首页 | 官方网站   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   13560篇
  免费   1289篇
  国内免费   152篇
医药卫生   15001篇
  2024年   42篇
  2023年   259篇
  2022年   440篇
  2021年   633篇
  2020年   618篇
  2019年   629篇
  2018年   596篇
  2017年   657篇
  2016年   639篇
  2015年   564篇
  2014年   924篇
  2013年   1133篇
  2012年   710篇
  2011年   807篇
  2010年   704篇
  2009年   713篇
  2008年   605篇
  2007年   656篇
  2006年   561篇
  2005年   501篇
  2004年   396篇
  2003年   346篇
  2002年   227篇
  2001年   178篇
  2000年   161篇
  1999年   139篇
  1998年   112篇
  1997年   103篇
  1996年   80篇
  1995年   82篇
  1994年   73篇
  1993年   80篇
  1992年   57篇
  1991年   52篇
  1990年   42篇
  1989年   47篇
  1988年   54篇
  1987年   36篇
  1986年   38篇
  1985年   38篇
  1984年   41篇
  1983年   28篇
  1982年   39篇
  1981年   26篇
  1980年   32篇
  1979年   18篇
  1978年   18篇
  1977年   14篇
  1976年   16篇
  1975年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
目的通过研究肺表面活性物质(PS)结合持续气道正压通气(CPAP)治疗新生儿呼吸窘迫综合征(NRDS)的治疗效果,进一步指导NRDS的临床治疗。方法选取于2017年4月-2018年10月间在本院收治的80例确诊为新生儿呼吸窘迫综合征的患儿作为研究对象,随机将患儿分为试验组和对照组,对照组给予持续气道正压通气治疗,试验组在对照组的基础上联合使用PS治疗。结果试验组对于呼吸窘迫缓解的有效率明显高于对照组,在气管插管内滴入PS治疗后试验组的血气情况明显优于对照组,且试验组患儿副作用发生率明显低于对照组,以上指标差异具有统计学意义,P <0.05。结论 PS结合CPAP在新生儿呼吸窘迫综合征的治疗中疗效很好。  相似文献   
3.
Intussusception is a very rare cause of intestinal obstruction in neonates. It is of extremely rare occurrence among premature neonates. We present a case of 11-day-old premature neonate who presented with abdominal distension, intolerance to feeds, vomiting, significant bilious aspirate and bleeding per rectum. The initial diagnosis of necrotizing enterocolitis (NEC) led to a delay in the diagnosis. On exploratory laparotomy, it turned out to be a case of ileo-colic intussusception with Meckel''s diverticulum as a lead point. This site of intussusception (ileo-colic) and presence of a lead point among premature neonate is of exceedingly rare occurrence and very few such cases have been reported.In this article, the published work about clinical features and management on intussusceptions in premature neonates has been reviewed. The authors intend to highlight the difficulty in distinguishing the NEC and intussusception. Subtle clinical and radiological features which can help in differentiating the two conditions have been emphasized. This can avoid the delay in diagnosis and management which can prove critical. High index of suspicion with timely intervention is the key for optimizing outcome. A diagnosis of intussusception should always be considered in any preterm infant with suspected NEC.  相似文献   
4.
Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight.  相似文献   
5.
目的 比较TRH、EGF与地塞米松对未成熟胎肺形态发育及表面活性物质水平的影响。方法 在兔妊娠第22-24d或第24-26d分别用TRH、EGF或地塞米松母体静脉注射治病,通过光镜、图像分析及电镜等技术观察胎肺的形态结构,并检测胎肺的磷脂水平。结果 光镜下,TRH、EGF与地塞米松治疗组第25d及27d胎肺肺泡腔、肺泡间隔发育均明显好于对照组;EGF、TRH与地塞米松治疗组第27d胎肺的肺泡腔与肺泡间隔的面积比无明显差异。但EGF和TRH治疗组第25d胎肺的肺泡腔与肺泡间隔之比明显小于地塞米松治疗组。电镜下,三个治疗组第27d胎肺内含有板层体的Ⅱ型上皮细胞数量明显多于对照组,但各治疗组及对照组第25d的胎肺Ⅱ型上皮细胞胞浆内几乎未见明显板层体,相反胞浆内糖原含量却非常丰富。此外,三个治疗组27d胎肺的磷脂水平均明显高于对照组。结论 EGF、TRH及地塞米松在兔妊娠第24-26d母体治疗均能促进胎肺的形态发育和表面活性物质的合成,三种治疗方法对胎肺的影响程序无明显不同;在妊娠第22-24d治疗,地塞米松对胎肺形态结构的促进作用较EGF和TRH更明显,但三者对Ⅱ型上皮细胞分化及表面活性物质的合成均无明显影响。  相似文献   
6.
