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   762篇
  免费   35篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   33篇
妇产科学   16篇
基础医学   106篇
口腔科学   2篇
临床医学   94篇
内科学   130篇
皮肤病学   19篇
神经病学   70篇
特种医学   15篇
外科学   71篇
综合类   5篇
预防医学   113篇
眼科学   4篇
药学   55篇
中国医学   1篇
肿瘤学   58篇
  2024年   2篇
  2023年   11篇
  2022年   12篇
  2021年   32篇
  2020年   27篇
  2019年   27篇
  2018年   31篇
  2017年   21篇
  2016年   29篇
  2015年   24篇
  2014年   31篇
  2013年   48篇
  2012年   38篇
  2011年   70篇
  2010年   24篇
  2009年   26篇
  2008年   39篇
  2007年   34篇
  2006年   47篇
  2005年   41篇
  2004年   27篇
  2003年   28篇
  2002年   29篇
  2001年   7篇
  2000年   4篇
  1999年   5篇
  1998年   5篇
  1997年   10篇
  1996年   11篇
  1995年   11篇
  1994年   4篇
  1992年   10篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   3篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1984年   3篇
  1983年   1篇
  1982年   3篇
  1981年   2篇
  1980年   1篇
  1979年   3篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有798条查询结果,搜索用时 15 毫秒
31.
Muscle-eye-brain disease (MEB), is caused by mutations in the POMGnT1 gene. We describe a white family with two siblings affected with congenital hypotonia early-onset glaucoma, and psychomotor delays. Brain magnetic resonance images (MRIs) showed hydrocephalus, bilateral frontal polymicrogyria, abnormal cerebellum, and characteristic flattened dystrophic pons. We identified novel POMGnT1 gene alterations in this family. Both affected siblings were found to be compound hetrozygotes and carried two missense changes inherited from their mother and one missense change (p.R442C) inherited from their father. Our findings further define the phenotypic spectrum of MEB and its occurrence in the US population.  相似文献   
32.
The US Department of Agriculture's MyPyramid guidelines introduced a near doubling of the dietary recommendations for vegetables. These recommendations target specific subgroups of vegetables, including dry beans and peas. Dry beans and peas provide an array of nutrients and phytochemicals that have been shown to have beneficial health effects, yet consumption levels in the United States are quite low. Few studies have examined the influence of legume consumption on nutrient intakes. Therefore, the purpose of this study was to assess nutrient and food group intakes of dry bean and pea consumers compared to nonconsumers. Dietary intake data from the 1999-2002 National Health and Nutrition Examination Survey for adults aged ≥19 years was used. Results show that on any given day only 7.9% of adults are consuming dry beans and peas; Mexican Americans or other Hispanics are more likely to be consumers than nonconsumers. Consuming approximately ½ c dry beans or peas resulted in higher intakes of fiber, protein, folate, zinc, iron, and magnesium with lower intakes of saturated fat and total fat. These data support the specific recommendation for dry beans and peas as part of the overall vegetable recommendation. Increased consumption of dry beans and peas—economical and nutrient-rich foods—could improve the diet quality of Americans.  相似文献   
33.
Convulsive status epilepticus (SE) in children is an important public health problem, particularly in low-resource countries. A surveillance study was performed with consecutive enrollment of all children presenting with convulsive SE to Hospital Escuela Materno-Infantil Emergency Department in Tegucigalpa, Honduras over a 13-week period in 2003. In the 47 children with SE, the mean age was 4.5 years and the median seizure duration was 95 min. Mortality and morbidity were higher in children from rural locations, with all six deaths and three cases of new neurologic abnormalities occurring in rural children who had acute symptomatic SE. We conclude that childhood SE is common in the low-resource developing country of Honduras. Given the long delays in obtaining initial treatment in pediatric emergency facilities, availability of prehospital treatment may be of particular importance in this setting.  相似文献   
34.
