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   11788篇
  免费   950篇
  国内免费   159篇
耳鼻咽喉   127篇
儿科学   163篇
妇产科学   331篇
基础医学   672篇
口腔科学   232篇
临床医学   1812篇
内科学   2792篇
皮肤病学   123篇
神经病学   317篇
特种医学   333篇
外国民族医学   1篇
外科学   2372篇
综合类   1006篇
预防医学   1505篇
眼科学   173篇
药学   675篇
  1篇
中国医学   93篇
肿瘤学   169篇
  2024年   3篇
  2023年   195篇
  2022年   272篇
  2021年   541篇
  2020年   659篇
  2019年   578篇
  2018年   599篇
  2017年   481篇
  2016年   451篇
  2015年   440篇
  2014年   947篇
  2013年   1074篇
  2012年   577篇
  2011年   672篇
  2010年   559篇
  2009年   508篇
  2008年   483篇
  2007年   462篇
  2006年   419篇
  2005年   375篇
  2004年   355篇
  2003年   314篇
  2002年   227篇
  2001年   188篇
  2000年   184篇
  1999年   135篇
  1998年   158篇
  1997年   132篇
  1996年   114篇
  1995年   122篇
  1994年   98篇
  1993年   77篇
  1992年   80篇
  1991年   50篇
  1990年   56篇
  1989年   56篇
  1988年   39篇
  1987年   40篇
  1986年   31篇
  1985年   31篇
  1984年   16篇
  1983年   22篇
  1982年   18篇
  1981年   11篇
  1980年   11篇
  1979年   12篇
  1978年   11篇
  1977年   4篇
  1976年   3篇
  1973年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
PurposeTo evaluate temporal trends, practice variation, and associated outcomes with the use of intravascular ultrasound (US) during deep venous stent placement among Medicare beneficiaries.Materials and MethodsAll lower extremity deep venous stent placement procedures performed between January 1, 2017, and December 31, 2019 among Medicare beneficiaries were included. Temporal trends in intravascular US use were stratified by procedural setting and physician specialty. The primary outcome was a composite of 12-month all-cause mortality, all-cause hospitalization, or repeat target vessel intervention. The secondary outcome was a composite of 12-month stent thrombosis, embolization, or restenosis.ResultsAmong the 20,984 deep venous interventions performed during the study period, 15,184 (72.4%) utilized intravascular US. Moderate growth in intravascular US use was observed during the study period in all clinical settings. There was a variation in the use of intravascular US among all operators (median, 77.3% of cases; interquartile range, 20.0%–99.2%). In weighted analyses, intravascular US use during deep venous stent placement was associated with a lower risk of both the primary (adjusted hazard ratio, 0.72; 95% confidence interval [CI], 0.69–0.76; P < .001) and secondary (adjusted hazard ratio, 0.32; 95% CI, 0.27–0.39; P < .001) composite end points.ConclusionsIntravascular US is frequently used during deep venous stent placement among Medicare beneficiaries, with further increase in use from 2017 to 2019. The utilization of intravascular US as part of a procedural strategy was associated with a lower cumulative incidence of adverse outcomes after the procedure, including venous stent thrombosis and embolization.  相似文献   
2.
为了在腰椎退变性疾病保守治疗和融合手术中间地带寻找一种有效的预防与辅助相结合的微创治疗方式,通过对比目前常用的几种腰椎棘突间动态稳定系统的临床疗效观察和优缺点,以及对腰椎棘突间的生理结构、生物力学和相关数据的分析,在充分了解记忆合金材质的基础上,自行设计研究一种记忆合金材料的新型腰椎棘突间动态固定装置,既能重建腰椎的正常生物力学特性,满足人体脊柱的正常活动,又避免对原有结构的破坏,减少术后并发症的发生,同时也可以优化目前的治疗方法。通过研究,腰椎棘突间记忆合金动态稳定装置在理论上效果满意,可以解决现有技术的不足,优于目前的几种腰椎棘突间动态稳定系统。  相似文献   
3.
4.
背景与目的:调强放疗(intensity-modulated radiation therapy,IMRT)中剂量投照失误可导致严重后果,而目前常用的治疗前计划验证方法并不能反映患者真实投照剂量。实现一种评估患者在体剂量执行准确度的方法,能够在分次治疗中及时发现较大剂量错误,避免发生患者投照剂量过高或不足。方法:复旦大学附属肿瘤医院收治的患者首次实施治疗前行锥形束计算机断层成像(cone beam computed tomography,CBCT)扫描,与定位CT图像进行配准保证治疗体位与模拟定位时一致,实时治疗中使用电子射野影像装置(electronic portal imaging device,EPID)获取患者出射剂量影像,并把首次出射EPID影像作为剩余分次治疗的基准值,后续分次实时治疗野结束后快速将其出射EPID影像与对应基准影像进行γ分析比较,以验证治疗计划是否准确执行于患者身上。设计模体实验对治疗部位错误和摆位误差情况进行分析,来评估本方法识别放疗差错的准确性。结果:本方法可有效地识别出IMRT放疗中患者治疗部位错误和非平行于射野角度方向的摆位误差,但对平行于射野角度方向的摆位误差并不敏感,30例鼻咽癌患者临床应用结果中能够直观显示分次治疗间摆位重复性情况。结论:基于EPID实现的一种在体剂量验证方法能够对调强放疗中患者实时剂量的准确性进行评估,在单个治疗野结束后可快速检测出较大治疗错误。  相似文献   
5.
日间手术在国外已有上百年的发展历史,现已成为欧美国家重要手术模式。我国于20世纪初开始开展日间手术,但目前尚未普及,发展不平衡问题比较突出,存在认识不清、开展不规范、与医保支付对接不畅等问题。日间手术是一种使国家、医院和病人三方均受益的新型手术模式。近年来,国家相关管理部门积极引导,开展日间手术的医院明显增多,可以预见,我国日间手术即将进入快速发展的新阶段。因此,有条件的医院可以从简单、易操作的病种开始,落实临床路径,积累经验,再逐步稳妥展开。在保证质量的前提下,不断拓展日间手术范围,提高三、四级手术比例。同时,积极与医保支付政策对接,采取灵活的方式,获得医保的支持,更好地促进我国日间手术的快速发展。  相似文献   
6.

