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   24965篇
  免费   2504篇
  国内免费   493篇
耳鼻咽喉   127篇
儿科学   490篇
妇产科学   713篇
基础医学   1350篇
口腔科学   1282篇
临床医学   3162篇
内科学   4045篇
皮肤病学   501篇
神经病学   1677篇
特种医学   315篇
外国民族医学   4篇
外科学   2421篇
综合类   2023篇
现状与发展   1篇
预防医学   2239篇
眼科学   245篇
药学   3326篇
  8篇
中国医学   2125篇
肿瘤学   1908篇
  2024年   80篇
  2023年   715篇
  2022年   757篇
  2021年   1482篇
  2020年   1275篇
  2019年   1336篇
  2018年   1290篇
  2017年   1191篇
  2016年   1011篇
  2015年   931篇
  2014年   2134篇
  2013年   2474篇
  2012年   1407篇
  2011年   1387篇
  2010年   1094篇
  2009年   1110篇
  2008年   1130篇
  2007年   1077篇
  2006年   992篇
  2005年   890篇
  2004年   727篇
  2003年   557篇
  2002年   482篇
  2001年   359篇
  2000年   286篇
  1999年   260篇
  1998年   212篇
  1997年   158篇
  1996年   151篇
  1995年   112篇
  1994年   122篇
  1993年   68篇
  1992年   78篇
  1991年   69篇
  1990年   73篇
  1989年   61篇
  1988年   53篇
  1987年   48篇
  1986年   37篇
  1985年   54篇
  1984年   45篇
  1983年   31篇
  1982年   20篇
  1981年   29篇
  1980年   25篇
  1979年   21篇
  1978年   11篇
  1977年   9篇
  1976年   10篇
  1975年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Background  Stress gated myocardial perfusion single photon emission computed tomography (gSPECT) is increasingly used before and after intercurrent therapeutic intervention and is the basis for ongoing evaluation in the Department of Veterans Affairs clinical outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial. Methods and Results  The COURAGE trial is a North American multicenter randomized clinical trial that enrolled 2287 patients to aggressive medical therapy vs percutaneous coronary intervention plus aggressive medical therapy. Three COURAGE nuclear substudies have been designed. The goals of substudy 0 are to examine the diagnostic accuracy of the extent and severity of inducible ischemia at baseline in COURAGE patients compared with patient symptoms and quantitative coronary angiography and to explore the relationship between inducible ischemia and the benefit from revascularization when added to medical therapy. Substudy 1 will correlate the extent and severity of provocative ischemia with the frequency, quality, and instability of recurrent symptoms in postcatheterization patients. Substudy 2 (n _ 300) will examine the usefulness of sequential gSPECT monitoring 6 to 18 months after therapeutic intervention. Together, these nuclear substudies will evaluate the role of gSPECT to determine the effectiveness of aggressive risk-factor modifications, lifestyle interventions, and anti-ischemic medical therapies with or without revascularization in reducing patients’ ischemic burdens. Conclusions  The unfolding of evidence on the application of gSPECT in trials such as COURAGE defines a new era for nuclear cardiology. We hope the evidence that emerges from the COURAGE trial will further establish the role of nuclear imaging in the evidence-based management of patients with stable coronary disease. The COURAGE trial was supported by the Cooperative Studies Program of the Department of Veterans Affairs Office of Research and Development in collaboration with the Canadian Institutes of Health Research. Unrestricted research grants were obtained from Merck & Co; Pfizer Pharmaceuticals; Bristol-Myers Squibb Medical Imaging; Astellas Pharma; Kos Pharmaceuticals; Data Scope; Astra Zeneca Pharmaceuticals; Astra-Zeneca-Canada; Schering-Plough Coorporation, Ltd; Sanofi-Aventis, Inc; First Horizon; and GE Healthcare. All industrial funding for this trial was directed through the Department of Veterans Affairs. Additional funding for this substudy was provided by grants to the Department of Veterans Affairs and Canadian Institutes of Health Research from Astellas Pharma and Bristol-Myers-Squibb Medical Imaging.  相似文献   
62.
Iron deficiency may exacerbate symptoms in the Restless Legs Syndrome (RLS). We investigated the effect of intravenous iron sucrose or placebo on symptoms in patients with RLS and mild to moderate iron deficit. Sixty patients with primary RLS (seven males, age 46 (9) years, S‐ferritin ≤45 μg/L) recruited from a cohort of 231 patients were randomly assigned in a 12‐months double‐blind, multi‐centre study of iron sucrose 1000 mg (n = 29) or saline (n = 31). The primary efficacy variable was the RLS severity scale (IRLS) score at week 11. Median IRLS score decreased from 24 to 7 (week 11) after iron sucrose and from 26 to 17 after placebo (P = 0.123, N.S. for between treatment comparison). The corresponding scores at week 7 were 12 and 20 in the two groups (P = 0.017). Drop out rate because of lack of efficacy at 12 months was 19/31 after placebo and 5/29 patients after iron sucrose (Kaplan–Meier estimate, log rank test P = 0.0006) suggesting an iron induced superior long term RLS symptom control. Iron sucrose was well tolerated. This study showed a lack of superiority of iron sucrose at 11 weeks but found evidence that iron sucrose reduced RLS symptoms both in the acute phase (7 weeks) and during long‐term follow up in patients with variable degree of iron deficiency. Further studies on target patient groups, dosing and dosing intervals are warranted before iron sucrose could be considered for treatment of iron deficient patients with RLS. © 2009 Movement Disorder Society  相似文献   
63.
