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   9260篇
  免费   432篇
  国内免费   248篇
耳鼻咽喉   753篇
儿科学   271篇
妇产科学   78篇
基础医学   1169篇
口腔科学   111篇
临床医学   986篇
内科学   1097篇
皮肤病学   20篇
神经病学   2546篇
特种医学   139篇
外科学   243篇
综合类   1087篇
预防医学   597篇
眼科学   32篇
药学   584篇
  1篇
中国医学   199篇
肿瘤学   27篇
  2023年   123篇
  2022年   362篇
  2021年   752篇
  2020年   597篇
  2019年   255篇
  2018年   365篇
  2017年   389篇
  2016年   332篇
  2015年   272篇
  2014年   670篇
  2013年   575篇
  2012年   465篇
  2011年   504篇
  2010年   418篇
  2009年   481篇
  2008年   464篇
  2007年   428篇
  2006年   329篇
  2005年   268篇
  2004年   226篇
  2003年   196篇
  2002年   153篇
  2001年   115篇
  2000年   108篇
  1999年   89篇
  1998年   60篇
  1997年   56篇
  1996年   45篇
  1995年   36篇
  1994年   36篇
  1993年   42篇
  1992年   34篇
  1991年   44篇
  1990年   34篇
  1989年   26篇
  1987年   29篇
  1986年   26篇
  1985年   33篇
  1984年   47篇
  1983年   31篇
  1982年   34篇
  1981年   26篇
  1980年   24篇
  1979年   22篇
  1978年   27篇
  1977年   31篇
  1976年   33篇
  1975年   34篇
  1974年   27篇
  1973年   45篇
排序方式: 共有9940条查询结果,搜索用时 15 毫秒
31.
A two and half year old male child was seen with systemic hypertension, left ventricular dysfunction, mitral regurgitation and congestive cardiac failure. Examination revealed adenoid hypertrophy. He was also suffering from obstructive sleep apnea. He was being treated with anti-hypertensive and anti-failure drugs. Adenoidectomy was performed following which obstructive sleep apnea symptoms disappeared and his cardiac status improved markedly. Subsequently he was weaned off anti-hypertensive and anti-failure therapy.  相似文献   
32.
Intermittent positive pressure ventilation delivered non-invasively through a well-fitting nasal mask has been used to control nocturnal hypoventilation in three patients with severe, combined cardio-respiratory and skeletal disease. The advantages of this approach to domiciliary ventilation are described and the requirements of the ventilator are defined.  相似文献   
33.
When administered systemically, glucose attenuates deficits in memory produced by several classes of drugs, including cholinergic antagonists and opiate agonists. Glucose also enhances memory in aged rats, mice, and humans. In addition, glucose ameliorates age-related reductions in paradoxical sleep. Because deficits in paradoxical sleep are most marked in those individual aged rats that also have deficits in memory, treatments which improve one of these functions may similarly improve the other. The present experiments show that glucose attenuates deficits in paradoxical sleep and memory after atropine administration, with similar dose-response curves for both actions. In the first experiment, rats received saline, atropine (1 mg/kg), glucose (100 mg/kg) or combinations of atropine + glucose (10, 100, 250, and 500 mg/kg) 30 min before assessment on a spontaneous alternation task. In the second experiment, 3-h EEGs were assessed for spontaneous daytime sleep in rats administered saline, atropine (1 mg/kg), glucose (100 mg/kg) or combinations of atropine + glucose (10, 100 and 250 mg/kg). In both experiments, glucose significantly attenuated deficits at an optimal dose of 100 mg/kg. A third experiment assessed blood glucose levels after injections of atropine + glucose (100 mg/kg) and determined that blood glucose levels were similar to those produced by other treatments which enhance memory. These results are consistent with the view that paradoxical sleep and at least one test of memory are similarly influenced by atropine and glucose.  相似文献   
34.
