and analyzed with mixed-method ANOVAs (group, walking condition).
Results: The stroke group demonstrated greater reductions in speed, step length and cadence and a greater increase in double-support time during BW compared to FW (p < .01). Compared to FW, the post-stroke group demonstrated greater reductions in hip extension and knee flexion during BW (p < .05). The control group demonstrated decreased plantarflexion and increased dorsiflexion during BW, but these increases were attenuated in the post-stroke group (p < .05).
Conclusions: Assessment of BW can unmask post-stroke walking impairments not detected during typical FW. BW impairments may contribute to the mobility difficulties reported by adults post-stroke. Therefore, BW should be assessed when determining readiness for home and community ambulation. 相似文献