首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5563篇
  免费   761篇
  国内免费   101篇
耳鼻咽喉   17篇
儿科学   371篇
妇产科学   70篇
基础医学   505篇
口腔科学   288篇
临床医学   582篇
内科学   1037篇
皮肤病学   30篇
神经病学   1038篇
特种医学   230篇
外科学   809篇
综合类   185篇
预防医学   858篇
眼科学   52篇
药学   194篇
中国医学   20篇
肿瘤学   139篇
  2024年   28篇
  2023年   187篇
  2022年   232篇
  2021年   351篇
  2020年   327篇
  2019年   374篇
  2018年   374篇
  2017年   282篇
  2016年   241篇
  2015年   240篇
  2014年   350篇
  2013年   468篇
  2012年   235篇
  2011年   258篇
  2010年   213篇
  2009年   241篇
  2008年   230篇
  2007年   214篇
  2006年   191篇
  2005年   139篇
  2004年   131篇
  2003年   138篇
  2002年   115篇
  2001年   71篇
  2000年   67篇
  1999年   70篇
  1998年   53篇
  1997年   73篇
  1996年   45篇
  1995年   47篇
  1994年   42篇
  1993年   37篇
  1992年   46篇
  1991年   46篇
  1990年   36篇
  1989年   31篇
  1988年   35篇
  1987年   34篇
  1986年   21篇
  1985年   20篇
  1984年   21篇
  1983年   16篇
  1982年   13篇
  1981年   13篇
  1980年   7篇
  1979年   8篇
  1978年   4篇
  1977年   5篇
  1976年   3篇
  1969年   1篇
排序方式: 共有6425条查询结果,搜索用时 31 毫秒
991.
The aim of this study was to clarify the effect of living alone on the cognitive function of older people and the mediating effect of instrumental activities of daily living (IADL) ability.The data for a final sample of 3276 participants aged 65 years and above who did not require long-term care at the baseline were used from a 4-year prospective cohort study conducted in Kasama City, Japan. Demographic data including age, sex, and depression at baseline were used as covariates. The Kihon checklist evaluated the IADL ability at baseline and cognitive function at follow-up. The characteristics of those living alone and with others were compared using the student t test and χ2 test. The effect of living alone on cognitive function was analyzed using logistic regression analysis. Mediation analyses determined the mediating effects of IADL.A total of 325 participants were living alone; they were significantly older than those living with others, more likely to be female, not provide emotional support, and have low physical function, more severe depression, and lower IADL disability. Living alone had a significantly lower risk of cognitive decline at follow-up than living with others. The mediation analysis revealed that IADL disability at follow-up was significantly associated with cognitive decline. Thus, greater IADL ability decreased cognitive decline risk.Older people living alone had a significantly lower risk of cognitive decline, and cognitive function significantly mediated IADL ability. Health support for enhancing IADL abilities may help older people living alone maintain good cognitive function.  相似文献   
992.
Objectives:Although higher occupational classes have been reported to be associated with better health, researchers do not fully understand whether such associations derive from the position or individual characteristics of the person in that position. We examined the association between being a manager and cardiovascular disease (CVD) risk factors using unique panel data in Japan that annually observed employees’ occupational class and health conditions.Methods:We analyzed data for 45 888 observations from a Japanese company from 2013 through 2017. The association between being a manager and CVD risk factors (metabolic risks and health-related behaviors) were evaluated using simple pooled cross-sectional analyses with adjustment for age, sex, marital status, and overtime-working hours. We further incorporated employee-level fixed-effects into the models to examine whether the associations were subject to individual time-invariant factors.Results:The pooled cross-sectional analyses showed that, compared to non-managers, managers had 2.0 mg/dl lower low density lipoprotein cholesterol (LDL-C) level, 1.4 mmHg-lower systolic blood pressure, and 0.2 kg/m2 lower body mass index (BMI). After adjusting for employee-level fixed-effects, being a manager was associated with a significantly 2.2 mg/dl higher LDL-C level. However, the associations between an individual’s management status and blood pressure or BMI were not significant. Furthermore, managers were 5.5% less likely to exercise regularly and 6.1% less likely to report sufficient sleep in the fixed-effects models, although the pooled cross-sectional analyses did not demonstrate these significant associations.Conclusions:Our findings suggest the necessity of considering these unfavorable health risks associated with being promoted to a manager.  相似文献   
993.