OBJECTIVE: The objective of this study was to evaluate the convergent validity of 3 types of utility measures: standard gamble, time tradeoff, and rating scale. RESEARCH DESIGN: A prospective cohort of 120 men with advanced prostate cancer were first asked to rank order 8 health states, and then utility values were obtained from each participant for each of the 8 health states through 2 of the 3 techniques evaluated (standard gamble, time tradeoff and rating scale). Participants were randomly assigned to 1 of 3 possible pairs of techniques. The validity of the 3 methods, as measured by the convergence and raw score differences of the techniques, was assessed with ANOVA. The ability of the techniques to differentiate health states was determined. The inconsistencies between rankings and utility values were also measured. Proportions of illogical utility responses were assessed as the percent of times when states with more symptoms were given higher or equal utility values than states with fewer symptoms. RESULTS: There were significant differences in raw scores between techniques, but the values were correlated across health states. Utility values were often inconsistent with the rank order of health states. In addition, utility assessment did not differentiate the health states as well as the rank order. Furthermore, utility values were often illogical in that states with more symptoms received equal or higher utility values than states with fewer symptoms. CONCLUSIONS: Use of the utility techniques in cost-effectiveness analysis and decision making has been widely recommended. The results of this study raise serious questions as to the validity and usefulness of the measures.  相似文献   
35.
In a retrospective cohort study of 47 Wilms' tumor survivors and their 77 sibling controls, female survivors had a fourfold excess risk (risk ratio, 4.1; 95% confidence interval, 1.7-10.1) for any adverse livebirth outcome, including birth defects, compared with their sibling controls. Wives of male survivors had no apparent excess risk for problem pregnancies. The families had a number of severe reproductive problems and major birth defects, such as primary amenorrhea in two survivors, bicornuate uterus in two survivors and one control, and mental retardation in one male survivor and a male control. The son of a female survivor died after bilateral Wilms' tumors. Birth defects in the offspring of female survivors are compatible either with intrauterine constraint, possibly due to radiation-induced fibrosis or with the complex of malformations associated with Wilms' tumor. Female survivors of Wilms' tumor appear to be at increased risk for a variety of reproductive problems, from sterility to fetal loss, early delivery, and birth defects in offspring. Furthermore, relatives of survivors of Wilms' tumor may be at risk of having associated birth defects, with clinically significant consequences.  相似文献   
36.
A recent study has suggested that the A218G polymorphism in the homeobox Al (HOXA1) gene may influence susceptibility to autism. We have determined the frequencies of the A and G alleles of the HOXA1 A218G polymorphism in both white and black patients from the South Carolina Autism Project (SCAP) and controls. Marked differences were found in allele frequencies between the races, but no deviations from Hardy-Weinberg equilibrium were seen in either white or black SCAP family members. More direct tests, comparing genotype frequencies between probands and controls and tracking transmission of the A versus G alleles to affected offspring, did not support the contention that allele status for the HOXA1 A218G polymorphism influences one's susceptibility to autism.  相似文献   
37.
Neural tube defects are common birth defects, the frequency of which appears to be reduced by maternal supplementation and/or fortification of folic acid. Latin Americans have a high incidence of neural tube defects. We surveyed the dietary intake of Honduran women of childbearing age using a 24-hour dietary recall questionnaire in inner-city, town, and country areas. We randomly checked blood folate in the surveyed population to compare to the normal range for the US population. Normal US recommended dietary allowance intake of folate was documented in association with a low intake of many other essential nutrients. There also were significant differences for nutrient intakes in city, town, and country areas. Blood folate levels in all locations were in the low normal range when compared to the presupplementation/prefortification US population. Our data support using an established folic acid fortification public health initiative to decrease the prevalence of neural tube defects in Honduras.  相似文献   
38.
39.
40.
OBJECTIVE: We sought to examine differences in valuation of health by individuals from different ethnic backgrounds and between patients and community members. RESEARCH DESIGN: We surveyed 193 community members identified by random-digit dialing (ie, 64 white, 65 black, and 64 Hispanic) and 198 patients with osteoarthritis (OA), 66 per ethnic group, drawn sequentially from clinic lists of an outpatient institution. MEASURES: Participants were interviewed and asked to rate 2 scenarios describing arthritis (mild and severe) using visual analog scale (VAS), standard gamble (SG), and time trade-off (TTO). Differences were adjusted for cohort, age, gender, and education. RESULTS: Members of the public had higher preference scores for the 2 health states than patients (SG severe state: 0.77 public, 0.66 patients; SG mild state: 0.90 public, 0.84 patients). The difference score between the mild and severe states was smaller for black than white subjects (P < 0.001) by SG and TTO. Scores for Hispanics and whites did not differ. Preference scores increased with age (SG, TTO). CONCLUSIONS: Significant differences were observed in the valuation of health between members of the public and patients, among ethnic groups, and in relation to educational status and age, with the difference between utilities of health states being a more efficient measure of preference than the utility of a single state. Utilities elicited through valuation of hypothetical health scenarios are dependent on sociodemographic traits, experience of disease, and method used. These findings suggest that utilities cannot be used interchangeably across populations, with implications for economic analyses.  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