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   264篇
  免费   8篇
  国内免费   18篇
耳鼻咽喉   1篇
儿科学   3篇
妇产科学   8篇
基础医学   88篇
口腔科学   18篇
临床医学   6篇
内科学   25篇
皮肤病学   1篇
神经病学   19篇
特种医学   4篇
外科学   43篇
综合类   38篇
预防医学   4篇
眼科学   2篇
药学   21篇
中国医学   3篇
肿瘤学   6篇
  2023年   1篇
  2022年   6篇
  2021年   5篇
  2020年   8篇
  2019年   4篇
  2018年   7篇
  2017年   2篇
  2016年   11篇
  2015年   10篇
  2014年   39篇
  2013年   20篇
  2012年   24篇
  2011年   27篇
  2010年   17篇
  2009年   13篇
  2008年   14篇
  2007年   22篇
  2006年   15篇
  2005年   13篇
  2004年   3篇
  2003年   8篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1996年   3篇
  1995年   2篇
  1994年   1篇
  1993年   2篇
  1990年   1篇
  1989年   4篇
  1985年   1篇
排序方式: 共有290条查询结果,搜索用时 218 毫秒
31.
Glutamate toxicity was compared in substantia nigra (SN)/striatum (STR) and SN/cerebellum (CRB) co-cultures on both the entire neuronal population (neuron specific enolase (NSE) immunopositive cells) and dopaminergic neurons (tyrosine hydroxylase (TH) immunopositive cells). In SN/CRB co-cultures NSE- and TH-positive cells were more sensitive to glutamate-induced toxicity than in SN/STR co-cultures. Moreover, in SN/STR co-cultures as compared to SN/CRB and SN cultures, glutamate toxicity was prevented to a larger extent by TCP, a non-competitive NMDA antagonist. These results suggest that target cells induce a differential expression of the different glutamate receptor subtypes in mesencephalic dopaminergic cells. Alternatively, the presence of target cells may induce the selective development of a subpopulation of dopaminergic neurons expressing predominantly NMDA receptors.  相似文献   
32.
Intra-articular drug delivery systems (DDSs) are envisaged as interesting alternative to locally release nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen to reduce pain in patients with osteoarthritis. The present study examines the toxicity of (S)-ibuprofen on chondrocytes and synoviocytes isolated from sheep shoulder joint and cultured in monolayers during 72 h, and on joint explants (cartilage and capsule) cultured in mono- or in co-culture for 13 days. (S)-ibuprofen (5 μM up to 1 mM) did not reduce the cell viability and protein content when added on chondrocyte monolayers, while at 1 mM (S)-ibuprofen reduced (by 8%, p = 0.01) the synoviocytes viability compared to untreated cells. During co-culture of joint explants, (S)-ibuprofen at 50 μM significantly reduced by 35% the spontaneous release of glycosaminoglycans (GAGs) from cartilage (p = 0.0065) whereas in monoculture, (S)-ibuprofen was inactive on GAG metabolism. (S)-ibuprofen at 1 mM significantly reduced cell lysis (lactate dehydrogenase leakage) by 74% during monoculture of capsule explants (p = 0.0136) and by 35% during co-culture of explants (p = 0.0013). Our findings demonstrate that the active isomer of ibuprofen at micro- and millimolar levels was not toxic for chondrocytes and synoviocytes and may reduce at 1 mM the cell lysis during culture of joint explants. The limited toxicity of (S)-ibuprofen at low and high concentration in sheep joint shoulder makes this enantiomer a promising drug candidate for the loading of intra-articular DDS.  相似文献   
33.
《Nanotoxicology》2013,7(8):1060-1072
Abstract

Nanoparticle-induced genotoxicity can arise through different mechanisms, and generally, primary and secondary genotoxicity can be distinguished where the secondary is driven by an inflammatory response. It is, however, yet unclear how a secondary genotoxicity can be detected using in vitro methods. The aim of this study was to investigate inflammation and genotoxicity caused by agglomerated nickel (Ni) and nickel oxide (NiO) nanoparticles and, furthermore, to explore the possibility to test secondary (inflammation-driven) genotoxicity in vitro. As a benchmark particle to compare with, we used crystalline silica (quartz). A proteome profiler antibody array was used to screen for changes in release of 105 different cytokines and the results showed an increased secretion of various cytokines including vascular endothelial growth factor (VEGF) following exposure of macrophages (differentiated THP-1 cells). Both Ni and NiO caused DNA damage (comet assay) following exposure of human bronchial epithelial cells (HBEC) and interestingly conditioned media (CM) from exposed macrophages also resulted in DNA damage (2- and 3-fold increase for Ni and NiO, respectively). Similar results were also found when using a co-culture system of macrophages and epithelial cells. In conclusion, this study shows that it is possible to detect a secondary genotoxicity in lung epithelial cells by using in vitro methods based on conditioned media or co-cultures. Further investigation is needed in order to find out what factors that are causing this secondary genotoxicity and whether such effects are caused by numerous nanoparticles.  相似文献   
34.
