全文获取类型
收费全文 | 10437篇 |
免费 | 888篇 |
国内免费 | 89篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 855篇 |
妇产科学 | 30篇 |
基础医学 | 1686篇 |
口腔科学 | 142篇 |
临床医学 | 369篇 |
内科学 | 824篇 |
皮肤病学 | 134篇 |
神经病学 | 358篇 |
特种医学 | 40篇 |
外科学 | 114篇 |
综合类 | 545篇 |
一般理论 | 1篇 |
预防医学 | 4993篇 |
眼科学 | 13篇 |
药学 | 937篇 |
4篇 | |
中国医学 | 252篇 |
肿瘤学 | 112篇 |
出版年
2024年 | 21篇 |
2023年 | 169篇 |
2022年 | 733篇 |
2021年 | 935篇 |
2020年 | 477篇 |
2019年 | 463篇 |
2018年 | 418篇 |
2017年 | 391篇 |
2016年 | 390篇 |
2015年 | 467篇 |
2014年 | 595篇 |
2013年 | 953篇 |
2012年 | 505篇 |
2011年 | 568篇 |
2010年 | 407篇 |
2009年 | 382篇 |
2008年 | 403篇 |
2007年 | 413篇 |
2006年 | 284篇 |
2005年 | 274篇 |
2004年 | 256篇 |
2003年 | 229篇 |
2002年 | 202篇 |
2001年 | 167篇 |
2000年 | 126篇 |
1999年 | 109篇 |
1998年 | 110篇 |
1997年 | 86篇 |
1996年 | 90篇 |
1995年 | 82篇 |
1994年 | 79篇 |
1993年 | 51篇 |
1992年 | 68篇 |
1991年 | 43篇 |
1990年 | 47篇 |
1989年 | 39篇 |
1988年 | 50篇 |
1987年 | 33篇 |
1986年 | 30篇 |
1985年 | 41篇 |
1984年 | 31篇 |
1983年 | 30篇 |
1982年 | 31篇 |
1981年 | 25篇 |
1980年 | 18篇 |
1979年 | 18篇 |
1978年 | 25篇 |
1977年 | 11篇 |
1976年 | 16篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
961.
《International journal of food sciences and nutrition》2013,64(6):708-712
The present study aimed to analyse the toxic metals in the baby fruit and vegetable desserts, juices and dinners available on the Polish market, and find that these products a less are safe for infants. The average daily intake of cadmium and lead found in one jar of dessert, one bottle of juice and one jar of baby dinner is, respectively, 0.20 μg (2% of PTDI) and 0.82 μg (2.2% of PTDI), 0.15 μg (2% of PTDI) and 4.86 μg (13.6% of PTDI), and 0.98 μg (10% of PTDI) and 2.36 μg (6.7% of PTDI). It was confirmed that all the examined baby food met the requirements regarding lead and cadmium contamination, and the obtained results were lower than the maximum acceptable level of the contamination with these metals. It may be assumed that fruit and vegetable products available on the Polish market are safe for infants. However, in some products, the levels of cadmium and lead were high. 相似文献
962.
《International journal of food sciences and nutrition》2013,64(6):668-673
AbstractThis study aimed to assess the relative validity of maternal dietary patterns derived from a semi-quantitative food frequency questionnaire (FFQ). A total of 162 pregnant women aged 19–40-years-old were enrolled from the Universiti Sains Malaysia (USM) Birth Cohort Study in year 2010 and 2011. The FFQ was compared with three 24-h dietary recalls (DRs). Two major dietary patterns were derived from the principle component analysis which are labeled as Healthy and Less-Healthy patterns. The Pearson correlation coefficients between FFQ and DRs for Healthy and Less-Healthy patterns were 0.59 and 0.63, respectively. At least 45% of the participants were correctly classified into the same third from the FFQ and DR for both dietary patterns. The weighted kappa showed moderate agreement for Healthy pattern while good agreement for Less-Healthy pattern between these two dietary assessment methods. Our results indicate reasonable validity of the dietary patterns identified from the FFQ in pregnant women. 相似文献
963.
