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   23227篇
  免费   2535篇
  国内免费   545篇
耳鼻咽喉   1137篇
儿科学   667篇
妇产科学   537篇
基础医学   3378篇
口腔科学   593篇
临床医学   2442篇
内科学   3556篇
皮肤病学   95篇
神经病学   3490篇
特种医学   357篇
外国民族医学   4篇
外科学   1734篇
综合类   2990篇
现状与发展   1篇
预防医学   1360篇
眼科学   187篇
药学   1293篇
  13篇
中国医学   1016篇
肿瘤学   1457篇
  2024年   73篇
  2023年   466篇
  2022年   792篇
  2021年   1358篇
  2020年   1392篇
  2019年   1082篇
  2018年   967篇
  2017年   1126篇
  2016年   1102篇
  2015年   970篇
  2014年   1588篇
  2013年   1676篇
  2012年   1296篇
  2011年   1370篇
  2010年   1153篇
  2009年   1167篇
  2008年   1125篇
  2007年   1045篇
  2006年   872篇
  2005年   745篇
  2004年   622篇
  2003年   549篇
  2002年   482篇
  2001年   399篇
  2000年   347篇
  1999年   317篇
  1998年   278篇
  1997年   199篇
  1996年   146篇
  1995年   176篇
  1994年   118篇
  1993年   132篇
  1992年   128篇
  1991年   72篇
  1990年   69篇
  1989年   69篇
  1988年   62篇
  1987年   60篇
  1986年   54篇
  1985年   77篇
  1984年   86篇
  1983年   66篇
  1982年   90篇
  1981年   67篇
  1980年   67篇
  1979年   47篇
  1978年   47篇
  1977年   27篇
  1976年   17篇
  1975年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Brief interruptions of REM sleep are considered to be part of the REM episode. The maximum allowable duration of such an interruption, which is used to define the end of the REM episode, is currently a matter of debate. Making measurements on individual REM cycles, inter-REM interval analysis was carried out to determine whether the generally adopted 15 minute empirical rule for this maximum needs to be extended to 25 minutes as suggested by several including Kobayashi et al. Our results show that there is no reason to alter the 15 minute rule and that measurements which do not take into account the time-of-night effect may be misleading. The proportion of interrupted REM episodes observed in our population of healthy adults is high. We have therefore also examined in some detail the phenomenology of the temporal evolution of the structure and content of the interrupted REM episodes. Both showed a definite change over the night: the interruptions in the earlier episodes tend to return the system to slow wave sleep while those in the later episodes tend to return it to wake. It is hypothesized that these interruptions reflect a measure of REM sleep pressure and its interaction with both slow wave sleep and wake pressures.  相似文献   
62.
悬雍垂保留在悬雍垂腭咽成形术中的作用   总被引:1,自引:0,他引:1  
申金霞  余力生 《北京医学》2003,25(2):104-105
目的 探讨悬雍垂保留在悬雍垂腭咽成形术(UPPP)中的作用。方法 比较43例UPPP与43例保留悬雍垂的改良UPPP的术中术后并发症、术后症状改善程度以及术后咽腔测量结果。结果 术中术后大出血、开放性鼻音、进流食返呛人鼻腔等并发症:改良UPPP明显低于UPPP(P<0.05);咽异物感:改良UPPP极明显低于UPPP(P<0.01)。术后1年患者主观症状改善程度:明显改善者,改良UPPP高于UPPP,无改善者,UPPP高于改良UPPP,有显著性差异(P<0.05)。术后1年咽腔扩大程度:下腭咽横径、前后径,改良UPPP较UPPP两者均明显扩大(P<0.05)。结论 UPPP中保留悬雍垂可明显降低术中术后大出血、开放性鼻音、进流食返呛人鼻腔、咽异物感等并发症,术后症状明显改善,咽腔得到明显扩大。  相似文献   
63.
Symptomatic narcolepsy, once regarded as common, is now believed to be very rare. A 32-year-old man had a history of recurrent sleep attacks. A magnetic resonance imaging scan revealed a third ventricle tumor. The tumor was totally removed, and the histology was a craniopharyngioma. The symptoms ceased after the operation. The chronological correlation and the anatomical location of the tumor suggest that the patient had a symptomatic narcolepsy caused by the tumor. This is the first report that documents the cessation of narcolepsy attacks after tumor removal.  相似文献   
64.
The combination of a stage model of psychotherapy and treatment manualization has been a major step forward in treatment development and efficacy testing, but not in dissemination. I argue that the technological model of treatment development makes research on the practical application of these technologies difficult. If we continue on our present course, research on dissemination will be uncommon, expensive, and largely irrelevant to the practical issues that need to be faced. It makes more sense to proceed directly to dissemination research. Alternative methods, including manipulated training designs, will permit this, but these fundamentally challenge the implicit assumptions of the stage model.  相似文献   
65.
