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   86篇
  免费   10篇
儿科学   1篇
妇产科学   2篇
基础医学   16篇
临床医学   9篇
内科学   6篇
皮肤病学   2篇
神经病学   23篇
外科学   2篇
综合类   1篇
预防医学   24篇
药学   3篇
肿瘤学   7篇
  2020年   1篇
  2019年   5篇
  2018年   5篇
  2017年   1篇
  2016年   7篇
  2015年   2篇
  2014年   7篇
  2013年   9篇
  2012年   7篇
  2011年   1篇
  2010年   7篇
  2009年   3篇
  2008年   6篇
  2007年   4篇
  2005年   2篇
  2004年   4篇
  2003年   3篇
  2002年   1篇
  2001年   1篇
  2000年   4篇
  1999年   1篇
  1998年   2篇
  1997年   3篇
  1994年   1篇
  1992年   2篇
  1991年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1976年   1篇
  1969年   1篇
  1961年   1篇
排序方式: 共有96条查询结果,搜索用时 15 毫秒
1.
Molecular analysis of circular excision products and composite genomic switch regions has demonstrated that in mice, immunoglobulin (Ig) isotype switching from IgM to IgE often proceeds sequentially via IgG1. Based on analysis of Ig production in cell cultures, it has been suggested that human B cells may switch to IgE via IgG4, whereas limited molecular data from in vitro switched B cells suggest a direct IgM to IgE switch program. To obtain a quantitative assessment of direct versus sequential IgE switching in humans, we have analyzed the nucleotide sequences of 29 composite Sμ/S? switch regions from freshly isolated human B lymphocytes from patients with atopic dermatitis and from B lymphocytes induced to switch to IgE synthesis in vitro. The data show that in these B cells IgE isotype switching progressed directly from IgM to IgE. We conclude that, in contrast to the murine IgM/IgE switch program, the IgM to IgE switch in B lymphocytes from patients with atopic dermatitis as well as in vitro stimulated B cells from healthy donors preferentially proceeds via direct Sμ to S? switch recombination.  相似文献   
2.
This longitudinal study examines the transition to adulthood in a randomly sampled, community-based cohort of adolescents. The study compares young adult outcomes of 33 adolescents with and 148 adolescents without psychiatric disorder. After adjustment for differences in age, gender, and social class, adolescents with psychiatric disorder were 13.74 times less likely to complete secondary school (95% confidence interval (CI): 4.17, 45.17), 4.07 times less likely to be employed or in college or trade school (95% CI: 1.4, 12.3), 3.13 times more likely to be involved in criminal activity (95% CI: 1.11, 8.87), and 6.46 times more likely to have gotten pregnant themselves or to have gotten someone else pregnant (95% CI: 1.75, 23.87). While adolescents with psychiatric disorder in this community-based study had outcomes that were somewhat more favorable than those of adolescents with psychiatric disorder in prior treatment-based studies, they nonetheless are at high risk of failing to meet young adult role expectations.  相似文献   
3.
4.
Eye movements towards a new target can be guided or disrupted by input from multiple modalities. The degree of oculomotor competition evoked by a distractor depends on both distractor and target properties, such as distractor salience or certainty regarding the target location. The ability to localize the target is particularly important when studying saccades made towards auditory targets, since determination of elevation and azimuth of a sound are based on different processes, and these processes may be affected independently by a distractor. We investigated the effects of a visual distractor on saccadic eye movements made to an auditory target in a two-dimensional plane. Results showed that the competition evoked by a vertical visual distractor was stronger compared with a horizontal visual distractor. The eye movements that were not captured by the vertical visual distractor were still influenced by it: a deviation of endpoints was seen in the direction of the visual distractor. Furthermore, the interference evoked by a high-contrast visual distractor was stronger compared with low-contrast visual stimuli, which was reflected by a faster initiation of an eye movement towards the high-contrast visual distractor and a stronger shift of endpoints in the direction of the high-contrast visual distractor. Together, these findings show that the influence of a visual distractor on aurally guided eye movements depends strongly on its location relative to the target, and to a lesser extent, on stimulus contrast.  相似文献   
5.