目的:比较不同剂量和疗程伐昔洛韦治疗带状疱疹的疗效和安全性。方法:选择带状疱疹患者为研究对象,采用多中心、随机、双盲、对照的临床试验。试验组患者采用伐昔洛韦1000mg每日3次口服,共服7d;对照组患者采用伐昔洛韦300mg每日2次口服,共服10d。用药后第3、6和10天观察疗效和不良反应。结果:共入组128例,全分析集(FAS)分析128例,符合方案集(PPS)分析118例。治疗后第3、6和10天,试验组和对照组患者的症状、体征积分下降值及有效率比较差异无统计学意义(P〉0.05);疼痛视觉模拟评分法(visnal analogue scale,VAS)值比较,两组间差异无统计学意义(P〉0.05),但入组时疼痛VAS值≥8的患者,FAS集分析显示,在治疗后第6、10天VAS值下降两组均存在统计学差异(P〈0.05);PPS集分析显示治疗后第10天VAS值下降,两组间存在统计学差异俨〈0.05)。试验组和对照组不良反应发生率分别为17.18%和12.50%.主要为嗜睡和恶心。结论:增加伐昔洛韦用量治疗带状疱疹安全、有效,与较低剂量伐昔洛韦组相比,对疼痛程度较严重的患者能更显著地减轻疼痛。  相似文献   
64.
Open, Double-Blind and Long-Term Study of Vigabatrin in Chronic Epilepsy   总被引:5,自引:4,他引:1  
We performed an open, double-blind, and long-term study of vigabatrin (gamma-vinyl-GABA, GVG) in patients with treatment-resistant epilepsy who were receiving only one or at most two standard antiepileptic drugs (AEDs). The novel design included a parallel, double-blind, placebo-controlled phase that minimized the number of patients receiving placebo and allowed determination of the optimum dose of GVG for each patient before initiation of the double-blind phase. The study was divided into four phases. The first phase was a 6-week period of baseline observation. In the second phase, GVG was added openly to previous AEDs for 8 weeks. During the first 2 weeks of this phase, the dose of GVG was increased weekly and then, in the absence of adverse effects, was held constant for the next 6 weeks. At the end of this open phase, seizure frequency during the 6 weeks of constant treatment was compared with the baseline seizure frequency for each patient. Patients who experienced reduction greater than 50% in the frequency of any seizure type during the open phase were defined as responders. These responders were then entered into the third and double-blind phase, in which they were randomly allocated wither to continue active GVG treatment or placebo for 8 weeks. Thirty-three patients entered the study; 31 of 33 patients completed the initial open phase. Twenty patients achieved a reduction greater than or equal to 50% in the frequency of one or more seizure types and were eligible for the double-blind phase; 10 were randomized to continue GVG and 10 were randomized to placebo.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
65.
In order to make effective use of the statistical theory of design of clinical trials for chronic diseases such as periodontal disease, certain issues must be considered. Any clinical trial requires that the disease definition be well-specified; that patient eligibility be explicit; that the observation times be explicit; that the duration and endpoint of therapy be specified; that the duration of subsequent followup observation be specified; and that the unit of observation (e.g., tooth, set of teeth, patient) be defined. In a chronic disease, the potential biases that can readily be introduced by self-selection of patients who enter the trial and/or who return for subsequent observation become more important, because subjects are required to remain on treatment and/or observation for prolonged periods. Further, the cyclical nature of some chronic diseases may require special attention to baseline definitions of active disease and disease outcome. These issues are illustrated with examples from clinical trials of hypertension, breast cancer screening, and Polycythemia Vera. Implications for periodontal disease are discussed.  相似文献   
66.
67.
Evidence of the effect of exercise on bone loss comes mainly from studies in voluntary postmenopausal women, and no population-based, long-term interventions have been performed. The purpose of this population-based, randomized, controlled trial was to determine the effect of long-term impact exercise on bone mass at various skeletal sites in elderly women with low bone mineral density (BMD) at the radius and hip. Participants ( n =160) were randomly assigned to 30 months either of supervised and home-based impact exercise training or of no intervention. The primary outcome measures were femoral neck, trochanter and total hip BMD, and the secondary outcomes were bone density measures at the radius and calcaneum. Outcomes were assessed at baseline, 12 months and 30 months using blinded operators. The analyses were performed on an intention-to-treat analysis. Mean femoral neck and trochanter BMD decreased in the control group [–1.1%, 95% confidence interval (CI) –0.1% to –2.1% and –1.6%, 95% CI –0.4% to –2.7%], while no change occurred in the exercise group. Mean trochanter BMC decreased more in the control group (–7.7%, 95% CI –9.7% to –5.6% vs. –2.9%, 95% CI –5.3 to –0.9). There were six falls that resulted in fractures in the exercise group and 16 in the control group during the 30-month intervention ( P =0.019). A significant bone loss occurred in both groups at the radius and calcaneum. In multivariate analysis, weight gain was associated with increased BMD and BMC at all femur sites both in the exercise group and in the pooled groups. In conclusion, impact exercise had no effect on BMD, while there was a positive effect on BMC at the trochanter. Exercise may prevent fall-related fractures in elderly women with low bone mass.There was no conflict of interest.  相似文献   
68.
