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   7728篇
  免费   379篇
  国内免费   158篇
耳鼻咽喉   17篇
儿科学   444篇
妇产科学   85篇
基础医学   265篇
口腔科学   90篇
临床医学   904篇
内科学   1152篇
皮肤病学   21篇
神经病学   146篇
特种医学   75篇
外科学   700篇
综合类   879篇
预防医学   2686篇
眼科学   20篇
药学   490篇
  2篇
中国医学   57篇
肿瘤学   232篇
  2023年   158篇
  2022年   330篇
  2021年   417篇
  2020年   344篇
  2019年   387篇
  2018年   328篇
  2017年   256篇
  2016年   288篇
  2015年   271篇
  2014年   626篇
  2013年   496篇
  2012年   445篇
  2011年   540篇
  2010年   441篇
  2009年   387篇
  2008年   341篇
  2007年   349篇
  2006年   271篇
  2005年   271篇
  2004年   207篇
  2003年   140篇
  2002年   123篇
  2001年   116篇
  2000年   71篇
  1999年   62篇
  1998年   58篇
  1997年   48篇
  1996年   39篇
  1995年   29篇
  1994年   38篇
  1993年   19篇
  1992年   15篇
  1991年   21篇
  1990年   19篇
  1989年   19篇
  1988年   16篇
  1987年   13篇
  1985年   23篇
  1984年   45篇
  1983年   30篇
  1982年   31篇
  1981年   34篇
  1980年   26篇
  1979年   10篇
  1978年   12篇
  1977年   11篇
  1976年   10篇
  1975年   6篇
  1974年   7篇
  1973年   6篇
排序方式: 共有8265条查询结果,搜索用时 15 毫秒
61.
BackgroundCalcium, one of the most abundant minerals in the human body, has a pivotal role in human physiology. However, only a few studies have examined the association of dietary calcium intake with mortality in a population with low calcium intake.ObjectiveThe aim of this study was to examine the association of dietary calcium intake with risk of all-cause and cause-specific mortality among Korean adults with low calcium intake.DesignThis study was a prospective cohort study.Participants/settingThe analysis was conducted using data from 44,327 eligible Korean adults aged 19 years and older who participated in the Korea National Health and Nutrition Examination Survey 2007-2015. Dietary calcium intake was assessed using 1-day 24-hour recall data.Main outcome measuresThe main outcomes of this study were mortality from all causes, cancer, cardiovascular disease, respiratory disease, and all other causes combined. The outcome was ascertained through linkage to the death registry compiled by Statistics Korea with the use of the resident registration number.Statistical analyses performedWeighted Cox proportional hazard models were used to estimate the hazard ratios and 95% CIs of the all-cause and cause-specific mortality according to dietary calcium intake.ResultsDuring a mean follow-up of 7.28 person-years, 1,889 deaths were ascertained. After multivariable adjustment, the hazard ratios for all-cause mortality for the second quintile to the highest quintile of dietary calcium intake, respectively, compared with the first quintile were 0.86 (95% CI 0.73 to 1.00), 0.82 (95% CI 0.69 to 0.98), 0.85 (95% CI 0.69 to 1.03), and 0.78 (95% CI 0.64 to 0.96) (P for trend from the lowest to the highest quintile = .04). There were no statistically significant associations between dietary calcium intake and risk of mortality from cancer, cardiovascular, or respiratory disease.ConclusionsIn this large prospective cohort study of Korean adults, lower dietary calcium intake was associated with a higher risk of all-cause mortality.  相似文献   
62.
罗凯  纪明章 《河北医学》2001,7(6):513-515
目的:空肠置管营养支持效果分析。方法:27例患者肠内营养支持,观察营养指标及并发症,结果:25例患者肠内营养支持,增加了营养的摄 入量,改善了氮平衡,并发症明显降低(见表1);2例因多脏器功能竭死亡,结论:大多数外科危重病人可通过肠内营养到营养支持的目的。  相似文献   
63.
