首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   9600篇
  免费   780篇
  国内免费   197篇
耳鼻咽喉   11篇
儿科学   385篇
妇产科学   75篇
基础医学   705篇
口腔科学   230篇
临床医学   593篇
内科学   1689篇
皮肤病学   83篇
神经病学   519篇
特种医学   92篇
外科学   378篇
综合类   623篇
现状与发展   1篇
预防医学   3762篇
眼科学   27篇
药学   566篇
  5篇
中国医学   278篇
肿瘤学   555篇
  2024年   46篇
  2023年   191篇
  2022年   887篇
  2021年   1056篇
  2020年   504篇
  2019年   404篇
  2018年   376篇
  2017年   328篇
  2016年   340篇
  2015年   396篇
  2014年   559篇
  2013年   801篇
  2012年   442篇
  2011年   413篇
  2010年   356篇
  2009年   316篇
  2008年   369篇
  2007年   327篇
  2006年   268篇
  2005年   237篇
  2004年   197篇
  2003年   198篇
  2002年   163篇
  2001年   110篇
  2000年   127篇
  1999年   98篇
  1998年   95篇
  1997年   95篇
  1996年   74篇
  1995年   66篇
  1994年   58篇
  1993年   58篇
  1992年   69篇
  1991年   54篇
  1990年   43篇
  1989年   39篇
  1988年   49篇
  1987年   38篇
  1986年   39篇
  1985年   45篇
  1984年   36篇
  1983年   31篇
  1982年   30篇
  1981年   28篇
  1980年   27篇
  1979年   17篇
  1978年   22篇
  1977年   12篇
  1975年   7篇
  1974年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
While plant-based eating has become increasingly popular, little is known of how this trend has impacted childcare center meals. The purpose of this study was to measure the nutrient content and diet quality of vegetarian alternative lunches and compare these measures to those of standard childcare lunches and nutrient benchmarks representing one-third of the Dietary Reference Intake for 3-year-olds and 4–5-year-olds. Menu data were obtained from seven urban Kansas childcare centers participating in the Child and Adult Care Food Program and regularly providing a vegetarian alternative lunch. The centers provided detailed menu information for 27 days’ worth of meals. The most common vegetarian substitution was cheese, which was used to fulfill all or part of the meat/meat alternative requirement in over three-quarters of the vegetarian alternative meals (n = 22). Compared to the standard meals, the vegetarian alternative meals were higher in calories, fat, saturated fat, calcium, and sodium and lower in protein, choline, and diet quality (p = 0.05). Both lunch options met the benchmarks for vitamin A, vitamin D, vitamin B12, calcium, and protein. Iron content for both (95% CI: standard 1.61–2.17 mg; vegetarian 1.37–2.7 mg) was below the benchmark. Although additional research is needed to better understand how vegetarianism has impacted childcare meals in the U.S., important differences in the nutrient contents were observed between the standard and vegetarian alternative meals. In addition, the results suggest vegetarian alternative meals that rely heavily on cheese may be of lower diet quality.  相似文献   
52.
Recent changes to the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) Cash-Value Benefit (CVB), which provides participants with money to spend on fruits and vegetables, have the potential to reduce disparities in healthy food access and food insecurity that were exacerbated by the COVID-19 pandemic. However, few studies have examined how the changes to the CVB allotment that occurred during the pandemic influenced WIC participants’ perceptions of the benefit or their fruit and vegetable purchasing and consumption. To address this gap, we conducted semi-structured interviews with 51 WIC participants in Wilmington, Delaware. Survey measures included demographic questions, the Hunger Vital Sign food insecurity screener, and open-ended questions regarding perceptions of the CVB increase and its influence on participants’ fruit and vegetable purchasing and consumption. Data were analyzed using a hybrid inductive and deductive coding approach. The results demonstrate that higher CVB allotments increased WIC participants’ purchasing and consumption of fruits and vegetables, increased the frequency of their shopping occasions, and enhanced their dietary variety. Our findings also suggest that WIC participants highly value the increased CVB. Consequently, maintaining the increased CVB allotment could improve the nutritional outcomes of low-income mothers, infants, and children participating in WIC.  相似文献   
53.
The ketogenic diet (KD) has been important in treating epilepsy since the 1920s. The benefits of KD further expanded to other neurological diseases, including Alzheimer’s diseases, autism spectrum disorder, and nutritional disorder (obesity). Although the therapeutic efficacy of KD has been generally accepted, there is limited knowledge about its underlying mechanism of action, particularly its effect on our gut microbiome. Gut dysbiosis has been proposed to be involved in those diseases, and KD can promote gut microbiota remodeling that may assist in recovery. This review explores the therapeutic applications of KD, the roles of the gut microbiome in neurological diseases and obesity, as well as the effect of KD on the gut microbiome. The present information suggests that KD has significant roles in altering the gut microbiome to improve disease symptoms, mainly by incrementing Bacteroidetes to Firmicutes (B/F) ratio and reducing Proteobacteria in certain cases. However, current gaps call for continued research to understand better the gut microbiota profile altered by KD.  相似文献   
54.
