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   272篇
  免费   20篇
  国内免费   5篇
耳鼻咽喉   4篇
儿科学   8篇
妇产科学   1篇
基础医学   42篇
口腔科学   4篇
临床医学   26篇
内科学   94篇
皮肤病学   1篇
神经病学   14篇
特种医学   3篇
外科学   34篇
综合类   5篇
预防医学   18篇
药学   27篇
中国医学   1篇
肿瘤学   15篇
  2023年   3篇
  2022年   7篇
  2021年   7篇
  2020年   11篇
  2019年   4篇
  2018年   16篇
  2017年   7篇
  2016年   2篇
  2015年   7篇
  2014年   13篇
  2013年   11篇
  2012年   24篇
  2011年   15篇
  2010年   9篇
  2009年   10篇
  2008年   17篇
  2007年   15篇
  2006年   9篇
  2005年   19篇
  2004年   12篇
  2003年   17篇
  2002年   12篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1992年   1篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1988年   1篇
  1987年   5篇
  1986年   8篇
  1985年   1篇
  1984年   4篇
  1983年   1篇
  1980年   2篇
  1978年   1篇
  1974年   2篇
  1972年   1篇
  1971年   3篇
  1968年   1篇
  1883年   1篇
排序方式: 共有297条查询结果,搜索用时 15 毫秒
61.
BACKGROUND: The objective of the current study was to identify biomarkers that reflect the clinical course of squamous cell carcinoma of the tongue (TSCC). METHODS: TSCC tissue samples from 66 patients were subjected to gene expression analysis by real-time polymerase chain reaction. Eleven integrin family genes and 14 genes used for normalization, including housekeeping genes and genes that encode desmosomal, cytoskeletal, and extracellular matrix molecules, were considered. Multivariate statistical analysis was performed on 154 expression ratios of integrin genes with clinical parameters. RESULTS: In principal-component analysis, the first principal component was related to the outcome of death, and the second principal component mainly reflected the tendency for cervical lymph node (LN) metastasis. The former axis consisted of the variance of the integrin beta4 gene (ITGB4) and ITGB5 expression levels, and the latter axis agreed with the expression level of the integrin alpha3 gene (ITGA3). Multivariate logistic regression analysis with cervical LN metastasis as the response variable concordantly identified ITGA3/junction plakoglobin gene (JUP) expression (P=.02) and ITGB5/paxillin gene (PXN) expression (P=.04) as significant factors. Only ITGB4/JUP expression was identified as a significant factor in terms of the outcome of death (P<.00049) by a Cox proportional hazards model. The group with high ITGB4/JUP levels exhibited a significantly high death rate on a Kaplan-Meier curve (P<.0001; Wilcoxon and log-rank tests). CONCLUSIONS: The expression levels of ITGA3, ITGB4, and ITGB5 with functional normalization by desmosomal or cytoskeletal molecule genes were selected as candidate biomarkers for cervical LN metastasis or for the outcome of death in TSCC.  相似文献   
62.
The effect of different concentrations of sodium fluoride (12, 24, 48 and 96 mM), instilled into the ligated intestine of anaesthetized rats for 30 min, on intestinal permeability and some brush border enzymes was investigated. A concentration-dependent change in permeability was observed; there was an increase in the volume of luminal fluid and altered net transport of Na+ and K K+ ions. The change in permeability was accompanied by increased protein, sialic acid and nucleic acid accumulation in the luminal fluid. A striking loss of brush border alkaline phosphatase (41%) sucrase (59%) and gamma-glutamyl transpeptidase (73%) activities was observed at 96 mM fluoride with a corresponding increase in the activity of these enzymes in luminal fluid, while 12 mM fluoride did not produce any significant effect. This loss was probably not due to an inhibition of the enzymes by fluoride since in vitro experiments did not produce any such effect over a range of NaF concentrations (0-32 mM) except on alkaline phosphatase activity at the 32 mM NaF concentration. The studies, therefore, suggest that the loss of brush-border enzyme activities observed in situ was most probably due to membrane damage caused by the high fluoride concentration.  相似文献   
63.
Two series of new 2,1-benzothiazine derivatives have been synthesized by condensation of 4-hydrazono-1-methyl-3,4-dihydro-1H-benzo[c][1,2]thiazine 2,2-dioxide (5) with 2-chloroquinoline-3-carbaldehydes and acetylthiophenes to acquire new heteroaryl ethylidenes 7(a–f) and 9(a–k) in excellent yields. After characterization by FTIR, 1H NMR, 13C NMR and elemental analyses, the newly synthesized analogues were investigated against monoamine oxidase enzymes (MAO A and MAO B). The titled compounds exhibited activity in the lower micromolar range among which 9e was the most potent compound against MAO A with IC50 of 1.04 ± 0.01 μM whereas 9h proved to be the most potent derivative against MAO B with an IC50 value of 1.03 ± 0.17 μM. Furthermore, in vitro results were further endorsed by molecular docking studies to determine the interaction between the potent compounds and the enzyme active site. These newly synthesized compounds represent promising hits for the development of safer and potent lead molecules for therapeutic use against depression and other neurological diseases.

