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   1316篇
  免费   264篇
  国内免费   10篇
耳鼻咽喉   2篇
儿科学   164篇
妇产科学   23篇
基础医学   51篇
口腔科学   59篇
临床医学   98篇
内科学   216篇
皮肤病学   3篇
神经病学   57篇
特种医学   11篇
外科学   79篇
综合类   76篇
预防医学   602篇
眼科学   9篇
药学   47篇
  1篇
中国医学   4篇
肿瘤学   88篇
  2024年   2篇
  2023年   29篇
  2022年   26篇
  2021年   83篇
  2020年   80篇
  2019年   117篇
  2018年   105篇
  2017年   94篇
  2016年   73篇
  2015年   89篇
  2014年   99篇
  2013年   132篇
  2012年   86篇
  2011年   83篇
  2010年   63篇
  2009年   48篇
  2008年   62篇
  2007年   66篇
  2006年   51篇
  2005年   35篇
  2004年   37篇
  2003年   27篇
  2002年   18篇
  2001年   17篇
  2000年   15篇
  1999年   12篇
  1998年   4篇
  1997年   5篇
  1996年   5篇
  1995年   6篇
  1994年   2篇
  1992年   2篇
  1991年   1篇
  1990年   6篇
  1989年   3篇
  1987年   1篇
  1985年   1篇
  1983年   1篇
  1981年   1篇
  1979年   1篇
  1977年   1篇
  1968年   1篇
排序方式: 共有1590条查询结果,搜索用时 15 毫秒
61.
Background: Over one-third of the world’s population is exposed to household air pollution (HAP) but the separate effects of cooking with solid fuel and kerosene on childhood mortality are unclear.Objectives: To evaluate the effects of both solid fuels and kerosene on neonatal (0-28 days) and child (29 days-59 months) mortality.Methods: We used Demographic and Health Surveys from 47 countries and calculated adjusted relative risks (aRR) using Poisson regression models.Results: The aRR of neonatal and child mortality in households exposed to solid fuels were 1.24 (95% CI: 1.14, 1.34) and 1.21 (95% CI: 1.12, 1.30), respectively, and the aRR for neonatal and child mortality in households exposed to kerosene were 1.34 (95% CI: 1.18, 1.52) and 1.12 (95% CI: 0.99, 1.27), controlling for individual, household, and country-level predictors of mortality.Conclusions: Kerosene should not be classified as a clean fuel. Neonates are at risk for mortality from exposure to solid fuels and kerosene.  相似文献   
62.
ABSTRACT

The use of adaptive methods in clinical development has become very popular in recent years due to its flexibility in modifying trial procedures and/or statistical procedures of on-going clinical trials. Modifications to trial procedures are usually documented by protocol amendments. However, the actual patient population after protocol amendments could deviate from the originally targeted patient population. In addition, protocol amendments made based on accrued data of the on-going trial may distort the sampling distribution of the statistic designed for the case of no protocol change. In this article, we model the population deviations due to protocol amendments using some covariates and study how to develop a valid statistical inference procedure. An example concerning an asthma trial is presented for illustration.  相似文献   
63.
Abstract

This paper investigates the role of race/ethnicity, language skills (a proxy for acculturation among Hispanics in Arizona, California, New Mexico, and Texas), income, and education level on alcohol-related fatal motor vehicle crashes. Using the Fatality Analysis Reporting System (FARS), we confirmed previous state-based studies showing that high income and education levels have a protective influence on alcohol-related fatal motor vehicle crashes. We also confirmed that language proficiency/acculturation tends to increase the vulnerability of Hispanic women to alcohol-related fatalities. Differences in alcohol-related fatality rates across Hispanic subgroups are observed. Future reductions in alcohol-related traffic fatalities may require prevention policies that take into account existent variations in acculturation, income, and education among racial/ethnic groups and subgroups.  相似文献   
64.
65.

