全文获取类型
收费全文 | 2051篇 |
免费 | 120篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 81篇 |
妇产科学 | 28篇 |
基础医学 | 304篇 |
口腔科学 | 12篇 |
临床医学 | 96篇 |
内科学 | 459篇 |
皮肤病学 | 25篇 |
神经病学 | 312篇 |
特种医学 | 87篇 |
外科学 | 144篇 |
综合类 | 26篇 |
一般理论 | 1篇 |
预防医学 | 311篇 |
眼科学 | 73篇 |
药学 | 106篇 |
肿瘤学 | 95篇 |
出版年
2022年 | 9篇 |
2021年 | 22篇 |
2020年 | 22篇 |
2019年 | 29篇 |
2018年 | 35篇 |
2017年 | 40篇 |
2016年 | 49篇 |
2015年 | 45篇 |
2014年 | 74篇 |
2013年 | 90篇 |
2012年 | 156篇 |
2011年 | 162篇 |
2010年 | 73篇 |
2009年 | 74篇 |
2008年 | 144篇 |
2007年 | 109篇 |
2006年 | 102篇 |
2005年 | 97篇 |
2004年 | 111篇 |
2003年 | 110篇 |
2002年 | 66篇 |
2001年 | 66篇 |
2000年 | 60篇 |
1999年 | 70篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 17篇 |
1992年 | 26篇 |
1991年 | 29篇 |
1990年 | 22篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 23篇 |
1986年 | 14篇 |
1985年 | 22篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1965年 | 4篇 |
排序方式: 共有2173条查询结果,搜索用时 31 毫秒
71.
Sandra J.E. Langeslag Marcus Schmidt Akhgar Ghassabian Vincent W. Jaddoe Albert Hofman Aad van der Lugt Frank C. Verhulst Henning Tiemeier Tonya J.H. White 《Human brain mapping》2013,34(12):3299-3307
It has been shown in adults that individual differences in intelligence are related to the integrity of the interaction between parietal and frontal brain regions. Since connectivity between distant brain regions strengthens during childhood, it is unclear when in the course of development this relationship emerges. Thus, the goal of this study was to determine whether parietal‐frontal functional connectivity is associated with intelligence in young children. We performed independent component analyses on resting‐state fMRI data of 115 children (6–8 years old) to select seed and target regions for a seed/target region correlation analysis. We found that higher nonverbal intelligence was associated with increased functional connectivity between right parietal and right frontal regions, and between right parietal and dorsal anterior cingulate regions. The association between intelligence and functional connectivity between certain brain regions was stronger in girls than boys. In conclusion, we found that connectivity between the parietal and frontal lobes is critically involved in intelligence in young children. Hum Brain Mapp 34:3299–3307, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
72.
73.
Ittermann T Noord Cv Friedrich N D?rr M Felix SB Nauck M V?lzke H Hofman A Witteman JC Stricker BH Wallaschofski H 《Growth hormone & IGF research》2012,22(1):1-5
ObjectivePrevious studies reported associations between insulin-like growth factor I (IGF-I) serum concentration and cardiac morbidity and mortality, but the association between IGF-I serum concentration and cardiac repolarization has not been investigated in a population-based study so far. Therefore, we analyzed the impact of IGF-I concentrations on QTc, QT and RR intervals in two population based studies, The Study of Health in Pomerania (SHIP) and the Rotterdam Study.Design457 individuals from SHIP and 155 individuals from the Rotterdam Study older than 55 years and without cardiovascular diseases and a left ventricular hypertrophy were investigated. IGF-I was determined by automated two-site chemiluminescence immunoassays and electrocardiograms were recorded by an ACTA electrocardiograph at a sampling frequency of 500 Hz. The association of IGF-I with QTc, QT and RR intervals was investigated by multivariable linear regression analyses adjusted for age, gender, diabetes mellitus, myocardial infarction, hypertension, body mass index, serum potassium and calcium in both studies separately and in pooled analysis.ResultsThere were no significant associations between log-transformed IGF-I and QTc interval in the single populations, whereas a significant inverse association was detectable in the pooled population (β, ? 15.6; 95%-confidence interval, ? 25.7, ? 5.5). The QTc interval was significantly higher in the first tertile of IGF-I compared to the third tertile (β, 5.4; 95%-confidence interval, 9.5–1.3) in the pooled analysis.ConclusionThe inverse association between IGF-I serum concentrations and QTc interval in our study is suggestive of a higher risk for cardiac arrhythmias and thus might provide additional evidence for increased cardiovascular mortality in subjects with low IGF-I secretion. 相似文献
74.
