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   503篇
  免费   28篇
  国内免费   34篇
耳鼻咽喉   2篇
儿科学   12篇
妇产科学   1篇
基础医学   80篇
口腔科学   2篇
临床医学   56篇
内科学   105篇
皮肤病学   3篇
神经病学   142篇
特种医学   43篇
外科学   43篇
综合类   12篇
预防医学   11篇
药学   38篇
中国医学   1篇
肿瘤学   14篇
  2023年   2篇
  2021年   7篇
  2020年   5篇
  2019年   8篇
  2018年   2篇
  2017年   8篇
  2016年   8篇
  2015年   5篇
  2014年   16篇
  2013年   15篇
  2012年   20篇
  2011年   18篇
  2010年   28篇
  2009年   20篇
  2008年   14篇
  2007年   27篇
  2006年   20篇
  2005年   26篇
  2004年   19篇
  2003年   17篇
  2002年   23篇
  2001年   21篇
  2000年   27篇
  1999年   14篇
  1998年   11篇
  1997年   17篇
  1996年   11篇
  1995年   11篇
  1994年   8篇
  1993年   6篇
  1992年   15篇
  1991年   5篇
  1990年   14篇
  1989年   4篇
  1988年   18篇
  1987年   9篇
  1986年   10篇
  1985年   12篇
  1984年   6篇
  1983年   6篇
  1982年   8篇
  1981年   3篇
  1980年   4篇
  1979年   5篇
  1978年   4篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1974年   1篇
  1972年   1篇
排序方式: 共有565条查询结果,搜索用时 15 毫秒
51.
Chronic benzodiazepine usage and withdrawal in insomnia patients   总被引:5,自引:0,他引:5  
We studied the sleep of patients with insomnia during continuous and very long-term use of benzodiazepines (BZDs), and after withdrawal. A group of 25 patients (mean age 44.3+/-11.8 years) with persistent insomnia, who had been taking BZDs nightly for 6.8+/-5.4 years was selected. The control group was comprised of 18 age-matched healthy individuals. Sleep stage parameters were analyzed during Night 1 (while taking BZDs), Night 2 (first night after completing BZD withdrawal), and Night 3 (15 days after gradual BZD withdrawal). Sleep data for control subjects was monitored in parallel. Sleep EEGs of the patients were analyzed using Period Amplitude Analysis (PAA), during Nights 1 and 3 only. During BZD use, a significant reduction of Total Sleep Time (TST) and increased sleep latency were found in the insomniac group when compared to controls. We found an increase in stage 2 non-REM (NREM) sleep, and a reduction in Slow Wave Sleep (SWS) when comparing to night 3 (after withdrawal). Sleep EEGs analysis showed an increase in sigma band and decrease in delta count in stages 2, 3, 4 NREM and REM sleep in the BZD group when comparing to night 3 (after withdrawal). During the BZD withdrawal period, six out of nine subjects taking lorazepam failed withdrawal. In the remaining 19 subjects, gradual withdrawal of BZDs was associated with immediate worsening of nocturnal sleep, as indicated by sleep parameters. However, 15 days after withdrawal (Night 3), some of the sleep structure parameters of patients were not significantly different from baseline (while taking BZDs), except for a significant increase in SWS and in delta count throughout most sleep stages, and a decrease in stage 2 NREM sleep. These values were not different from those shown by control subjects. REM sleep parameters showed no significant variation across the experimental conditions. Subjective sleep quality was significantly improved on Night 3 compared with Night 1. Conclusions: Chronic intake of BZDs may be associated with poor sleep in this population. A progressive 15-day withdrawal did not avoid an immediate worsening of sleep parameters. But at the end of the protocol, SWS, delta count, and sleep quality were improved compared to those recorded during the chronic BZD intake, despite the lack of change in sleep efficiency.  相似文献   
52.
53.
54.
55.