Summary Thermoregulatory sweating [total body (m sw,b), chest (m sw,c) and thigh (m sw,t) sweating], body temperatures [oesophageal (T oes) and mean skin temperature (T sk)] and heart rate were investigated in five sleep-deprived subjects (kept awake for 27 h) while exercising on a cycle (45 min at approximately 50% maximal oxygen consumption) in moderate heat (T air andT wall at 35° C. Them sw,c andm sw,t were measured under local thermal clamp (T sk,1), set at 35.5° C. After sleep deprivation, neither the levels of body temperatures (T oes,T sk) nor the levels ofm sw, b,m sw, c orm sw, t differed from control at rest or during exercise steady state. During the transient phase of exercise (whenT sk andT sk,1 were unvarying), them sw, c andm sw, t changes were positively correlated with those ofT oes. The slopes of them sw, c versusT oes, orm sw, t versusT oes relationships remained unchanged between control and sleep-loss experiments. Thus the slopes of the local sweating versusT oes, relationships (m sw, c andm sw, t sweating data pooled which reached 1.05 (SEM 0.14) mg·cm–2·min–1°C–1 and 1.14 (SEM 0.18) mg·cm–2·min–1·°C–1 before and after sleep deprivation) respectively did not differ. However, in our experiment, sleep deprivation significantly increased theT oes threshold for the onset of bothm sw, c andm sw, t (+0.3° C,P<0.001). From our investigations it would seem that the delayed core temperature for sweating onset in sleep-deprived humans, while exercising moderately in the heat, is likely to have been due to alterations occurring at the central level.  相似文献   
35.
The physiological function of benzodiazepine (BDZ) receptors includes regulation of sleep and neuroendocrine activity. Most of the pharmacological effects of BDZ are blocked by flumazenil. However, recent neurological and behavioral studies suggest that flumazenil has its own central intrinsic activity. This issue was addressed in a study of the sleep EEG and the nocturnal secretion of growth hormone and cortisol in ten normal male controls, who were given flumazenil either alone or in combination with the BDZ agonist midazolam, placebo and midazolam alone. Flumazenil prompted an increase in sleep onset latency, a decrease in slow wave sleep and an increase in wakefulness. Plasma cortisol concentrations after flumazenil administration were lower than after midazolam. Both flumazenil and midazolam decreased nocturnal growth hormone secretion. After simultaneous application of both BDZ receptor ligands the growth hormone blunting was amplified. Our study demonstrates that at the level of the sleep EEG and neuroendocrine activity flumazenil is capable of exerting both agonistic and inverse agonistic or antagonistic effects.Parts of this study were presented at the 69th Meeting of the Deutsche Physiologische Gesellschaft, Freiburg, 6–8 March, 1991  相似文献   
36.
目的 探讨失眠症患者对睡眠质量的主观评估,并通过对多导睡眠图(PSG)睡眠参数的定量分析,对失眠症患者的睡眠状况进行客观评估,进一步将二者进行对比分析.方法 对失眠症患者和健康人各100例运用匹兹堡睡眠质量指数问卷(PSQI)进行评定,并分别进行多导睡眠图的整夜睡眠描记,次日晨起后询问夜间睡眠情况.结果 失眠症组PSQI各成分得分及总分均高于对照组,差异有统计学意义(P<0.01).与对照组相比,失眠症组的睡眠潜伏期(min)延长(失眠症组43.69±11.54,对照组16.01±10.44)、总睡眠时间(min)减少(失眠症组314.65±91.89,对照组446.41±77.81)、睡眠效率降低(失眠症组64.51%±18.59%,对照组91.32%±3.58%)、快眼动睡眠时间(min)减少(失眠症组33.26±15.61,对照组93.21±21.63),差异有统计学意义(P<0.01).失眠症组对总睡眠时间的评估较PSG检测值显著减低、对睡眠潜伏期的评估较PSG检测值显著增高,自我评估与实际睡眠情况不一致.结论 失眠症患者睡眠质量较差.失眠症患者的PSG各睡眠参数有特征性的改变,利用PSG检查发现失眠症患者对失眠情况的主客观评估不一致,存在过高估价睡眠潜伏期和过低估价睡眠时间的倾向.  相似文献   
37.
南海某岛礁作业人员睡眠状况与身心健康状况关系的研究   总被引:2,自引:2,他引:0  
目的 研究南海某岛礁作业人员睡眠状况与身心健康状况的关系。方法 由经过统一培训的医务人员连续91d每日逐人逐项当面调查、记录。其中的“指数”指标,采用视觉模糊评分法。结果 随着在礁时阃的延长,作业人员睡眠状况明显变差,其主要影响因素依次为值勤(28.73%)、情绪(20.09%)、多梦(10.16%)、噪音(8.86%)和气候(7.73%)等。睡眠状况与身心健康状况明显相关,相关系数7=0.937~0.980,P<0.01;睡眠指数对身心健康状况各指标均有明显影响(P<0.01),睡眠时间主要影响体能指数、健康指数、工作质量指数、工作积极性指数、注意力指数及情绪指数等(P<0.05~0.01),对食欲指数、记忆力指数影响则不明显。结论 在岛礁期间,影响作业人员睡眠的主要因素是值勤和情绪,睡眠状况明显影响身心健康状况。  相似文献   
38.
