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   824篇
  免费   44篇
  国内免费   16篇
耳鼻咽喉   6篇
儿科学   46篇
妇产科学   46篇
基础医学   88篇
口腔科学   6篇
临床医学   68篇
内科学   129篇
皮肤病学   10篇
神经病学   38篇
特种医学   191篇
外科学   55篇
综合类   41篇
预防医学   43篇
眼科学   34篇
药学   46篇
中国医学   1篇
肿瘤学   36篇
  2023年   2篇
  2022年   1篇
  2021年   8篇
  2020年   10篇
  2019年   10篇
  2018年   13篇
  2017年   10篇
  2016年   8篇
  2015年   10篇
  2014年   23篇
  2013年   26篇
  2012年   33篇
  2011年   30篇
  2010年   29篇
  2009年   39篇
  2008年   30篇
  2007年   27篇
  2006年   30篇
  2005年   29篇
  2004年   34篇
  2003年   32篇
  2002年   29篇
  2001年   26篇
  2000年   17篇
  1999年   21篇
  1998年   31篇
  1997年   45篇
  1996年   33篇
  1995年   24篇
  1994年   25篇
  1993年   20篇
  1992年   7篇
  1991年   18篇
  1990年   10篇
  1989年   29篇
  1988年   16篇
  1987年   19篇
  1986年   12篇
  1985年   11篇
  1984年   6篇
  1983年   10篇
  1982年   9篇
  1981年   11篇
  1980年   6篇
  1979年   3篇
  1978年   3篇
  1977年   5篇
  1976年   2篇
  1975年   1篇
  1967年   1篇
排序方式: 共有884条查询结果,搜索用时 31 毫秒
1.
Ratneswaran  C.  Steier  J.  Reed  K.  Khong  T. K. 《Lung》2019,197(5):533-540
Introduction

In contrast to tobacco smoking, electronic cigarette (“vaping”) advertisement had been approved in the United Kingdom (UK) in January 2013. Currently, there are an estimated 3.2 million UK e-cigarette users. The impact of e-cigarette advertisement on tobacco use has not been studied in detail. We hypothesised that e-cigarette advertisement impacts on conventional smoking behaviour.

Methods

A cross-sectional structured survey assessed the impact of e-cigarette advertising on the perceived social acceptability of cigarette and e-cigarette smoking and on using either cigarettes or e-cigarettes (on a scale of 1 to 5/‘not at all’ to ‘a lot’). The survey was administered between January to March 2015 to London university students, before and after viewing 5 UK adverts including a TV commercial.

Results

Data were collected from 106 participants (22 ± 2 years, 66% male), comprising cigarette smokers (32%), non-smokers (54%) and ex-smokers (14%). This included vapers (16%), non-vapers (77%) and ex-vapers (7%). After viewing the adverts, smokers (2.6 ± 1.0 vs. 3.8 ± 1.1, p = 0.001) and non-smokers (3.2 ± 0.7 vs. 3.7 ± 0.8, p = 0.007) felt smoking was more socially acceptable, compared to before viewing them. Participants were more likely to try both e-cigarettes (1.90 ± 1.03 to 3.09 ± 1.11, p < 0.001) and conventional cigarettes (1.73 ± 0.83 to 2.27 ± 1.13, p < 0.001) after viewing the adverts compared to before. Vapers were less likely to smoke both an e-cigarette, and a conventional cigarette after viewing the adverts.

Conclusion

E-cigarette advertising encourages both e-cigarette and conventional cigarette use in young smokers and non-smokers. The adverts increase the social acceptability of smoking without regarding the importance of public health campaigns that champion smoking cessation.