本研究以发酵盒法代替常规管发酵法检验食品中大肠菌群.以外形尺寸为79×36×56mm~3的塑料发酵盒代替9支玻璃发酵管;以0.15%软琼脂代替玻璃小倒. 管观察发酵过程中的产气现象.操作简便,结果准确,便于应用. 相似文献
964.
上海地区79种动物性食物的硒含量分析 总被引:3,自引:0,他引:3
<正>近年对硒的生物化学与营养学研究日趋深入,进一步证实了硒对人体营养的重要性,国内外已发表的食物硒含量的论文数量不断增加,这为评价群体的硒摄入量和选择 相似文献
965.
氯霉素的毒性作用和检测方法研究进展 总被引:1,自引:0,他引:1
氯霉素是一种广谱抗生素,因其抗菌效果好且价格低廉而被广泛用于畜牧养殖业,但对人体有不良反应,主要是引起人类骨髓功能抑制,从而导致再生障碍性贫血、血小板减少性紫癜等疾病.目前,我国已禁止在动物性食品生产过程中使用氯霉素,但私自使用的现象仍然存在,这就使氯霉素有可能残留在动物性食品中进而对人体健康构成危害.目前用于氯霉素残留的检测方法主要有:微生物法、免疫学法、气相色谱、液相色谱、气质联用及液质联用等,其中微生物及免疫学法常作为初步筛选实验;色谱法作为确证及定量方法;气质联用与液质联用为我国国标中氯霉素残留检测方法. 相似文献
966.
Naoko Matsuda-Inoguchi Chigusa Date Kozue Sakurai Mikiko Kuwazoe Takao Watanabe Chihiro Toji 《International journal of food sciences and nutrition》2013,64(5-6):279-291
A revised edition of the standard tables of food composition was implemented in Japan in 2005; one of the major revision points is the change of retinol activity equivalents for pro-vitamin A carotenoids. This preliminary analysis was conducted to examine whether the revision affects the estimation of vitamin A intake; and if so, to what extent. Accordingly, a field survey was conducted to collect 24-h duplicates of daily foods of citizens, and 26 adult women volunteered. Application of the procedures in the new and previous standard tables of food composition gave 537 µg retinol activity equivalent and 704 µg retinol equivalence, respectively, for daily vitamin A intake. Thus, the changes in retinol activity equivalents induced substantial reduction (by 24%) in estimation of vitamin A intake among the Japanese population, for whom pro-vitamin A carotenoids in plant foods are the major sources (76%) for vitamin A, and retinol accounts for only 35% (on the retinol activity equivalent basis). 相似文献
967.
V. Sudha G. Radhika R. M. Sathya A. Ganesan 《International journal of food sciences and nutrition》2013,64(7-8):481-493
We report on the reproducibility and validity of a food frequency questionnaire (FFQ) developed for southern India. One hundred and two adult subjects aged ≥20 years drawn from the Chennai Urban Rural Epidemiology Study participated. The FFQ was developed based on local foods and habits, and was administered three times at 0, 6 and 12 month periods (called FFQ1, FFQ2 and FFQ3) to assess the reproducibility. To test the validity of the FFQ, multiple 24-h recalls collected at 2-monthly intervals for a period of 1 year and the estimated energy intake/basal metabolic rate (EI/BMR) ratio were used. The ‘EpiNu’ in-house food and nutrient database was used to compile dietary intakes, which were analyzed for statistical analysis. The intraclass correlation coefficient for all three FFQs ranged from 0.72 for carbohydrates to 0.45 for folate. The de-attenuated Pearson correlation for the energy adjusted nutrients between FFQ3 and 24-h recalls ranged from 0.73 for carbohydrates to 0.35 for calcium. Bland and Altman plots for energy intake between the two methods showed the limits of agreement ranged from 768 to ?1358 calories/day (±2 standard deviations). Misclassification was low for most of the nutrients. Under-reporting of the energy intake (EI/BMR ratio<1.2) was higher in females than males. This FFQ appears to be a robust tool to measure dietary intakes in southern India. 相似文献
968.