Objective:To investigate the effect of co-culture with peritoneal macrophage to the fertility rate and blastocyst formation rate of the mouse's oocytes.Methods:A total of 15 KunMing mice aged 10-14 weeks were undergone ovulation induction and oocytes collection.The oocytes were randomly divided into three groups.The first group was the control group and cultured without macrophage;the second group(experimental group 1)was co-cultured with macrophages right after oocytes collection;the third group(experimental group 2)was cultured alone after oocytes retrieval,and co-cultured with macrophages from 8 cell stage.Results:1.The fertility rate in control group(91.0%)and experimental group 2(93.7%)was significantly higher than that in experimental group 1(72.0%,P<0.001).2.Blastocyst formation rate of the fertilized oocytes in the experimental group 2(78.2%)was much higher than control group(60.3%,P<0.001).3.Blastocyst formation rate of the oocytes in experimental group 2(73.2%)was much higher than control group(54.8%)and experimental group 1(50.0%),which were statistically significant.Conclusions:1.Co-culture with peritoneal macrophages had an adverse influence on the fertilization process.2.Peritoneal macrophages could enhance the mouse embryonic development and increase the blastocyst formation rate.  相似文献   
35.
36.
Despite the availability of toxicity studies on cellular exposure to gold nanoparticles (AuNPs), there is scarcity of information with regard to the bystander effects induced by AuNPs on neighboring cells not exposed to the NPs. In this study, we showed that exposure of small airway epithelial cells (SAECs) to AuNPs induced changes in protein expression associated with functional effects in neighboring MRC5 lung fibroblasts in a co-culture system. Uptake of 20 nm size AuNPs by SAECs was first verified by focused ion beam scanning electron microscopy. Subsequently, pretreated SAECs were co-cultured with unexposed MRC5 lung fibroblasts, which then underwent proteome profiling using a quantitative proteomic approach. Stable-isotope labeling by amino acids in cell culture (SILAC)–based mass spectrometry identified 109 proteins (which included 47 up-regulated and 62 down-regulated proteins) that were differentially expressed in the lung fibroblasts co-cultured with AuNP pretreated SAECs. There was altered expression of proteins such as Paxillin, breast cancer anti-estrogen resistance 1 and Caveolin-1, which are known to be involved in the cell adhesion process. Morphological studies revealed that there was a concomitant increase in cell adhesion and altered F-actin stress fiber arrangement involving vinculin in the lung fibroblasts. It is likely that phenotypic changes observed in the underlying lung fibroblasts were mediated by AuNP-induced downstream signals in the pretreated SAECs and cell–cell cross talk.  相似文献   
37.
Physiologically relevant in vitro models are needed to study disease progression and to develop and screen potential therapeutic interventions for disease. Heart valve disease, in particular, has no early intervention or non-invasive treatment because there is a lack of understanding the cellular mechanisms which lead to disease. Here, we establish a novel, customizable synthetic hydrogel platform that can be used to study cell–cell interactions and the factors which contribute to valve disease. Spatially localized cell adhesive ligands bound in the scaffold promote cell growth and organization of valve interstitial cells and valve endothelial cells in 3D co-culture. Both cell types maintained phenotypes, homeostatic functions, and produced zonally localized extracellular matrix. This model extends the capabilities of in vitro research by providing a platform to perform direct contact co-culture with cells in their physiologically relevant spatial arrangement.  相似文献   
38.
