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   8088篇
  免费   316篇
  国内免费   91篇
耳鼻咽喉   138篇
儿科学   2070篇
妇产科学   498篇
基础医学   388篇
口腔科学   58篇
临床医学   943篇
内科学   283篇
皮肤病学   69篇
神经病学   339篇
特种医学   183篇
外科学   450篇
综合类   973篇
预防医学   1337篇
眼科学   102篇
药学   585篇
  1篇
中国医学   54篇
肿瘤学   24篇
  2023年   81篇
  2022年   199篇
  2021年   250篇
  2020年   212篇
  2019年   218篇
  2018年   227篇
  2017年   149篇
  2016年   251篇
  2015年   201篇
  2014年   561篇
  2013年   567篇
  2012年   545篇
  2011年   576篇
  2010年   468篇
  2009年   499篇
  2008年   438篇
  2007年   408篇
  2006年   426篇
  2005年   334篇
  2004年   297篇
  2003年   216篇
  2002年   173篇
  2001年   180篇
  2000年   172篇
  1999年   131篇
  1998年   83篇
  1997年   81篇
  1996年   65篇
  1995年   61篇
  1994年   54篇
  1993年   38篇
  1992年   28篇
  1991年   23篇
  1990年   28篇
  1989年   46篇
  1988年   15篇
  1987年   27篇
  1986年   14篇
  1985年   30篇
  1984年   21篇
  1983年   8篇
  1982年   14篇
  1981年   14篇
  1980年   8篇
  1979年   11篇
  1978年   6篇
  1977年   9篇
  1976年   11篇
  1974年   5篇
  1971年   4篇
排序方式: 共有8495条查询结果,搜索用时 156 毫秒
1.
Child benefits are typically paid from birth. This paper asks whether starting universal child benefits in pregnancy leads to improvements in infant health. Leveraging administrative birth registry and hospital microdata from England and Wales, I study the effects of the Health in Pregnancy Grant, a universal conditional cash transfer equivalent to three months of child benefit (190 GBP) as a lump sum to pregnant mothers from 2009 to 2011. I exploit quasi-experimental variation in eligibility with a regression discontinuity design in the date of birth of the baby. I find that the policy increased birth weight by 8–12 grams on average, reduced low birth weight (<2500 g) by 3-6 percent and decreased prematurity by 9–11 percent. Younger mothers, particularly those living in deprived areas, benefit the most. I present evidence that the mechanisms are unlikely to be antenatal care, nutrition or smoking, with reductions in stress remaining a possible explanation.  相似文献   
2.
3.
4.
改良超滤(MUF)技术作为心肺转流中节约用血的重要手段之一,具有浓缩血液、清除炎性介质、减轻组织水肿等优点,但随着微小化体外循环技术的应用,MUF在临床应用中的获益性和必要性开始受到各中心的重新审视。本文对近年来MUF的临床使用进展予以综述。  相似文献   
5.
《Vaccine》2020,38(42):6508-6516
BackgroundPneumococcal conjugate vaccine (PCV) effectiveness against radiographic pneumonia in South Asia is unknown. Bangladesh introduced PCV10 in 2015 using a three dose primary series (3 + 0). We sought to measure PCV10 effectiveness for two or more vaccine doses on radiographic pneumonia among vaccine-eligible children in rural Bangladesh.MethodsWe conducted a matched case-control study over two years from 2015 to 2017 using clinic and community controls in three subdistricts of Sylhet, Bangladesh. Cases were vaccine eligible 3–35 month olds at Upazila Health Complex outpatient clinics with World Health Organization-defined radiographic primary endpoint pneumonia (radiographic pneumonia). Clinic controls were matched to cases within a one week time window by age, sex, and clinic and had an illness unlikely to be Streptococcus pneumoniae; community controls were healthy and similarly matched within a one week time window by age and sex, and distance from the clinic. We estimated adjusted vaccine effectiveness (aVE) using conditional logistic regression.ResultsWe matched 1262 cases with 2707 clinic and 2461 community controls. Overall, aVE using clinic controls was 21.4% (95% confidence interval, −0.2%, 38.4%) for ≥2 PCV10 doses and among 3–11 month olds was 47.3% (10.5%, 69.0%) for three doses. aVE increased with higher numbers of doses in clinic control sets (p = 0.007). In contrast, aVE using community controls was 7.6% (95% confidence interval, −22.2%, 30.0%) for ≥2 doses. We found vaccine introduction in the study area faster and less variable than expected with 75% coverage on average, which reduced power. Information bias may also have affected community controls.ConclusionsClinic control analyses show PCV10 prevented radiographic pneumonia in Bangladesh, especially among younger children receiving three doses. While both analyses were underpowered, community control enrollment – compared to clinic controls – was more difficult in a complex, pluralistic healthcare system. Future studies in comparable settings may consider alternative study designs.  相似文献   
6.