第2产程剖宫产术对母婴的影响   总被引:1,自引:0,他引:1  
本文对我院近 4年来第 2产程 (以下简称 2程 )剖宫产 6 1例进行回顾性分析。资料表明 :第 2产程剖宫产术易合并羊水污染及术时并发症 ,新生儿Apgar氏评分低 ,术后并发症高于对照组 (P <0 .0 5 ) ,提示第 2产程剖宫产术比一般头位急症剖宫产术对母婴不利 ,其并发症的发生与第 2产程的延长相关 (P <0 .0 1) ,故应把握时机尽量减少宫口开全后施行剖宫产。  相似文献   
66.
We describe a unique gait phenomenon of bent knees in 9 patients with idiopathic Parkinson disease (mean age, 73.1 +/- 11.1 years), 3 of whom also manifested tiptoeing. The bent-knee posture appeared only during ambulation; in the recumbent position, full or nearly full extension was possible in all patients. The abnormality emerged after long-standing disease (6-23 years from onset) and failed to respond to dopaminergic treatment. Most of the patients also had bent spine (camptocormia). The pathogenesis of these phenomena are unknown, but they might represent a rare type of dystonia.  相似文献   
67.
目的通过观察OSAS患者经过有效治疗前后HRV的变化,评价患者的心率变异性变化情况。方法对51例OSAS病人在有效治疗前后同步进行PSG检查及动态心电监测,统计其HRV的时阈指标SDNN、rMSSD及频阈指标LF、HF及LF/HF,采用SPSS/PC统计软件中配对样本t检验进行处理。结果SDNN、LF、LF/HF等指标在治疗前后的差异有显著性(p<0·05),rMSSD、HF的变化无显著性差异(p>0·05)。结论有效治疗OSAS可使植物神经系统的功能得到恢复,降低心脏事件发生的危险性。  相似文献   
68.
The aim of this research was to quantify sleep problems in patients suffering from Parkinson's disease by means of the new Parkinson's Disease Sleep Scale (PDSS) and to correlate such problems with the possible influence of current drug treatment. A total of 70 patients (36 men and 34 women) with a diagnosis of Parkinson's disease were enrolled. Their mean age was 69.7 +/- 8.2 years, and duration of disease was 7.4 +/- 4.8 years. All patients completed the PDSS and the Unified Parkinson's Disease Rating Scale (UPDRS Parts I-IV). Drug consumption and doses were registered. The mean score on the PDSS scale was 109.23 +/- 19.75 and on the UPDRS III scale was 25.24 +/- 11.35. The lowest scores were obtained in Item 3 (sleep fragmentation): 5.53 (2.46); and in Item 8 (nocturia): 5.75 (2.91). There was a weak correlation between the PDSS and UPDRS III (cc = -0.355, P = 0.003), PDSS and UPDRS I (cc = -0.272, P = 0.02), and PDSS and UPDRS IV (cc = -0.416, P < 0.001). Motor conditions, mental state, and drug complications influence sleep quality. Although this effect was significant, it was not of a great magnitude. Dopaminergic drugs did not increase daytime sleepiness. As a whole, sleep quality in patients who took dopaminergic agonists did not differ from that of patients who took levodopa in monotherapy.  相似文献   
69.
目的探讨舒利迭(吸入型肾上腺皮质激素与长效β2-受体激动剂的预混制剂)联合双水平气道正压通气(B iPAP)对稳定期慢性阻塞性肺疾病(COPD)的治疗作用。方法稳定期COPD病人52例,舒利迭TM50/250,1吸/次,2次/d;B iPAP,吸气压力(IPAP)10~20cm H2O,呼气压力(EPAP,也称PEEP)3~6cm H2O,吸氧浓度(FiO2)3L/m in,每天夜间通气6~8h。观察治疗前、治疗后12周病人临床症状、生活质量、健康状态和肺功能。结果治疗前、治疗后12周病人的临床症状、急性加重次数及严重程度、健康状态和生活质量、肺功能等指标比较差异有统计学意义(P<0.05)。结论舒利迭联合B iPAP治疗稳定期COPD病人能够明显改善其症状,提高生活质量,有一定的临床应用价值,对减缓COPD病人肺功能下降有积极意义。  相似文献   
70.
OBJECTIVE: To assess misoprostol's ability to prevent postpartum hemorrhage (PPH) where no alternatives exist. Comparison to oxytocics demonstrates how similarly misoprostol achieves a level of effectiveness-obtainable only in hospitals-in remote locations around the world. METHOD: Using the Mantel-Haenszel fixed-effects model and the DerSirmonian and Laird random-effects model, summary statistics indicated that misoprostol's excess risk of PPH was only 4% when compared to oxytocics. RESULT: This risk difference was well within the range of expected results for all uterotonic agents and does not warrant branding misoprostol as an inferior drug. CONCLUSION: Conventional uterotonic drugs should not be used to set the lowest-accepted level of effectiveness in settings where they are entirely unsuitable. Continuing to weigh the benefits of one effective drug against another only delays the distribution of misoprostol in countries where it is the only feasible choice and must be measured against no treatment at all.  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