Heidi C. Saavedra Perez Nese Direk Albert Hofman Meike W. Vernooij Henning Tiemeier Mohammad Arfan Ikram 《Psychiatry Research: Neuroimaging》2013,211(2):180-182
The present study included 1047 elderly participants. At baseline, brain magnetic resonance imaging (MRI) was performed to detect infarcts and white matter lesions; further, depressive disorders were assessed. Participants were followed up during 3.6 years to determine incident and recurrent depression. We found an increased risk of recurrent depression associated with silent brain infarcts. 相似文献
75.
76.
Chantal M. Koolhaas K. Dhana F. J. A. van Rooij J. D. Schoufour A. Hofman O. H. Franco 《The journal of nutrition, health & aging》2018,22(2):246-253
Objectives
Physical activity (PA) is associated with health-related quality of life (HRQL). The specific PA types that provide beneficial effects in an older population remain unclear. We assessed the association of total PA, walking, cycling, domestic work, sports and gardening with HRQL in middle-aged and elderly adults.Design
Cross-sectional study.Setting
Rotterdam, the Netherlands.Participants
5,554 participants, with a mean age of 69 years.Measurements
Total PA was categorized in five groups to evaluate the dose-response effect of PA and specific PA types were categorized in tertiles. HRQL was measured with the EuroQoL 5-dimension. The outcome of every HRQL domain (i.e. mobility, self-care, daily activities, pain and mood) was expressed as having any problems versus not having problems. Logistic and linear regression analyses were used, adjusting for confounders, to examine associations of total PA and PA types with HRQL domains.Results
In both middle-aged (<65 years) and elderly adults (>65 years), we found a dose-response association between total PA and better HRQL (i.e. lower odds of having problems in HRQL domains). In the middle-aged, sports was the only PA type associated with lower odds of having problems with all HRQL domains. In the elderly, all PA types were associated with less problems with HRQL domains, but cycling contributed most to the beneficial effect.Conclusions
Total PA was associated with better HRQL. Sports and cycling were the activity types that contributed most to this association in the middle-aged and elderly, respectively. Since PA levels tend to decline with aging, cycling and sports should be promoted with the aim to improve HRQL.77.
Hanneke Bakker Romy Gaillard Oscar H. Franco Albert Hofman Albert J. van der Heijden Eric A.P. Steegers H. Rob Taal Vincent W.V. Jaddoe 《Journal of the American Society of Nephrology : JASN》2014,25(11):2607-2615
Low birth weight is associated with ESRD. To identify specific growth patterns in early life that may be related to kidney function in later life, we examined the associations of longitudinally measured fetal and infant growth with kidney function in school-aged children. This study was embedded in a population-based prospective cohort study among 6482 children followed from fetal life onward. Fetal and childhood growth was measured during second and third trimesters of pregnancy, at birth, and at 6, 12, 24, 36, and 48 months postnatally. At the age of 6 years, we measured kidney volume by ultrasound. GFR was estimated using blood creatinine levels. Higher gestational age-adjusted birth weight was associated with higher combined kidney volume and higher eGFR (per 1 SD score increase in birth weight; 1.27 cm3 [95% confidence interval, 0.61 to 1.93] and 0.78 ml/min per 1.73 m2 [95% CI, 0.16 to 1.39], respectively). Fetal weight, birth weight, and weight at 6 months were positively associated with childhood kidney volume, whereas higher second trimester fetal weight was positively associated with higher GFR (all P values<0.05). Fetal and childhood lengths were not consistently associated with kidney function. In this cohort, lower fetal and early infant weight growth is associated with smaller kidney volume in childhood, whereas only lower fetal weight growth is associated with lower kidney function in childhood, independent of childhood growth. Whether these associations lead to an increased risk of kidney disease needs to be studied further.Low birth weight is associated with higher risks of ESRD and hypertension in later life.1–3 Clearly, low birth weight is not the causal factor per se leading to kidney diseases in later life. Birth weight is the result of various exposures and growth patterns in fetal life and the starting point of childhood growth. It has been hypothesized that especially third trimester fetal growth restriction leads to persistently smaller kidneys with a reduced number of nephrons, which may predispose the individual to kidney disease