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   152篇
  免费   11篇
  国内免费   1篇
耳鼻咽喉   2篇
儿科学   9篇
妇产科学   2篇
基础医学   34篇
口腔科学   1篇
临床医学   6篇
内科学   27篇
皮肤病学   20篇
神经病学   31篇
外科学   2篇
综合类   1篇
预防医学   14篇
药学   4篇
肿瘤学   11篇
  2023年   4篇
  2022年   1篇
  2021年   3篇
  2020年   3篇
  2019年   3篇
  2018年   2篇
  2017年   2篇
  2016年   2篇
  2015年   2篇
  2014年   7篇
  2013年   8篇
  2012年   8篇
  2011年   14篇
  2010年   6篇
  2009年   8篇
  2008年   20篇
  2007年   16篇
  2006年   11篇
  2005年   7篇
  2004年   10篇
  2003年   7篇
  2002年   9篇
  2001年   1篇
  1998年   1篇
  1996年   1篇
  1993年   1篇
  1992年   1篇
  1984年   1篇
  1981年   1篇
  1979年   1篇
  1978年   3篇
排序方式: 共有164条查询结果,搜索用时 15 毫秒
51.
The distribution of immunocompetent cells was analysed in allergic (nickel) and irritant (dithranol) patch tests using conventional transmission electron microscopy and labelling with monoclonal antibodies in an avidin-biotin immunoperoxidase study. The biopsies were taken 24 or 48 h after the allergen/irritant application. In allergic and irritant reactions, most inflammatory cells were OKT11 positive (pan T lymphocytes). The majority of these cells were also OKT4 positive (helper/inducer T lymphocytes), while the minority were OKT8 positive (suppressor/cytotoxic T lymphocytes). NK9 positive cells (natural killer cells) were observed in small numbers. The number of dendritic OKT6 and OKIal positive cells (Langerhans cells) in the epidermis was unaffected in allergic reactions. In irritant reactions, a normal number of OKT6 positive Langerhans cells was observed, while the number of OKIal positive cells had increased in the epidermis. Dithranol caused prominent fine structural changes in the mitochondria of the Langerhans cells, while the keratinocytes appeared largely unaffected. The present study indicates that allergic and irritant patch tests cannot be differentiated reliably using current immunohistopathological or electron microscopic techniques, in spite of the small differences observed.  相似文献   
52.

Purpose

Becoming a smoker usually starts during adolescence and is a dynamic process involving experimentation before the establishment of daily smoking. It has been suggested that adolescents who smoke differ from those who do not in their attitudes to smoking. The purpose of this study was to find out whether attitudes related to smoking legislation and restrictions, social pressures in smoking and image of smokers are associated with smoking experimentation, daily smoking and best friends’ smoking.

Method

The data were gathered with a self-administered questionnaire in North Karelia, Eastern Finland and in the Pitkyaranta district, Republic of Karelia, Russia. The respondents were 15-year-old 9th grade pupils in local schools. In Pitkyaranta, the data analyses covered pupils in all eight schools in the area (n?=?179). In North Karelia, the data analyses comprised of selected eight schools (n?=?601). Data were analysed with exploratory factor analysis.

Results

The models revealed that attitudes related to restrictions and social pressure were significantly associated with experimenting with smoking [OR (95 % CI) 7.923 (5.787–10.847)], daily smoking [OR (95 % CI) 9.575 (6.727–13.628)] and the likelihood of best friends’ smoking [OR (95 % CI) 3.154 (2.579–3.858)]. The stronger the young peoples’ attitudes and opinions, for example, towards restrictions and with more difficulties in refusing smoking, the higher the likelihood for smoking experimentations, daily smoking as well as the likelihood for their best friends’ smoking. The country and factor interactions were not associated with smoking experimentations, daily smoking or best friends’ smoking.