目的:评价足月新生儿营养状况及探讨出生体重与营养不良的关系。方法:连续测定了200例正常孕妇的足月单胎新生儿的营养指标。结果:以“三褶”及“三褶”及“二围”均≤第10百分位数为新生儿营养不良,在165例适龄儿中有14例(8.5%)为营养不良儿,15例小于胎龄儿中8例(53.3%)为营养不良儿。结论:“三褶”及“二围”是评价新生儿营养状况的简便,实用且准确的指标,由于小于胎龄儿与营养不良儿的出生结局及预后并不完全一致,故准确评估新生儿营养状况以判断胎儿生长及结局非常重要。  相似文献   
64.
BackgroundWhether nutrition therapy benefits all burn victims equally is unknown. To identify patients who will benefit the most from optimal nutrition, the modified Nutrition Risk in Critically Ill (mNUTRIC) Score has been validated in the Intensive Care Unit. However, the utility of mNUTRIC in severe burn victims is unknown. We hypothesized that a higher mNUTRIC (≥5) will be associated with worse clinical outcomes, but that greater nutritional adequacy will be associated with better clinical outcomes in patients with higher mNUTRIC score.MethodsThis prospective study included data from mechanically ventilated, severe burn patients (n = 359) from 51 Burn Units worldwide included in a randomized trial. Our primary and secondary outcomes were hospital mortality and the time to discharge alive (TTDA) from hospital. We described the association between nutrition performance and clinical outcomes.ResultsCompared to low mNUTRIC (n = 313), the high mNUTRIC group (n = 46) had higher mortality (61% vs. 19%, p = 0.001), and longer TTDA (>90 [87–>90] vs. 64 [38–90] days, p = <0.0001). Only in the high mNUTRIC group, increased calorie intake (per 20% increase) was associated with lower mortality and a faster TTDA.ConclusionsThe mNUTRIC score identifies those with poor clinical outcomes and may identifies those mechanically ventilated, severe burn patients in whom optimal nutrition therapy may be more advantageous.  相似文献   
65.
BackgroundPostbariatric hypoglycemia (PBH) affects up to 38% of Roux-en-Y gastric bypass (RYGB) patients. Severe cases are refractory to diet and medications. Surgical treatments including bypass reversal and pancreatectomy are highly morbid and hypoglycemia often recurs. We have developed a highly effective method of treatment by which enteral nutrition administered through a gastrostomy (G) tube placed in the remnant stomach replaces oral diet: if done correctly this reverses hyperinsulinemia and hypoglycemia, yielding substantial health and quality of life benefits for severely affected patients.ObjectivesTo provide clinical guidelines for placement of a G-tube to treat postRYGB hypoglycemia, including candidate selection, preoperative evaluation, surgical considerations, and post-RYGB management.SettingStanford University Hospital and Clinics.MethodsBased on our relatively large experience with placing and managing G-tubes for PBH treatment, an interdisciplinary task force developed guidelines for practitioners.ResultsA team approach (endocrinologist, dietitian, surgeon, psychologist) is recommended. Appropriate candidates have a history of RYGB, severe hypoglycemia refractory to medical-nutrition therapy, and significantly affected quality of life. Preoperative requirements include education and expectation setting, determination of initial enteral feeding program, and establishing service with a home enteral provider. Close postoperative follow-up is needed to ensure success and may require adjustments in formula and mode/rate of delivery to optimize tolerance and meet nutritional goals. G-tube nutrition must fully replace oral nutrition to prevent hypoglycemia.ConclusionsG-tube placement in the remnant stomach represents a relatively well-tolerated and effective treatment for severe, refractory hypoglycemia after RYGB.  相似文献   
66.
67.
BackgroundPrevious studies have suggested that the possible relationship between serum uric acid (SUA) and testosterone. However, the results of previous studies are controversial and there is limited evidence examining the relationship between SUA and testosterone in a general US population of men. The objective of this study is to explore the correlation of SUA and testosterone among adult males from the US.MethodsData from the National Health and Nutrition Examination Survey 2011–2016 were used, including a total of 7,796 male participants aged 18 years or older and excluding those lacking serum testosterone and uric acid data. Clinical characteristics of the participants among different SUA groups and testosterone groups are compared. Univariate and multivariate linear regression analyses were applied to evaluate the association between SUA and testosterone.ResultsWe found an inverse association between SUA and testosterone after fully adjusted the potential confounding factors in general US adult males. In the multivariate linear regression analysis, we found that increasing age (estimate testosterone percent difference: −0.20% per year, P<0.01), uric acid (estimate testosterone percent difference: −4.40% per md/dL, P<0.01) and BMI (estimate testosterone percent difference: −2.86% per kg/m2, P<0.01) were associated with declining serum testosterone. This association remained significant in sensitivity analysis, while in the stratified analysis, above association was not significant in men with diabetes or aged 65 and over.ConclusionsSUA levels might be negatively associated with serum testosterone in adult males.  相似文献   
68.
