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   3319篇
  免费   301篇
  国内免费   103篇
耳鼻咽喉   15篇
儿科学   39篇
妇产科学   54篇
基础医学   535篇
口腔科学   47篇
临床医学   303篇
内科学   392篇
皮肤病学   47篇
神经病学   210篇
特种医学   246篇
外科学   194篇
综合类   567篇
现状与发展   1篇
预防医学   323篇
眼科学   46篇
药学   293篇
  10篇
中国医学   189篇
肿瘤学   212篇
  2024年   7篇
  2023年   48篇
  2022年   67篇
  2021年   88篇
  2020年   82篇
  2019年   102篇
  2018年   92篇
  2017年   91篇
  2016年   106篇
  2015年   121篇
  2014年   228篇
  2013年   223篇
  2012年   177篇
  2011年   191篇
  2010年   161篇
  2009年   166篇
  2008年   136篇
  2007年   164篇
  2006年   165篇
  2005年   128篇
  2004年   130篇
  2003年   120篇
  2002年   97篇
  2001年   102篇
  2000年   94篇
  1999年   78篇
  1998年   69篇
  1997年   63篇
  1996年   44篇
  1995年   35篇
  1994年   42篇
  1993年   28篇
  1992年   44篇
  1991年   47篇
  1990年   29篇
  1989年   22篇
  1988年   25篇
  1987年   26篇
  1986年   20篇
  1985年   7篇
  1984年   9篇
  1983年   10篇
  1982年   6篇
  1981年   9篇
  1980年   7篇
  1979年   3篇
  1978年   6篇
  1977年   3篇
  1975年   2篇
  1967年   1篇
排序方式: 共有3723条查询结果,搜索用时 15 毫秒
51.
尼群地平与非洛地平对高血压患者血压变异性的影响   总被引:1,自引:0,他引:1  
目的:观察尼群地平和非洛地平对原发性高血压(EH)患者血压变异性的影响.方法:随机分为两组:(1)尼群地平组;(2)非洛地平组.治疗后进行24 h动态血压监测,观察血压变异性变化.结果:(1)两组治疗后均能使血压变异性降低,其中非洛地平组治疗第4周后即有非常显著性差异(P<0.01),下降幅度大于尼群地平组,两组比较,有显著性差异(P<0.05);(2)两组治疗后均能使24 h平均收缩压(SBP)和平均舒张压(DBP)降低,两组比较,无显著性差异(P>0.05),但非洛地平对夜间血压nSBP和nDBP下降率改变较小,两组比较,有显著性差异(P<0.05);(3)两组中男女之间血压变异性无显著性差异(P>0.05);(4)两组血压变异性与年龄关系:年龄≤60岁患者其血压变异性随年龄增加而增大,年龄≥60岁患者血压变异性不再继续增加.结论:两组均能使血压变异性降低,但非洛地平组优于尼群地平组,且对夜间血压下降改变较小.因此,治疗EH患者优选非洛地平,在一定范围内年龄越大血压变异性越大,亦表明早期治疗高血压具有重要意义.  相似文献   
52.
骨关节放大摄影的临床应用和诊断价值   总被引:1,自引:0,他引:1  
目的 :评价和比较X线放大像与普通X线平片诊断价值。方法 :对 386例患者 (男 2 6 7例 ,女 119例 )。患处原有普通X线平片部位进行X线放大摄影 ,并与原片进行对比分析。结果 :放大像发现病变阳性率为 75 .91%(2 93/ 386 ) ,普通X线平片发现病变阳性率为 5 7.5 1% (2 2 2 / 386 ) ,两者比较 ,前者的阳性率明显高于后者。结论 :对普通X线平片不能作出确切诊断的病例 ,摄X线放大像可提高诊断准确性 ,且有重要诊断价值  相似文献   
53.
