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   13147篇
  免费   1094篇
  国内免费   520篇
耳鼻咽喉   38篇
儿科学   170篇
妇产科学   151篇
基础医学   1191篇
口腔科学   194篇
临床医学   1079篇
内科学   2010篇
皮肤病学   196篇
神经病学   1352篇
特种医学   260篇
外国民族医学   1篇
外科学   628篇
综合类   1386篇
现状与发展   1篇
一般理论   4篇
预防医学   917篇
眼科学   101篇
药学   3689篇
  5篇
中国医学   1178篇
肿瘤学   210篇
  2024年   21篇
  2023年   211篇
  2022年   211篇
  2021年   432篇
  2020年   409篇
  2019年   531篇
  2018年   518篇
  2017年   543篇
  2016年   492篇
  2015年   474篇
  2014年   631篇
  2013年   1929篇
  2012年   685篇
  2011年   677篇
  2010年   542篇
  2009年   513篇
  2008年   511篇
  2007年   498篇
  2006年   541篇
  2005年   426篇
  2004年   362篇
  2003年   365篇
  2002年   334篇
  2001年   246篇
  2000年   204篇
  1999年   187篇
  1998年   179篇
  1997年   154篇
  1996年   136篇
  1995年   146篇
  1994年   176篇
  1993年   115篇
  1992年   113篇
  1991年   117篇
  1990年   105篇
  1989年   101篇
  1988年   69篇
  1987年   72篇
  1986年   106篇
  1985年   130篇
  1984年   146篇
  1983年   93篇
  1982年   92篇
  1981年   66篇
  1980年   55篇
  1979年   22篇
  1978年   25篇
  1977年   20篇
  1976年   10篇
  1971年   4篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
何金娜  谭建勋  梁霞 《全科护理》2022,20(7):939-941
目的:探讨增进积极体验为目标的健康干预对抑郁症病人抑郁情绪及生活质量的影响。方法:选择2019年9月—2021年3月在医院就诊的68例抑郁症病人为研究对象,按照随机数字表法分为观察组与对照组,每组34例。对照组予以常规护理,观察组在常规护理基础上予以增进积极体验为目标的健康干预。干预前后分别采用汉密尔顿抑郁量表(HAMD)、世界卫生组织生存质量测定量表简表(WHOQOL-BREF)评估病人的抑郁情绪和生活质量,同时对两组病人的护理满意度进行比较。结果:干预后观察组病人抑郁评分低于对照组(P<0.05);两组病人的生理功能、心理功能、社会功能及环境功能指标均较干预前有明显改善,且观察组评分均高于对照组(P<0.05);观察组病人对护理干预的总满意度为97.06%,高于对照组的61.76%(P<0.05)。结论:增进积极体验为目标的健康干预可明显缓解抑郁症病人的抑郁情绪,提高病人的生活质量。  相似文献   
2.
3.
PurposeThe aim of this study was to compare catheter angiography (CA) and colonoscopy outcomes after successful CT angiographic (CTA) localization for patients with overt lower gastrointestinal bleeding (LGIB).MethodsSeventy-one consecutive patients from two institutions between 2010 and 2020 had both contrast extravasation on CTA imaging in the lower gastrointestinal tract and subsequent CA or colonoscopy. The primary outcome was confirmation of active bleeding during CA or colonoscopy (defined as confirmation yield). The secondary outcomes were to determine therapeutic yield (hemostatic therapy), time to procedure, rebleeding rate, and adverse outcome rates (defined as surgery, acute kidney injury, initiation of dialysis, and overall mortality). Univariate analyses and multivariable analyses with P < .05 were used to determine statistical significance.ResultsForty-four patients underwent CA and 27 underwent colonoscopy. CA had higher overall confirmation yield (55% vs 26%, P = .026), whereas therapeutic yields were similar (70% vs 56%, P = .214). Time to procedure was 5.1 ± 3.4 hours for CA and 15.5 ± 13.6 hours for colonoscopy (P < .001). On multivariable analysis, shorter time to procedure was the only statistically significant predictor of confirmation yield (P = .037) and therapeutic yield (P = .013), whereas procedure, hemoglobin, transfusions, and hemodynamic instability were not. Adverse events and rebleeding were not statistically different between patients who underwent CA and colonoscopy (P > .05).ConclusionsShorter time to procedure was the only statistically significant predictor of confirmation and therapeutic yield after CTA localization of LGIB. Because CA can be performed sooner than colonoscopy without increased rates of adverse outcomes or rebleeding, CA may be a reasonable first-line treatment option in patients with CTA localization of LGIB.  相似文献   
4.
5.

Background

Weaning from mechanical ventilation and tracheostomy after prolonged intensive care consume enormous resources with optimal management not currently well described. Restoration of respiratory flow via the upper airway is essential and early cuff-deflation using a one-way valve (OWV) is recommended. However, extended OWV use may cause dry airways and thickened secretions which challenge the weaning process. High-flow therapy via the tracheostomy tube (HFT-T) humidifies inspired air and may be connected via an in-line OWV (HFT-T-OWV) alleviating these problems. We aim to provide clinical and experimental data on the safety of HFT-T-OWV along with a practical guide to facilitate clinical use during weaning from mechanical ventilation and tracheostomy.