Background/purposePertussis incidence markedly decreased due to universal vaccination, but outbreaks had been noted worldwide in recent decade. This study was conducted to know the epidemiology of pertussis and its impact on infants in Taiwan.MethodsEpidemiologic parameters for confirmed pertussis cases were collected from the Taiwan Centers for Disease Control. The incidence of each age group over years was calculated using population data. We also did retrospective reviews of laboratory-confirmed pertussis cases in NTUH to analyze clinical characteristics and disease severity.ResultsA total of 668 confirmed pertussis cases were obtained from the Taiwan CDC open database between 2003 and 2017. There was higher incidence during the period 2009–2015, with a mean incidence of 0.27 cases per 100,000 population, about 2-fold increase compared with mean incidence of 0.12 cases per 100,000 population during the period 2003–2008. Infants accounted for the highest proportion of all cases (49.8%), with mean incidence of 16.1 cases per 100,000 people per year during 2009–2015, and a trend of increase was found from 2003 to 2015. In NTUH, a total of 17 laboratory-confirmed pertussis cases were diagnosed during 2012–2016, and 14 cases were young infants. Among them, 9 infants had been admitted to intensive care unit and 2 infant needed invasive ventilator support.ConclusionThere was a resurgence of pertussis during 2009–2015 and it had significant impact on infants. Young infants with pertussis may be severe and need intensive care, so preventive strategy may be advocated for them.  相似文献   
7.
8.
丁斌 《浙江医学》2016,38(24):1977-1979,1988
目的观察并比较枸橼酸咖啡因及氨茶碱对早产儿不同时相血糖的影响程度。方法选择新生儿监护室诊断为原发性呼吸暂停的出生胎龄<34周的早产儿172例,采用随机数字表法分为咖啡因组与氨茶碱组各86例。比较两组早产儿用药前及用药后15、30min、1、1.5、2、4、6、12、12.5、24.5、36.5和48h血糖的变化。结果两组早产儿用药后除6、12和48h血糖值比较差异均无统计学意义(均P>0.05),其他用药后时相比较差异均有统计学意义(均P<0.05)。咖啡因组早产儿用药后30min血糖值上升,至1h达峰值,后逐渐回落;用药后30min、1、1.5、2及24.5h血糖值与用药前比较差异均有统计学意义(均P<0.05)。氨茶碱组早产儿用药后血糖值上升,30min达峰值,后逐渐回落;用药后15、30min、1、1.5、2、4、6、12.5、24.5、36.5h血糖值与用药前比较差异均有统计学意义(均P<0.05)。结论枸橼酸咖啡因可引起早产儿血糖升高,但升高幅度较氨茶碱小、持续时间也较短。  相似文献   
9.
10.
目的探讨新生儿胃穿孔的临床特点及影响预后的相关因素。方法本研究为回顾性研究。研究对象为山西省儿童医院新生儿外科2008年1月至2017年12月手术治疗的49例新生儿胃穿孔病例。分析这些患儿的临床表现、辅助检查、手术情况及预后等临床资料。根据预后将患儿分为存活组和死亡组,探讨影响患儿预后的相关因素。采用独立样本t检验或连续性校正χ^2检验(或Fisher精确概率法)分析数据。结果(1)49例患儿中,男29例(59.2%),女20例(40.8%);早产儿30例(61.2%),足月儿19例(38.8%);体重(2450±700)g,范围为1010~5000 g。29例(59.2%)为低出生体重儿。11例(22.4%)有围产期不良事件;17例(34.7%)术前合并感染性休克;6例(12.2%)合并其他消化道畸形。2例(4.1%)有生后窒息复苏史,2例(4.1%)合并呼吸窘迫综合征行机械通气,12例(24.5%)有留置胃管或洗胃史。(2)49例患儿的发病时间为(3.8±2.0)d,47例(95.9%)于生后1周内发病,其中36例于生后≤4 d发病;25例(51.0%)发病到手术时间≤12 h。(3)首发症状以单纯腹胀最常见[69.4%(34/49)],12例(24.5%)腹胀伴呕吐,39例(79.6%)患儿术前腹部立位X射线片可见膈下大量游离气体,肝脏受压下移,胃泡影减小或消失。(4)所有患儿入院后均急诊行开腹探查、胃壁一期修补术。术中见27例(55.1%)穿孔位于胃大弯,5例(10.2%)位于胃小弯,14例(28.6%)位于胃前壁,3例(6.1%)位于胃后壁。33例(67.3%)穿孔长径≥3 cm。术后3例(6.1%)发生切口感染,2例(4.1%)吻合口漏;1例术后48 h发现大量气液胸,再次手术证实为食道重复并食道穿孔。(5)49例中,35例(71.4%)的病因为先天性胃壁肌层缺损,4例(8.2%)为损伤,10例(20.4%)为自发性穿孔。(6)49例中,8例(16.3%)死亡,36例(73.5%)存活,5例(10.2%)术后放弃治疗。剔除5例放弃治疗的患儿后,存活组中发病到手术时间≤12 h及穿孔长径<3 cm患儿的比例高于死亡组[61.1%(22/36)与1/8,χ^2=4.404;41.7%(15/36)与0/8];死亡组合并感染性休克的比例高于存活组[6/8与22.2%(8/36),χ^2=6.147](P值均<0.05)。结论新生儿胃穿孔病死率较高,先天性胃壁肌层缺损是新生儿胃穿孔的病理基础和主要病因,突然出现的腹胀是其主要的临床表现。尽早手术有助于提高治愈率。  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