全文获取类型
收费全文 | 1335877篇 |
免费 | 94488篇 |
国内免费 | 2908篇 |
专业分类
耳鼻咽喉 | 19732篇 |
儿科学 | 40230篇 |
妇产科学 | 38659篇 |
基础医学 | 187218篇 |
口腔科学 | 39818篇 |
临床医学 | 112624篇 |
内科学 | 262511篇 |
皮肤病学 | 30211篇 |
神经病学 | 106367篇 |
特种医学 | 53676篇 |
外国民族医学 | 435篇 |
外科学 | 208236篇 |
综合类 | 31050篇 |
现状与发展 | 6篇 |
一般理论 | 436篇 |
预防医学 | 92037篇 |
眼科学 | 31358篇 |
药学 | 100056篇 |
4篇 | |
中国医学 | 2988篇 |
肿瘤学 | 75621篇 |
出版年
2018年 | 11740篇 |
2015年 | 11871篇 |
2014年 | 16685篇 |
2013年 | 25239篇 |
2012年 | 32995篇 |
2011年 | 34861篇 |
2010年 | 20727篇 |
2009年 | 20224篇 |
2008年 | 33571篇 |
2007年 | 36676篇 |
2006年 | 37249篇 |
2005年 | 36004篇 |
2004年 | 35081篇 |
2003年 | 34057篇 |
2002年 | 33585篇 |
2001年 | 63613篇 |
2000年 | 65322篇 |
1999年 | 55386篇 |
1998年 | 14650篇 |
1997年 | 13458篇 |
1996年 | 12937篇 |
1995年 | 12221篇 |
1994年 | 11467篇 |
1992年 | 42761篇 |
1991年 | 41280篇 |
1990年 | 40553篇 |
1989年 | 39550篇 |
1988年 | 36963篇 |
1987年 | 36408篇 |
1986年 | 34899篇 |
1985年 | 33101篇 |
1984年 | 24822篇 |
1983年 | 21052篇 |
1982年 | 12664篇 |
1981年 | 11568篇 |
1980年 | 10772篇 |
1979年 | 23923篇 |
1978年 | 17068篇 |
1977年 | 14834篇 |
1976年 | 13386篇 |
1975年 | 15267篇 |
1974年 | 18080篇 |
1973年 | 17560篇 |
1972年 | 16810篇 |
1971年 | 15717篇 |
1970年 | 14914篇 |
1969年 | 14346篇 |
1968年 | 13460篇 |
1967年 | 12015篇 |
1966年 | 11258篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
Lindsey Haynes-Maslow Lauri Andress Stephanie Jilcott Pitts Isabel Osborne Barbara Baquero Lisa Bailey-Davis Carmen Byker-Shanks Bailey Houghtaling Jane Kolodinsky Brian K. Lo Emily H. Morgan Emily Piltch Elaine Prewitt Rebecca A. Seguin Alice S. Ammerman 《Journal of the Academy of Nutrition and Dietetics》2018,118(9):1664-1672
Background
In 2016, the US Department of Agriculture (USDA)’s Supplemental Nutrition Assistance Program (SNAP) Retailer Rule proposed several changes for SNAP-authorized retailers, including: requiring retailers to have at least 85% of their food sales come from items that are not cooked or heated on site before or after purchase; requiring stores to stock seven varieties of qualifying foods from four staple food groups; requiring stores to carry perishable foods in three of the four staple groups; requiring stores to carry six units of qualifying foods at all times (depth of stock); disqualifying multiple ingredient foods and accessory foods from counting toward depth of stock requirements.Objectives
To better understand arguments used to support or oppose the USDA’s proposed rule that all SNAP-authorized retailers carry more nutritious foods.Design
We conducted a qualitative content analysis of a random sample of public comments posted to the US Federal Register (a publicly available database) in response to the USDA’s proposed rule.Participants/setting
A random sample of 20% of all public comments submitted by individuals and organizations to the US Federal Register were analyzed (n=303) for this study.Results
Three main themes were discussed: 1) arguments used in opposition to the rule; 2) arguments used in support of the rule; and 3) facilitators to assist stores in implementing the rule. Some of the subthemes included focusing on definitions used in the rule, reduced food access caused by stores leaving the SNAP program, lack of space and equipment for healthy foods, and the potential for increasing healthy food access.Conclusions
Nutrition and dietetics practitioners may be tasked with working with stores to implement healthy changes. Nutrition and dietetics practitioners must understand the role that the USDA has in food policy. In addition, understanding how federal food policy influences the environments in which dietetics professionals’ clients are making food choices is important. 相似文献66.
