全文获取类型
收费全文 | 442篇 |
免费 | 38篇 |
专业分类
儿科学 | 6篇 |
妇产科学 | 31篇 |
基础医学 | 22篇 |
口腔科学 | 1篇 |
临床医学 | 21篇 |
内科学 | 18篇 |
皮肤病学 | 1篇 |
神经病学 | 76篇 |
特种医学 | 5篇 |
外科学 | 24篇 |
综合类 | 13篇 |
预防医学 | 224篇 |
眼科学 | 1篇 |
药学 | 22篇 |
肿瘤学 | 15篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 4篇 |
2012年 | 25篇 |
2011年 | 31篇 |
2010年 | 10篇 |
2009年 | 15篇 |
2008年 | 32篇 |
2007年 | 22篇 |
2006年 | 21篇 |
2005年 | 27篇 |
2004年 | 23篇 |
2003年 | 11篇 |
2002年 | 17篇 |
2001年 | 26篇 |
2000年 | 22篇 |
1999年 | 21篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 13篇 |
1993年 | 4篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 5篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1971年 | 2篇 |
1968年 | 3篇 |
1967年 | 1篇 |
1966年 | 3篇 |
1965年 | 2篇 |
排序方式: 共有480条查询结果,搜索用时 15 毫秒
1.
Preterm birth subtypes among blacks and whites. 总被引:2,自引:0,他引:2
The differences in preterm birth between blacks and whites are poorly understood. Our study examined subtypes of moderately preterm delivery (34-36 completed weeks of gestation) and very preterm delivery (20-33 weeks) in blacks and whites using North Carolina birth certificate data for 1988-1989. We divided the causes of preterm birth into three categories: preterm premature rupture of the membranes, indication of pregnancy complication, and idiopathic preterm deliveries. The overall prevalence of preterm birth was 8.0% and 16.7% for whites and blacks, respectively. The entire gestational age distribution of blacks was shifted to earlier ages relative to whites. More highly educated blacks still had higher risks of moderately and very preterm deliveries than less educated whites. Multivariate analysis, controlling for other factors, showed that blacks had 3.3, 2.5, and 3.5 times the risk of whites to have preterm premature rupture of the membranes, complication-related, and idiopathic delivery, respectively, among very preterm births, and 1.6, 1.9, and 2.0 times the risk of whites for moderately preterm births of the same three types. 相似文献
2.
Kurtis W. Andrews David A. Savitz Irva Hertz-Picciotto 《American journal of industrial medicine》1994,26(1):13-32
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
3.
The effect of pesticide exposure on time to pregnancy 总被引:10,自引:0,他引:10
The Ontario Farm Family Health Study provided data for examination of the effects of pesticide exposure on time to pregnancy. In this retrospective cohort study of farm couples in Ontario, Canada, the farm operator, husband, and wife completed questionnaires during 1991-1992. We asked about pesticides used on the farm and pesticide activities of the husband and wife for each month of trying to conceive. After exclusions, 2,012 planned pregnancies remained for analysis. We used an analog of the Cox proportional hazards model to calculate conditional fecundability ratios (conditional on pregnancy). There was no strong or consistent pattern of associations of pesticide exposure with time to pregnancy. During exposure intervals in which women participated in pesticide activities (during most of which the men also participated), however, 6 of 13 pesticide exposure categories were associated with a decrease in fecundability (conditional fecundability ratio range = 0.51-0.80). For exposure intervals in which only the men participated in pesticide activities or in which neither men nor women participated in pesticide activities but pesticides had been used on the farm, conditional fecundability ratios ranged from 0.75 to 1.50, with no apparent consistency among pesticide classes, chemical families, or active ingredients. 相似文献
4.
Savitz Dole Williams Thorp McDonald Carter & Eucker 《Paediatric and perinatal epidemiology》1999,13(1):114-125
We describe the study design and patterns of participation for a cohort study of preterm delivery, focused on genital tract infections, nutrition, tobacco use, illicit drugs and psychosocial stress. Women are recruited at 24–29 weeks' gestation from prenatal clinics at a teaching hospital and a county health department. We recruited 57% of the first 1843 eligible women; 29% refused and 8% could not be contacted. White women were somewhat more likely to participate than African-American women (61% vs. 54% respectively). More notable differences were found comparing teaching hospital and health department clinics (71% vs. 47% participation respectively), with the health department clinic having a greater proportion refuse (24% vs. 33%) and more women who could not be contacted (4% vs. 11%). Participation was affected only minimally by day or timing of recruitment, but inability to contact diminished substantially as the study continued (13–0%). Refusals were largely unrelated to patient attributes. Lower education predicted inability to contact. Risk of preterm delivery was 14% among recruited women, 10% among women who refused, and 15% among women whom we were not able to contact, demonstrating that, overall, risk status was not lower among recruited women. 相似文献
5.