Methods

Data on adverse events of HFT-T-OWV were retrieved from a quality register for patients treated at an intensive care rehabilitation center between 2019 and 2022. Benchtop experiments were performed to measure maximum pressures and pressure support generated by HFT-T-OWV at 25–60 L/min flow using two different HFT-T adapters (interfaces). In simulated airway obstruction using a standard OWV (not in-line) maximum pressures were measured with oxygen delivered via the side port at 1–3 L/min.

Results

Of 128 tracheostomized patients who underwent weaning attempts, 124 were treated with HFT-T-OWV. The therapy was well tolerated, and no adverse events related to the practice were detected. The main reason for not using HFT-T-OWV was partial upper airway obstruction using a OWV. Benchtop experiments demonstrated HFT-T-OWV maximum pressures <4 cmH2O and pressure support 0–0.6 cmH2O. In contrast, 1–3 L/min supplemental oxygen via a standard OWV caused pressures between 84 and 148 cmH2O during simulated airway obstruction.

Conclusions

Current study clinical data and benchtop experiments indicate that HFT-T-OWV was well tolerated and appeared safe. Pressure support was low, but humidification may enable extended use of a OWV without dry airway mucosa and thickened secretions. Results suggest the treatment could offer advantages to standard OWV use, with or without supplementary oxygen, as well as to HFT-T without a OWV, for weaning from mechanical ventilation and tracheostomy. However, for definitive treatment recommendations, randomized clinical trials are needed.  相似文献   
6.
7.
目的研究47份不同来源、不同表型正品细辛样品的有效成分含量,评价正品细辛样品的质量,揭示有效成分形成与遗传和地域的关系,为细辛优良品种选育与开发利用提供理论依据。方法冷凝回流法提取挥发油、乙醇热浸法提取醇溶性浸出物,HPLC法测定细辛脂素含量、气质联用(GC-MS)分析挥发油组分,组间联接法进行聚类分析。结果 47份细辛样品挥发油量0.81%~3.32%。有5份样品挥发油量超过3.0%。醇溶性浸出物量为9.87%~29.40%,含量超过20%的样品占总数的63.8%。细辛脂素质量分数为0.118%~0.424%,有26份样品细辛脂素质量分数超过0.25%;47份细辛挥发油可分离出的化合物种类48~77种,化合物种类和含量有较大差异。基于有效成分的聚类分析将不同来源地、不同表型的细辛分为10类,聚类方式基本是按照来源地为基础进行聚类,同一来源地的汉城细辛和北细辛聚在一类中。结论在同一栽培环境和条件下,不同来源地、不同植物学表型的样品个体间有效成分含量间存在差异,新品种选育时可依照植物表型选择优良育种材料。大部分样品聚类与来源地域有关而与植物表型以及植物学分类无关。  相似文献   
8.
Ductal carcinoma in situ (DCIS) of the breast is a nonobligate precursor of invasive breast cancer, accounting for 20 % of screen-detected breast cancers. Little is known about the natural progression of DCIS because most patients undergo surgery upon diagnosis. Many DCIS patients are likely being overtreated, as it is believed that only around 50 % of DCIS will progress to invasive carcinoma. Robust prognostic markers for progression to invasive carcinoma are lacking. In the past, studies have investigated women who developed a recurrence after breast-conserving surgery (BCS) and compared them with those who did not. However, where there is no recurrence, the patient has probably been adequately treated. The present narrative review advocates a new research strategy, wherein only those patients with a recurrence are studied. Approximately half of the recurrences are invasive cancers, and half are DCIS. So-called “recurrences” are probably most often the result of residual disease. The new approach allows us to ask: why did some residual DCIS evolve to invasive cancers and others not? This novel strategy compares the group of patients that developed in situ recurrence with the group of patients that developed invasive recurrence after BCS. The differences between these groups could then be used to develop a robust risk stratification tool. This tool should estimate the risk of synchronous and metachronous invasive carcinoma when DCIS is diagnosed in a biopsy. Identification of DCIS patients at low risk for developing invasive carcinoma will individualize future therapy and prevent overtreatment.  相似文献   
9.
《Clinical neurophysiology》2019,130(10):1859-1868
ObjectivePreterm infants are at risk for altered brain maturation resulting in neurodevelopmental impairments. Topographical analysis of high-density electroencephalogram during sleep matches underlying brain maturation. Using such an EEG mapping approach could identify preterm infants at risk early in life.Methods20 preterm (gestational age < 32 weeks) and 20 term-born infants (gestational age > 37 weeks) were recorded by 18-channel daytime sleep-EEG at term age (GA 40 weeks for preterm and 2–3 days after birth for term infants) and 3 months (corrected age for preterm infants).ResultsPreterm infant’s power spectrum at term age is immature, leveling off with term infants at 3 months of age. Topographical distribution of maximal power density however, reveals qualitative differences between the groups until 3 months of age. Preterm infants exhibit more temporal than central activation at term age and more occipital than central activation at 3 months of age. Moreover, being less mature at term age predicts being less mature at 3 months of age.ConclusionTopographical analysis of sleep EEG reveals changes in brain maturation between term and preterm infants early in life.SignificanceIn future, automated analysis tools using topographical power distribution could help identify preterm infants at risk early in life.  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