Luis Alfonso Ortíz-Reyes Lilia Castillo-Martínez Arianne Itzel Lupián-Angulo Daniel Dante Yeh Héctor Isaac Rocha-González Aurora Elizabeth Serralde-Zúñiga 《Journal of the Academy of Nutrition and Dietetics》2018,118(1):52-61
Background
Unintentional underfeeding is common in patients receiving enteral nutrition (EN), and is associated with increased risk of malnutrition complications. Protocols for EN in critically ill patients have been shown to enhance adequacy, resulting in better clinical outcomes; however, outside of intensive care unit (ICU) settings, the influence of a protocol for EN is unknown.Objective
To evaluate the efficacy and safety of implementing an EN protocol in a noncritical setting.Design
Randomized controlled clinical trial.Participants and settings
This trial was conducted from 2014 to 2016 in 90 adult hospitalized patients (non-ICU) receiving exclusively EN. Patients with carcinomatosis, ICU admission, or <72 hours of EN were excluded.Intervention
The intervention group received EN according to a protocol, whereas the control group was fed according to standard practice.Main outcome measures
The proportion of patients receiving ≥80% of their caloric target at Day 4 after EN initiation.Statistical analyses performed
Student t test or Wilcoxon rank-sum test were used for continuous variables and the difference between the groups in the time to receipt of the optimal amount of nutrition was analyzed using Kaplan-Meier curves.Results
Forty-five patients were randomized to each group. At Day 4 after EN initiation, 61% of patients in the intervention arm had achieved the primary end point compared with 23% in the control group (P=0.001). In malnourished patients, 63% achieved the primary end point in the intervention group compared with 16% in the control group (P=0.003). The cumulative deficit on Day 4 was lower in the intervention arm compared with the control arm: 2,507 kcal (interquartile range [IQR]=1,262 to 2,908 kcal) vs 3,844 kcal (IQR=2,620 to 4,808 kcal) (P<0.001) and 116 g (IQR=69 to 151 g) vs 191 g (IQR=147 to 244 g) protein (P<0.001), respectively. The rates of gastrointestinal complications were not significantly different between groups.Conclusions
Implementation of an EN protocol outside the ICU significantly improved the delivery of calories and protein when compared with current standard practice without increasing gastrointestinal complications. 相似文献67.
Laura A. Smith Ciara H. O’Flanagan Laura W. Bowers Emma H. Allott Stephen D. Hursting 《Journal of the Academy of Nutrition and Dietetics》2018,118(4):652-667
Prevalence of obesity, an established risk factor for many cancers, has increased dramatically over the past 50 years in the United States and across the globe. Relative to normoweight cancer patients, obese cancer patients often have poorer prognoses, resistance to chemotherapies, and are more likely to develop distant metastases. Recent progress on elucidating the mechanisms underlying the obesity?cancer connection suggests that obesity exerts pleomorphic effects on pathways related to tumor development and progression and, thus, there are multiple opportunities for primary prevention and treatment of obesity-related cancers. Obesity-associated alterations, including systemic metabolism, adipose inflammation, growth factor signaling, and angiogenesis, are emerging as primary drivers of obesity-associated cancer development and progression. These obesity-associated host factors interact with the intrinsic molecular characteristics of cancer cells, facilitating several of the hallmarks of cancer. Each is considered in the context of potential preventive and therapeutic strategies to reduce the burden of obesity-related cancers. In addition, this review focuses on emerging mechanisms behind the obesity?cancer link, as well as relevant dietary interventions, including calorie restriction, intermittent fasting, low-fat diet, and ketogenic diet, that are being implemented in preclinical and clinical trials, with the ultimate goal of reducing incidence and progression of obesity-related cancers. 相似文献
68.
Background
Representative surveys collecting weight, height and MUAC are used to estimate the prevalence of acute malnutrition. The results are then used to assess the scale of malnutrition in a population and type of nutritional intervention required. There have been changes in methodology over recent decades; the objective of this study was to determine if these have resulted in higher quality surveys.Methods
In order to examine the change in reliability of such surveys we have analysed the statistical distributions of the derived anthropometric parameters from 1843 surveys conducted by 19 agencies between 1986 and 2015.Results
With the introduction of standardised guidelines and software by 2003 and their more general application from 2007 the mean standard deviation, kurtosis and skewness of the parameters used to assess nutritional status have each moved to now approximate the distribution of the WHO standards when the exclusion of outliers from analysis is based upon SMART flagging procedure. Where WHO flags, that only exclude data incompatible with life, are used the quality of anthropometric surveys has improved and the results now approach those seen with SMART flags and the WHO standards distribution. Agencies vary in their uptake and adherence to standard guidelines. Those agencies that fully implement the guidelines achieve the most consistently reliable results.Conclusions
Standard methods should be universally used to produce reliable data and tests of data quality and SMART type flagging procedures should be applied and reported to ensure that the data are credible and therefore inform appropriate intervention. Use of SMART guidelines has coincided with reliable anthropometric data since 2007.69.
70.
High efficacy of sofosbuvir/velpatasvir and impact of baseline resistance‐associated substitutions in hepatitis C genotype 3 infection 下载免费PDF全文