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   74428篇
  免费   4568篇
  国内免费   848篇
耳鼻咽喉   1408篇
儿科学   835篇
妇产科学   1081篇
基础医学   12781篇
口腔科学   1753篇
临床医学   6592篇
内科学   13650篇
皮肤病学   2527篇
神经病学   5343篇
特种医学   4566篇
外科学   9815篇
综合类   280篇
现状与发展   1篇
一般理论   27篇
预防医学   3338篇
眼科学   1641篇
药学   7178篇
中国医学   951篇
肿瘤学   6077篇
  2023年   579篇
  2022年   1876篇
  2021年   2861篇
  2020年   1381篇
  2019年   1853篇
  2018年   2312篇
  2017年   1822篇
  2016年   2594篇
  2015年   3623篇
  2014年   4242篇
  2013年   4830篇
  2012年   7173篇
  2011年   6660篇
  2010年   3862篇
  2009年   3212篇
  2008年   4501篇
  2007年   4082篇
  2006年   3586篇
  2005年   3176篇
  2004年   2670篇
  2003年   2218篇
  2002年   1863篇
  2001年   1541篇
  2000年   1407篇
  1999年   1008篇
  1998年   431篇
  1997年   292篇
  1996年   236篇
  1995年   194篇
  1994年   173篇
  1993年   151篇
  1992年   356篇
  1991年   338篇
  1990年   295篇
  1989年   273篇
  1988年   262篇
  1987年   258篇
  1986年   190篇
  1985年   170篇
  1984年   131篇
  1983年   114篇
  1982年   60篇
  1981年   64篇
  1979年   83篇
  1978年   71篇
  1976年   50篇
  1975年   50篇
  1974年   64篇
  1973年   52篇
  1972年   53篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Fluid is usually restricted during thoracic surgery, and vasoactive agents are often administered to maintain blood pressure. One-lung ventilation (OLV) decreases arterial oxygenation; thus oxygen delivery to the brain can be decreased. In this study, we compared phenylephrine and dopamine with respect to maintaining cerebral oxygenation during OLV in major thoracic surgery.Sixty-three patients undergoing lobectomies were randomly assigned to the dopamine (D) or phenylephrine (P) group. The patients’ mean arterial pressure was maintained within 20% of baseline by a continuous infusion of dopamine or phenylephrine. Maintenance fluid was kept at 5 mL/kg/h. The depth of anesthesia was maintained with desflurane 1MAC and remifentanil infusion under bispectral index guidance. Regional cerebral oxygen saturation (rScO2) and hemodynamic variables were recorded using near-infrared spectroscopy and esophageal cardiac Doppler.The rScO2 was higher in the D group than the P group during OLV (OLV 60 min: 71 ± 6% vs 63 ± 12%; P = 0.03). The number of patients whose rScO2 dropped more than 20% from baseline was 0 and 6 in the D and P groups, respectively (P = 0.02). The D group showed higher cardiac output, but lower mean arterial pressure than the P group (4.7 ± 1.0 vs 3.9 ± 1.2 L/min; 76.7 ± 8.1 vs 84.5 ± 7.5 mm Hg; P = 0.02, P = 0.02). Among the variables, age, hemoglobin concentration, and cardiac output were associated with rScO2 by correlation analysis.Dopamine was superior to phenylephrine in maintaining cerebral oxygenation during OLV in thoracic surgery.  相似文献   
32.
33.
Recent studies have reported an association between gastroesophageal reflux disease (GERD) and atrial fibrillation (AF). The objective of the present study was to evaluate whether AF is one of the risk factors for GERD occurrence.In this hospital-based, retrospective, case–control study, the patients were classified into 2 groups. The patients diagnosed with new AF were assigned to the AF group (n = 1612); those diagnosed without AF and GERD were assigned to the control group (n = 1612). The subjects in the control group were selected from outpatients of total healthcare center without a history of AF or GERD, and matched for age and gender. We evaluated the incidence of GERD and risk factors for GERD occurrence between the 2 groups.The number of patients experiencing occurrence of GERD during the follow-up period was significantly higher in the AF group than those in the control group, respectively (129 patients vs 98 subjects, P = 0.037). The incidence of GERD was significantly higher in the AF group than in the control group by Kaplan–Meier analysis with log-rank test (P = 0.008). The AF group''s adjusted hazard ratio of GERD occurrence against that of the control group was 1.37 (95% confidence interval [CI]: 1.16–1.57; P = 0.009) according to Cox''s proportional hazard model.The presence of AF appears to increase the incidence of GERD and may be considered a risk factor for the development of GERD. Further, large prospective and cohort studies will be required to better establish the correlation of GERD with AF.  相似文献   
34.
35.
While decreasing trend in gender differences in alcohol use disorders was reported in Western countries, the change in Asian countries is unknown. This study aims to explore the shifts in gender difference in alcohol abuse (AA) and dependence (AD) in Korea. We compared the data from two nation-wide community surveys to evaluate gender differences in lifetime AA and AD by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Face-to-face interviews using the Composite International Diagnostic Interview (CIDI) were applied to all subjects in 2001 (n=6,220) and 2011 (n=6,022). Male-to-female ratio of odds was decreased from 6.41 (95% CI, 4.81-8.54) to 4.37 (95% CI, 3.35-5.71) for AA and from 3.75 (95% CI, 2.96-4.75) to 2.40 (95% CI, 1.80-3.19) for AD. Among those aged 18-29, gender gap even became statistically insignificant for AA (OR, 1.59; 95% CI, 0.97-2.63) and AD (OR, 1.18; 95% CI, 0.80-2.41) in 2011. Men generally showed decreased odds for AD (0.55; 95% CI, 0.45-0.67) and women aged 30-39 showed increased odds for AA (2.13; 95% CI 1.18-3.84) in 2011 compared to 2001. Decreased AD in men and increased AA in women seem to contribute to the decrease of gender gap. Increased risk for AA in young women suggests needs for interventions.  相似文献   
36.
37.
38.
39.
Objective: This study investigated the effect of regular swimming exercise according to the duration-intensity on neurocognitive function in a cerebral infarction rat model.

Methods: Forty male Sprague–Dawley 10-week-old rats, weighing 300 ± 50 g, were subjected to photothrombotic cerebral infarction. The remaining 36 rats were randomly divided into four groups (n = 9 per group: non-exercise (group A); swimming exercise of short duration-intensity (5 min/day, group B); swimming exercise of moderate duration-intensity (10 min/day, group C); and swimming exercise of long duration-intensity (20 min/day, group D). Exercise was performed five times a week for 4 weeks, beginning the day after cerebral infarction. Neurocognitive function was evaluated with the Morris water maze test. Immunohistochemistry and western blot analysis examined brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) at 4 weeks postinfarction.

Results: At 4 weeks postinfarction, escape latency was found to be shorter in group C than in any of groups A, B, or D. Immunohistochemistry revealed the most significant immunoreactivity for BDNF and VEGF in group C. Western blot analysis demonstrated that BDNF and VEGF proteins were markedly expressed in group C.

Conclusions: Regular swimming exercise of moderate duration-intensity may be the most effective exercise protocol for the recovery of neurocognitive function in cerebral infarction rat model.  相似文献   

40.
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