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   3067篇
  免费   303篇
  国内免费   39篇
耳鼻咽喉   37篇
儿科学   108篇
妇产科学   85篇
基础医学   342篇
口腔科学   51篇
临床医学   326篇
内科学   723篇
皮肤病学   23篇
神经病学   505篇
特种医学   42篇
外科学   187篇
综合类   210篇
预防医学   320篇
眼科学   54篇
药学   240篇
  7篇
中国医学   58篇
肿瘤学   91篇
  2024年   18篇
  2023年   103篇
  2022年   129篇
  2021年   191篇
  2020年   189篇
  2019年   120篇
  2018年   127篇
  2017年   142篇
  2016年   123篇
  2015年   99篇
  2014年   206篇
  2013年   210篇
  2012年   110篇
  2011年   134篇
  2010年   135篇
  2009年   124篇
  2008年   137篇
  2007年   109篇
  2006年   124篇
  2005年   91篇
  2004年   74篇
  2003年   66篇
  2002年   74篇
  2001年   51篇
  2000年   41篇
  1999年   49篇
  1998年   31篇
  1997年   33篇
  1996年   32篇
  1995年   22篇
  1994年   22篇
  1993年   20篇
  1992年   33篇
  1991年   21篇
  1990年   17篇
  1989年   18篇
  1988年   16篇
  1987年   14篇
  1986年   14篇
  1985年   28篇
  1984年   26篇
  1983年   10篇
  1982年   16篇
  1981年   13篇
  1980年   12篇
  1979年   7篇
  1978年   4篇
  1977年   5篇
  1975年   5篇
  1974年   5篇
排序方式: 共有3409条查询结果,搜索用时 15 毫秒
61.
目的:探究肝细胞癌(HCC)患者应用15 min肝胆期普美显的临床诊断效果。方法:选择本院收治的80例HCC患者,同一患者分别进行15 min和20 min普美显肝胆期延迟扫描(分为15 min组和20 min组)。比较两组视觉模拟评分(VAS)、患者配合度评分、病灶检出率评分以及图像指标评分。结果:15 min组VAS明显低于20 min组(t=3.14,P=0.003),并且配合度得分更高(t=2.36,P=0.02);两组均表现出有效的病灶检出率(P=0.18);3个动态时期(动脉期、门静脉期和延迟期)均反映出良好的HCC血供情况(均P>0.05);两组对象图像指标评分(Cm和CER)结果对于HCC不同分化程度(高分化、中分化以及低分化)均未表现出显著性差异(均P>0.05)。结论:使用15 min普美显肝胆期时间检测与目前临床使用的20 min在影像结果上无显著差异,但是HCC患者的配合度更高,体验更佳。  相似文献   
62.
目的:观察稳心颗粒联合尼可地尔治疗缺血性心肌病合并房性心律失常患者的效果。方法:选取103例缺血性心肌病合并房性心律失常患者作为研究对象,以电脑随机数字表法将其分为研究组51例和对照组52例。两组均开展常规基础治疗,在此基础上,对照组采用尼可地尔治疗,研究组在对照组基础上联合稳心颗粒治疗,比较两组治疗前后心功能指标[左室舒张末期内径(LVEDD)、左室收缩末期内径(LVESD)、左室射血分数(LVEF)]水平、P波最大时限、P波离散度、6 min步行试验(6MWT)距离和不良反应发生率。结果:治疗后,研究组LVEDD和LVESD水平均低于对照组,LVEF水平高于对照组,6MWT距离长于对照组,差异有统计学意义(P<0.05);治疗后,研究组P波最大时限和P波离散度均小于对照组,差异有统计学意义(P<0.05);两组不良反应发生率比较,差异无统计学意义(P>0.05)。结论:稳心颗粒联合尼可地尔治疗缺血性心肌病合并房性心律失常患者可改善心功能指标水平,延长6MWT距离,减小P波最大时限和P波离散度,效果优于单纯尼可地尔治疗。  相似文献   
63.
Present communication reports the effects of environmentally available, low doses of tetra chloro di benzo-p-dioxin (2,3,7,8 TCDD) to lysosomal enzymes in mice liver. The study tests the hypothesis, in vivo exposure of low dose TCDD provokes dose and duration dependent toxic effects to key lysosomal enzymes and thereby causes cellular apoptotic changes. Three groups of female Swiss albino mice were subjected to two doses of TCDD (0.004 mg/kg bw/d, 0.04 mg/kg bw/d) for 2, 4 and 6 days of exposure durations. The results indicated significant exposure duration dependent effects of TCDD in mice liver cells. The results suggested that TCDD possibly induced an increase in intracellular ions or ROS which in turn altered different physiological activities by affecting different metabolic pathway of the liver cells. The altered functions of key lysosomal enzymes by TCDD may also evoke the process of cellular apoptosis.  相似文献   
64.
