全文获取类型
收费全文 | 455篇 |
免费 | 40篇 |
国内免费 | 11篇 |
专业分类
儿科学 | 98篇 |
妇产科学 | 6篇 |
基础医学 | 85篇 |
口腔科学 | 8篇 |
临床医学 | 47篇 |
内科学 | 62篇 |
皮肤病学 | 5篇 |
神经病学 | 14篇 |
特种医学 | 19篇 |
外科学 | 29篇 |
综合类 | 8篇 |
一般理论 | 1篇 |
预防医学 | 86篇 |
眼科学 | 3篇 |
药学 | 10篇 |
中国医学 | 12篇 |
肿瘤学 | 13篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 13篇 |
2013年 | 11篇 |
2012年 | 25篇 |
2011年 | 13篇 |
2010年 | 20篇 |
2009年 | 14篇 |
2008年 | 13篇 |
2007年 | 20篇 |
2006年 | 21篇 |
2005年 | 19篇 |
2004年 | 30篇 |
2003年 | 23篇 |
2002年 | 16篇 |
2001年 | 22篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 17篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1980年 | 6篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1971年 | 2篇 |
1961年 | 4篇 |
1921年 | 2篇 |
1889年 | 1篇 |
排序方式: 共有506条查询结果,搜索用时 437 毫秒
31.
Friis H Gomo E Nyazema N Ndhlovu P Krarup H Kaestel P Michaelsen KF 《The American journal of clinical nutrition》2004,80(1):178-184
BACKGROUND: Multiple micronutrient deficiencies may contribute to low birth weight, which is a major global determinant of mortality. OBJECTIVE: We assessed the effect of prenatal multimicronutrient supplementation on gestational length and birth size. DESIGN: We conducted a randomized, placebo-controlled, double-blind effectiveness trial among antenatal care attendees in Harare, Zimbabwe. Pregnant women (22-35 wk of gestation) were randomly allocated to receive a multimicronutrient or placebo supplement daily until delivery. Supplementation with iron and folic acid was part of antenatal care. RESULTS: Of 1669 women, birth data were available from 1106 (66%), of whom 360 (33%) had HIV infection. The mean gestational length was 39.1 wk, and 16.6% of the women had a gestational length < 37 wk. The mean birth weight was 3030 g, and 10.5% of the infants had a birth weight < 2500 g. Multimicronutrient supplementation was associated with tendencies for increased gestational length (0.3 wk; 95% CI: -0.04, 0.6 wk; P = 0.06), birth weight (49 g; -6, 104 g; P = 0.08), and head circumference (0.2 cm; -0.02, 0.4 cm; P = 0.07) but was not associated with low birth weight (birth weight < 2500 g) (relative risk: 0.84; 0.59, 1.18; P = 0.31). The effect of multimicronutrient supplementation on birth weight was not significantly different between HIV-uninfected (26 g; -38, 91 g) and HIV-infected (101 g; -3, 205 g) subjects (interaction, P > 0.10). CONCLUSION: Antenatal multimicronutrient supplementation may be one strategy to increase birth size. 相似文献
32.
Hoppe C Mølgaard C Thomsen BL Juul A Michaelsen KF 《The American journal of clinical nutrition》2004,79(3):494-501
BACKGROUND: During the complementary feeding period, infants shift from a daily protein intake (PI) of approximately 1 g/kg body wt to an intake 3-4 times as high. A high PI probably has both endocrine and physiologic effects and may increase the risk of obesity. OBJECTIVE: We examined the associations between PI in infancy and body size and composition in late childhood. DESIGN: We conducted an observational cohort study of 142 Danish healthy term infants (63 boys) born during 1987-1988. At 9 mo of age, diet, weight, length, skinfold thicknesses, insulin-like growth factor I, and serum urea nitrogen were determined. At 10 y of age, 105 children (51 boys) participated in a follow-up study. Diet, weight, height, skinfold thicknesses, percentage of body fat (dual-energy X-ray absorptiometry), insulin-like growth factor I, and serum urea nitrogen were determined. RESULTS: At 9 mo of age, PI (in g/d and percentage of energy) was strongly correlated with body size (length and weight) but not with measures of adiposity. PI at 9 mo of age was positively associated with height and weight but not with percentage of body fat at 10 y of age. Inclusion of parental body size in the models did not change the associations, but the significant associations were attenuated when body size at 9 mo of age was included. CONCLUSIONS: PI in infancy seems to stimulate early growth. This might explain part of the association between early PI and body size at 10 y of age, but a continuous effect of protein on growth during childhood cannot be excluded. PI in infancy was not associated with any measure of body fat at 10 y of age. 相似文献
33.