The objective of this study was to determine behavioral, personal, and environmental factors that influence low‐income children's fruit and vegetable intake. Focus group questions were developed using the social cognitive theory (SCT). Four Caucasian (27 children) and six Mexican American focus groups (30 children) were conducted. Mexican‐American children stated they had the ability to prepare vegetables and fruits whereas Caucasian children expressed they would rather have their parents do the preparation. This is an example of the behavioral capability construct of SCT. Both ethnic groups mentioned they did not know where vegetables and fruits were stored in the home and this is an environmental construct of SCT. Personal factors of the SCT included Caucasian children preferring to add peanut butter and Ranch dip to vegetables compared to Mexican‐American children preferring to add salt, lime, and chili to vegetables. Sweetness, sourness, juiciness, and crunchiness were seen as good characteristics. All focus groups perceived vegetables and fruits as healthy. All of these issues need to be considered when developing nutrition programming for children.  相似文献   
66.

Two hundred and fifty households comprising in general three adults and four children were randomly sampled in and around Nsukka Local Government Area in Anambra State, Nigeria, to investigate the patterns of consumption and utilisation of cowpea ( Vigna unguiculata), with the long‐term aim of finding ways of maximising its production and consumption. Information was obtained by means of a questionnaire administered in the households, and general physique was assessed by anthropométrie measurements on pre‐school children. The study showed that 13 % of the children investigated were mildly malnourished according to their weight‐for‐height, while 41 % were stunted. It was found that cowpea was very popular; being consumed twice a week or more often by 88 % of respondents, usually in the form of bean‐staple mixes, and 96 % of the households used cowpea for infant feeding. Different techniques for repelling weevils during household storage and current methods of preparing traditional cowpea foods were reported. Reasons for infrequent preparation of these foods were identified. The possible role of an inexpensive, locally manufactured weaning food based on cowpea is discussed.  相似文献   
67.
68.
69.
Past research indicates that socioeconomic status (SES) accounts for differences in sensitivity across ethnic groups. However, comparatively little work has been conducted in Asia, with none examining whether ethnicity moderates the relation between SES and sensitivity. We assessed parenting behavior in 293 Singaporean citizen mothers of 6-month olds (153 Chinese, 108 Malay, 32 Indian) via the Maternal Behavioral Q-Sort for video interactions. When entered into the same model, SES (F(1,288) = 17.777, p < .001), but not ethnicity, predicted maternal sensitivity (F(2,288) = .542, p = .582). However, this positive relation between SES and sensitivity was marginally moderated by ethnicity. SES significantly positively predicted sensitivity in Chinese, but not Malay dyads. Within Indian dyads, SES marginally positively predicted sensitivity only when permanent residents were included in analyses. We discuss the importance of culture on perceived SES-associated stress. However, because few university-educated Malays participated, we also consider whether university education, specifically, positively influences sensitivity.  相似文献   
70.
Objective: To examine self‐reported alcohol consumption and relationships between consumption, awareness of the 2009 NHMRC guidelines of no more than two standard drinks per day, drinking in excess of the guideline threshold and perceptions of alcohol as a risk factor for cancer. Methods: Questions were included in annual, cross‐sectional surveys of approximately 2,700 South Australians aged 18 years and over from 2004 to 2012. Consumption data for 2011 and 2012 were merged for the majority of analyses. Results: In 2011 and 2012, 21.6% of adults drank in excess of the guideline threshold (33.0% males; 10.7% females). While 53.5% correctly identified the NHMRC consumption threshold for women, only 20.3% did so for men (39.0% nominated a higher amount). A large minority said they did not know the consumption threshold for women (39.2%) or men (40.4%). In 2012, only 36.6% saw alcohol as an important risk factor for cancer. Important predictors of excess consumption for men were: higher household income; and not perceiving alcohol as an important risk factor for cancer. Predictors for women were similar but the role of household income was even more prominent. Conclusions: Men were nearly three times as likely to drink in excess of the guidelines as women. The majority of the population did not see an important link between alcohol and cancer. Awareness of the latest NHMRC guidelines consumption threshold is still low, particularly for men. Implications: A strategy to raise awareness of the NHMRC guidelines and the link between alcohol and cancer is warranted.  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