Purpose. In a patient with internal derangement of the shoulder, the diagnostic method of choice is controversial. Conventional arthrography can diagnose most rotator cuff tears accurately; however, in many institutions MR arthrography is usually necessary to diagnose labral tears. We utilized decision tree methodology to compare the cost- effectiveness of conventional arthrography and conventional MRI with a hypothetical algorithm in which a patient underwent arthrography, performed with admixed gadolinium, which if negative, was followed by MRI. Design. The use of double-contrast arthrography alone, conventional MRI alone, and gadolinium-enhanced MRI used as an adjunct to conventional arthrography were modeled for the diagnosis of full-thickness rotator cuff tears (RCT), partial RCTs, labral tears, and the absence of cuff/labral tears using decision analysis methodology. English language medical publications were searched to determine the base probabilities for the accuracy of the diagnostic tests. The outcome utilities ranged from –1 to +1 to reflect the value of correct diagnostic evaluation. Charges for diagnostic tests and appropriate surgical treatments were based on 1997 Medicare reimbursement rates for professional fees and hospital charges in an outpatient setting. Sensitivity analyses were performed to evaluate the effects of uncertainty regarding the prevalence of each disease state and the accuracy of several diagnostic tests. Results. In the base-case analysis, the average effectiveness of double-contrast arthrography alone, MRI alone and arthrography selectively followed by MRI were 0.6610, 0.6715, and 0.7204, respectively. The average costs for each of these strategies were $1090, $2033, and $2339, respectively. Conclusion. Arthrography performed with admixed diluted gadolinium, which if negative is immediately followed by MRI, was somewhat more expensive than conventional MRI. However, because of much greater effectiveness, cost-effectiveness was significantly higher for our proposed algorithm. Conventional arthrography without gadolinium, although less expensive, had severely limited effectiveness. Received: 4 June 1999 Revision requested: 6 August 1999 Revision received: 30 August 1999 Accepted: 1 September 1999  相似文献   
54.
张梅  黄体钢 《天津医药》1999,27(3):135-138
目的:评价急性心肌梗死发病前48小时内的心绞痛发作对急性心肌梗死近期预后的影响。方法:将871例急性心肌梗死前48小时内有心绞痛组378例,梗死前无心绞痛493例,对两组住院期间的并发症和病死率进行比较分析,结果:发生心绞痛组的心肌梗死范围较小,住院期间病率、心力衰竭、心源性休克、室速的发生率均低于梗死前无心绞痛组。末溶栓组和溶栓未再通组,梗死前有心绞痛发作者的近期预后较无心绞痛者好,而两组溶栓冠  相似文献   
55.
Summary 20 patients (12 female) with moderately severe essential hypertension [blood pressure during placebo treatment 181±6 (systolic), 107±3 (diastolic)] completed a double-blind, cross-over dosetitrated comparison of labetalol and methyldopa. Both drugs reduced lying and standing arterial blood pressure to a similar extent, although only labetalol reduced heart rate. Compliance was high (>95%) with both drugs, and the incidence of subjective adverse effects was similar.  相似文献   
56.
38例经前期综合征患者,经基础体温测定或宫内膜活检。诊断为黄体功能不健33例(86.89%),无排卵月经周期5例。其中原发不孕5例,继发不孕19例,均有典型的经前期综合征症状。其中30例用自行研制的中药“坤月安”冲剂治疗。每次服坤月安1所,每日2次,于月经来潮前10天开始服用,10天为一疗程,均服用3个疗程,痊愈10例(33.43%),显效13例(43.33%),好转6例(20%),无效1例(3.33%),总有效率96.67%。  相似文献   
57.
目的 对比评价电视腹腔镜腹股沟疝修补术和切开法填充式无张力疝修补术的临床疗效。方法 对 12 0例腹股疝患者进行随机分组 ,其中 6 2例实施腹腔镜下疝修补术 ,5 8例实施切开法无张力疝修补术 ,比较两组的手术时间、术后疼痛持续时间、术后并发症发生率 (伤口出血、感染、尿潴留、阴囊水肿等 )、出院时间、复发率、切口美观指数。结果 腹腔镜组除手术时间长于切开法组外 ,其余各指标均优于切开法组 ,具有显著的统计学意义。结论 腹腔镜下行腹股沟疝修补术较之切开法无张力疝修补术确实有术后疼痛轻、下床活动早、住院时间短、恢复快、切口美观和并发症少等较多优点 ,为腹股沟疝的治疗提供更多更优良的选择方法。  相似文献   
58.