Benn CS Wohlfahrt J Aaby P Westergaard T Benfeldt E Michaelsen KF Björkstén B Melbye M 《American journal of epidemiology》2004,160(3):217-223
The role of breastfeeding in allergic diseases remains controversial. The authors studied the association between breastfeeding and development of atopic dermatitis during the first 18 months of life among children with and without a parental history of allergy. A cohort study of 15,430 mother-child pairs enrolled in The Danish National Birth Cohort was carried out between 1998 and 2000. Data on breastfeeding, atopic dermatitis, and potential confounders was obtained from telephone interviews conducted during pregnancy and when the children were 6 and 18 months of age. The cumulative incidence of atopic dermatitis was 11.5% at 18 months of age. Overall, current breastfeeding was not associated with atopic dermatitis (incidence rate ratio (IRR) = 0.91, 95% confidence interval (CI): 0.80, 1.04). Exclusive breastfeeding for at least 4 months was associated with an increased risk of atopic dermatitis in children with no parents with allergies (IRR = 1.29, 95% CI: 1.06, 1.55) but not for children with one (IRR = 1.11, 95% CI: 0.94, 1.31) or two (IRR = 0.88, 95% CI: 0.69, 1.13) parents with allergies (test for homogeneity, p = 0.03). The authors found no overall effects of exclusive or partial breastfeeding on the risk of atopic dermatitis. However, the effect of exclusive breastfeeding for 4 months or more depended on parental history of allergic diseases. 相似文献
34.
Nondigestible carbohydrates in the diets of infants and young children: a commentary by the ESPGHAN Committee on Nutrition 总被引:1,自引:0,他引:1
Aggett PJ Agostoni C Axelsson I Edwards CA Goulet O Hernell O Koletzko B Lafeber HN Micheli JL Michaelsen KF Rigo J Szajewska H Weaver LT;ESPGHAN Committee on Nutrition 《Journal of pediatric gastroenterology and nutrition》2003,36(3):329-337
The consumption of nondigestible carbohydrates is perceived as beneficial by health professionals and the general public, but the translation of this information into dietary practice, public health recommendations, and regulatory policy has proved difficult. Nondigestible carbohydrates are a heterogeneous entity, and their definition is problematic. Without a means to characterize the dietary components associated with particular health benefits, specific attributions of these cannot be made. Food labeling for "fiber" constituents can be given only in a general context, and the development of health policy, dietary advice, and education, and informed public understanding of nondigestible carbohydrates are limited. There have, however, been several important developments in our thinking about nondigestible carbohydrates during the past few years. The concept of fiber has expanded to include a range of nondigestible carbohydrates. Their fermentation, fate, and effects in the colon have become a defining characteristic; human milk, hitherto regarded as devoid of nondigestible carbohydrates, is now recognized as a source for infants, and the inclusion of nondigestible carbohydrates in the diet has been promoted for their "prebiotic" effects. Therefore, a review of the importance of nondigestible carbohydrates in the diets of infants and young children is timely. The aims of this commentary are to clarify the current definitions of nondigestible carbohydrates, to review published evidence for their biochemical, physiologic, nutritional, and clinical effects, and to discuss issues involved in defining dietary guidelines for infants and young children. 相似文献
35.
Aim: To describe the prevalence of nutritional rickets among children admitted to three large paediatric departments in the Copenhagen area during a 10 y period. Methods: Retrospective analysis of cases identified from the diagnosis registers fulfilling the diagnostic criteria for nutritional rickets. Results: Forty cases were identified, distributed in two distinct age groups: 0.5-4 y (n = 31) and 9-15 y (n = 9). All cases were immigrants, of whom 95% were born in Denmark. The main symptoms in the younger age group were bowed legs and clumsy walk, and in the peri-pubertal group were painful joints. Two children had generalized convulsions. None of the cases had received vitamin D supplementation. Conclusion: Nutritional rickets is still present among immigrants in Denmark, and it is likely that the prevalence of mild cases is high. Prevention through vitamin D supplementation is important, but requires a dedicated health education effort. 相似文献
36.
