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   5762篇
  免费   218篇
  国内免费   42篇
耳鼻咽喉   97篇
儿科学   143篇
妇产科学   90篇
基础医学   784篇
口腔科学   677篇
临床医学   421篇
内科学   1106篇
皮肤病学   140篇
神经病学   338篇
特种医学   190篇
外科学   612篇
综合类   37篇
一般理论   2篇
预防医学   676篇
眼科学   93篇
药学   380篇
  2篇
中国医学   58篇
肿瘤学   176篇
  2024年   32篇
  2023年   57篇
  2022年   130篇
  2021年   248篇
  2020年   158篇
  2019年   204篇
  2018年   273篇
  2017年   165篇
  2016年   216篇
  2015年   214篇
  2014年   288篇
  2013年   298篇
  2012年   463篇
  2011年   519篇
  2010年   318篇
  2009年   213篇
  2008年   330篇
  2007年   293篇
  2006年   242篇
  2005年   207篇
  2004年   165篇
  2003年   144篇
  2002年   132篇
  2001年   79篇
  2000年   78篇
  1999年   50篇
  1998年   49篇
  1997年   39篇
  1996年   33篇
  1995年   35篇
  1994年   24篇
  1993年   30篇
  1992年   26篇
  1991年   23篇
  1990年   21篇
  1989年   29篇
  1988年   22篇
  1987年   21篇
  1986年   22篇
  1985年   20篇
  1984年   11篇
  1983年   15篇
  1982年   9篇
  1981年   15篇
  1980年   7篇
  1979年   8篇
  1978年   6篇
  1977年   11篇
  1976年   7篇
  1969年   7篇
排序方式: 共有6022条查询结果,搜索用时 15 毫秒
51.
Cryptococcus gattii is the main etiological agent of cryptococcosis in immunocompetent individuals. The triazole drug itraconazole is one of the antifungals used to treat patients with cryptococcosis. Heteroresistance is an adaptive mechanism to counteract the stress of increasing drug concentrations, and it can enhance the ability of a microorganism to survive under antifungal pressure. In this study, we evaluated the ability of 11 C. gattii strains to develop itraconazole heteroresistance. Heteroresistant clones were analyzed for drug susceptibility, alterations in cell diameter, capsule properties, and virulence in a murine model. Heteroresistance to itraconazole was intrinsic in all of the strains analyzed, reduced both the capsule size and the cell diameter, induced molecular heterogeneity at the chromosomal level, changed the negatively charged cells, reduced ergosterol content, and improved the antioxidant system. A positive correlation between surface/volume ratio of original cells and the level of heteroresistance to itraconazole (LHI) was observed in addition to a negative correlation between capsule size of heteroresistant clones and LHI. Moreover, heteroresistance to itraconazole increased the engulfment of C. gattii by macrophages and augmented fungal proliferation inside these cells, which probably accounted for the reduced survival of the mice infected with the heteroresistant clones and the higher fungal burden in lungs and brain. Our results indicate that heteroresistance to itraconazole is intrinsic and increases the virulence of C. gattii. This phenomenon may represent an additional mechanism that contributes to relapses of cryptococcosis in patients during itraconazole therapy.  相似文献   
52.
We evaluated the combination of posaconazole with amphotericin B in vitro and in a murine model of systemic infections caused by Sporothrix brasiliensis and Sporothrix schenckii sensu stricto. In vitro data demonstrated a synergistic effect, and although posaconazole alone was effective against sporotrichosis, efficacy in terms of survival and burden reduction was increased with the combination. This combination might be an option against disseminated sporotrichosis, especially when itraconazole or amphotericin B at optimal doses are contraindicated.  相似文献   
53.
BACKGROUND: Idiopathic adolescent scoliosis (AIS) causes not only spinal deformities but rib cage abnormalities that lead to abnormal volumes and pulmonary capacity on pulmonary function testing (PFT). The objective of this study was to analyze the impact of a physical rehabilitation program on respiratory function in surgical patients with AIS. METHODS: From October 2003 to October 2004, a total of 34 patients (age range, 10 to 18 years) presenting with AIS and a thoracic curvature between 45 degrees and 88 degrees were studied prospectively at a tertiary academic hospital. The patients underwent clinical and radiographic evaluations of the vertebral deformity, chest radiographs, PFT, evaluation of peak expiratory flow, and 6-min walk tests (6MWTs) before and after joining a physical rehabilitation program for 4 months. RESULTS: An improvement in FVC, inspiratory capacity, FEV(1), expiratory reserve volume, and performance assessed by 6MWT were observed after rehabilitation. CONCLUSIONS: Global conditioning improved after the rehabilitation program. This was expressed by both PFT and 6MWT results.  相似文献   
54.