in adulthood.4–6 This hypothesis is supported by both animal and human studies, showing that kidney volume and nephron number are reduced in fetal growth-restricted subjects and hypertensive subjects.7–9 Although nephrogenesis is known to continue until 36 weeks of gestation and cease thereafter, not much is known about the specific critical periods and early growth patterns related to kidney function in later life.10 Also, whether and to what extent the associations of low birth weight with CKD are explained by preterm birth are not known.1 Longitudinal studies suggested that the associations of low birth weight with hypertension were stronger in subjects with rapid weight gain in childhood, but results are inconclusive.11,12 A similar growth pattern has not been identified as a risk factor for kidney diseases yet.Prospective studies linking fetal and early childhood growth patterns to kidney outcomes in later life might help to identify early critical periods for developing impaired kidney function in later life.Therefore, we examined, in a population-based prospective cohort study among 6482 children followed from early fetal life onward (Figure 1), the associations of birth weight, gestational age, birth weight for gestational age, and longitudinally measured fetal and early childhood growth patterns with kidney size and function at school age. We used subclinical variations of kidney function in childhood as outcomes, because they relate to kidney disease in later life.13Open in a separate windowFigure 1.Flow chart: exclusion criteria and numbers of participants are given. Total numbers of available outcome measurements are given. 相似文献
78.
Geelhoed JJ Mook-Kanamori DO Witteman JC Hofman A van Duijn CM Moll HA Steegers EA Hokken-Koelega AC Jaddoe VW 《Clinical endocrinology》2008,68(3):382-389
Objective The objective of this study was to examine whether variants of the IGF1 gene are associated with growth patterns from foetal life until infancy. Study design and measurements This study was embedded in the Generation R Study, a population‐based prospective cohort study of foetal life. Foetal growth (head circumference, abdominal circumference, femur length, estimated foetal weight) was assessed by ultrasound in early, mid‐ and late pregnancy. Growth in infancy was assessed at birth (weight) and at the ages of 6 weeks, 6 months and 14 months (head circumference, length, weight). The IGF1 promoter region genotype was determined in 738 children. Results Eight alleles of the IGF1 promoter region were identified. In total, 43% of the subjects were homozygous for the most common 192‐bp allele (wild‐type), 45% were heterozygous, and 12% were noncarriers of the 192‐bp allele. No differences were found in birthweight between the three groups. However, noncarriers had a lower estimated foetal weight in mid‐pregnancy (P = 0·040), followed by an increased growth rate until 6 months (P < 0·005) in comparison to the 192‐bp homozygotes. A similar difference in growth rate was found for length (P < 0·001). Conclusions Variants of the IGF1 promoter region are not associated with birthweight. However, noncarriers of the 192‐bp allele tend to have a smaller foetal size, followed by an increased growth rate from mid‐pregnancy to early infancy. Studies in larger cohorts are necessary to replicate our findings and to examine whether these effects persist throughout childhood. 相似文献
79.
80.
A new human B lymphocyte membrane antigen, CB2, has been detected by a mouse monoclonal IgM antibody. CB2 appears to be predominantly expressed on normal and malignant cells expressing surface membrane immunoglobulin (SmIg). By indirect immunofluorescence, the number of CB2-positive cells in normal peripheral blood correlated well with the number of SmIg-positive cells. Cytotoxicity studies on isolated cell populations showed that CB2 was present on normal B cells isolated from the spleens of 52 donors and on peripheral blood B cells from 8 donors. Monocytes, T cells, granulocytes, platelets, and red cells were CB2 negative. Only malignant cells expressing SmIg were positive. These included B-CLL, B lymphoma, prolymphocytic leukemia, and B lymphoma cell lines Daudi, Raji, and Conception. SmIg-negative leukemia cells, such as common acute lymphoblastic leukemia, acute and chronic myelogenous leukemia, and T cell leukemias, were negative. Blocking studies with human immunoglobulin suggests that the CB2 antigen is not directed against immunoglobulin determinants. Immunoperoxidase studies on normal lymph node sections show that CB2-positive cells are predominantly present in the mantle region of the follicle, whereas B1- positive cells are mainly in the germinal center. 相似文献