Respiratory depression has been attributed to buprenorphine (BUP) misuse or combination with benzodiazepines. BUP/naloxone (NLX) has been marketed as maintenance treatment, aiming at preventing opiate addicts from self-injecting crushed pills. However, to date, BUP/NLX benefits in comparison to BUP alone remain debated. We investigated the plethysmography effects of BUP/NLX in comparison to BUP/solvent administered by intravenous route in naive and BUP-tolerant Sprague-Dawley rats, and in combination with diazepam (DZP) or its solvent. In naive rats, BUP/NLX in comparison to BUP significantly increased respiratory frequency (f, P < 0.05) without altering minute volume (VE). In combination to DZP, BUP/NLX significantly increased expiratory time (P < 0.01) and decreased f (P < 0.01), tidal volume (VT, P < 0.001), and VE (P < 0.001) while BUP only decreased VT (P < 0.5). In BUP-tolerant rats, no significant differences in respiratory effects were observed between BUP/NLX and BUP. In contrast, in combination to DZP, BUP/NLX did not significantly alter the plethysmography parameters, while BUP increased inspiratory time (P < 0.001) and decreased f (P < 0.01) and VE (P < 0.001). In conclusion, differences in respiratory effects between BUP/NLX and BUP are only significant in combination with DZP, with increased depression in naive rats but reduced depression in BUP-tolerant rats. However, BUP/NLX benefits in humans remain to be determined.  相似文献   
65.
66.
67.
68.
The effect of acute hyperglycaemia on QTc duration in healthy man   总被引:18,自引:0,他引:18  
Aims/hypothesis. Prolongation of heart rate-adjusted QT (QTc) is associated with an increased risk of coronary heart disease and sudden death. The objective of this study was to investigate whether acute increases of plasma glucose concentrations in healthy subjects could influence QTc and QTc dispersion. Methods. Plasma glucose concentrations were quickly raised to 15 mmol/l in 20 healthy subjects (10 men/10 women) and maintained for 2 h. On another occasion, and in random order, all subjects underwent the same hyperglycaemic clamp as above and an infusion of the somatostatin analogue octreotide (25 μg as iv bolus followed by a 0.5 g/min infusion) to block the release of endogenous insulin. Results. Systolic and diastolic blood pressures, heart rate and plasma catecholamine concentrations showed significant increases (p < 0.05) starting after 60 min of hyperglycaemia. QTc, QTc dispersion and PR interval also showed significant increments at 120 min of the hyperglycaemic clamp. The infusion of octreotide did not influence QTc duration, QTc dispersion, PR interval and the haemodynamic effects of acute hyperglycaemia. Conclusion/interpretation. The results show that acute hyperglycaemia produces significant increments of QTc and QTc dispersion in normal subjects. In this context, endogenously released insulin during acute hyperglycaemia seems to play a minor part. [Diabetologia (2000) 43: 571–575] Received: 12 October 1999 and in revised form: 24 January 2000  相似文献   
69.
Conclusion: Psychosocial factors should be considered during cochlear implantation (CI). There were differences in psychosocial characteristics according to the etiology of deafness. The outcomes may be affected by psychosocial variables such as the severity of mental distress and social problems as well as duration of deafness. Objective: To evaluate the psychosocial characteristics of deaf people undergoing CI and to determine which psychosocial factors affect performance after CI. Methods: A total of 289 subjects who underwent CI were enrolled. The participants were classified into prelingually deaf (pre-LD) and postlingually deaf groups (post-LD), including progressive and sudden deafness subgroups. The Minnesota Multiphasic Personality Inventory (MMPI) was administered before CI to measure psychosocial and emotional problems. To measure CI outcomes, speech perception ability was assessed by the open-set Korean version of the Central Institute of Deafness (K-CID) test and categories of auditory performance (CAP) scores before and after CI. Results: Approximately 45% of subjects experienced psychological problems before undergoing CI. Subjects in the Pre-LD group had more psychosocial distress and were more likely to be oversensitive in interpersonal situations, while those in the post-LD group were more depressed. Deafness duration and psychosocial factors significantly predicted hearing ability after CI. Deafness duration directly and indirectly affected the outcome of CI. That is, duration of deafness caused psychosocial problems, which may have resulted in negative effects on outcomes of CI.  相似文献   
70.
《Annals of epidemiology》2014,24(8):612-619
PurposeTo examine whether allostatic load (AL), a measure of cumulative physiologic dysregulation across biological systems, was associated with sleep apnea, insomnia, and other sleep disturbances.MethodsData from the National Health and Nutrition Examination Survey 2005–2008 were used. AL was measured using nine biomarkers representing cardiovascular, inflammatory, and metabolic system functioning. A total of 3330 US adults aged 18 years and older were included in this study.ResultsThe prevalence of high AL (AL score ≥3) was the highest among African Americans (26.3%), followed by Hispanic Americans (20.3%), whites (17.7%), and other racial/ethnic group (13.8%). After adjustment for sociodemographic and lifestyle factors, high AL was significantly associated with sleep apnea (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.40–2.63), snoring (OR, 2.20; 95% CI, 1.79–2.69), snorting/stop breathing (OR, 2.16; 95% CI, 1.46–3.21), prolonged sleep latency (OR, 1.42; 95% CI, 1.08–1.88), short sleep duration (<6 hours) (OR, 1.35; 95% CI, 1.00–1.82), and diagnosed sleep disorder (OR, 2.26; 95% CI, 1.66–3.08). There was no clear evidence that observed associations varied by sociodemographic characteristics.ConclusionsThis study suggests significant associations of high AL with sleep apnea, sleep apnea symptoms, insomnia component, short sleep duration, and diagnosed sleep disorder among US adults.  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