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   485篇
  免费   36篇
耳鼻咽喉   3篇
儿科学   12篇
妇产科学   9篇
基础医学   69篇
口腔科学   3篇
临床医学   18篇
内科学   71篇
皮肤病学   8篇
神经病学   118篇
特种医学   34篇
外科学   31篇
预防医学   48篇
眼科学   4篇
药学   14篇
肿瘤学   79篇
  2023年   9篇
  2022年   11篇
  2021年   21篇
  2020年   10篇
  2019年   11篇
  2018年   16篇
  2017年   19篇
  2016年   12篇
  2015年   22篇
  2014年   24篇
  2013年   19篇
  2012年   51篇
  2011年   41篇
  2010年   18篇
  2009年   18篇
  2008年   40篇
  2007年   21篇
  2006年   20篇
  2005年   22篇
  2004年   25篇
  2003年   14篇
  2002年   22篇
  2001年   6篇
  2000年   7篇
  1999年   2篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   2篇
  1994年   3篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1985年   2篇
  1983年   3篇
  1979年   1篇
  1977年   3篇
  1976年   1篇
  1975年   2篇
  1974年   2篇
  1972年   5篇
  1971年   2篇
排序方式: 共有521条查询结果,搜索用时 15 毫秒
471.
Contamination of Elbe River (Germany) sediments with dioxin-like toxicants was investigated following the 500-year flood (flood that statistically occurs once in 500 years) of 2002. It was hypothesized that large amounts of particulate matter from river beds and associated dioxin-like toxicants were mobilized and transported during this flood event. The investigation focused on polychlorinated naphthalenes (PCNs) that have not been determined previously in the Elbe River. The in vitro H4IIE-luc assay was used as an overall measure for toxicants capable of binding to the aryl hydrocarbon receptor (AhR). The assay was combined with congener-specific instrumental analyses and fractionation to quantify PCN contributions to total AhR-mediated activity relative to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). Penta- to octachloronaphthalene concentrations of 30 ng/kg dry weight up to 13 microg/kg dry weight were found in Elbe River sediments downstream of Bitterfeld. Concentrations of penta- to octachloronaphthalenes, however, were only approximately 3 microg/kg dry weight at a site in the vicinity of Bitterfeld, where a level of approximately 3 mg/kg dry weight was reported before the flood. Also, the congener pattern of PCNs at this site changed after the flood, and PCN patterns reported previously for Bitterfeld and assigned to chlor-alkali electrolysis with graphite electrodes could now be observed at the sites from downstream of Bitterfeld and Magdeburg. Whereas PCDD/Fs dominated the dioxin-like activity in the middle and lower Elbe River, PCNs contributed as much as 10% of the total AhR-mediated activity. The contribution of PCBs was less significant (maximum, 0.2%). Thus, in Elbe River sediments, PCNs should be considered as relevant contaminants and be included in future monitoring and risk assessment programs.  相似文献   
472.
473.
474.

Background  

Scaffold Attachment Factor B1 (SAFB1) is a multifunctional protein which has been implicated in breast cancer previously. We recently generated SAFB1 knockout mice (SAFB1-/-), but pleiotropic phenotypes including high lethality, dwarfism associated with low IGF-I levels, and infertility and subfertility in male and female mice, respectively, do not allow for straightforward tumorigenesis studies in these mice. Therefore, we asked whether SAFB1 heterozygosity would influence tumor development and progression in MMTV-Wnt-1 oncomice or DMBA induced tumorigenicity, in a manner consistent with haploinsufficiency of the remaining allele.  相似文献   
475.
476.
477.

Purpose

The prevalence of protective anti-diphtheria toxin antibodies decreases with age. Therefore, the elderly might serve as reservoir for potentially toxigenic Corynebacterium (C.) species (C. diphtheriae, C. ulcerans, and C. pseudotuberculosis). This study aimed to examine the colonization rate of the nasopharynx with corynebacteria of individuals aged 65 years and older.

Methods

In the period from October 2012 to June 2013, nasal and throat swabs were taken from 714 asymptomatic subjects aged 65–106 years (average age 77.2) at three regions in Germany and investigated for Corynebacterium species.

Results

A total of 402 strains of Corynebacterium species were isolated from 388 out of 714 asymptomatic subjects (carriage rate 54.3%). The carriage rate was significantly higher in study participants living in retirement homes (68.4%) compared to those living autonomously at home (51.1%). Strains were isolated mostly from the nose (99%). Corynebacterium accolens was the most often isolated species (39.8%), followed by C. propinquum (24.1%), C. pseudodiphtheriticum (19.4%), and C. tuberculostearicum (10.2%). No C. diphtheriae, C. ulcerans, and C. pseudotuberculosis strains were isolated. A subsample of 74 subjects was tested serologically for anti-diphtheria antibodies. Protective anti-diphtheria toxin antibodies were found in 29.7% of the subjects; 70.3% showed no protective immunity.

Conclusions

These results suggest that carriage of potentially toxigenic corynebacteria is very rare among people aged 65 and older in Germany. However, the low prevalence of protective anti-diphtheria toxin antibodies might pose a risk for acquiring diphtheria especially for the elderly.
  相似文献   
478.
In this study, we investigated the relation between global and domain-specific self-esteem and psychiatric disorders. A sample of 577 children aged 8–14 years was recruited via psychiatric hospitals and from the general population. Parents were given a diagnostic interview to assess children’s psychiatric diagnoses (current/past). Parents and children completed questionnaires on child symptoms. Children completed a questionnaire on global and domain-specific self-esteem (scales: scholastic competence, social acceptance, athletic performance and physical appearance, global self-esteem). Self-esteem of children with current psychiatric disorders was lower than that of healthy controls (η p 2 between 0.01 and 0.08). Concerning scholastic competence, social acceptance and global self-esteem, children with past psychiatric disorders scored also lower than healthy controls. Different current psychiatric disorders showed specific but small effects on dimensions of self-esteem (β between ?0.08 and 0.19). Moreover, we found a gender × group interaction, indicating that girls with depressive and adjustment disorders were specifically impaired in their global self-esteem and perception of their physical appearance. Findings might help clinicians to focus on particular domains of self-esteem during the diagnostic process and to define adequate treatment goals.  相似文献   
479.
480.
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