This study examined racial/ethnic and socioeconomic differences in service utilization across sectors (specialty mental health, school, primary care) for youth at risk for depression. Our sample included 362 adolescents who were enrolled in a larger project examining the effects of an indicated school-based depression prevention program. Service use across sectors mirrored national trends and previous research findings in which the education sector was most frequently utilized for mental health services. Race/ethnicity was significantly associated with parent-reported specialty mental health service utilization, even when controlling for other predictors of use. The study also suggests that racial disparities in service access generally appear to be reduced through the availability of education sector mental health services. Socioeconomic status was not associated with service use in any sector when controlling for other predictors. Parent–child agreement was moderate for report of specialty mental health service use and low for report of use of services within the education and primary care sectors.  相似文献   
6.
Social media is being used for recruitment and the study of health‐care choices and behavior, and could be particularly helpful to reach young adult populations outside of a 4 year college setting. The aim of this study was to report on overall success of recruiting young adults in diverse settings with respect to education and employment into a study using Facebook (FB). Young adults (n = 380, 50% male, 44% white) who had been involved in a longitudinal research project received a friend request from the research study group's profile. Acceptance rates of friend requests and sociodemographic and mental health factors associated with acceptance were evaluated. Approximately 67% of 318 participants who received a friend request accepted the request. Sociodemographic and mental health characteristics were similar between those who did and did not accept friend requests, suggesting non‐differential recruitment through FB. Friending through FB is a feasible way to reach young adults involved in health and behavioral research, and could be a way to expand the populations that are studied in health science research to maximize generalizability of the conclusions drawn.  相似文献   
7.
This study examines diagnostic and service utilization patterns of transition-age youth in outpatient care derived from the 2007 nationally representative Client/Patient Sample Survey. Comparisons between 16–17, 18–21, and 22–25 year olds are highlighted. Among transition-age outpatients, the oldest youth had the highest rates of depression and bipolar disorder and co-occurring medical and substance use problems. Controlling for sociodemographic and clinical characteristics, 18–21 year olds were less likely to receive individual therapy than 16–17 year olds, but there were no age group differences in receipt of specialized therapy or psychotropic medication. Female gender and Hispanic ethnicity were positively associated with the number of services received and specialized service use, respectively; youth with private insurance were more likely than those with public insurance to receive psychotropic medication. Implications are discussed regarding access to and adequacy of services provided for young people in the critical transition to adulthood, especially with the implementation of the 2010 Affordable Care Act.  相似文献   
8.

Background  

The use of short screening questionnaires may be a promising option for identifying children at risk for depression in a community setting. The objective of this study was to assess the validity of the Short Mood and Feelings Questionnaire (SMFQ) and one- and two-item screening instruments for depressive disorders in a school-based sample of young adolescents.  相似文献   
9.
Prior studies have consistently found the occurrence of depression to be higher among persons with lower socio-economic status (SES), but causal mechanisms for this relationship are often not well understood. For example, while depression has been shown to increase during spells of unemployment, little work has been done on job attributes that may be related to depression among employed people early in their careers. This study links the 1992 wave of the National Longitudinal Survey of Youth 1979 cohort-which included Depression symptom scores on the Center for Epidemiologic Studies Depression (CES-D) instrument-to the US Department of Labor's new occupational characteristics O*Net dataset. The resulting dataset includes information regarding depression, SES, and specific attributes of jobs held by the young adult respondents. Job attributes included measures of social status, interpersonal stressors, and physical conditions. Multivariate analysis revealed that for young men, higher job status is associated with lower CES-D scores. Higher scores on the opposition scale, which measures the extent to which employees are obliged to take a position opposed to others, is associated with higher CES-D scores. For young women, physically uncomfortable or dangerous jobs are associated with more depressive symptoms. Results are stratified by race/ethnicity. For Black men, unlike for White men or Latinos, job security is associated with fewer depressive symptoms; and for Latino men, but not for Black or White men, physically uncomfortable or dangerous jobs are associated with more depressive symptoms. For Black women, job status is associated with fewer depressive symptoms. We conclude that part of the SES-depression relationship may arise from the psychosocial aspects of jobs, which we have found to be significantly and meaningfully associated with depressive symptoms among employed young adults.  相似文献   
10.
Frontally lesioned monkeys (Macaca fasicularis) were significantly impaired relative to controls on a task (similar to that used by Piaget to test the development of object permanency) which required subjects to retrieve a grape hidden under one of three baskets. All monkeys with such lesions completely failed to reach criterion on an additional set of tasks in which the baskets were moved (i.e. the spatial context was modified) while controls performed these tasks with relative ease. Both deficits were shown to be attributable to an inability of “frontal” monkeys to process a varying spatial context.  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