Bariatric surgery (BS) is the most effective treatment in reducing weight and the burden of comorbidities in patients with severe obesity. Despite the overall low mortality rate, intra- and post-operative complications remains quite common. Weight loss before BS reduces surgical risk, but studies are inconclusive regarding which is the best approach to apply. In this review, we summarize the current evidence on the effect of a ketogenic diet (KD) before BS. All studies agree that KD leads to considerable weight loss and important improvements in terms of surgical risk, but populations, interventions and outcomes are very heterogeneous. KD appears to be a safe and effective approach to induce weight loss before BS. However, randomized controlled trials with better-defined dietary protocols and homogeneous outcomes are necessary in order to draw firm conclusions.  相似文献   
55.
(1) Background: Developing countries have experienced a rapid recent rise in Inflammatory Bowel Disease (IBD) incidence and emerging evidence suggests processed foods and food additives may predispose one to the development and perpetuation of Crohn’s disease (CD). The aim of this study was to evaluate processed food and food additive intake in CD patients and controls, in Australia (high CD incidence), Hong Kong (intermediate incidence) and mainland China (emerging incidence). (2) Methods: In 274 CD patients (CD), 82 first-degree relatives (FDR), 83 household members (HM) and 92 healthy unrelated controls (HC) from Australia (n = 180), Hong Kong (HK) (n = 160) and mainland China (n = 191) we estimated early life (0–18 years), recent (12 months), and current processed and food additive intake, using validated questionnaires and a 3-day-food diary. (3) Results: Early life processed food intake: Combining all regions, CD were more likely to have consumed soft drinks and fast foods than HM, more likely to have consumed processed fruit and snacks than their FDR, and more likely to have consumed a range of processed foods than HC. HK and China CD patients were more likely to have consumed a range of processed foods than HC. Recent food-additive intake (12-months): Combining all regions, CD patients had significantly higher intakes of aspartame and sucralose, and polysorbate-80, than HC, and more total emulsifiers, artificial sweeteners, and titanium dioxide than FDR and HC. HK and China CD patients had a higher intake of almost all food additives than all controls. Current additive intake (3-days): Australian and HK CD patients had higher total food-additive intake than FDR, and HK CD patients had a higher intake of total food-additives and emulsifiers than HM. (4) Conclusions: CD patients have been exposed to more processed food and food additives than control groups, which may predispose them to CD development and ongoing inflammation.  相似文献   
56.
A lack of adequate exercise threatens human health, weakening human capital accumulation. The relationship between exercise and income has become the focus of attention in health economics. In terms of reducing body weight and improving physical fitness, diet and physical exercise are intertwined and become effective ways to shape a healthy state. Based on individual-level survey data from China, this study quantified the economic returns of habitual exercise behavior by using an endogenous switching regression model (ESRM) to eliminate selection bias. The study shows that (1) participants in the group with regular exercise behavior increased their income by 3.79% compared with those not exercising regularly; (2) for the group with no regular exercise behavior, regular exercise increased their income by 13.36% compared with those not exercising regularly. Additionally, empirical evidence shows that both drinking and smoking can significantly increase individual income, despite unhealthy habits. These results suggest that the habit of regular physical activity plays a vital role in increasing individual income and improving overall national health, and the effect of individual behavior on income is affected by national culture. The outcomes are empirical evidence for the Chinese government to promote Healthy China Action and support developing countries worldwide to enable habitual exercise, stimulating a policy of exercise behavior.  相似文献   
57.
Current evidence on the impact of Mediterranean diet (MeDi) on white matter hyperintensity (WMH) trajectory is scarce. This study aims to examine whether greater adherence to MeDi is associated with less accumulation of WMH. This population-based longitudinal study included 183 cognitively intact adults aged 20–80 years. The MeDi score was obtained from a self-reported food frequency questionnaire; WMH was assessed by 3T MRI. Multivariable linear regression was used to estimate the effect of MeDi on WMH change. Covariates included socio-demographic factors and brain markers. Moderation effects by age, gender, and race/ethnicity were examined, followed by stratification analyses. Among all participants, WMH increased from baseline to follow-up (mean difference [follow-up-baseline] [standard deviation] = 0.31 [0.48], p < 0.001). MeDi adherence was negatively associated with the increase in WMH (β = −0.014, 95% CI = −0.026–−0.001, p = 0.034), adjusting for all covariates. The association between MeDi and WMH change was moderated by age (young group = reference, p-interaction[middle-aged × MeDi] = 0.075, p-interaction[older × MeDi] = 0.037). The association between MeDi and WMH change was observed among the young group (β = −0.035, 95% CI = −0.058–−0.013, p = 0.003), but not among other age groups. Moderation effects by gender and race/ethnicity did not reach significance. Greater adherence to MeDi was associated with a lesser increase in WMH over time. Following a healthy diet, especially at younger age, may help to maintain a healthy brain.  相似文献   
58.