A woman's partner and the characteristics of their partnership can play an important role in the health of her pregnancy. Yet, with the notable exception of intimate partner violence, there has been little previous research addressing the associations between partner- or partnership-related factors and birth outcomes. This analysis tested the hypothesis that risk factors related specifically to partner or partnership characteristics increased the risk for preterm birth. Between 2003 and 2005, a total of 580 preterm cases (20–36 weeks gestational age at delivery) and 633 term controls (≥37 weeks) were selected from women delivering at an obstetric hospital in Lima, Peru. Each woman completed a confidential, structured interview and provided biological specimens within 48 h after delivery. Multivariable logistic regression was used to assess associations between partner and partnership characteristics and preterm birth. After adjustment for behavioral, demographic, and obstetric risk factors, ever having had a partner with a history of drug use (aOR = 1.91, 95% CI 1.22–2.99), ever having had anal sex (aOR = 1.40, 95% CI 1.07–1.84), having a current partner with a history of visiting prostitutes (aOR = 1.69, 95% CI 1.22–2.33), and perceiving one's current partner as a “womanizer” (aOR = 1.34, 95% CI 1.02–1.77) were significantly associated with an elevated risk of preterm birth when tested in separate models. These four factors were then used to create a composite partnership risk score, which showed an increasing dose-response relationship with preterm birth risk (per additional partner risk factor: aOR = 1.31, 95% CI 1.16–1.49). These results highlight the importance of considering a broader set of risk factors for preterm birth, specifically those related to a woman's partner and partnership characteristics. Further research could clarify the specific mechanisms through which these partner and partnership characteristics may increase the risk of preterm birth.  相似文献   
7.
目的:了解和探讨新生儿出生信息的分布态势及规律。方法:对本院2006年1~6月间所有新生儿出生信息进行样本分析。结果:半年间分娩的新生儿共1075例,其中死亡19例,双胞胎15例,以1028例单胎活产新生儿的出生体重、胎龄及产妇年龄作为研究样本进行分析,统计数据与传统意义上的正常胎龄和新生儿体重基本相符,胎龄、体重均值均有所提高。结论:孕产妇的健康状况和新生儿的体质均有所改善,随胎龄的增加,新生儿出生体重亦随之增加,并且,目前新生儿的整体统计体重要大于现有的临床指标,因此,应对现有的临床指标进行适当调整,重新确定低出生体重儿和巨大儿的临床指标。  相似文献   
8.
The aim of the study was to assess if lung function at birth predicts lung function at 2 yr and secondly, if lung function development was influenced by the common phenotypes of recurrent bronchial obstruction (rBO) or atopic eczema (AE) by 2 yr. Lung function was assessed at birth (n = 802) and at 2 yr within the prospective birth cohort study 'the Environment and Childhood Asthma Study' in Oslo. The 135 children with lung function measured at birth by tidal flow volume (TFV) loops and passive respiratory mechanics, who were included in a nested case-control study were reinvestigated at 2 yr with clinical examination, TFV loops (n = 90) (mean age 26.6 (3.7 s.d.) months), skin prick test and parental interview. Children were categorized into quartiles (lower, middle two, upper) according to time to peak tidal expiratory flow/total expiratory time (t(PTEF)/t(E)) at birth as well as clinical phenotype based on the presence of rBO and/or AE (ever) by 2 yr. The observed reduction in mean t(PTEF)/t(E) from birth to 2 yr within the quartiles, were not significantly different after controlling for 'regression to the mean'. t(PTEF)/t(E) at birth correlated significantly with t(PTEF)/t(E) at 2 yr, (r = 0.475, p < 0.001). Children with both rBO and AE by 2 yr had significantly lower t(PTEF)/t(E) at 2 yr (p = 0.002) and at birth (p = 0.027), compared with children with no rBO or AE. Clinical phenotype at 2 yr did not influence the change in t(PTEF)/t(E) from birth to 2 yr. This study demonstrates a clear tracking of lung function from birth, not influenced by rBO or AE by 2 yr.  相似文献   
9.
How many subjects are needed in a longitudinal birth cohort study?   总被引:8,自引:8,他引:0  
One of the first decisions that needs to be taken when planning a birth cohort concerns the size of the study. This in turn will depend on the research questions to be answered and thence whether environmental exposures and outcomes are measured on a continuum or as dichotomous variables. Here we describe ways in which different birth cohorts have addressed this issue and explore the advantages of smaller detailed studies over larger less-detailed studies.  相似文献   
10.
AIMS: The aim of this study was to investigate the significance of simple 24-h Holter (24H) data after electrical cardioversion (CV) for atrial fibrillation (AF) recurrence. METHODS: We prospectively studied 47 consecutive patients subjected to CV, who successfully converted to sinus rhythm. All underwent echocardiography and 24H after CV. AF recurrence was studied at 14 days and 1 month by second 24H or by interim report of AF. RESULTS: About 53.2% remained in sinus rhythm (group I) and the rest recurred to AF (group II). Group I had fewer atrial premature complexes per hour (APC/h) (P = 0.002) and lower maximum (max HR), average, and minimum heart rates compared with group II (all Ps < 0.05). The optimal value of APC/h and max HR with best sensitivity and specificity was 32 APC/h and 90 bpm, respectively. These findings were the predictors of AF recurrence [hazard ratio (HR) = 4.5 with 95% CI = 1.7-11.7 and HR = 4.3 with 95% CI = 1.7-10.9, respectively]. Patients with the combination of both predictors had greater HR of AF recurrence compared with those with < 32 APC/h and max HR < 90 bpm (HR = 8.8 with 95% CI = 2.5-31.4). CONCLUSION: Patients with frequent APC/h and high max HR are at high risk for 1-month AF recurrence after electrical CV.  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-23

京公网安备 11010802026262号