Treatment resistance (TR) in patients with first-episode psychosis (FEP) is a major cause of disability and functional impairment, yet mechanisms underlying this severe disorder are poorly understood. As one view is that TR has neurodevelopmental roots, we investigated whether its emergence relates to disruptions in synchronized cortical maturation quantified using gyrification-based connectomes. Seventy patients with FEP evaluated at their first presentation to psychiatric services were followed up using clinical records for 4 years; of these, 17 (24.3%) met the definition of TR and 53 (75.7%) remained non-TR at 4 years. Structural MRI images were obtained within 5 weeks from first exposure to antipsychotics. Local gyrification indices were computed for 148 contiguous cortical regions using FreeSurfer; each subject’s contribution to group-based structural covariance was quantified using a jack-knife procedure, providing a single deviation matrix for each subject. The latter was used to derive topological properties that were compared between TR and non-TR patients using a Functional Data Analysis approach. Compared to the non-TR patients, TR patients showed a significant reduction in small-worldness (Hedges’s g = 2.09, P < .001) and a reduced clustering coefficient (Hedges’s g = 1.07, P < .001) with increased length (Hedges’s g = −2.17, P < .001), indicating a disruption in the organizing principles of cortical folding. The positive symptom burden was higher in patients with more pronounced small-worldness (r = .41, P = .001) across the entire sample. The trajectory of synchronized cortical development inferred from baseline MRI-based structural covariance highlights the possibility of identifying patients at high-risk of TR prospectively, based on individualized gyrification-based connectomes.  相似文献   
994.
995.
996.
997.
Objective Patients with Prader-Willi syndrome (PWS) are known to have a high mortality rate. However, little is known about the exact reason for this, particularly in adults, because so few reports have been published. The present study examined cardiovascular abnormalities to determine the cause of death in adults with PWS. Methods From September 2017 to April 2019, a total of 18 adults with PWS, and, no history of cardiovascular diseases, were enrolled. We investigated the levels of the cardiovascular biomarkers: high-sensitivity C-reactive protein (hs-CRP) and troponin T (TnT). To estimate the cardiac function, we measured the left ventricular ejection fraction (LVEF), global longitudinal systolic strain (GLS) of the left ventricle, ratio of peak early mitral filling velocity (E) to early diastolic mitral annular velocity (E/e'' ratio), mitral annular plane systolic excursion (MAPSE) and tricuspid annular plane systolic excursion (TAPSE) using standard and tissue Doppler echocardiography. Results The mean patient age was 28±9 years old. There were 11 men, and the mean body mass index was 45.1 kg/m2. Dyslipidemia (82%), diabetes mellitus (82%) and hypertension (83%) were commonly found as comorbidities. Most patients had elevated levels of hs-CRP (mean 1.007±0.538 mg/dL). The LVEF (mean 61%±5%) showed normal values, while the GLS (mean 15.0%±3.0%) was decreased. The TAPSE was mildly reduced (mean 16±3 mm). Conclusion These results suggest that subtle cardiovascular abnormalities have already begun in young adults with PWS. We need to manage obesity and the resultant obesity-related disorders in order to prevent heart failure and coronary atherosclerosis in PWS patients.  相似文献   
998.
999.
We evaluated the natural history of median nerve sensory conduction, hand/wrist symptoms, and carpal tunnel syndrome (CTS) in an 11-year longitudinal study of 289 workers from four industries. Twenty hands which had carpal tunnel release surgery were excluded, leaving 558 hands for the primary study group. Overall, the trend was for mean sensory latencies and prevalence of slowing to increase, the prevalence of symptoms to decrease, and the prevalence of CTS to remain unchanged. Among individual hands, nerve conduction abnormalities tended to persist (82% 11-year persistence), while symptoms fluctuated widely (13% 11-year persistence). There was a strong, direct linear correlation between initial severity of slowing and subsequent development of CTS; however, most workers who developed de novo slowing did not develop symptoms or CTS. We conclude that changes in conduction status of the median nerve occur naturally with increasing age and do not necessarily lead to symptoms and CTS. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:711–721, 1998.  相似文献   
1000.
Clifton L. Gooch 《Muscle & nerve》1998,21(11):1537-1539
We elicited three single motor unit action potentials (S-MUAPs) via multiple point stimulation and subjected them to repetitive stimulation (RS) in 3 healthy subjects. We tracked each S-MUAP and its RS trains over two separate sessions as well as the compound motor action potential (CMAP) RS trains obtained from the same muscle following whole nerve stimulation. Repetitive axonal stimulation yields consistent results when carefully performed with minimal variation in each S-MUAP RS train from session to session, providing previously unobtainable data regarding neuromuscular junction function in the same single motor unit over time. In this small, normative sample, no significant correlation between S-MUAP and CMAP RS responses was observed. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 1537–1539, 1998  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号