全文获取类型
收费全文 | 4033篇 |
免费 | 419篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 196篇 |
妇产科学 | 151篇 |
基础医学 | 486篇 |
口腔科学 | 52篇 |
临床医学 | 530篇 |
内科学 | 644篇 |
皮肤病学 | 209篇 |
神经病学 | 269篇 |
特种医学 | 221篇 |
外科学 | 687篇 |
综合类 | 120篇 |
一般理论 | 1篇 |
预防医学 | 387篇 |
眼科学 | 64篇 |
药学 | 260篇 |
中国医学 | 11篇 |
肿瘤学 | 155篇 |
出版年
2023年 | 19篇 |
2022年 | 20篇 |
2021年 | 62篇 |
2020年 | 38篇 |
2019年 | 60篇 |
2018年 | 84篇 |
2017年 | 76篇 |
2016年 | 76篇 |
2015年 | 87篇 |
2014年 | 122篇 |
2013年 | 157篇 |
2012年 | 197篇 |
2011年 | 203篇 |
2010年 | 139篇 |
2009年 | 137篇 |
2008年 | 175篇 |
2007年 | 215篇 |
2006年 | 173篇 |
2005年 | 208篇 |
2004年 | 170篇 |
2003年 | 152篇 |
2002年 | 141篇 |
2001年 | 119篇 |
2000年 | 104篇 |
1999年 | 118篇 |
1998年 | 90篇 |
1997年 | 82篇 |
1996年 | 68篇 |
1995年 | 75篇 |
1994年 | 54篇 |
1993年 | 58篇 |
1992年 | 80篇 |
1991年 | 85篇 |
1990年 | 68篇 |
1989年 | 78篇 |
1988年 | 49篇 |
1987年 | 65篇 |
1986年 | 58篇 |
1985年 | 66篇 |
1984年 | 42篇 |
1983年 | 43篇 |
1982年 | 25篇 |
1981年 | 28篇 |
1980年 | 22篇 |
1979年 | 24篇 |
1978年 | 22篇 |
1977年 | 19篇 |
1976年 | 34篇 |
1974年 | 26篇 |
1973年 | 19篇 |
排序方式: 共有4463条查询结果,搜索用时 15 毫秒
61.
Getahun D Ananth CV Oyelese Y Chavez MR Kirby RS Smulian JC 《Obstetrics and gynecology》2007,110(6):1319-1325
OBJECTIVE: To examine the association between changes in prepregnancy body mass index (BMI) between a woman's first two pregnancies and incidence of preeclampsia in the second pregnancy. METHODS: We performed a population-based retrospective cohort analysis using data on women's first two singleton pregnancies (n=136,884) in Missouri (1989-1997). The study was restricted to women without preeclampsia in the first pregnancy. Prepregnancy BMI (kg/m(2)) was categorized as underweight (less than 18.5), normal (18.5-24.9), overweight (25-29.9), and obese (30 or greater). Analyses were adjusted for confounders through multivariable logistic regression. RESULTS: The incidence rate of preeclampsia in the second pregnancy was 2.0%. In comparison with women who were of normal BMI in both pregnancies, the risk for preeclampsia increased when BMI changed between the first two pregnancies from underweight to obese (odds ratio [OR] 5.6, 95% confidence interval [CI] 1.7-18.2), normal to overweight (OR 2.0, 95% CI 1.7-2.3), normal to obese (OR 3.2, 95% CI 2.5-4.2), and overweight to obese (OR 3.7, 95% CI 3.1-4.3). Being obese or overweight in both pregnancies was associated with increased risk of preeclampsia in the second pregnancy. Women who increased their BMI from underweight to normal or overweight between pregnancies had risks of preeclampsia comparable with those with normal BMI in both pregnancies. African-American, but not white, women who had a reduction in BMI from obese or overweight to normal between pregnancies remained at increased risk for preeclampsia. CONCLUSION: Increases in prepregnancy BMI from normal weight to overweight or obese between pregnancies are associated with increased risk of preeclampsia in the subsequent pregnancy. LEVEL OF EVIDENCE: II. 相似文献
62.