Conclusion

Regardless of cultural background, adolescents who smoke have more positive attitudes to smoking, and perceive more social support for smoking, than do adolescents who do not smoke. The study stresses the similarity of the results in both Karelia’s despite the enormous differences in culture, economy and public policy.
  相似文献   
53.
54.
Bipolar disorder (BPD) and schizophrenia (SCZ) have at least a partially convergent aetiology and thus may share genetic susceptibility loci. Multiple lines of evidence emphasize the role of disrupted-in-schizophrenia-1 (DISC1) gene in psychotic disorders such as SCZ. We monitored the association of allelic variants of translin-associated factor X (TSNAX)/DISC1 gene cluster using 13 single-nucleotide polymorphisms (SNPs) in 723 members of 179 Finnish BPD families. Consistent with an earlier finding in Finnish SCZ families, the haplotype T-A of rs751229 and rs3738401 at the 5' end of DISC1 was over-transmitted to males with psychotic disorder (P = 0.008; for an extended haplotype P = 0.0007 with both genders). Haplotypes at the 3' end of DISC1 associated with bipolar spectrum disorder (P = 0.0002 for an under-transmitted haplotype T-T of rs821616 and rs1411771, for an extended haplotype P = 0.0001), as did a two-SNP risk haplotype at the 5' end of TSNAX (P = 0.007). The risk haplotype for psychotic disorder also associated to perseverations (P = 0.035; for rs751229 alone P = 0.0012), and a protective haplotype G-T-G with rs1655285 in addition to auditory attention (P = 0.0059). The 3' end variants associated with several cognitive traits, with the most robust signal for rs821616 and verbal fluency and rs980989 and psychomotor processing speed (P = 0.011 for both). These results support involvement of DISC1 in the genetic aetiology of BPD and suggest that its distinct variants contribute to variation in the dimensional features of psychotic and bipolar spectrum disorders. Finding of alternative associating haplotypes in the same set of BPD families gives evidence for allelic heterogeneity within DISC1, eventually leading to heterogeneity in the clinical outcome as well.  相似文献   
55.
Human embryonic and mesenchymal stem cell therapies may offer significant benefit to a large number of patients. Recently, however, human embryonic stem cell lines cultured on mouse feeder cells were reported to be contaminated by the xeno-carbohydrate N-glycolylneuraminic acid (Neu5Gc) and considered potentially unfit for human therapy. To determine the extent of the problem of Neu5Gc contamination for the development of stem cell therapies, we investigated whether it also occurs in cells cultured on human feeder cells and in mesenchymal stem cells, what are the sources of contamination, and whether the contamination is reversible. We found that N-glycolylneuraminic acid was present in embryonic stem cells cultured on human feeder cells, correlating with the presence of Neu5Gc in components of the commercial serum replacement culture medium. Similar contamination occurred in mesenchymal stem cells cultured in the presence of fetal bovine serum. The results suggest that the Neu5Gc is present in both glycoprotein and lipid-linked glycans, as detected by mass spectrometric analysis and monoclonal antibody staining, respectively. Significantly, the contamination was largely reversible in the progeny of both cell types, suggesting that decontaminated cells may be derived from existing stem cell lines. Although major complications have not been reported in the clinical trials with mesenchymal stem cells exposed to fetal bovine serum, the immunogenic contamination may potentially be reflected in the viability and efficacy of the transplanted cells and thus bias the published results. Definition of safe culture conditions for stem cells is essential for future development of cellular therapies.  相似文献   
56.

Introduction

Low socio-economic status (SES) is strongly related to smoking, but studies examining the association of SES with nicotine dependence (ND) are scarce. The aim of this study was to examine the associations of SES and marital status with smoking, multiple measures of ND, and cotinine as a nicotine intake biomarker.

Methods

The sample comprised 1746 ever smokers, sampled from the National FINRISK 2007 Study, who had completed a tobacco specific questionnaire in addition to the standard clinical examination. The Fagerström Test for Nicotine Dependence (FTND), the Heaviness of Smoking Index (HSI), the Nicotine Dependence Syndrome Scale (NDSS), and the Hooked On Nicotine Checklist (HONC) were assessed, while plasma cotinine was measured as a biomarker of nicotine exposure in daily smokers. Univariate and multivariate associations were assessed by linear regression and multinomial logistic regression.

Results

In multivariate models, lower education was associated with higher FTND and HSI, income with HSI, and occupation with HSI (men only), FTND, HONC and NDSS scores. Lower education was related to higher cotinine levels among daily smokers, although the association diminished slightly after adjusting for daily smoking amount. Living without a spouse was associated with daily smoking and higher ND.

Conclusion

In this cross-sectional study low SES was linked with higher ND among current smokers, while low SES was associated with higher cotinine levels among daily smokers. Living alone was linked with higher ND. Longitudinal studies are warranted to further explore these associations. As lower SES smokers are more addicted they may need more targeted cessation services to succeed in quitting smoking.  相似文献   
57.
Background. Surfactant protein (SP) C has been shown to be expressed also outside pulmonary alveoli. Certain SP-C gene (SFTPC) polymorphisms associate with lung diseases and very preterm birth.

Aims. We investigated the association of SFTPC single nucleotide polymorphism (SNP) rs4715 with factors affecting spontaneous preterm birth and characterized the SP-C expression in human and mouse gestational tissues.

Methods. The SFTPC SNP rs4715 polymorphism was genotyped in a homogeneous northern European population of mothers and infants in spontaneous preterm birth and term controls. The expression and protein of SP-C in gestational tissues was analyzed.