Variation in clinical outcome following shock wave lithotripsy   总被引:9,自引:0,他引:9  
PURPOSE: We measure and compare operator specific success rates of extracorporeal shock wave lithotripsy (ESWL) performed by 12 urologists in 1 unit to determine interoperator variation. MATERIALS AND METHODS: From January 1, 1994 to September 1, 1997 a total of 5,769 renal and ureteral stones received 9,607 ESWL treatments by 15 urologists with a Dornier MFL 5000 lithotriptor. The 3-month followup data are available for 4,409 stones. Outcome measures consisted of patient demographics, stone characteristics, technical details of lithotripsy, and stone-free and success rates by treating urologists. RESULTS: Treatment results were analyzed for 12 urologists (surgeons A to L) who treated more than 100 stones each, totaling 4,244 with followup information available. Mean stone-free and success rates were 50.6% and 72.3%, respectively. Surgeon A had significantly higher stone-free and success rates of 56.2% and 76.7%, respectively (p<0.05), with treatment results from 877 stones, which was a significantly higher number than others (p<0.05). Significant differences existed in mean number of shocks delivered among urologists (p = 0.0001), with surgeons A and J delivering the highest mean numbers (2,317 and 2,801, respectively). There was no difference in treatment duration (p = 0.75) but variation existed among urologists in terms of mean maximum treatment voltage (p = 0.0001). Mean fluoroscopy time at 4.1 minutes was higher for surgeon A than others (p<0.05). Mean complication rate following ESWL was 4.9% with no difference among urologists (p = 0.175). Re-treatment was required in 21.7% of cases and surgeon A had the lowest rate (15.9%, p<0.05). CONCLUSIONS: We demonstrated clinically and statistically significant intra-institutional differences in success rates following ESWL. The best results were obtained by the urologist who treated the greatest number of patients, used a high number of shocks and had the longest fluoroscopy time. Accurate targeting is crucial when using a lithotriptor, such as the Dornier MFL 5000, with a narrow focal zone of 6.5 mm. in diameter. Other centers should be encouraged to develop similar programs of outcome analysis in an attempt to improve performance.  相似文献   
59.
Objective. To determine whether clinical vignettes can measure variations in the quality of clinical care in two economically divergent countries.
Data Source/Study Setting. Primary data collected between February 1997 and February 1998 at two Veterans Affairs facilities in the United States and four government-run outpatient facilities in Macedonia.
Study Design. Randomly selected, eligible Macedonian and U.S. physicians (>97 percent participation rate) completed vignettes for four common outpatient conditions. Responses were judged against a master list of explicit quality criteria and scored as percent correct.
Data Collection/ Extraction. An ANOVA model and two-tailed t-tests were used to compare overall scores by case, study site, and country.
Principal Findings. The mean score for U.S. physicians was 67 percent (+/−11 percent) compared to 48 percent (+/−11 percent) for Macedonian physicians. The quality of clinical practice, which emphasizes basic skills, varied greatly in both sites, but more so in Macedonia. However, the top Macedonian physicians in all sites approached or—in one case—exceeded the median score in the U.S. sites.
Conclusions. Vignettes are a useful method for making cross-national comparisons of the quality of care provided in very different settings. The vignette measurements revealed that some physicians in Macedonia performed at a standard comparable to that of their counterparts in the United States, despite the disparity of the two health systems. We infer that in poorer countries, policy that promotes improvements in the quality of clinical practice—not just structural inputs—could lead to rapid improvements in health.  相似文献   
60.
目的研究中枢神经细胞瘤全基因组的遗传学异常,探讨该肿瘤的发病机制。方法应用比较基因组杂交技术,研究10例中枢神经细胞瘤的遗传学改变。结果10例中枢神经细胞瘤中,6例发现有染色体的失衡,主要表现为遗传物质在染色体2p(4/10)、10 q(4/10)和18 q(3/10)上的获得。结论染色体2p、10 q和18 q的遗传学改变很可能与中枢神经细胞瘤的发病机制有关。  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