目的: 研究人脐带间充质干细胞(human umbilical cord mesenchymal stem cells, hUCMSCs)与经骨形态发生蛋白2(bone morphogenetic protein 2,BMP2)诱导后的人牙髓细胞(human dental pulp cells,hDPCs)共培养对细胞生物学特性的影响。方法: 分别取原代培养的hUCMSCs和hDPCs,分别通过流式细胞术、成骨诱导、成脂诱导以及免疫组织化学染色鉴定细胞;使用BMP2诱导hDPCs,14 d后检查其DSPP、ALP、DMP1的mRNA表达情况;按照1∶1、1∶5、5∶1的比例直接共培养hUCMSCs与经BMP2诱导后的hDPCs,实时定量PCR检测其DSPP、ALP、DMP1、OCN、VEGF、HGF、Nanog的mRNA表达情况。根据实时定量PCR结果选取1∶1组与单独培养hUCMSCs组、hDPCs组比较,分别培养21 d后进行茜素红染色,在酶标仪上于562 nm处检测沉淀物形成情况。采用SPSS21.0软件包对数据进行统计学分析。结果: 直接共培养14 d后,1∶1细胞组的DSPP、ALP、DMP1、OCN、VEGF、HGF的mRNA表达量比单独培养的hUCMSCs组显著升高(P<0.05),而Nanog mRNA表达量比单独培养的hUCMSCs组降低(P<0.05)。茜素红染色结果显示,1∶1组的OD值显著高于hUCMSCs组(P<0.05)。结论: 将hUCMSCs与经BMP2诱导后的hDPCs按照1∶1比例共培养,可以诱导细胞向成牙本质细胞方向分化,并促进血管生成因子的表达。  相似文献   
39.
目的 探讨体外联合HaCaT细胞共同培养诱导骨髓间充质干细胞(MSCs)向表皮细胞分化的可行性.方法 用聚碳酸酯细胞插入板分层后联合共同培养HaCaT细胞与MSCs,观察培养3、6、9d后的细胞形态,进行角蛋白(CK-19、CK-10)、整合素(α6、β1)染色并用流式细胞仪统计细胞阳性率.结果 共同培养后细胞形态变化明显,共培养3、6d后表皮细胞标志物CK-19、α6整合素、β1整合素免疫荧光染色阳性,细胞阳性率分别为9.3%、8.2%、11.5%和21.7%、34.1%、39.6%,CK10表达呈阴性;共培养9d后CK-19、α6整合素、β1整合素、表达较前减少,阳性率为12.2%、18.6%、16.3%,CK1O出现阳性表达,细胞阳性率为10.7%.结论 分层联合HaCaT细胞共同培养可以诱导骨髓干细胞向表皮细胞进行分化.  相似文献   
40.
目的:分离兔髓核脊索细胞(notochordal cells,NC)及骨髓间充质干细胞(mesenchymal stem cell,MSC),通过非接触共培养探讨NC对MSC细胞表型的影响。方法:4~6周龄新西兰兔8只,取胸腰段脊柱的髓核,用密度梯度离心提取NC,同时取其股骨骨髓用FICOLL液分离MSC,将NC和MSC等比例(1∶1)通过transwell培养板进行非接触共培养作为实验组,单纯MSC细胞培养作为对照组,光镜下观察细胞的生长情况。对两组的MSC行免疫组化及RT-PCR、Western-blot检测MSC细胞表型的改变情况。结果:原代NC呈圆形或椭圆形,细胞体积大,细胞增殖不明显;MSC贴壁生长,呈三角形或梭形,漩涡状排列。甲苯胺蓝染色:对照组MSC细胞核淡染,胞体染色不明显,染色阴性;实验组MSC可见从第3天开始胞体及胞外基质出现紫红色,第5天染色更加明显。Ⅱ型胶原免疫组化对照组MSC淡染,细胞形态不清楚;实验组第3天出现MSC内出现棕黄色深染,随着时间推移细胞染色加深呈阳性表现。RT-PCR检测,经过5d非接触共培养后实验组蛋白聚糖的基因表达为对照组的2.35倍(P<0.05),Ⅱ型胶原的基因表达为对照组的1.61倍(P<0.05),对照组Ⅰ型胶原的基因表达为实验组的2.56倍(P<0.05)。Western-blot检测后发现:经过5d非接触共培养,实验组蛋白聚糖的含量为对照组的1.61倍(P<0.05),Ⅱ型胶原的表达为对照组的10.04倍(P<0.05)(P<0.05)。结论:在非接触共培养条件下脊索细胞可以诱导骨髓间充质干细胞表型发生变化,向类软骨细胞方向分化,这将为组织工程化髓核的种子细胞筛选提供新选择。  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