55.
A large neurofibroma associated with gastrointestinal hemorrhage was demonstrated by visceral arteriography. The findings are correlated with those of resected pathologic specimen.  相似文献   
56.
Adaptive laboratory evolution has been used to improve production of influenza hemagglutinin (HA)-displaying virus-like particles (VLPs) in insect cells. However, little is known about the underlying biological mechanisms promoting higher HA-VLP expression in such adapted cell lines. In this article, we present a study of gene expression patterns associated with high-producer insect High Five cells adapted to neutral pH, in comparison to non-adapted cells, during expression of influenza HA-VLPs. RNA-seq shows a decrease in the amount of reads mapping to host cell genomes along infection, and an increase in those mapping to baculovirus and transgenes. A total of 1742 host cell genes were found differentially expressed between adapted and non-adapted cells throughout infection, 474 of those being either up- or down-regulated at both time points evaluated (12 and 24 h post-infection). Interestingly, while host cell genes were found up- and down-regulated in an approximately 1:1 ratio, all differentially expressed baculovirus genes were found to be down-regulated in infected adapted cells. Pathway analysis of differentially expressed genes revealed enrichment of ribosome biosynthesis and carbohydrate, amino acid, and lipid metabolism. In addition, oxidative phosphorylation and protein folding, sorting and degradation pathways were also found to be overrepresented. These findings contribute to our knowledge of biological mechanisms of insect cells during baculovirus-mediated transient expression and will assist the identification of potential engineering targets to increase recombinant protein production in the future.  相似文献   
57.
AI-based software applications for personalized nutrition have recently gained increasing attention to help users follow a healthy lifestyle. In this paper, we present a knowledge-based recommendation framework that exploits an explicit dataset of expert-validated meals to offer highly accurate diet plans spanning across ten user groups of both healthy subjects and participants with health conditions. The proposed advisor is built on a novel architecture that includes (a) a qualitative layer for verifying ingredient appropriateness, and (b) a quantitative layer for synthesizing meal plans. The first layer is implemented as an expert system for fuzzy inference relying on an ontology of rules acquired by experts in Nutrition, while the second layer as an optimization method for generating daily meal plans based on target nutrient values and ranges. The system’s effectiveness is evaluated through extensive experiments for establishing meal and meal plan appropriateness, meal variety, as well as system capacity for recommending meal plans. Evaluations involved synthetic data, including the generation of 3000 virtual user profiles and their weekly meal plans. Results reveal a high precision and recall for recommending appropriate ingredients in most user categories, while the meal plan generator achieved a total recommendation accuracy of 92% for all nutrient recommendations.  相似文献   
58.
BackgroundCoronary stenosis can be caused de novo atherosclerosis, in-stent restenosis, and in-stent neoatherosclerosis, three entities that develop from a diverse pathophysiological milieu.ObjectiveThis study aims to investigate, using optical coherence tomography (OCT), whether or not coronary lesions related to these processes differ in their local inflammatory profile.MethodsRetrospective analysis of patients with diagnosed or suspected coronary lesions who had undergone OCT imaging for clinical reasons. Macrophage and intra-plaque neovascularization were assessed by OCT and used as surrogates of local inflammation. A significance level of < 0.05 was adopted as statistically significant.ResultsFrom the 121 lesions, 74 were de novo, 29 were restenosis, and 18 were neoatherosclerosis. Neovascularization was found in 65.8% of de novo, 10.3% in restenosis, and 94.4% in neoatherosclerosis (p<0.01 for all). The volume of neovascularization was different among lesion types (950 vs. 0 vs. 6220, respectively [median values in 1000 x µm3/mm]; p<0.01 for all), which were significantly higher in neoatherosclerosis and lower in restenosis. The presence of macrophages differed among the lesions (95.9% in de novo vs. 6.9% in restenosis vs. 100% in neoatherosclerosis [p<0.01 for all]). Moreover, the intensity of macrophagic infiltration was different among lesion types (2.5 vs. 0.0 vs. 4.5, respectively [median values of macrophage score]; p<0.01 for all), significantly higher in neoatheroscleosis and lower in restenosis.ConclusionWhen compared using coronary OCT, de novo atherosclerosis, in-stent restenosis, and neoatherosclerosis presented markedly different inflammatory phenotypes.  相似文献   
59.
Clinical Rheumatology - Rheumatoid vasculitis (RV) is one of the most severe extra-articular manifestations of rheumatoid arthritis, with significant morbidity and mortality, requiring aggressive...  相似文献   
60.
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