Kristensen S Salihu HM Keith LG Kirby RS Pass MA Fowler KB 《The journal of obstetrics and gynaecology research》2007,33(3):259-265
AIM: We examined the impact of advanced maternal age (>40 years old) on the survival of twin small-for-gestational-age (SGA) infants, that is, infants who were smaller in size than was expected for the baby's sex, genetic heritage, and gestational age. METHODS: The present study was a retrospective cohort study on twin live births in the USA from 1995 to 1998 inclusive. Two categories of SGA babies were defined: discordant (when only one of a twin pair was SGA) and concordant (when both were SGA). Otherwise, the twin pair was appropriate-for-gestational-age (AGA) concordant. RESULTS: 192,195 twin pairs were analyzed. The incidence of SGA discordance and concordance was 11.8% and 3.9%, respectively. The occurrence of both SGA subtypes tended to decrease with increasing maternal age. The unadjusted risk for neonatal mortality increased when both twins were affected (15.8: 22.8 and 56.6 per 1000 among AGA concordant, SGA discordant and SGA concordant twins; P-value for trend < 0.0001). Using maternal-age-specific AGA babies as reference, the adjusted risk for neonatal mortality climbed progressively with advancing maternal age in a dose-dependent pattern, being lowest among teenagers and highest in mothers aged > or =40 years. CONCLUSIONS: SGA discordance and concordance declined with advancing maternal age. In contrast, neonatal mortality of both SGA subtypes worsened with the increase in maternal age compared with that of the age-specific AGA infants. These findings are potentially useful to care providers in counseling older women, a group that is progressively increasing in size and is most susceptible to twining. 相似文献
63.
Daniel B. Kirby 《The Journal of experimental medicine》1927,45(6):1009-1016
1. Differentiation of the posterior cells of the lens vesicle into lens cortex has been observed in vitro. 2. It is possible to dissect out the lens of the 5 day embryo chick in such a manner as to free it from all extraneous cells. 3. Lens epithelium even at a very early stage is contained within a cuticula. 4. Lens epithelium under proper conditions will live, migrate, divide, and multiply in vitro in primary explants. 5. An unmixed strain of lens epithelium can be propagated from a primary explant by successive subcultures. This strain can be utilized for controlled experiments on the nutrition of the cells of the lens. 相似文献
64.
Mary E. Patrick Kelly A. Shaw Patricia M. Dietz Jon Baio Marshalyn Yeargin-Allsopp Deborah A. Bilder Russell S. Kirby Jennifer A. Hall-Lande Rebecca A. Harrington Li-Ching Lee Maya Liza C. Lopez Julie Daniels Matthew J. Maenner 《Disability and health journal》2021,14(2):101023
BackgroundChildren with intellectual disability (ID), characterized by impairments in intellectual functioning and adaptive behavior, benefit from early identification and access to services. Previous U.S. estimates used administrative data or parent report with limited information for demographic subgroups.ObjectiveUsing empiric measures we examined ID characteristics among 8-year-old children and estimated prevalence by sex, race/ethnicity, geographic area and socioeconomic status (SES) area indicators.MethodsWe analyzed data for 8-year-old children in 9 geographic areas participating in the 2014 Autism and Developmental Disabilities Monitoring Network. Children with ID were identified through record review of IQ test data. Census and American Community Survey data were used to estimate the denominator.ResultsOverall, 11.8 per 1,000 (1.2%) had ID (IQ ≤ 70), of whom 39% (n = 998) also had autism spectrum disorder. Among children with ID, 1,823 had adaptive behavior test scores for which 64% were characterized as impaired. ID prevalence per 1,000 was 15.8 (95% confidence interval [95% CI], 15.0–16.5) among males and 7.7 (95% CI, 7.2–8.2) among females. ID prevalence was 17.7 (95% CI, 16.6–18.9) among children who were non-Hispanic black; 12.0 (95% CI, 11.1–13.0), among Hispanic; 8.6 (95% CI, 7.1–10.4), among non-Hispanic Asian; and 8.0 (95% CI, 7.5–8.6), among non-Hispanic white. Prevalence varied across geographic areas and was inversely associated with SES.ConclusionsID prevalence varied substantively among racial, ethnic, geographic, and SES groups. Results can inform strategies to enhance identification and improve access to services particularly for children who are minorities or living in areas with lower SES. 相似文献
65.
Enio R Vasques Estela RR Figueira Joel A Rocha-Filho Cinthia Lanchotte Jorge LS Ximenes Helena B Nader Ivarne LS Tersariol Marcelo A Lima Tiago Rodrigues José EM Cunha Eleazar Chaib Luiz AC D'Albuquerque Flávio HF Galv?o 《Hepatobiliary & pancreatic diseases international : HBPD INT》2022,21(2):190-192
<正>To the Editor:Ischemia-reperfusion injury following surgery and transplantation can lead to irreversible multiorgan failure.Intracellular calcium overload is associated to cellular death during ischemiareperfusion.A recently discovered heparin fragment (HF),trisulfated disaccharide (TD),that acts on sodium-calcium exchanger(NCX) decreasing intracellular Ca2+,showed effectiveness on protecting hepatocytes from ischemia-reperfusion injury [1], 相似文献
66.