Results. SFTPC SNP rs4715 did not associate with spontaneous preterm birth. However, fetuses with short interval (<72 hours) between preterm premature rupture of fetal membranes (PPROM) and preterm birth had significant over-representation of the minor allele A, whereas in fetuses with prolonged PPROM (≥72 hours) the frequency was decreased. Maternal SFTPC did not associate with the duration of PPROM. SP-C mRNA and proprotein were detected in fetal membranes, placenta, and pregnant uterus.

Conclusion. SFTPC SNP rs4715 associates with the duration of PPROM, and SP-C is expressed in gestational tissues. We propose that fetal SFTPC moderates the inflammatory activation within the fetal extra-embryonic compartment.  相似文献   
58.
Detection of a clonal T cell receptor (TCR) gene rearrangement is used in the diagnosis of primary cutaneous T cell lymphomas (CTCL) whereas chromosomal aberrations serve as a diagnostic tool for leukaemias and nodal lymphomas. To what extent both approaches specify the same cell population remains unknown. We investigated the coincidence of TCR clonality with complex clonal chromosomal aberrations, indicating qualitative alteration of the affected cells, in 17 CTCL patients. Out of 41 skin, blood, and lymph node samples studied, 34 gave results in chromosome and TCR analyses. With 88%, most specimens revealed corresponding results by both techniques (27 of 34 clonal, three of 34 non-clonal). In two patients, analysis of micro-dissected cells demonstrated that neoplastic T cells bear both a dominant TCR rearrangement and a complex chromosomal aberration. The cutaneous clone was found in blood samples of 11 of 12 patients (including early stages), and investigation of follow-up skin and blood samples indicated persistence of the T cell clone in 11 of 14 cases. In conclusion, we show that dominant TCR clones and chromosomal clones converge in all stages of CTCL. These clones disseminate into blood and skin at early disease stages and persist despite therapy. The coexistence of a dominant TCR clone and a clonal chromosomal aberration can thus be used as a hallmark of malignancy.  相似文献   
59.
ABSTRACT: BACKGROUND: Poor sleep tends to be patterned by sociodemographic and socioeconomic factors. The aim of this study was to examine the associations of sociodemographic and socioeconomic factors with sleep duration and insomnia-related symptoms across life course. METHODS: We used cross-sectional Health 2000 Survey (2000-2001) among a total of 5,578 adult Finns, aged 30-79 years, representative of adult Finnish population. Data about sociodemographic and socioeconomic circumstances, insomnia-related symptoms over the previous month as well as average sleep duration were collected by questionnaires. Multinomial logistic regression models were adjusted first for gender and age, second for sociodemographic factors, and third for all covariates simultaneously. RESULTS: On average 70% of Finnish adults slept 7-8 hours a day. Frequent insomnia-related symptoms were more prevalent among women (14%) than men (10%). Not being married, not having children, having low education, low income, being unemployed, and being a disability retiree were associated with frequent insomnia-related symptoms. Similar factors were associated with short and long sleep duration. However, childhood socioeconomic position was mostly unrelated to sleep in adulthood except parental education had some associations with short sleep duration. CONCLUSIONS: Disadvantaged socioeconomic position in adulthood, in particular income and employment status, is associated with poorer sleep. When promoting optimal sleep duration and better sleep quality, families with low incomes, unemployed people, and disability retirees should be targeted. Key words: marital status; parental status; education; employment status; household income; residential area; insomnia-related symptoms; sleep duration; life course; self-perceived health.  相似文献   
60.
Classical cadherins are important cell adhesion molecules specifying and separating brain nuclei and developmental compartments. Cadherin‐22 (Cdh22) belongs to type II subfamily of classical cadherins, and is expressed at the midbrain‐hindbrain boundary during early embryogenesis. In Fgfr1 mutant mouse embryos, which have a disturbed midbrain‐hindbrain border, Cdh22 is down‐regulated. Here, we studied expression of Cdh22 in developing mouse brain in more detail and compared it to expression of related family members. This revealed both complementary and overlapping patterns of Cdh22, Cdh11, Cdh8, and Cdh6 expression in distinct regions of the forebrain and midbrain. We used a mutated allele of Cdh22 to study its function in brain development. Loss of Cdh22 caused reduced postnatal viability. Despite strong Cdh22 expression in the developing brain, we did not observe defects in compartmentalization or abnormalities in the midbrain and forebrain nuclei in Cdh22 mutants. This may be explained by functional redundancy between type II cadherins. Developmental Dynamics 240:1989–2001, 2011. © 2011 Wiley‐Liss, Inc.  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