6.
7.
Marcas M. Bamman Gary R. Cutter David M. Brienza John Chae Daniel M. Corcos Stephanie DeLuca Edelle Field-Fote Mona N. Fouad Catherine E. Lang Anne Lindblad Robert W. Motl Carla G. Perna Darcy Reisman Kenneth M. Saag Sean I. Savitz Kathryn H Schmitz Jennifer Stevens-Lapsley John Whyte Mary E. Michel 《Archives of physical medicine and rehabilitation》2018,99(12):2637-2648
The purpose of this Special Communication is to summarize guidelines and recommendations stemming from an expert panel convened by the National Institutes of Health, National Center for Medical Rehabilitation Research (NCMRR) for a workshop entitled The Future of Medical Rehabilitation Clinical Trials, held September 29-30, 2016, at the NCMRR offices in Bethesda, Maryland. The ultimate goal of both the workshop and this summary is to offer guidance on clinical trials design and operations to the medical rehabilitation research community, with the intent of maximizing the effect of future trials. 相似文献
8.
Lisa M. McKenzie Ruixin Guo Roxana Z. Witter David A. Savitz Lee S. Newman John L. Adgate 《Environmental health perspectives》2014,122(4):412-417
Background: Birth defects are a leading cause of neonatal mortality. Natural gas development (NGD) emits several potential teratogens, and U.S. production of natural gas is expanding.Objectives: We examined associations between maternal residential proximity to NGD and birth outcomes in a retrospective cohort study of 124,842 births between 1996 and 2009 in rural Colorado.Methods: We calculated inverse distance weighted natural gas well counts within a 10-mile radius of maternal residence to estimate maternal exposure to NGD. Logistic regression, adjusted for maternal and infant covariates, was used to estimate associations with exposure tertiles for congenital heart defects (CHDs), neural tube defects (NTDs), oral clefts, preterm birth, and term low birth weight. The association with term birth weight was investigated using multiple linear regression.Results: Prevalence of CHDs increased with exposure tertile, with an odds ratio (OR) of 1.3 for the highest tertile (95% CI: 1.2, 1.5); NTD prevalence was associated with the highest tertile of exposure (OR = 2.0; 95% CI: 1.0, 3.9, based on 59 cases), compared with the absence of any gas wells within a 10-mile radius. Exposure was negatively associated with preterm birth and positively associated with fetal growth, although the magnitude of association was small. No association was found between exposure and oral clefts.Conclusions: In this large cohort, we observed an association between density and proximity of natural gas wells within a 10-mile radius of maternal residence and prevalence of CHDs and possibly NTDs. Greater specificity in exposure estimates is needed to further explore these associations.Citation: McKenzie LM, Guo R, Witter RZ, Savitz DA, Newman LS, Adgate JL. 2014. Birth outcomes and maternal residential proximity to natural gas development in rural Colorado. Environ Health Perspect 122:412–417; http://dx.doi.org/10.1289/ehp.1306722 相似文献
9.
10.
Savitz LA Kaluzny AD Kelly DL 《Journal of healthcare management / American College of Healthcare Executives》2000,45(5):307-15; discussion 315-6
The changing healthcare environment has created a sense of urgency for continuous innovation in clinical care processes. Managers and clinicians are investing unprecedented funds and energy in the development of various clinical process innovations (CPI) such as clinical pathways, electronic workstations, and various forms of information technology. While increasing attention has been paid to the development of such initiatives, our understanding of how best to disseminate and ensure their use is limited. In this first of two articles dealing with the dissemination and use of CPI in integrated delivery systems, we present a "life cycle" model of the dissemination process and suggest opportunities for managing CPI. The management of CPI requires more than just an understanding of the factors that may facilitate or impede its implementation and use. Managers require an understanding of the actual process so that they can assess the specific implementation stage at which the organization is presently operating, and design appropriate interventions that can affect the process. A future article will identify the factors that facilitate and inhibit the process and suggest some intervention strategies. 相似文献