激素间歇冲击及小剂量维持治疗IgA肾病的随机对照研究   总被引:2,自引:2,他引:0  
目的:探讨激素间歇冲击及小剂量维持与血管紧张素转换酶抑制剂治疗中度蛋白尿IgA肾病的疗效及其影响因素。方法:47例IgA肾病患者随机分为实验组和对照组。对照组(21例)给予ACEI药物治疗,实验组(26例)在此基础上口服泼尼松0.5mg/kg,隔日给药,治疗12个月,并在治疗的第1、3、5个月初分别给予甲基泼尼松龙0.5g/d,冲击3d。对肾脏病理改变进行WHO分级并对各种病变进行半定量分析。结果:两组间在性别、年龄、临床及病理资料间无统计学差异。平均随访14个月后,实验组尿蛋白完全缓解8例(30.8%),部分缓解14例(53.8%),无缓解4例(15.4%);而对照组分别为4例(19.1%),3例(23.8%),12例(57.1%),有统计学差异(P<0.01)。治疗前后,实验组血肌酐分别为(89.9±30.3)μmol/L及(88.2±32.8)μmol/L;对照组分别为(89.5±37.9)μmol/L及(104.0±49.7)μmol/L,但两者比较均无统计学意义(P>0.05)。多因素分析显示疗效与肾小球硬化率及肾小管间质病变呈负相关。结论:激素间歇冲击及小剂量维持治疗能显著减少蛋白尿,维持肾功能稳定。影响疗效的主要因素为肾小球硬化率及肾小管间质病变程度。  相似文献   
69.
An open, randomized, controlled study with two parallel treatment groups was done to evaluate the efficacy of a Lippia sidoides essential oil (EO) 1% mouthrinse compared with chlorhexidine 0.12% mouthrinse, applied two times daily for 1 week, in the treatment of dental plaque and gingivitis. Fifty‐five patients were included in the study. The efficacy variables were the colony count of Streptococcus mutans from the stimulated saliva and periodontal indices on days 0, 7 and 30 after commencement of therapy. Twenty eight patients received chlorhexidine mouthrinse (Periogard®) and 27 Lippia sidoides essential oil mouthrinse (Cepakill®). The clinical and microbiological parameters were significantly reduced by both mouthrinses. No significant difference was seen between the two groups (p > 0.05). There was a significant reduction in the colony count of S. mutans in both groups (p < 0.05). Chlorhexidine treatment reduced more efficiently than L. sidoides, however, no statistical difference was seen, the efficacy of both groups was similar (p = 0.3). The results indicate that Chlorhexidine mouthrinse reduced plaque index, gingival bleeding and the number of CFU (colonies forming units) more efficiently than L. sidoides but did not reach statistical significance. This study demonstrated that Lippia sidoides EO mouthrinse is effective in reducing microbial plaque and gingival inflammation. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
70.
目的:研究腹腔镜全腹膜外腹股沟疝修补术(totally extraperitoneal prosthetic,TEP)在临床应用中的价值。方法:71例成人腹股沟疝患者前瞻性随机分成两组,分别进行TEP和无张力疝修补术(Lichtenstein)。TEP组35例,Lichtenstein组36例。手术后1周和1年内对患者作出临床观察和评估,并在3个月和1年时进行电话及门诊随访。观察指标为:手术时间、使用镇痛药物的频率、下床活动时间、住院天数、并发症、暂时性神经感觉异常、正常活动时间、腹股沟疼痛持续时间、疝复发。将两组数据进行统计学处理和分析。结果:使用镇痛药物的频率、下床活动时间、住院天数、恢复正常活动时间、腹股沟疼痛持续时间、并发症方面TEP组优于Lichtenstein组,有显著性差异(P〈0.05)。手术时间、复发例数TEP组少于Lichtenstein组,但无统计学差异。结论:TEP对于复发疝、老年人疝以及双侧疝更加具有优势。但TEP手术费用较高、需要腹腔镜等设备、学习曲线较长,这些可能是目前TEP尚未广泛开展的主要原因。我们认为,缩短TEP学习曲线的关键在于掌握手术空间的建立,腹白线中隔是影响手术空间建立的主要因素,打开下方部分腹白线中隔是手术的要点。  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