G.N. Marta D. Ramiah O. Kaidar-Person A. Kirby C. Coles R. Jagsi T. Hijal G. Sancho Y. Zissiadis J.-P. Pignol A.Y. Ho S.H.-C. Cheng B.V. Offersen I. Meattini P. Poortmans 《Clinical oncology (Royal College of Radiologists (Great Britain))》2021,33(5):322-330
AimsModerately hypofractionated breast irradiation has been evaluated in several prospective studies, resulting in wide acceptance of shorter treatment protocols for postoperative breast irradiation. Reimbursement for radiation therapy varies between private and public systems and between countries, impacting variably financial considerations in the use of hypofractionation. The aim of this study was to evaluate the financial impact of moderately hypofractionated breast irradiation by reimbursement system in different countries.Materials and methodsThe study was designed by an international group of radiation oncologists. A web-questionnaire was distributed to representatives from each country. The participants were asked to involve the financial consultant at their institution.ResultsData from 13 countries from all populated continents were collected (Europe: Denmark, France, Italy, the Netherlands, Spain, UK; North America: Canada, USA; South America: Brazil; Africa: South Africa; Oceania: Australia; Asia: Israel, Taiwan). Clinicians and/or departments in most of the countries surveyed (77%) receive remuneration based on the number of fractions delivered to the patient. The financial loss per patient estimated resulting from applying moderately hypofractionated breast irradiation instead of conventional fractionation ranged from 5–10% to 30–40%, depending on the healthcare provider.ConclusionAlthough a generalised adoption of moderately hypofractionated breast irradiation would allow for a considerable reduction in social and economic burden, the financial loss for the healthcare providers induced by fee-for-service remuneration may be a factor in the slow uptake of these regimens. Therefore, fee-for-service reimbursement may not be preferable for radiation oncology. We propose that an alternative system of remuneration, such as bundled payments based on stage and diagnosis, may provide more value for all stakeholders. 相似文献
67.
Carissa M. Baker-Smith MD Angelo S. Milazzo MD Donald P. Frush MD James Jaggers MD Margaret L. Kirby MD Ronald J. Kanter MD Piers C. Barker MD 《Congenital heart disease》2010,5(3):316-320
Aortic valve atresia with interruption of the aortic arch is an extremely rare anomaly; only eleven cases of this anomaly have been reported to date. In the absence of additional sources of blood flow to the ascending aorta, aortic valve atresia with interruption of the aortic arch is fatal. We present, to the best of our knowledge, the first case of a live birth with aortic valve atresia and interrupted left aortic arch (type B) without evidence of an aorticopulmonary communication or ductal supply to the native ascending aorta. Instead, blood flow to the native aortic root was derived from a persistent right embryonic dorsal aorta. 相似文献
68.
69.
70.
Monika Oláhová Tobias B Haack Charlotte L Alston Jessica AC Houghton Langping He Andrew AM Morris Garry K Brown Robert McFarland Zofia MA Chrzanowska-Lightowlers Robert N Lightowlers Holger Prokisch Robert W Taylor 《European journal of human genetics : EJHG》2015,23(7):935-939
Isolated mitochondrial complex IV (cytochrome c oxidase) deficiency is an important cause of mitochondrial disease in children and adults. It is genetically heterogeneous, given that both mtDNA-encoded and nuclear-encoded gene products contribute to structural components and assembly factors. Pathogenic variants within these proteins are associated with clinical variability ranging from isolated organ involvement to multisystem disease presentations. Defects in more than 10 complex IV assembly factors have been described including a recent Lebanese founder mutation in PET100 in patients presenting with Leigh syndrome. We report the clinical and molecular investigation of a patient with a fatal, neonatal-onset isolated complex IV deficiency associated with multiorgan involvement born to consanguineous, first-cousin British Asian parents. Exome sequencing revealed a homozygous truncating variant (c.142C>T, p.(Gln48*)) in the PET100 gene that results in a complete loss of enzyme activity and assembly of the holocomplex. Our report confirms PET100 mutation as an important cause of isolated complex IV deficiency outside of the Lebanese population, extending the phenotypic spectrum associated with abnormalities within this gene. 相似文献