Objective

To determine the association between provider training level and postplacental intrauterine device (IUD) outcomes following insertion instruction by email only.

Study design

We conducted a single-center chart review of demographics, insertion and clinical outcomes within 6 months of delivery for 116 patients who underwent postplacental levonorgestrel 52?mg IUD placement from October 1, 2016, to March 31, 2017.

Results

We confirmed IUD retention, removal or expulsion in 87 of 116 (75.0%) patients by 6 months after delivery. Complete expulsion or removal for malposition occurred in 20 (23.0%) patients and more frequently after vaginal than cesarean delivery (30.2% vs. 4.2%, OR 9.93 [95% CI 1.25–78.96]) and when a postgraduate year (PGY) 1 physician placed the IUD compared to a PGY 2–4 or attending physician (37.5% vs. 14.5%, OR 3.52 [95% CI 1.25–9.94]).

Conclusion

Postplacental levonorgestrel 52?mg IUD expulsion rates are associated with provider training level as well as delivery route, though the individual association of each of these factors is difficult to ascertain given the high degree of collinearity between these two variables in our study.  相似文献   
7.

Objectives

We explored levonorgestrel (LNG) concentrations, bleeding patterns and endometrial thickness in women with epilepsy (WWE) initiating an LNG-intrauterine device (IUD) co-administered with antiepileptic drugs (AEDs).

Study design

This pilot study included 20 WWE ages 18 to 45 years with well-controlled seizures and stable AED regimens initiating a 52-mg LNG-IUD (20 mcg/d initial release). We collected blood and measured endometrial thickness before IUD placement and 21 days, 3 months and 6 months thereafter. Participants recorded bleeding/spotting daily. We measured total LNG (radioimmunoassay), serum hormone binding globulin (SHBG, immunoassay) and calculated the free LNG index. We compared total LNG, free LNG index, SHBG and endometrial thickness over time using a linear mixed-effects model.

Results

Total LNG, free LNG index and SBHG levels remained stable from day 21 throughout. Endometrial thickness decreased from a median of 5.9 mm [interquartile range (IQR) 4.6–7.5] at day 21 to 3.3mm (2.8–4.9) by month 6 (p=0.02). Bleeding and spotting days decreased from a median of 16 (IQR 13–23) in month 1 to 6.5 (IQR 4–8.5) in month 6 regardless of AED regimen.

Conclusion

Like women without epilepsy, WWE initiating the LNG-IUD experience stable total LNG concentrations and decreasing endometrial thickness and bleeding over the first 6 months of use.

Implications

Like women without epilepsy, WWE using antiepileptic drugs can expect a stable LNG concentration and decreasing bleeding during the first 6 months of LNG-IUD use. Our data can be useful for guidance of WWE considering use the LNG-IUD.  相似文献   
8.
9.
ObjectiveTo assess the impact of training on use of inhalational techniques of different inhaler devices in spirometry proved cases of COPD and Bronchial Asthma in a tertiary care centre.MethodsA total of 128 spirometry proved cases of Asthma and COPD were enrolled. They were equally distributed in four groups comprising of 32 patients each according to their inhalation devices namely pMDI, Rotahaler, Accuhaler and Turbohaler. Patients were asked to demonstrate their inhalation technique and errors were noted according to their inhaler specific checklist. Patients were also interviewed regarding their knowledge about inhalation devices. Training about proper inhalation techniques was given to every participant. Rechecking of inhalation technique was again done at the second visit after 2 wks in the similar manner. Correct and incorrect steps of inhalation technique again evaluated by filling the checklist of the individual device to see post training improvement.ResultIn our study, out of total cases more than one third of the patients were >60 yrs of age (41.4%) and most of the patients were males (62.5%). During the interview at first visit, almost 92% patients claimed to know how to use the inhalation device correctly but in reality most of the patients (around 96.1%) had committed at least one mistakes in their inhalation technique among all the inhalation steps. Errors were noted in different steps of inhalation including the essential steps among all the four devices. Statistically significant improvement in inhalation techniques including the essential steps were found among all the four devices after educational intervention and demonstration of sequential steps involved in particular inhaler.ConclusionOur study confirmed a significant increase in the percentage of improvement in inhalation technique after proper demonstration and training about the inhalation devices. Inhalation technique including essential steps of inhalation significantly improved in all the four devices used.  相似文献   
10.
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