Background: Minimum Acceptable Diet (MAD), developed by the WHO and UNICEF, is a binary indicator of infant and young child feeding practice that assesses the quality and sufficiency of a child’s diet between the ages of 6 and 23 months. Identifying factors associated with MAD among children can inform policymakers to improve children’s nutritional status. Methods: We extracted data of 1930 children aged 6–23 months from the Nepal Multiple Indicator Cluster Survey 2019. Multilevel analysis was performed to identify factors associated with MAD. Results: Only 30.1% of the children received MAD. Children aged 13–18 months [aOR (Adjusted odds ratio): 2.37, 95% CI (95% Confidence Interval): 1.77, 3.17] and 19–23 months (aOR: 2.6, 95% CI: 1.95, 3.47) were more likely to receive MAD than children aged 6–12 months. Early breastfed children (aOR: 1.34, 95% CI: 1.05, 1.72), those currently breastfeeding (aOR: 4.13, 95% CI: 2.21, 7.69) and children without siblings aged under five (aOR: 1.33, 95% CI: 1.03, 1.73) were more likely to receive MAD. Younger maternal age (aOR: 0.97, 95% CI: 0.95–1.0), higher level of mother’s education (aOR: 1.04, 95% CI: 1.0–1.08) and more media exposure among mothers (aOR: 1.66, 95% CI: 1.24, 2.21) were positive predictors of MAD. Relatively disadvantaged ethnicity/caste (aOR: 0.71, 95% CI: 0.53, 0.94), rural residence (aOR: 1.45, 95% CI: 1.06, 2.00) and residing in Madhesh province (aOR: 0.61, 95% CI: 0.37, 1.0) were also significant predictors of MAD. Conclusions: Children aged 6–12 months, without appropriate breastfeeding, having under-five years siblings, with older mother or mother without media exposure or low education, from relatively disadvantaged ethnicity/caste, from urban areas and residing in Madhesh Province were less likely to receive MAD. Our findings can inform infant and young child feeding policies and practices in Nepal.  相似文献   
59.
Dietary intervention is widely used as a therapeutic approach ranging from the treatment of neurological disorders to attempts to extend lifespan. The most important effect of various diets is a change in energy metabolism. Since muscles constitute 40% of total body mass and are one of the major sites of glucose and energy uptake, various diets primarily affect their metabolism, causing both positive and negative changes in physiology and signaling pathways. In this review, we discuss changes in the energy metabolism of muscles under conditions of the low-carbohydrate, high-fat diet/ketogenic diet (KD), fasting, or administration of exogenous ketone bodies, which are all promising approaches to the treatment of various diseases. KD’s main influence on the muscle is expressed through energy metabolism changes, particularly decreased carbohydrate and increased fat oxidation. This affects mitochondrial quantity, oxidative metabolism, antioxidant capacity, and activity of enzymes. The benefits of KD for muscles stay controversial, which could be explained by its different effects on various fiber types, including on muscle fiber-type ratio. The impacts of KD or of its mimetics are largely beneficial but could sometimes induce adverse effects such as cardiac fibrosis.  相似文献   
60.
High carbohydrate, lower fat (HCLF) diets are recommended to reduce cardiometabolic disease (CMD) but low carbohydrate high fat (LCHF) diets can be just as effective. The effect of LCHF on novel insulin resistance biomarkers and the metabolome has not been fully explored. The aim of this study was to investigate the impact of an ad libitum 8-week LCHF diet compared with a HCLF diet on CMD markers, the metabolome, and insulin resistance markers. n = 16 adults were randomly assigned to either LCHF (n = 8, <50 g CHO p/day) or HCLF diet (n = 8) for 8 weeks. At weeks 0, 4 and 8, participants provided fasted blood samples, measures of body composition, blood pressure and dietary intake. Samples were analysed for markers of cardiometabolic disease and underwent non-targeted metabolomic profiling. Both a LCHF and HCLF diet significantly (p < 0.01) improved fasting insulin, HOMA IR, rQUICKI and leptin/adiponectin ratio (p < 0.05) levels. Metabolomic profiling detected 3489 metabolites with 78 metabolites being differentially regulated, for example, an upregulation in lipid metabolites following the LCHF diet may indicate an increase in lipid transport and oxidation, improving insulin sensitivity. In conclusion, both diets may reduce type 2 diabetes risk albeit, a LCHF diet may enhance insulin sensitivity by increasing lipid oxidation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号