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   101篇
  免费   7篇
儿科学   4篇
妇产科学   2篇
基础医学   5篇
口腔科学   1篇
临床医学   2篇
神经病学   22篇
综合类   1篇
预防医学   64篇
药学   5篇
肿瘤学   2篇
  2022年   2篇
  2021年   1篇
  2019年   1篇
  2018年   3篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2014年   4篇
  2013年   5篇
  2012年   10篇
  2011年   13篇
  2010年   9篇
  2009年   3篇
  2008年   13篇
  2007年   5篇
  2006年   7篇
  2005年   3篇
  2004年   6篇
  2003年   10篇
  2002年   4篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1994年   2篇
  1991年   1篇
排序方式: 共有108条查询结果,搜索用时 24 毫秒
1.
Although the adverse effect on pregnancy outcomes at high levels of lead exposure in the workplace has been recognized for years, there is uncertainty regarding the impact of exposure at the lower community exposure levels commonly encountered today. This review summarizes the epidemiologic literature and discusses pertinent methodologic issues and possible sources of interstudy variation. The authors conclude that prenatal lead exposure is unlikely to increase the risk of premature membrane rupture but does appear to increase the risk of preterm delivery. Whether prenatal lead exposure decreases gestational age in terms of infants is unclear. Prenatal lead exposure also appears to be associated with reduced birth weight, but results vary in relation to study design and degree of control for confounding. Adjustment for gestational age, a possible confounder of the birth weight-lead exposure association, did not yield clearer results.  相似文献   
2.

Prior work proposed a shortened version of the Social Responsiveness Scale (SRS), a commonly used quantitative measure of social communication traits. We used data from 3031 participants (including 190 ASD cases) from the Environmental Influences on Child Health Outcomes (ECHO) Program to compare distributional properties and criterion validity of 16-item “short” to 65-item “full” SRS scores. Results demonstrated highly overlapping distributions of short and full scores. Both scores separated case from non-case individuals by approximately two standard deviations. ASD prediction was nearly identical for short and full scores (area under the curve values of 0.87, 0.86 respectively). Findings support comparability of shortened and full scores, suggesting opportunities to increase efficiency. Future work should confirm additional psychometric properties of short scores.

  相似文献   
3.
Background: Some experimental and human data suggest that exposure to polychlorinated biphenyls (PCBs) may induce ototoxicity, though results of previous epidemiologic studies are mixed and generally focus on either prenatal or postnatal PCB concentrations exclusively.Objectives: Our aim was to evaluate the association between pre- and postnatal PCB concentrations in relation to cochlear status, assessed by distortion product otoacoustic emissions (DPOAEs), and to further clarify the critical periods in development where cochlear status may be most susceptible to PCBs.Methods: A total of 351 children from a birth cohort in eastern Slovakia underwent otoacoustic testing at 45 months of age. Maternal pregnancy, cord, and child 6-, 16-, and 45-month blood samples were collected and analyzed for PCB concentrations. At 45 months of age, DPOAEs were assessed at 11 frequencies in both ears. Multivariate, generalized linear models were used to estimate the associations between PCB concentrations at different ages and DPOAEs, adjusting for potential confounders.Results: Maternal and cord PCB-153 concentrations were not associated with DPOAEs at 45 months. Higher postnatal PCB concentrations at 6-, 16-, and 45-months of age were associated with lower (poorer) DPOAE amplitudes. When all postnatal PCB exposures were considered as an area-under-the-curve metric, an increase in PCB-153 concentration from the 25th to the 75th percentile was associated with a 1.6-dB SPL (sound pressure level) decrease in DPOAE amplitude (95% CI: –2.6, –0.5; p = 0.003).Conclusions: In this study, postnatal rather than maternal or cord PCB concentrations were associated with poorer performance on otoacoustic tests at age 45 months.Citation: Jusko TA, Sisto R, Iosif AM, Moleti A, Wimmerová S, Lancz K, Tihányi J, Šovčíková E, Drobná B, Palkovičová L, Jurečková D, Thevenet-Morrison K, Verner MA, Sonneborn D, Hertz-Picciotto I, Trnovec T. 2014. Prenatal and postnatal serum PCB concentrations and cochlear function in children at 45 months of age. Environ Health Perspect 122:1246–1252; http://dx.doi.org/10.1289/ehp.1307473  相似文献   
4.
Objective: Reporting categorical relative risk estimates for a series of exposure levels versus a common reference category is a widespread practice. In meta-analysis, categorical regression estimates a dose–response trend from such results. This method requires the assignment of a single score to each exposure category. We examined how closely meta-analytical categorical regression approximates the results of analysis based on the individual-level continuous exposure.Methods: The analysis included five studies on tea intake and outcomes related to colorectal cancer. In addition, we derived categorical mean and median values from published distributions of tea consumption in similar populations to assign scores to the categories of tea intake when possible. We examined whether these derived mean and median values well approximate the individual-level results.Results: In meta-analytical categorical regression, using the midrange scores approximated the individual-level continuous analyses reasonably well, if the value assigned to the uppermost, open-ended category was at least as high as the lower bound plus the width of the second-highest category. Categorical mean values derived from the published distributions of regular tea (in the US) and green tea (in Japan) well approximated the slope obtained from individual-level analysis.Conclusion: Publication of both the categorical and the continuous estimates of effect in primary studies, with their standard errors, can enhance the quality of meta-analysis, as well as providing intrinsically valuable information on dose–response.  相似文献   
5.