BACKGROUND: Recently, new immunoblot assays for the detection of antibodies to hepatitis C virus (HCV) became available. STUDY DESIGN AND METHODS: The performance of five confirmatory anti-HCV immunoblot assays was studied with samples with known HCV antibody and HCV RNA status. The assays were a third-generation strip recombinant immunoblot assay (RIBA-3, Chiron Corp., Emeryville, CA), a second-generation HCV blot (DB-2 blot, Diagnostic Biotechnology, Singapore), the Wellcozyme HCV Western blot (Murex blot, Murex Diagnostics, Dartford, UK), an immunodot HCV assay (Matrix, Abbott Laboratories, Chicago, IL), and the third-generation HCV line immunoassay (Liatek-III, Organon Teknika, Boxtel, The Netherlands). RESULTS: Sensitivity on samples from 48 HCV RNA-positive, second-generation RIBA (RIBA-2)-positive persons and specificity on samples from 31 low-risk donors was 96 percent or better for all assays. The sensitivity on 31 HCV RNA-positive, RIBA-2- indeterminate samples was as follows: Liatek-III, 94 percent; RIBA-3, 90 percent; Murex blot, 61 percent; Matrix, 55 percent; and DB-2 blot, 39 percent. In testing 39 HCV RNA-negative, RIBA-2-indeterminate donor samples, the percentage found to be negative was Liatek-III, 77 percent; RIBA-3, 67 percent; Murex blot, 49 percent; DB-2 blot, 33 percent; and Matrix, 15 percent. The order of sensitivity on four HCV seroconversion series was (from high to low): RIBA-3, Liatek-III, DB-2 blot, Murex blot, and Matrix; the differences were small. CONCLUSION: Detection of HCV antibodies was not refined by the addition of new HCV antigens (NS5, E2/NS1), but by improved classical antigens (core, NS3, NS4). Replacement of the commonly used RIBA-2 will resolve the status of a high proportion of RIBA-2-indeterminate samples.  相似文献   
56.
BACKGROUND: Assays that detect human T-lymphotropic virus type I and type II antibody (HTLV-I/II) are widely used in the routine screening of blood donors. STUDY DESIGN AND METHODS: Four commercially available anti-HTLV-I (Fujirebio and Organon Teknika) or -HTLV-I/II assays (Murex and Ortho) were evaluated in various serum panels: A) HTLV-I-positive specimens (n = 41), confirmed by Western blot and polymerase chain reaction; B) a commercially available anti-HTLV-I/II panel; C) serial dilutions of sera from HTLV-I-positive individuals (n = 30), confirmed by immunofluorescence assay and Western blot: D) serial dilutions of HTLV-II-positive blood donors (n = 20), confirmed by Western blot and polymerase chain reaction, and E) sera from first-time blood donors (n = 1055). RESULTS: All four assays elicited reactions in all 82 HTLV-I- positive samples in Panels A, B, and C. Of 32 HTLV-II-positive specimens in Panels B and D, 31 (96.9%) reacted in the Organon Teknika assay and all 32 reacted in the remaining tests. Probit analysis of test results in Panels C and D indicated that the Fujirebio test was the most sensitive assay, followed by Organon Teknika, Ortho, and Murex. The specificities of Fujirebio, Murex, Organon Teknika, and Ortho tests in 1055 first-time blood donors were 99.9, 100, 99.6, and 99.9 percent, respectively. CONCLUSION: All four studied assays for detecting HTLV-I or HTLV-I/II antibodies are appropriate as screening tests.  相似文献   
57.
目的:实验以移植后3个月、6个月时间超声心动图客观指标评估了自体干细胞冠状动脉内移植治疗老龄心肌梗死后心力衰竭的效果和安全性。方法:选择2004—06/2006—06江苏省苏北人民医院心内科自愿接受干细胞移植的7例心肌梗死后心力衰竭患者,平均年龄69岁,心功能Ⅲ-Ⅳ级,左室射血分数〈50%。药物治疗基础上加用自体干细胞冠状动脉内移植治疗的方法,其中2例骨髓干细胞在体外扩增后获得,5例经粒细胞集落刺激因子皮下注射动员自体骨髓干细胞后分离外周血获得干细胞悬液。将采集的干细胞悬液经0ver-the-wire球囊导管中心腔注入梗死相关动脉。观察自体干细胞动员,培养,采集和回输过程中的不良反应。在移植前、移植后3月、6月应用超声心动图评价左室形态和心功能变化,室壁运动积分指数及6min步行距离。结果:7例患者均进入结果分析。移植3个月后,心功能得到改善,超声心动图检查左室收缩期内径及射血分数变化不大,6min步行距离有所提高,但差异无显著性(P〉0.05)。移植6个月后,患者心功能明显改善,超声心动图检查左室收缩期内径及射血分数和室壁运动积分均有明显提高(P〈0.05),6min步行距离也有明显提高(P〈0.05)。整个过程中未出现严重并发症。结论:自体干细胞冠状动脉内移植治疗老龄心肌梗死后心力衰竭,6个月时超声心动图客观指标评估能够改善患者心功能,且安全。  相似文献   
58.