37.
Friis H Gomo E Nyazema N Ndhlovu P Krarup H Madsen PH Michaelsen KF 《Journal of acquired immune deficiency syndromes (1999)》2003,33(1):74-81
BACKGROUND: Viral load is a determinant of HIV-1 progression and transmission. Iron status and the phenotype of haptoglobin, a heme-binding acute phase reactant, may be determinants of viral load. We aimed to describe the effect of iron status, haptoglobin phenotype (Hp), and other predictors on HIV-1 viral load. METHODS: Based on a cross-sectional study among 1669 antenatal care attenders (22-35 weeks) in Zimbabwe, 526 (31.5%) were found to be HIV infected. The role of season, age, gravidity, gestational age, malaria parasitemia, Hp, and elevated serum alpha(1)-antichymotrypsin (ACT) as well as serum ferritin, folate, retinol, and beta-carotene on HIV viral load among the 526 HIV-infected women was assessed using multiple linear regression analysis. RESULTS: The distribution of Hp 1-1 (32%), Hp 2-1 (48%), and Hp 2-2 (20%) was not different from that of 53 uninfected women. Mean viral load was 3.85 log(10) (95% CI: 3.77-3.93) genome equivalents (geq)/mL, ranging from 3.77 (95% CI: 3.64-3.90) geq/mL in women with Hp 1-1 to 4.05 (95% CI: 3.81-4.21) geq/mL in women with Hp 2-2. With elevated serum ACT controlled for, women with Hp 2-2 had viral loads twice (95% CI: 1.4-4.0, p =.002) that of women with Hp 1-1, whereas those with serum ferritin <6 micro g/L had viral loads less than one third (95% CI: 0.13-0.53, p =.013) that of women with serum ferritin >24 micro g/L. Viral loads were also higher in women enrolled in the early rainy season compared with the dry season, in gravidae 4+ compared with gravidae 1 through 3, and in those with moderately elevated compared with low serum alpha(1)-antichymotrypsin, but neither age, gestational age, serum folate, serum retinol, nor serum beta-carotene were predictors. CONCLUSION: Storage iron, Hp 2-2, and elevated ACT are independent positive predictors of HIV-1 viral load. The positive relationship between serum ferritin and viral load was not the result of an acute phase response or iron accumulation with advanced HIV infection. A possible detrimental role of iron in HIV infection would have serious public health implications. 相似文献
38.
39.
40.
Aase A Naess LM Sandin RH Herstad TK Oftung F Holst J Haugen IL Høiby EA Michaelsen TE 《Vaccine》2003,21(17-18):2042-2051
A serogroup B meningococcal outer membrane vesicle (OMV) vaccine was delivered either intranasally or intramuscularly to 12 and 10 volunteers, respectively. The mucosal vaccine was given as four weekly doses followed by a fifth dose after 5 months; each dose consisted of OMVs equivalent to 250 microg of protein. The intramuscular (i.m.) vaccine, consisting of the same OMVs but adsorbed to Al(OH)(3), was administered as three doses each of 25 microg of protein, with 6 weeks interval between first and second doses and the third dose after 10 months. Both groups of vaccinees demonstrated significant immune responses when measured as specific IgG antibodies against live meningococci, as serum bactericidal activity (SBA) and as opsonophagocytic activity. Two weeks after the last dose, the anti-meningococcal IgG concentrations were significantly higher in the i.m. group (median IgG concentration: 43.1 microg/ml) than in the intranasal group (10.6 microg/ml) (P=0.001). The corresponding opsonophagocytic activity was 7.0 and 3.0 (median log(2) titre) (P=0.001), and the SBA was 5.0 and 2.0 (median log(2) titre) (P=0.005), for the i.m. and intranasal groups, respectively. The last immunisation induced an enhanced immune response in the i.m. group, whereas the intranasal group showed no significant booster response. Accordingly, affinity maturation of anti-OMV-specific IgG antibodies was seen only after i.m. vaccination. The IgG1 subclass dominated the responses in both groups, whereas the significant IgG3 responses observed in the i.m. group were absent in the intranasal group. Although the intranasal OMV vaccination schedule used here induced functional immune responses relevant to protection, an improved vaccine formulation and/or a modified mucosal immunisation regimen may be needed to achieve a systemic effect comparable to that seen after three doses of intramuscular vaccination. 相似文献