Two series of new 2,1-benzothiazine-heteroaryl ethylidene derivatives 7(a–f) and 9(a–k) have been synthesized in excellent yields and tested against MAOs.  相似文献   
64.
Inhibition on uptake of D-glucose by isolated intestinal epithelial cells (IIEC) was observed when the fluoride concentration ranged between 0.25 and 5 mM. Active transport was almost completely inhibited at 5 mM. When CaCl2 was added to fluoride, the inhibitory effect on glucose uptake was abolished. Preincubation of IIEC with different concentrations of fluoride (2.5-5.0 mM) for different intervals of time (2-20 min) at different pH levels (6.2-7.8) and temperatures (0-37 degrees C) revealed that the conditions which led to higher uptake of fluoride by IIEC produced maximum inhibition. The degree of inhibition was not appreciably altered by a change in glucose concentrations. A concentration-dependent effect of fluoride on lactic acid and carbon dioxide production by IIEC was also observed.  相似文献   
65.
66.

Objectives

High-resolution microendoscopy (HRME) is an optical imaging modality that allows real time imaging of epithelial tissue and structural changes within. We hypothesize that HRME, using proflavine, a contrast agent that preferentially stains cell nuclei and allows detection of cellular morphologic changes, can distinguish sinonasal pathology from uninvolved mucosa, potentially enabling real-time surgical margin differentiation.

Study design

Ex vivo imaging of histopathologically confirmed samples of sinonasal pathology and uninvolved, normal sinus epithelium.

Setting

Single tertiary-level institution.

Subjects and methods

Five inverted papillomas, one oncocytic papilloma, two uninvolved sinus epithelia specimens, and three inflammatory polyps were imaged ex vivo with HRME after surface staining with proflavine. Following imaging, the specimens were submitted for hematoxylin and eosin staining to allow histopathological correlation.

Results

Results show that sinonasal pathology and normal sinus epithelia have distinct HRME imaging characteristics. Schneiderian papilloma specimens show increased nuclear-to-cytoplasmic ratio, nuclear crowding, and small internuclear separation, whereas normal sinus epithelia specimens show small, bright nuclei with dark cytoplasm and relatively large internuclear separation. Inflammatory polyps, however, have varying imaging characteristics, that resemble both Schneiderian papilloma and normal sinus epithelia.

Conclusions

This study demonstrates the feasibility of HRME imaging to discriminate sinonasal pathology from normal sinus epithelia. While the system performed well in the absence of inflammation, discrimination of inflamed tissue was inconsistent, creating a significant limitation for this application. Novel imaging systems such as HRME with alternative contrast agents may assist with real-time surgical margin differentiation, enabling complete surgical resection of inverted papilloma and reducing recurrence rates.  相似文献   
67.
68.
69.
70.
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