BACKGROUND: The purpose of this study was to search for a more effective transfusion-monitoring system than the existing system of retrospective peer review. STUDY DESIGN AND METHODS: This research used a study-control, preintervention and postintervention design, to evaluate the effectiveness of a prospective physician self-audit transfusion-monitoring system that functioned without the direct involvement of transfusion service physicians. This research also evaluated the effectiveness of issuing to physicians a memo with transfusion guidelines. Three process indicators were used to assess physician behavior at various stages of the blood-ordering process: 1) the number of crossmatches ordered per admission, 2) the transfusion-to- crossmatch ratio, and 3) the number of blood units returned to the laboratory after physician self-auditing. The study used two outcome indicators to reflect overall blood utilization: 1) the percentage of patients who received red cell transfusions and 2) the number of blood units transfused per recipient each month. RESULTS: The prospective physician self-audit system implemented at the study hospital did not reverse physician transfusion decisions, and the process of issuing to physicians a memo with transfusion guidelines at the control hospital failed to reduce blood usage. However, a transient reduction in blood utilization was observed at the study hospital. CONCLUSION: The reduction was hypothesized to be due to a Hawthorne effect, in which observed behavior is affected by the subject's awareness of the research study.  相似文献   
59.
Whole cells of Mycobacterium avium, characterized by their negative response in the nine biochemical tests used for mycobacterial identification in our laboratory, turned positive for nitrate reductase, Tween-80 hydrolysis, beta-glucosidase, acid phosphatase, alkaline phosphatase, penicillinase, and trehalase after their wall portion was removed to yield spheroplasts. This suggested that the negative results in most of the biochemical procedures were caused by the exclusion mechanism at the wall level. Preliminary transmission and scanning electron microscopic studies showed differences at wall level between laboratory-maintained opaque, dome-shaped (SmD) and host-recycled smooth, transparent (SmT) colony type variants of M. avium and suggested the presence of an outer regularly structured layer in SmT variants. Comparative ultrastructural studies utilizing different polysaccharide coloration methods confirmed the presence of an outer polysaccharide layer in SmT variants which was probably related to their enhanced pathogenicity for experimental animals and drug resistance as compared to that of SmD variants. These findings are discussed with respect to multiple drug resistance, virulence, and gene expression of M. avium.  相似文献   
60.
胚胎嗅鞘细胞移植治疗脑性瘫痪:4例术后4周结果报告   总被引:7,自引:3,他引:7  
目的:观察胚胎嗅鞘细胞移植治疗脑性瘫痪的有效性和安全性。方法:①病例资料:4例因出生时缺血缺氧确诊为脑性瘫痪的患者,男2例,女2例,年龄分别为14岁、岁、个月、岁。嗅92817鞘细胞由北京市虹天济神经科学研究院细胞中心提供,实验经医学伦理委员会批准,4例脑性瘫痪患者均签署知情同意书。②实验方法:根据术前MRI或CT片,患者均在局麻下行微创立体定向嗅鞘细胞移植术,选取双额放射冠为注射靶点,每侧注射1.0×106个细胞。术后给予止血、抗感染、康复等常规处理。③实验评估:分别于嗅鞘细胞移植前、移植后4周采用脑瘫综合功能评定量表、脑瘫日常生活能力量表评价患者神经功能及生活质量的改善。结果:①嗅鞘细胞移植术后4周,4例患者较术前均有不同程度的神经功能改善,未出现手术并发症。②脑瘫综合功能评定总分:病例1由92.5分增至94分,病例2由55分增至56分,病例3由10.5分增至11.5分,病例4由9.5分增至13分。③脑性瘫痪日常生活能力量表总分:病例1由82.0分增至83.5分,病例2无变化,为16.5分,病例3由5.0分增至7.5分,病例4由5.0分增至8分。结论:嗅鞘细胞移植治疗脑性瘫痪患者近期评价安全可行,可部分改善神经功能与生活质量,长期效果有待进一步随访。  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