医科研究生睡眠质量与心理健康状况的关系   总被引:14,自引:2,他引:12  
目的了解在校研究生睡眠质量情况及其与心理健康的关系 ,为心理健康教育提供参考。方法使用匹兹堡睡眠质量指数 (PSQI)和症状自评量表 (SCL 90 ) ,对 2 44名在校研究生进行睡眠及心理健康状况调查 ,并进行相关和回归分析。结果以PSQI总分≥ 8分作为判断睡眠质量问题的标准 ,有 7.8%的研究生有睡眠质量问题 ,男女生的比例分别为 6.7%和 10 .0 % ;睡眠状况不佳主要体现在日间功能障碍( 3 4.0 % )、睡眠时间不足 ( 2 4.6% ) ,入睡慢 ( 13 .9)和自感睡眠质量不佳 ( 11.1% )。研究生中博士和硕士 ,男性和女性 ,已婚者与未婚者的睡眠质量比较无显著差异。睡眠质量不同者的心理健康状况有显著差异 (P<0 .0 0 1) ,两两比较发现 ,睡眠越好 ,心理健康状况也越好 (P <0 .0 5 ) ;相关分析表明PSQI总分与SCL 90总均分间有显著的相关 (r =0 .5 0 1) ;多元逐步回归分析表明 :影响睡眠质量的心理症状因子主要为强迫和焦虑 ,这两个因素可解释PSQI总分变异的 2 6.4%。结论心理因素对研究生的睡眠质量有显著影响。  相似文献   
39.
目的探讨经历不同时间快速眼动(REM)睡眠剥夺对大鼠皮质及海马各区神经元形态结构的影响。方法选择微管相关蛋白(MAP2)和神经丝(NF)作为正常神经元结构的标识物,利用免疫组织化学法和Western blot技术观察REM睡眠剥夺1、3、5、7 d4个时间点大鼠皮质及海马MAP2和NF表达的时空变化规律。同时运用电镜技术观察睡眠剥夺后神经元超微结构的变化。我们的实验是用改良的多平台睡眠剥夺模型进行REM睡眠剥夺,结合免疫组织化学染色技术和蛋白质电泳以及电镜超微结构分析。结果REM睡眠剥夺后5d大鼠皮质、海马CA1及齿状回神经元结构蛋白MAP2和NF表达较对照组明显减少(P〈0.05);电镜神经元核仁偏位,胞质中出现少量肿胀的线粒体和内质网;部分神经轴突的髓鞘溶解与浓集。环境对照组、REM睡眠剥夺5d和7d组,皮质中超微结构改变的神经元所占比例分别为1.2%、3.6%和5.8%。结论REM睡眠剥夺能够导致大鼠脑内神经元的超微结构发生异常变化。  相似文献   
40.
Objective To analyze the relations between obstructive sleep apnea and bradyarrhythmia.Methods From 1999 to 2005,203 patients who came from Bering Tongren Hospital and Fuwai Hospital were found to have sleep apnea in an ambulatory study. A Hoher electrecardiogram was recorded for 24 hours within 2 weeks after patients were diagnosed as obstructive sleep apnem Results Nocturnal episodes of bradyarrhythmia were identified in 12(5.9%)of 203 patients.Body mass index and respiratory disturbance index in patients with bradyarrhythmia(n=12)were higher than those in patientswithour bradyarrhymia(n=191)(34±5 735.24±6 and 63±15 vs.25±5,respectively,both P<0.01).There was a significant difference in end-apneic oxygen saturation in apnea/hypopnea episodes with and without bradyarrhythmia(63%±15% vs.75%±11%,P<0.05).A linear relation between end-apneic oxygen saturation and number of sinus arrests and heart blocks was not found.Conclusions Patients with apnea-associated bradyarrhythmia have higher body mflgB index and higher respiratory disturbance index than patients without bradyarrhythmi&Bradyarrhythmia occurres independently from decrease in oxygen saturation.  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