收费全文 | 79656篇 |
免费 | 5838篇 |
国内免费 | 256篇 |
耳鼻咽喉 | 911篇 |
儿科学 | 2046篇 |
妇产科学 | 1083篇 |
基础医学 | 10755篇 |
口腔科学 | 843篇 |
临床医学 | 8411篇 |
内科学 | 17082篇 |
皮肤病学 | 884篇 |
神经病学 | 7745篇 |
特种医学 | 3067篇 |
外科学 | 12932篇 |
综合类 | 888篇 |
一般理论 | 91篇 |
预防医学 | 5959篇 |
眼科学 | 1964篇 |
药学 | 5366篇 |
中国医学 | 94篇 |
肿瘤学 | 5629篇 |
2024年 | 55篇 |
2023年 | 668篇 |
2022年 | 1039篇 |
2021年 | 2414篇 |
2020年 | 1358篇 |
2019年 | 2206篇 |
2018年 | 2529篇 |
2017年 | 1802篇 |
2016年 | 1894篇 |
2015年 | 2215篇 |
2014年 | 3211篇 |
2013年 | 4060篇 |
2012年 | 6518篇 |
2011年 | 6762篇 |
2010年 | 3694篇 |
2009年 | 3240篇 |
2008年 | 5404篇 |
2007年 | 5602篇 |
2006年 | 5190篇 |
2005年 | 5143篇 |
2004年 | 4652篇 |
2003年 | 4256篇 |
2002年 | 3864篇 |
2001年 | 601篇 |
2000年 | 401篇 |
1999年 | 567篇 |
1998年 | 786篇 |
1997年 | 588篇 |
1996年 | 478篇 |
1995年 | 426篇 |
1994年 | 399篇 |
1993年 | 395篇 |
1992年 | 250篇 |
1991年 | 197篇 |
1990年 | 179篇 |
1989年 | 164篇 |
1988年 | 157篇 |
1987年 | 131篇 |
1986年 | 136篇 |
1985年 | 144篇 |
1984年 | 185篇 |
1983年 | 150篇 |
1982年 | 237篇 |
1981年 | 232篇 |
1980年 | 165篇 |
1979年 | 94篇 |
1978年 | 115篇 |
1977年 | 100篇 |
1976年 | 71篇 |
1975年 | 59篇 |
Background Context
Low back pain (LBP) is a common complaint in clinical practice of multifactorial origin. Although obesity has been thought to contribute to LBP primarily by altering the distribution of mechanical loads on the spine, the additional contribution of obesity-related conditions such as diabetes mellitus (DM) to LBP has not been thoroughly examined.Purpose
To determine if there is a relationship between DM and LBP that is independent of body mass index (BMI) in a large cohort of adult survey participants.Study Design
Retrospective analysis of prospectively collected National Health and Nutrition Examination Survey (NHANES) data to characterize associations between LBP, DM, and BMI in adults subdivided into 6 subpopulations: normal weight (BMI 18.5–25), overweight (BMI 25–30), and obese (BMI >30) diabetics and nondiabetics. Diabetes was defined with glycohemoglobin A1c (HbA1c) ≥6.5%.Patient Sample
11,756 participants from NHANES cohort.Outcome Measures
Percentage of LBP reported.Methods
LBP reported in the 1999-2004 miscellaneous pain NHANES questionnaire was the dependent variable examined. Covariates included HbA1c, BMI, age, and family income ratio to poverty as continuous variables as well as race, gender, and smoking as binary variables. Individuals were further subdivided by weight class and diabetes status. Regression and graphical analyses were performed on the study population as a whole and also on subpopulations.Results
Increasing HbA1c did not increase the odds of reporting LBP in the full cohort. However, multivariate logistic regression of the 6 subpopulations revealed that the odds of LBP significantly increased with increasing HbA1c levels in normal weight diabetics. No other subpopulations reported significant relationships between LBP and HbA1c. LBP was also significantly associated with BMI for normal weight diabetics and also for obese subjects regardless of their DM status.Conclusions
LBP is significantly related to DM status, but this relationship is complex and may interact with BMI. These results support the concept that LBP may be improved in normal weight diabetic subjects with improved glycemic control and weight loss, and that all obese LBP subjects may benefit from improved weight loss alone. 相似文献Background
Physicians treating nonvalvular atrial fibrillation (AF) assess stroke and bleeding risks when deciding on anticoagulation. The agreement between empirical and physician-estimated risks is unclear. Furthermore, the association between patient and physician sex and anticoagulation decision-making is uncertain.Methods
We pooled data from 2 national primary care physician chart audit databases of patients with AF (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation and Coordinated National Network to Engage Physicians in the Care and Treatment of Patients with Atrial Fibrillation Chart Audit) with a combined 1035 physicians (133 female, 902 male) and 10,927 patients (4567 female and 6360 male).Results
Male physicians underestimated stroke risk in female patients and overestimated risk in male patients. Female physicians estimated stroke risk well in female patients but underestimated the risk in male patients. Risk of bleeding was underestimated in all. Despite differences in risk assessment by physician and patient sex, > 90% of patients received anticoagulation across all subgroups. There was modest agreement between physician estimated and calculated (ie, CHADS2 score) stroke risk: Kappa scores were 0.41 (0.35-0.47) for female physicians and 0.34 (0.32-0.36) for male physicians.Conclusions
Our study is the first to examine the association between patient and physician sex influences and stroke and bleeding risk estimation in AF. Although there were differences in agreement between physician estimated stroke risk and calculated CHADS2 scores, these differences were small and unlikely to affect clinical practice; further, despite any perceived differences in the accuracy of risk assessment by sex, most patients received anticoagulation. 相似文献Methods: Wild-type [alpha]1, [beta]2, [gamma]2s GABAA receptor subunit complementary DNAs were transfected into human embryonic kidney cells grown on glass coverslips using a calcium phosphate transfection method. After transfection (36-72 h), cells were whole cell patch clamped and exposed to combinations of the following: 0.3-1,000 [mu]m [gamma]-aminobutyric acid (GABA), 0-10 [mu]m propofol, and 0-1,650 [mu]m sevoflurane. Chemicals were delivered to the cells using two 10-channel infusion pumps and a rapid solution exchanger.
Results: Both propofol and sevoflurane alone enhanced the amplitude of GABAA receptor responses to submaximal concentrations of GABA in a dose-dependent manner. The enhancement was underpinned by an increase in the apparent affinity of the receptor for GABA. Coapplication of both anesthetics further enhanced the apparent affinity of the receptor for GABA. 相似文献