6.
OBJECTIVE: The aim of this study was to examine the prevalence of regressive autism and associated demographic, medical, and developmental factors by using 2 different definitions of regression based on the Autism Diagnostic Interview, Revised. METHODS: Subjects were aged 2 to 5 years, with autism (AU) or autism spectrum disorder (ASD) confirmed by standardized measures. Children with regression, defined as a) loss of both language and social skills or b) loss of either language or social skills, were compared with each other and to children with AU or ASD with no reported loss of skills on developmental and adaptive functioning. Parents reported on seizure, gastrointestinal, and sleep concerns. RESULTS: Fifteen percent (50/333) of the combined AU-ASD group lost both language and social skills; 41% (138/333) lost either language or social skills. No differences were found between the 2 samples of children with regression. Few developmental, demographic, or medical differences were found between the combined regression group and children without loss of skills, in both the larger AU-ASD sample and the more homogeneous AU-only sample. Children with regression had significantly lower communication scores than children without regression. CONCLUSIONS: The prevalence of regression in a large sample of young children with AU and ASD varies depending on the definition used; requiring loss of language significantly underestimates the frequency of developmental regression. Children with regression performed significantly less well than those without regression on 2 measures of communication, but the clinical meaningfulness of these differences is uncertain because of the small effect sizes.  相似文献   
7.
Autism: maternally derived antibodies specific for fetal brain proteins   总被引:3,自引:1,他引:2  
Autism is a profound disorder of neurodevelopment with poorly understood biological origins. A potential role for maternal autoantibodies in the etiology of some cases of autism has been proposed in previous studies. To investigate this hypothesis, maternal plasma antibodies against human fetal and adult brain proteins were analyzed by western blot in 61 mothers of children with autistic disorder and 102 controls matched for maternal age and birth year (62 mothers of typically developing children (TD) and 40 mothers of children with non-ASD developmental delays (DD)). We observed reactivity to two protein bands at approximately 73 and 37kDa in plasma from 7 of 61 (11.5%) mothers of children with autism (AU) against fetal but not adult brain, which was not noted in either control group (TD; 0/62 p=0.0061 and DD; 0/40 p=0.0401). Further, the presence of reactivity to these two bands was associated with parent report of behavioral regression in AU children when compared to the TD (p=0.0019) and DD (0.0089) groups. Individual reactivity to the 37kDa band was observed significantly more often in the AU population compared with TD (p=0.0086) and DD (p=0.002) mothers, yielding a 5.69-fold odds ratio (95% confidence interval 2.09-15.51) associated with this band. The presence of these antibodies in the plasma of some mothers of children with autism, as well as the differential findings between mothers of children with early onset and regressive autism may suggest an association between the transfer of IgG autoantibodies during early neurodevelopment and the risk of developing of autism in some children.  相似文献   
8.
Spontaneous abortion studies that recruit pregnant women are left truncated because an unknown proportion of the source population experiences losses prior to enrollment. Unconditional logistic regression, commonly used in such studies, ignores left truncation, whereas survival analysis can accommodate left truncation and is therefore more appropriate. This study assessed the magnitude of bias introduced by fitting logistic versus Cox models using left-truncated data from a 1998 US pregnancy cohort study (n = 5,104) of trihalomethanes and spontaneous abortion. In addition, the conditions producing bias were explored by using simulated exposure data. The odds ratios and hazard ratios from the actual study differed by 10% or less. However, when the exposed women entered observation earlier on average than those unexposed, the hazard ratio was closer to the null than the odds ratio, whereas the reverse was true when the exposed entered later. The simulation suggests that bias in the odds ratio will exceed 20% when average gestational age at entry for the exposed versus the unexposed differs by 10 days or more, as has been observed regarding some socioeconomic factors, such as education and ethnicity. Cox regression can correct for left truncation and is no more difficult to perform than logistic regression.  相似文献   
9.
10.
Objective : This study seeks to determine whether lower survival of black versus white oral and pharyngeal cancer patients is due to, or differs by, stage at diagnosis. Methods : Subjects identified through the North Carolina Central Cancer Registry included all black and white North Carolina residents diagnosed from 1987 to 1990 with malignant squamous cell carcinoma of the oral cavity or pharynx. Proportional hazards regression models were used to calculate hazard ratios for all-cause mortality during the first 18 months after diagnosis, adjusting for age, reported histologic grade, site, and several time-dependent interactions. Results : Within the first two months after diagnosis, the black/white hazard ratio for mortality among those with localized disease was 11.8 (95% Cl=3.7, 37.5), compared to 6.4 (95% Cl=2.6, 15.8) for those with advanced disease. During months 3 to 18 after diagnosis, black/white hazard ratios were 2.07 (95% Cl=1.03, 4.18) among those with localized disease and 1.12 (95% Cl=0.85, 1.47) for those with advanced disease. Conclusion : In the first 18 months after diagnosis, blacks with oral and pharyngeal cancer have higher all-cause mortality than whites diagnosed at the same stage of disease. Racial differences are greater among those with localized disease than for those with more advanced conditions.  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