InterventionThis study examined whether the impacts of sugar taxes and front-of-pack (FOP) nutrition labels differ across socio-demographic subgroups.Research questionWhat are the main and moderating effects of individual-level characteristics on the nutrient content of participants’ purchases in response to varying taxation levels and FOP labels?MethodsData from an experimental marketplace were analyzed. A sample of 3584 Canadians aged 13 years and older received $5 to purchase an item from a selection of 20 beverages and 20 snack foods. Participants were shown products with one of five FOP labels and completed eight within-subject purchasing tasks with different tax conditions. Linear mixed models were used to estimate the main and moderating effects of 11 individual-level variables on the sugars, sodium, saturated fats, and calorie content of participants’ purchases.ResultsParticipants who were younger, male, and more frequent consumers of sugary drinks purchased products containing more sugars, sodium, saturated fats, and calories. Sex and age moderated the relationship between tax condition and sugars or calories purchased: female participants were more responsive than males to a tax that included fruit juice, and younger participants were more responsive to all sugar tax conditions than older participants. Reported thirst and education level also moderated the relationship between tax condition and calories purchased. No individual-level characteristics moderated the effects of FOP labels.ConclusionA small proportion (7 of 176) of the moderating effects tested in this study were significant. Sugar taxes and FOP labelling policies may therefore produce similar effects across key socio-demographic groups.Supplementary InformationThe online version contains supplementary material available at 10.17269/s41997-021-00475-x.  相似文献   
69.
ObjectiveTo systematically describe the school nutritional policies of the 17 autonomous communities of Spain.MethodThrough a search of bibliographic databases, web pages and other official information systems, 183 documents of interest were identified. Information was systematically collected with the SNIPE (school nutrition index of programme effectiveness) questionnaire, adapted to Spain, and validated by reference staff of the regional government's health and education ministries.ResultsThe main objective of the policies is to prevent obesity and improve the nutrition of schoolchildren. The 17 autonomous communities cover the school canteen service, 11 cafeteria and vending machines, and 9 the breakfast service. All communities use the Consensus Document on School Food as a reference for the content of the menu and the nutritional quality of the products offered at the school; however, only 4 of them have regulated these aspects. The evaluation of policy objectives ranges from 58.8% of the autonomous communities for food supply to 5.9% for rotation and menu quality.ConclusionAlthough all the autonomous communities have standards for the school menu, the standards for the rest of the food supply vary across them; also, evaluation of objectives is scarce and only 4 communities have approved mandatory regulations. Nutritional standards should be reviewed according to current scientific knowledge and enacted by law, in compliance with the current legislation (Act 17/2011).  相似文献   
70.
ObjectiveTo describe food-industry sponsorships of associations active in the field of childhood nutrition and obesity prevention in Spain in 2017-2018.MethodThe associations were located at https://www.google.es/ using the words “society”, “foundation” or “federation” in combination with the terms “nutrition”, “obesity”, “childhood”, “paediatrics” and “diabetes”. Sponsorship was defined as the declaration of funding received or the appearance of a food company logo on an association's website or in the programmes of its congresses or courses. The percentage of sponsored societies and its association with the existence of ethical codes was calculated using MS Excel.Results64% of the associations displayed some type of sponsorship, with this being most frequent among paediatric and nutrition societies, 83% and 80% respectively, and non-existent among public health societies. No association was found between the existence of an ethical code and sponsorship (odds ratio: 0.75; 95% confidence interval: 0.14-3.94). The leading corporate sponsors were Nestlé, Coca-Cola and Danone. Whereas the initiatives of sponsored societies were targeted at changing eating individual behaviours, those of unsponsored societies sought to promote changes in the food system and eating environments.ConclusionsFood industry sponsorship of foundations and scientific societies is very widespread in Spain, except among public health associations. Unlike sponsored associations, those unsponsored propose policies opposed by the food industry, which are aimed at improving the system and food and eating environments.  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