Manuel Salas Carmen Torrero Mirelta Regalado Esther Perez 《Nutritional neuroscience》2013,16(6):399-405
AbstractIn the rat, perinatal food and maternal deprivation provoke long-lasting effects upon the retrieving responses of dams to displaced pups. In the current study, the retrieving latency and the disruption in the body area of pups chosen by the mother to transport them to a new location was investigated on days 4, 8 and 12 postpartum in lactating Wistar rats. Rats, neonatally underfed by daily (12 h) mother-litter separation in an incubator from days 1 to 23 postpartum, exhibited prolonged retrieving latencies and disruption in the body area of young ones chosen by the dam to transport them to the nest. Furthermore, neonatally underfed dams frequently transported pups in a rude manner eliciting sonic distress cries from them compared to control mothers. These findings are possibly relevant to understand the impact of epigenetic influences on offspring brain and physiological maturation partly mediated through maternal care. 相似文献
969.
Tania Beninga Morais Dirce Maria Sigulem 《Journal of the American College of Nutrition》2013,32(3):284-288
Objectives: To determine the macronutrients composition of home-prepared milk feeding bottles, by chemical analysis, and assess their contribution to the energy and protein requirements of children under two years of age from high (HSE) and low (LSE) socioeconomic classes.Methods: 72 samples were analyzed for energy density and protein, fat and carbohydrate content: 41 from the LSE group and 31 from the HSE group. The assessment of the percentages of the energy and protein requirements met by the consumption of the milk bottles was calculated as follows: the energy and protein per 100 mL obtained through chemical analysis were multiplied by the volume consumed at each feeding, then by the number of feedings per day, the results divided by the energy and protein requirements and multiplied by 100. Energy and protein requirements were those recommended by the FAO/WHO/UNU Committee and the Food and Nutrition Board. The children’s weight-for-age index was assessed.Results: Unmodified cow’s milk was largely consumed by both groups. The addition of sugar and other ingredients to the milk was significantly higher in the LSE group. Moisture, protein and fat content were lower in the LSE group, whereas carbohydrate and energy content were higher. The percentages of energy and protein requirements provided by feeding bottles were higher in the LSE group. Children in the LSE group had lower z-scores for weight-for-age.Conclusions: Differences in the preparation practices led to differences in the chemical results. The feeding bottles in the LSE group were high in energy, due to the addition of sugar and cereals to the milk in the bottle. The milk feeding bottles were an important weaning food providing more than 50% and 100% of the children’s energy and protein requirements, respectively. The children’s weight-for-age index was within the normal limits. 相似文献
970.
Won O. Song Chin-Eun Chung Ock Kyoung Chun Susan Cho 《Journal of the American College of Nutrition》2013,32(6):503-509
Background: Elevated serum total homocysteine (tHcy) concentration is implicated in the etiology of cardiovascular disease (CVD). A significant food source of B-vitamins involved in homocysteine metabolism is ready-to-eat cereal (RTEC) in the U.S.Objective: To test the hypothesis that tHcy concentration is inversely associated with RTEC intake and blood B-vitamin levels in the U.S. general population.Design: A cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES 1999–2000). Data were stratified according to age and gender. Men and women ≥ 19 y (n = 4,218) were classified as RTEC consumers (RTEC-C; n = 824) and RTEC non-consumers (RTEC-NC; n = 3,394) based on 24-hr dietary recall.Results: Forty nine percent of participants showed folate intake with below the estimated average requirements (EARS). Serum folate and red blood cell (RBC) folate concentrations were increased with age in both genders, and significantly higher among RTEC-C than RTEC-NC (p < 0.05). Mean tHcy concentration increased with age, and was significantly lower among both men and women RTEC-C than among RTEC-NC. In multivariate linear regression analyses, RTEC consumption strongly predicted serum folate and tHcy concentrations.Conclusion: tHcy concentrations were significantly lower in RTEC-C among the majority of age/gender groups than in RTEC-NC. RTEC consumption may potentially reduce the risk for CVD, mediated through tHcy. 相似文献