  相似文献   
2.
3.
Aetiological factors for oral manifestations of HIV   总被引:2,自引:0,他引:2  
OBJECTIVES: Describe the oral diseases in HIV-infected individuals in London, UK and identify social and medical factors related to the presence of specific oral diseases.
DESIGN: Cross-sectional analytic study.
SETTING: Dental clinics.
SUBJECTS: Consecutive sample of 456 patients with HIV infection.
METHODS: Social and medical history and clinical examinations. Univariate and logistic regression analysis.
OUTCOMES: Presence of HIV-associated oral disease.
RESULTS: 80% of patients with AIDS and 50% of patients with HIV had a specific oral disease. The most common diseases were hairy leukoplakia (30%), erythematous candidiasis (24%), pseudomembranous candidiasis (14%), angular chielitis (6%), necrotising periodontal disease (8%) and non-recurrent ulceration (6%).
CONCLUSIONS: The presence of erythematous candidiasis was not related to advanced HIV disease. Pseudomembranous candidiasis, hairy leukoplakia and mucosal ulceration were significantly associated with advanced HIV disease. Smoking was also identified as a strong aetiological factor in oral diseases. Longitudinal studies are required to further explore the prognostic significance of oral diseases in HIV infection.  相似文献   
4.
5.
Qiu D  Tan LH  Zhou K  Khong PL 《NeuroImage》2008,41(2):223-232
Using diffusion tensor MR imaging (DTI) and advanced voxel-wise analysis tools, we study diffusivity and anisotropy changes of white matter from late childhood to young adulthood, and correlate quantitative diffusion indices with Chinese and English reading performance scores. Seventy-five normal healthy school going ethnic Chinese students and young adults of three age groups were recruited (group 1, n=24, mean+/-SD=7.4+/-0.3 years; group 2, n=27, mean+/-SD=10.3+/-0.5 years; group 3, n=24, mean+/-SD=22.8+/-2.3 years). DTI was performed with 3 mm isotropic resolution to cover the entire brain. Voxel-wise analysis was performed using Tract-Based Spatial Statistics (TBSS) to localize regions of white matter showing significant changes of fractional anisotropy (FA), mean diffusivity (MD), and axial and radial diffusivities between groups. We found increased FA and decreased MD with increasing age in regions of cerebellar white matter, right temporal white matter, and a large portion of the superior frontal and parietal white matter driven by both the reduction of radial diffusivity and axial diffusivity with the former to a greater extent. Changes were continual from late childhood to young adulthood. Findings were confirmed by region-of-interest analysis in specific white matter tracts. After controlling for the effect of age, significant correlation was found between diffusion indices of the anterior limb of the left internal capsule and Chinese reading score (p=0.05), and of the corona radiata and English reading score (p=0.026 and p=0.029 for left and right, respectively).These DTI indices likely reflect the multiple biological processes that occur during brain development which provide the neural substrate for ongoing functional connectivity including for reading development.  相似文献   
6.
INTRODUCTION Crohn’s disease (CD) is a chronic inflammatory disease of the gastrointestinal tract which commonly affects young adults. It follows a relapsing and remitting course and there is no known cure. However, approximately 10% to 15% have chronic …  相似文献   
7.
Cross‐presentation defines the unique capacity of an APC to present exogenous Ag via MHC class I molecules to CD8+ T cells. DCs are specialized cross‐presenting cells and as such have a critical role in antitumor immunity. DCs are routinely found within the tumor microenvironment, but their capacity for endogenous or therapeutically enhanced cross‐presentation is not well characterized. In this study, we examined the tumor and lymph node DC cross‐presentation of a nominal marker tumor Ag, HA, expressed by the murine mesothelioma tumor AB1‐HA. We found that tumors were infiltrated by predominantly CD11b+ DCs with a semimature phenotype that could not cross‐present tumor Ag, and therefore, were unable to induce tumor‐specific T‐cell activation or proliferation. Although tumor‐infiltrating DCs were able to take up, process, and cross‐present exogenous cell‐bound and soluble Ags, this was significantly impaired relative to lymph node DCs. Importantly, however, systemic chemotherapy using gemcitabine reversed the defect in Ag cross‐presentation of tumor DCs. These data demonstrate that DC cross‐presentation within the tumor microenvironment is defective, but can be reversed by chemotherapy. These results have important implications for anticancer therapy, particularly regarding the use of immunotherapy in conjunction with cytotoxic chemotherapy.  相似文献   
8.
9.
Funk  PE; Kincade  PW; Witte  PL 《Blood》1994,83(2):361-369
In suspensions of murine bone marrow, many stromal cells are tightly entwined with hematopoietic cells. These cellular aggregations appear to exist normally within the marrow. Previous studies showed that lymphocytes and stem cells adhered to stromal cells via vascular cell adhesion molecule 1 (VCAM1). Injection of anti-VCAM1 antibody into mice disrupts the aggregates, showing the importance of VCAM1 in the adhesion between stromal cells and hematopoietic cells in vivo. Early hematopoietic stem cells were shown to be enriched in aggregates by using a limiting-dilution culture assay. Myeloid progenitors responsive to WEHI-3CM in combination with stem cell factor (c-kit ligand) and B220- B-cell progenitors responsive to insulin-like growth factor-1 in combination with interleukin-7 are not enriched. We propose a scheme of stromal cell-hematopoietic cell interactions based on the cell types selectively retained within the aggregates. The existence of these aggregates as native elements of bone marrow organization presents a novel means to study in vivo stem cell-stromal cell interaction.  相似文献   
10.
The advent of whole‐exome next‐generation sequencing (WES) has been pivotal for the molecular characterization of Mendelian disease; however, the clinical applicability of WES has remained relatively unexplored. We describe our exploration of WES as a diagnostic tool in a 3½‐year old female patient with a 2‐year history of episodic muscle weakness and paroxysmal dystonia who presented following a previous extensive but unrevealing diagnostic work‐up. WES was performed on the proband and her two parents. Parental exome data was used to filter potential de novo genomic events in the proband and suspected variants were confirmed using di‐deoxy sequencing. WES revealed a de novo non‐synonymous mutation in exon 21 of the calcium channel gene CACNA1S that has been previously reported in a single patient as a rare cause of atypical hypokalemic periodic paralysis. This was unexpected, as the proband's original differential diagnosis had included hypokalemic periodic paralysis, but clinical and laboratory features were equivocal, and standard clinical molecular testing for hypokalemic periodic paralysis and related disorders was negative. This report highlights the potential diagnostic utility of WES in clinical practice, with implications for the approach to similar diagnostic dilemmas in the future.  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