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   2119篇
  免费   173篇
  国内免费   9篇
耳鼻咽喉   14篇
儿科学   47篇
妇产科学   26篇
基础医学   309篇
口腔科学   2篇
临床医学   245篇
内科学   504篇
皮肤病学   44篇
神经病学   206篇
特种医学   84篇
外科学   287篇
综合类   21篇
一般理论   1篇
预防医学   192篇
眼科学   35篇
药学   122篇
中国医学   1篇
肿瘤学   161篇
  2023年   23篇
  2022年   29篇
  2021年   54篇
  2020年   36篇
  2019年   59篇
  2018年   73篇
  2017年   43篇
  2016年   54篇
  2015年   48篇
  2014年   68篇
  2013年   111篇
  2012年   137篇
  2011年   166篇
  2010年   90篇
  2009年   89篇
  2008年   99篇
  2007年   111篇
  2006年   108篇
  2005年   86篇
  2004年   87篇
  2003年   87篇
  2002年   67篇
  2001年   44篇
  2000年   30篇
  1999年   40篇
  1998年   20篇
  1997年   14篇
  1996年   10篇
  1995年   8篇
  1994年   8篇
  1992年   26篇
  1991年   34篇
  1990年   26篇
  1989年   22篇
  1988年   29篇
  1987年   27篇
  1986年   26篇
  1985年   22篇
  1984年   12篇
  1983年   12篇
  1981年   12篇
  1979年   14篇
  1978年   11篇
  1975年   11篇
  1974年   7篇
  1973年   12篇
  1972年   12篇
  1971年   9篇
  1970年   7篇
  1969年   9篇
排序方式: 共有2301条查询结果,搜索用时 15 毫秒
1.
2.

Background

We have recently shown that human epididymis protein 4 (HE4) levels correlate with the severity of cystic fibrosis (CF) lung disease. However, there are no data on how HE4 levels alter in patients receiving CFTR modulating therapy.

Methods

In this retrospective clinical study, 3 independent CF patient cohorts (US-American: 29, Australian: 12 and Irish: 19 cases) were enrolled carrying at least one Class III CFTR CF-causing mutation (p.Gly551Asp) and being treated with CFTR potentiator ivacaftor. Plasma HE4 was measured by immunoassay before treatment (baseline) and 1–6?months after commencement of ivacaftor, and were correlated with FEV1 (% predicted), sweat chloride, C-reactive protein (CRP) and body mass index (BMI).

Results

After 1?month of therapy, HE4 levels were significantly lower than at baseline and remained decreased up to 6?months. A significant inverse correlation between absolute and delta values of HE4 and FEV1 (r?=??0.5376; P?<?.001 and r?=??0.3285; P?<?.001), was retrospectively observed in pooled groups, including an independent association of HE4 with FEV1 by multiple regression analysis (β?=??0.57, P?=?.019). Substantial area under the receiver operating characteristic curve (ROC-AUC) value was determined for HE4 when 7% mean change of FEV1 (0.722 [95% CI 0.581–0.863]; P?=?.029) were used as classifier, especially in the first 2?months of treatment (0.806 [95% CI 0.665–0.947]; P?<?.001).

Conclusions

This study shows that plasma HE4 levels inversely correlate with lung function improvement in CF patients receiving ivacaftor. Overall, this potential biomarker may be of value for routine clinical and laboratory follow-up of CFTR modulating therapy.  相似文献   
3.
A chemically defined medium for the culture of mature oligodendrocytes   总被引:3,自引:0,他引:3  
A new chemically defined medium consisting of equal parts of Dulbecco modified Eagle's and Ham's F-12 media supplemented with insulin, sodium selenite, putrescine, and D+ galactose, which allows the long-term survival of mature oligodendrocyte pure cultures, is described. Immunohistochemical staining has shown that over 90% of the cells become positive for myelin proteins shortly following subculture. Contaminating astrocytes (2%) do not survive in this medium. Biochemical data have indicated that these purified oligodendrocytes express 2'3'-cyclic nucleotide 3'-phosphohydrolase and UDP-galactose ceramide galactosyltransferase activities. Electron microscopical examination revealed that the oligodendrocytes were mostly of medium-dark type and appeared to be identical to cells cultured in serum-containing medium. The ability to maintain pure oligodendrocyte cultures in such a defined medium will allow investigations concerning exogenous and endogenous factors involved in oligodendrocyte metabolism.  相似文献   
4.
5.
6.
A 20-month-old Kuwaiti girl had manifestations of lipoid proteinosis, a rare autosomal recessive disorder seen more commonly in Caucasians. This condition is diagnosed based on clinical, histopathologic, and ultrastructural criteria. Its biochemical and genetic aspects are still poorly understood.  相似文献   
7.
The present study sought to investigate the moderating function that social problem-solving effectiveness serves in relation to negative stressful life events and depressive symptomatology. It was also hypothesized that knowledge of problem solving would improve upon the prediction of level of depressive symptoms beyond the assessment of stressful events. Results involving 462 undergraduate students provide support for both predictions. Specifically, findings from a multiple regression analysis indicated that (1) differences in reported depressive mood between subjects under high and low stress levels were minimal for individuals characterized as effective problem-solvers, relative to those persons with problem-solving scores reflective of ineffective problem solving; and (2) assessment of problem-solving scores and their interaction with stress level provided for an additional three times the amount of explained variance in predicting depression scores beyond life stress scores. Additionally, a cross-validation of the regression analysis was conducted and found to result in a minimal amount of shrinkage that could be due to samplespecific characteristics.We would like to extend our appreciation to two anonymous reviewers for their helpful comments on an earlier draft of this article. The study was supported in part by a grant funded by Fairleigh Dickinson University to the first author.  相似文献   
8.
The culture supernatant from a single Pseudomonas aeruginosa strain has been reported to show neuraminidase activity, leading to the speculation that this bacterium may use this enzyme as a virulence factor to act on host macromolecules. In order to extend this finding, we have examined the activity of concentrated P. aeruginosa culture supernatants and cells on synthetic and natural substrates containing sialic acid, such as human respiratory mucins. Four P. aeruginosa strains showed some activity on the synthetic substrate 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid but failed to liberate N-acetylneuraminic acid from six different natural substrates. Attempts to induce enzyme production by use of human respiratory mucins in the culture medium were also unsuccessful. The supernatants also showed N-acetyl-beta-D-glucosaminidase-like activity on a synthetic substrate but did not liberate N-acetylhexosamines from natural substrates. We conclude that the neuraminidase-like activity observed in P. aeruginosa can be defined as an arylneuraminidase and that the possession of a neuraminidase active on natural substrates is not a common attribute of P. aeruginosa strains.  相似文献   
9.
This paper presents some of the findings from the Smoking in Pregnancy study of attitudes towards smoking among pregnant women, mothers of young children and their partners in East Surrey. As part of the study, respondents completed a General Health Questionnaire to identify mental health difficulties and, if they were smoking at the time of the study, they also completed the Fagerstrom nicotine addiction test. Eleven female respondents had high scores on the General Health Questionnaire, suggesting symptoms of depression, anxiety and/or social dysfunction for these women. There was no evidence that smokers were suffering from greater mental health difficulties than ex-smokers or non-smokers. However, the General Health Questionnaire scores of smokers were positively associated with their level of nicotine dependence. Furthermore, when General Health Questionnaire scores of all respondents were compared with self-reported health status there was a marked discrepancy suggesting under-reporting of symptoms by women.  相似文献   
10.
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